geology of panamint valley saline valley pull apart system california palinspastic evidence for low angle geometry of a neogene range bounding fault geological studies support the interpretation that northern panamint valley and saline valley southeast california form paired pull apart basins on opposite sides of the right slip hunter mountain fault zone eight to ten km of late cenozoic net slip can be established on the hunter mountain fault zone palinspastic reconstruction of northern panamint valley indicates that the valley was formed by movement on a shallow crustal low angle normal fault of 0 15 degree west dip during the last 3 0 ma this interpretation appears to contradict the notions that little extension is accomodated in the uppermost crust by low angle faulting and that the most recent extension in the basin and range province is accomodated exclusively by high angle faulting saline valley however is interpreted to have formed by extension on closely spaced rotated planar normal faults thus within one geometric system of paired pull apart basins extension appears to have been accommodated in the shallow crust in two different ways

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

experiments on simultaneous faulting and folding above a basement wrench fault abstract wrench zones commonly show en echelon patterns of folds in the stratified cover above a basement fault examples are the darien basin in panama and the inglewood fault trend in california folds are often associated with synthetic and antithetic wrench faults but the time relationships between folds and faults may not be obvious we have done experiments where simultaneous faulting and folding occur above a basement fault four experiments were performed using a simple apparatus capable of imposing localised strike slip motions this apparatus consists of two plastic plates one can be moved laterally past the other by a piston thus modelling lateral motion on a single basement fault models were properly scaled to account for gravitational forces brittle behaviour of sandstone and ductile behaviour of clay or shales in the upper crust each model is a vertical succession of silicone layers and sand layers each layer is 2 mm thick except for the basal silicone layer which is 2 4 6 or 8 mm thick in experiments 1 2 3 or 4 respectively all models were deformed at the same slip rate on the basal fault 1 cm h 1 experiments 1 2 and 3 with 8 cm total horizontal sinistral offset were designed to investigate the influence of basal silicone layer thickness on the deformation of a multilayered model experiment 4 with 20 cm of total offset was designed to investigate the influence of an increasing left lateral offset on folding and faulting with a 2 mm thick basal silicone layer experiment 1 synthetic strike slip faults appeared en echelon above the basement fault no folds were visible at the surface of the experiment but the interfaces between sand and silicone layers showed millimetric folds en echelon above the basement fault with a 4 mm thick basal silicone layer experiment 2 en echelon synthetic strike slip faults and folds appeared above the basement fault faults and folds rotated progressively anticlockwise and synclines were activated as dextral antithetic shear zones with a 6 mm thick basal silicone layer experiment 3 synthetic faults and en echelon folds appeared as before but the fold amplitude was larger than in experiment 2 an increasing left lateral offset produced anticlockwise rotation of faults and folds as before and synclines were activated as dextral antithetic shear zones in experiment 4 after 16 cm of left lateral offset the anticlockwise rotation of the folds was such that antithetic dextral shear zones became almost parallel to the basement fault and were then reactivated as synthetic sinistral shear zones

relay ramp forms and normal fault linkages canyonlands national park utah fieldwork within a series of mesoscale grabens in southeast utah has revealed a particularly well exposed system of interlinked extensional faults a series of down faulted grabens are developed within a 460 m thick brittle layer of upper paleozoic sandstone and shale which overlies a ductile layer with a high gypsum content all the major grabens consist of two or more overlapping elements which are composed of fault segments these segments may be hard linked fault surfaces are joined or soft linked fault surfaces are isolated but linked by ductile strain of the rock volume between them in map view relay structures are defined as zones connecting the footwalls and hanging walls of overlapping fault segments representing soft linkage of fault segments in the canyonlands grabens the transfer of displacement between soft linked fault segments is characterized by well de fined dipping relay ramps commonly rotated and extended to accommodate the ductile strain between the overlapping fault segments relay ramps develop as ephemeral structures eventually becoming breached by hard linkage of the fault segments breakdown of ramps by breaching is part of the process of fault growth by segment linkage within the canyonlands graben system four orders of segmentation are present this may be a consequence of different scales of mechanical heterogeneity but evidence from the canyonlands grabens and elsewhere points to a fundamental process of discontinuous fault growth by segment linkage

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

kinematic analysis of faults in a physical model of growth faulting above a viscous salt analogue abstract syn sedimentary faults overlying an extended ductile layer within a sand model provide an analogue for studying some aspects of the geometry and kinematics of basin scale extensional listric faults associated with salt rollers the displacement analysis techniques used to examine displacement variations over fault surfaces within the sand model show that displacement varies in a regular and predictable manner deviations from simple fault displacement patterns are due to transfers of displacement onto adjacent synthetic faults aggregation of the displacements on adjacent synthetic faults produces more regular patterns of displacement distribution and demonstrates the geometric coherence of the aggregated faults rapid upward decreases in displacement on the model faults are due to fault growth during sedimentation elsewhere in the model post sedimentary faulting is associated with very low upward displacement gradients and pre and syn faulting sedimentation are readily distinguished on cross sectional fault traces in three dimensions a non horizontal line separating the pre faulting and syn faulting sequences tracks the lateral extent of a fault through time backstripping of fault displacements by subtracting the fault displacement of a sedimentary horizon from the displacements of underlying horizons gives the displacement distribution on a fault surface at the time of deposition of the backstripped horizon backstripped fault displacement distributions also allow examination of the general fault structure through time backstripping of fault displacements on one of the larger faults within the model and on an associated hanging wall synthetic splay shows that the two structures originated as a relay zone which was breached by lateral propagation of one of the overlapping faults which form the relay zone the backstripping technique allows determination of the geometrical changes during growth of a fault system

characterization of a gold tailings with hypersaline pore fluid a series of samples obtained from adjacent to piezocone penetration test cptu locations within a gold tailings storage facility with hypersaline pore fluid was tested to compare the inferred stat

experiments on shortening of a 4 layer model of the continental lithosphere davy ph and cobbold p r 1991 experiments on shortening of a 4layer model of the continental lithosphere in p r cobbold editor experimental and numerical modelling of continental deformation tecronophysics 188 l 25 we present an experimental method for modelhng lithospheric deformation the method is based on a simplified profile of lithosphere rheology where only four layers are considered brittle crust ductile crust brittle mantle and ductile mantle the strengths of the four layers calculated from laboratory determined flow laws depend strongly on geothenns and slightly on strain rates and deformation regimes the rheological profiles of the lithosphere have been recreated in experimental models built with analog materials sand silicone putty and golden syrup which flow under their own weight during lithospheric shortening the style of deformation depends on the relative strengths of the four layers especially those in the mantle of special importance is the existence or non existence of a brittle mantle the initial stages of compression often produce flexures or buckles without local isostatic compensation buckling exerts a strong control on the localisation of thrust faults in later stages the thrusts tend to form at the inflexion points of buckles the style of crustal thickening depends on the relative thicknesses and resistances of the lithospheric layers in 2 layer lithospheric models without resistant mantle shortening was concentrated upon a small number of thrusts widely spaced in 3 layer models shortening was concentrated into a large number of reverse faults more closely spaced and more steeply dipping than before in clayer models a single thrust formed in the brittle mantle motion on this thrust dragged the crustal layers down forming an asymmetric crustal root with steep imbricate slices

development of pull apart basins a comparative study of well mapped active and ancient pull apart basins suggests a qualitative model for their continuous development pull aparts evolve from incipient to extremely developed basins through a sequence of closely related states new and compiled map data from several areas including the northern caribbean and turkey suggests the following stages in pull apart development 1 in rigid intracontinental strike slip plate boundary zones larger pull aparts nucleate at releasing fault bends along segments of the principal displacement strike slip fault zone which are oblique to the theoretical interplate slip lines 2 initial opening across releasing fault bends produces spindle shaped basins defined and often bisected by oblique slip faults connecting the discontinuous ends of the strike slip faults 3 increased strike slip offset produces basin shapes which we colloquially call lazy s shape for basins between sinistral faults and lazy z shape for basins between dextral faults 4

three dimensional model of the late cenozoic history of the death valley region southeastern california the accumulation of a large database on the timing and kinematics of late cenozoic deformation in the death valley region of southeastern california indicates a complex three dimensional history on the basis of paleogeographic reconstructions we suggest the system was initiated as a localized pull apart between two conjugate strike slip faults the garlock and furnace creek faults and evolved into a system characterized by distributed transtension related to the eastern california shear zone our reconstructions differ from previous models in the incorporation of significant vertical axis rotations of a number of crustal blocks to explain paleomagnetic data from the region the model may resolve 1 a long standing problem of the eastern termination of the garlock fault which is explained here as a complex system of splays that initially terminated in the pull apart between the furnace creek and garlock systems and 2 the complex architecture of the black mountains which is explained here in terms of initial extreme attenuation between the garlock and furnace creek systems with overprinting by a fold and normal fault system that operated simultaneously as a result of distributed transtension this model suggests much of the displacement field is taken up in rotations and translations and the actual crustal thinning in our model is relatively small 50 66 of original thickness

how normal faulting and sedimentation interact to produce listric fault profiles and stratigraphic wedges abstract in a series of scale experiments we generated listric normal faults by extending models composed of colored sand layers deposited at regular time intervals throughout deformation during syntectonic sedimentation progressive bulk extension along a single set of faults caused domino type tilting of fault blocks underlying tilted faults propagated upwards with constant dips into newly sedimented layers hence fault profiles become progressively more listric tilting of the free surface resulted in asymmetrical depressions and in fan shaped deposits stepwise or continuous geometric models of domino tilting and synchronous sedimentation yield the same structural and stratigraphic features as observed in the sand models the continuous geometric model shows that a critical parameter governing fault curvature is the ratio r between rates of bulk strain and sedimentation both types of models reveal that synchronous sedimentation and bulk extension are capable by themselves of generating listric normal faults

vertical motion structure in maritime continent mesoscale convective systems results from a 50 mhz profiler abstract wind profiler data wore used to determine the vertical motion structure in four tropical mcsoscale convective systems mcss which occurred during the down under doppler and electricity experiment dundee near darwin northern territory australia three of the mcss occurred during the monsoon break convective regime and one occurred during the monsoon regime in the break regime cases each with a leading convective and trailing stratiform region structure the wind profiler sampled low level convective cells on the leading edge of the convective region trailed by deeper updrafts of comparable magnitude surface rainfall measurements from a network of raingauges showed two comparable peaks in rainfall intensity that roughly corresponded to the passage of low level and deep convective updraft 71 80 of the system total rainfall was associated with the passage of the convective line in the stratiform region the profiler data showed generally weak vertical drafts 1 m s 1 and the presenc

origin of rollover rollover is the folding of hanging wall fault blocks by bending or collapse in response to slip on nonplanar commonly listric normal faults the shapes of rollover folds are controlled by a number of variables including 1 the shape of the fault 2 the total fault slip after a bed is deposited 3 the direction of relative particle motion in hanging wall collapse 4 the history of sedimentation rate relative to fault slip rate and 5 compaction the importance and role of each of these variables is illustrated by a two dimensional balanced structural modeling technique that treats continuously curved faults as though composed of a large number of straight fault segments in this modeling an active axial surface oriented parallel to the direction of relative p rticle motion in hanging wall collapse emanates from each fault bend and is the instantaneous locus of folding the quantitative correctness of this theory of rollover is tested by modeling natural structures from the gulf of mexico for which both fault shape and fold shape are known from high quality seismic and well sections the direction of hanging wall collapse commonly is in the antithetic or synthetic normal fault or coulomb shear orientations although sliding along weak bedding planes also is an important collapse mechanism in some regions collapse is in the antithetic shear direction for concave fault bends and in the synthetic shear direction for convex bends these collapse directions can be observed directly in some high quality seismic images as axial surfaces emanating from fault bends the shapes of rollovers within growth strata depend strongly on the sedimentation rate relative to fault slip rate as well as the total slip after a bed is deposited the crests of classic gulf coast rollovers are growth axial surfaces along which are abrupt changes in sedimentation rate within the growth st atigraphic interval these changes are produced by deformation of the sediment water interface along active axial surfaces compaction can substantially modify the relationship between fault shape and rollover shape however under certain common conditions the history of compaction can be neglected if the folding is modeled in the compacted state

analogue models of pull apart basins sandbox analogue models of pull apart basins that developed in sedimentary strata above releasing steps in underlying basement faults are characterized by rhombic basins that are flat bottomed box grabens with a subhorizontal synkinematic basin infill steep to nearly vertical sigmoidal oblique slip and segmented oblique extensional faults are the dominant bounding structures of the pull apart basins cross basin short cut faults link the offset principal displacement zones that are characterized by flower structure development the structural architectures of the physical models compare directly in form and dimensions to natural examples of strike slip pull apart basins

extensional tectonics in the death valley area california transport of the panamint range structural block 80 km northwestward in the hypothesis presented here the panamint range is a structural block that was detached during late cenozoic time from underlying rocks that now form the black mountains and was transported tectonically an estimated 80 km to the northwest transport occurred along a single low angle westward dipping detachment fault or perhaps along a system of such faults the estimate of 80 km of transport distance is based on the apparent right lateral offset of late precambrian and paleozoic facies and thickness trends along the furnace creek fault zone that bounds the detached block on the northeast the death valley turtleback surfaces are considered to be gigantic mullions related to the detachment surface

physical analog modeling of pull apart basin evolution abstract pull apart basins are structural depressions formed by localized extension along strike slip fault systems typically at releasing bends or steps in the fundamental strike slip system analog modeling is used to evaluate the sequence of structural evolution of pull apart basins and factors that control their degree of structural asymmetry and geometry basin evolution internal structure and overall symmetry are investigated for oblique releasing step angles and with varying rates of displacement between brittle and ductile crust on opposing sides of the strike slip system while maintaining relative rates between brittle crust on opposing sides of the basin pull apart basin evolution is separated into three stages incipient early and mature incipient pull apart basins are characterized by formation of a normal fault bounded graben or half graben parallel to the oblique step between main strike slip zones in the early stage of formation additional normal faults form toward the basin interior from the original bounding faults and cross basin strike slip faults cut diagonally across the basin interior basin bounding normal fault systems are characterized by lateral variations of fault throw and localized relay ramps in the mature stage of evolution strike slip and normal faults join to completely bound the pull apart basin analog model results indicate that displacement associated with cross basin faults causes development of a through going strike slip fault that links the two main strike slip displacement zones ultimately resulting in a decline in normal fault activity asymmetric symmetric and hybrid pull apart basins all follow the same overall deformation sequence just described the asymmetry of a pull apart basin is controlled by the degree of decoupling between brittle and ductile crust beneath the two crustal blocks in relative motion this is modeled by maintaining a constant relative rate of motion between opposing fault blocks in all models but varying the rate between the blocks and the fixed model basement absolute rate models in which one side of the detachment is fixed with respect to the basement form asymmetric pull apart basins defined by a half graben with the master fault on the mobile side in models where opposing sides of the fault system are equally decoupled from the basement symmetrical pull apart basins form defined by horst and graben structures and master fault dominance switching sides along the length of the basin fault segmentation associated with relatively immature pull apart basins may be capable of arresting earthquake rupture late linkage of main strike slip zones by a cross basin fault could extend potential rupture area dramatically increasing the possibility for large magnitude earthquakes

experimental fracture strain and subsidence patterns over en echelon strike slip faults implications for the structural evolution of pull apart basins abstract claybox experiments show that with progressive left lateral displacement on basal left stepping en echelon strike slip faults an extremely complicated zone of evolving fracture strain and subsidence patterns develops in the overlying clay the fracture pattern is more complex than predicted by theoretical models and consists of a progressively widening array of riedel shears conjugate riedel shears and tension gashes above basal master faults conjugate riedel shears rotate anticlockwise and lengthen forming s shaped fractures riedel shears rotate both anticlockwise and clockwise those that rotate anticlockwise eventually open as tension gashes other tension gashes open where the ends of riedel and conjugate riedel shears link strain contours in the deformed clay show an asymmetrical z shaped pattern over the stepover area between basal en echelon faults in the early stages of displacement strain is distributed penetratively over a progressively broadening zone in later stages of displacement strain is partitioned into a narrow middle zone maximum strain is sustained always in the middle of the sheared zone and increases exponentially with progressive displacement subsidence is accommodated in the stepover area by oblique slip on many riedel and conjugate riedel shears distributed throughout the stepover area subsidence y exhibits a linear relationship with master fault displacement x described by y 0 36 x 1 4 the experimental fracture strain and subsidence patterns in clay over en echelon faults can be used as interpretive and predictive tools with which to constrain interpretations of static field examples especially in pull apart basins on the crustal scale where many similarities with the models exist

topological constraints on imbricate thrust networks examples from the mountain city window tennessee u s a abstract the geometry of thrust belts is best described in three dimensions as a network of linear geometric elements trailing branch lines where two thrusts diverge leading branch lines where two thrusts converge tip lines where thrust displacement vanishes and cutoff lines where a stratigraphic horizon intersects a thrust plane there are a number of topological constraints in three dimensions on the interrelationship of these linear elements these constraints provide a method of deciphering the three dimensional structure of an area from the geologic map pattern alone if topography or structural culminations and depressions create significant structural relief the mountain city window tennessee is an example of an imbricate thrust network which reveals its topology on the map pattern because of the presence of culminations the analysis of linear elements in this area allows the regional structural geometry to be described and also two kinematically distinct types of imbricate thrust systems to be characterized namely hinterland and foreland dipping duplexes the doe ridges culmination is a hinterland dipping duplex characterized by leading branch lines in a common roof thrust with the branch lines arranged in the same order hinterland to foreland as in the undeformed state the limestone cove culmination is a foreland dipping duplex characterized by trailing branch lines in a common roof thrust with the branch lines reversed in order hinterland dipping duplexes are the common and well known type foreland dipping duplexes are formed by successive trailing branch lines moving up off the lower flat horizon onto the ramp at which the imbricate slices are formed

correlation between cyclic resistance and shear wave velocity for providence silts as an alternative to a field based liquefaction resistance approach cyclic triaxial tests with bender elements were used to develop a new correlation between cyclic resistance ratio crr and overburden stress corrected shear wave velocity vs1 for two nonplastic silts obtained from providence rhode island samples of natural nonplastic silt were recovered by block sampling and from geotechnical borings split spoon sampling the data show that the correlation is independent of the soils stress history as well as the method used to prepare the silt for cyclic testing the laboratory results indicate that using the existing field based crr vs1 correlations will significantly overestimate the cyclic resistance of the providence silts the strong dependency of the crr vs1 curves on soil type also suggests the necessity of developing silt specific liquefaction resistance curves from laboratory cyclic tests performed on reconstituted samples

structure of the central death valley pull apart basin and vicinity from cocorp profiles in the southern great basin cocorp deep seismic reflection profiles in the vicinity of the central death valley pull apart basin in southeastern california provide three dimensional information on the subsurface of an active extensional terrane variations in the orientation and density of reflectors indicate that the crust and upper mantle of the region is divisible into three seismic zones which may represent regions of differing lithology rheology or both the reflections in the upper 5 s 15 km of the data have gentle to moderate dips between 5 and 10 s reflections are predominantly subhorizontal and below 10 s 30 km there are no notable reflections the boundaries between the above reflecting zones are marked by prominent reflecting horizons which are continuous throughout the survey region the observed reflection geometries resemble those predicted by the crustal model of the region proposed by wright and troxel 1973 on the basis of geological studies in addition many of the upper crustal reflectors can be traced directly to mapped features based on those correlations the upper reflecting zone 0 5 s is interpreted to be a region of brittle deformation with the various upper crustal reflectors interpreted as faults and basin sediments the reflecting horizon at the base of the upper zone appears to be the lower boundary of the faulted upper crustal blocks and it has been suggested that it locally includes partially molten rock the observed geometries and amplitudes of reflections from the lower crust 15 30 km depth or 5 10 s two way traveltime are consistent with the model of wright and troxel for a ductilely deformed and intruded lower crust the prominent reflecting horizon at the base of that zone is designated the reflection moho and the seismically transparent lowest zone appears to correspond to the upper mantle the seismic data define a zone of faults referred to here as the wingate wash fault zone which appears to form the southern boundary of the central death valley basin and also may have provided a conduit for the migration of magma from a mid crustal magma body to the surface the wingate wash fault zone appears to intersect the southern death valley fault zone and the frontal faults of the black mountains in the subsurface beneath the youngest volcanic edifice in the region those three fault zones appear to separate the panamint owlshead and black mountain upper crustal fault blocks from the available data a reconstruction of the possible fault block movements during the time of basin subsidence is presented that reconstruction suggests that the central death valley basin formed as a result of the combined down to the east rotation and northwest translation of the fault blocks in manner similar to that proposed by reches for other parts of the basin and range

the geometry of listric normal faults and deformation in their hangingwalls abstract in cross sections containing listric extensional faults area balancing techniques for depth to decollement are usually based on either bed length conservation or displacement conservation listric fault geometry may be constructed from a hangingwall roll over profile using the chevron construction this construction based on conservation of heave necessitates a reduction in fault displacement with decreasing fault dip a modification of this construction utilizing conservation of fault displacement predicts a listric fault that detaches at a shallower depth a new construction based on slip lines uses fault perpendicular displacement segments to generate listric fault shape fault propagation strain may be responsible for anomalous hangingwall geometries and these can be predicted by forward modelling using either a modified chevron construction or a slip line construction

measurements of friction coefficients and cohesion for faulting and fault reactivation in laboratory models using sand and sand mixtures abstract simple laboratory tests have been made on dry quartz sand and on mixtures of sand and clay and sand and cement tests were made on both low and high density specimens of each mixture as determined by physical handling techniques the tests included measurements of density estimates of the coefficient of internal friction based on fault orientation and estimates of the friction coefficients and cohesion values for fault initiation and reactivation in a shear frame apparatus which was also used to test artificial fault zones made from pure clay glass microspheres and wheat flour the results suggest that density is determined more by handling technique than by composition and that friction coefficients and perhaps cohesion both increase with increasing density the shear testing revealed a consistent drop in cohesion for fault reactivation in all densely packed mixtures tested although small this drop may be significant for some types of laboratory models

kinematics of the eastern california shear zone evidence for slip transfer from owens and saline valley fault zones to fish lake valley fault zone late quaternary slip rates and satellite based geodetic data for the western great basin constrain regional fault slip distribution and evolution the geologic slip rate on the fish lake valley fault zone the northwest extension of the furnace creek fault zone increases northward from about 3 to 5 mm yr in agreement with modeled geodetic data the increase coincides with the intersections of the deep springs fault connected to the owens valley fault zone and of other faults connected to the saline valley fault the combined geologic and geodetic data suggest that 1 the northwest striking faults of the eastern california shear zone north of the garlock fault are connected by north to northeast striking normal faults that transfer slip in a series of right steps and 2 the amount and distribution of slip among the many faults of this broad complex plate boundary have changed through time

black mountains crustal section death valley extended terrain california recent reconstructions of cenozoic extension in the southern great basin juxtapose the panamint range above the black mountains and indicate major tectonic denudation of the black mountains during tertiary extension structural and geologic characteristics of the black mountains and consideration of the regional geology of surrounding ranges suggest that the black mountains block may represent a 10 to 30 km preextensional crustal section that has been uplifted along a major detachment zone geobarometry and ductile deformation features in a synrift intermediate to mafic batholith and metamorphism of eocambrian sedimentary rock on the western side of the range appear to support this hypothesis these data suggest that the black mountains block is one of the youngest and perhaps among the deepest exposed examples of cordilleran metamorphic core complexes

experiments on strike slip faulting and block rotation analogue model experiments investigating strike slip faulting in zones of distributed shear deformation show that fault orientations and fault evolution indicate modifications of the stress field with increasing bulk shear strain dextral bulk shear deformation at low strain is accommodated dominantly by synthetic strike slip faults riedel shears at higher strain secondary antithetic and synthetic faults develop mostly between earlier formed major riedel shears closely spaced parallel antithetic faults cross faults delimit domains that rotate about vertical axes with continuing shear deformation rotation of fault bounded domains results in sigmoidal antithetic faults that have a dip slip component and a dip direction that changes along strike there is good agreement between models and natural examples of distributed shear zones where block rotations about vertical axes have been documented