wave induced advective transport below a rippled water sediment interface the exchange between the water column and the sediment bed and the transport inside the permeable sediment layer are important processes in the cycles of chemical elements in this paper we examine quantitatively the effects of modulations in the profile of the water sediment interface on this exchange and on the advective transport inside the sediment bed the flow field inside a sediment layer bounded between spatially periodic ripples on top and an impermeable bottom surface is modeled using darcy s law the forcing is due to progressive gravity waves in the water above the results of two different models for the pressure variation imposed on the upper boundary are compared the two pressure profiles are derived from potential flow theory and from a numerical solution to the navier stokes equations for the oscillatory flow over a rippled bed from an analytic solution to the two dimensional model the trajectories of pore water particles immediately below the ripple profile are found to be quite different from the simple elliptical pattern found below a flat bed the shapes of these trajectories can be quite complicated and vary considerably both along the length of the ripple and over the depth of the sediment layer close to its surface the total exchange across the water sediment interface averaged over one wave period is significantly higher across a rippled interface than across a flat bed this difference increases with increasing ripple slope and the strength of the wave motion and it decreases with increasing thickness of the sediment layer relative to the length of the gravity wave since rippled bed forms are commonly found in coastal waters the increase in the total exchange across a rippled water sediment boundary can enhance the exchange of solutes due to wave pumping immediately below the water sediment interface circulation cells with net advective transport over a wave period are found such net advection patterns can lead to spatial in the horizontal direction inhomogeneities of the vertical concentration or temperature profiles if the overlying water column and or the sediment bed act s as source or sink this gives a plausible physical mechanism to explain the spatial variations in vertical concentration profiles found in field measurements

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

seismic study of pull apart induced sedimentation and deformation in the northern gulf of aqaba elat abstract new multichannel seismic and bathymetric data are presented which clarify the plio quaternary evolution of the northern gulf of aqaba elat and the dead sea transform dst the seismic data reveal two main seismic sequences a lower pretectonic and an upper syntectonic unit separated by a prominent unconformity these units are each linked to a distinct tectonic phase in the history of the dst parallel horizons and an undisturbed internal structure point to a tectonic quite time or pure strike slip without extension or compression during the first pretectonic phase the second syntectonic phase which begins in the early pliocene is characterized by a major change in the activity of the dst the pretectonic sedimentary unit subsided and consequently dips southward with a supplementary inclination to the east the coeval sedimentation of the syntectonic unit is recorded by the divergent reflection pattern and onlap terminations on the unconformity the apparent fault system seems to be rearranged in the second phase the stepover of the main strand of the dst from the eastern side of the elat deep to the western side of the northern gulf of aqaba was mapped in detail for the first time the very smooth shape of the stepover and the apparent lack of extensional tectonics do not fit with the classical pull apart basin model for the elat deep and point to a decoupling of the crystalline basement from the sedimentary overburden comparisons of the new geophysical findings with analog models support this assertion

evaluating sand and clay models do rheological differences matter abstract dry sand and wet clay are the most frequently used materials for physical modeling of brittle deformation we present a series of experiments that shows when the two materials can be used interchangeably document the differences in deformation patterns and discuss how best to evaluate and apply results of physical models extension and shortening produce similar large scale deformation patterns in dry sand and wet clay models indicating that the two materials can be used interchangeably for analysis of gross deformation geometries there are subtle deformation features that are significantly different 1 fault propagation and fault linkage 2 fault width spacing and displacement 3 extent of deformation zone and 4 amount of folding vs faulting these differences are primarily due to the lower cohesion of sand and its larger grain size if these features are of interest the best practice would be to repeat the experiments with more than one material to ensure that rheological differences are not biasing results dry sand and wet clay produce very different results in inversion models almost all faults are reactivated in wet clay and few if any are significantly reactivated in sand models fault reactivation is attributed to high fluid pressure along the fault zone in the wet clay a situation that may be analogous to many rocks sand inversion models may be best applied to areas where most faults experience little to no reactivation while clay models best fit areas where most pre existing normal faults are reactivated

seismic and aseismic weakening effects in transtension field and microstructural observations on the mechanics and architecture of a large fault zone in se tibet

continental break up along strike slip fault zones observations from the equatorial atlantic the study focuses on equatorial atlantic margins and draws from seismic well gravimetric and magnetic data combined with thermo mechanical numerical modelling our data and numerical modelling indicates that early drift along strike slip originated margins is frequently characterized by up to 10 20 spreading vector adjustments in combination with the warm thinned crust of the continental margin these adjustments control localized transpression our observations indicate that early drift margin slopes are too steep to hold sedimentary cover which results in their inability to develop a moderately steep slope undergoing cycles of gravitational instability resulting in cyclic gravity gliding these slopes either never develop such conditions or gain them at later development stages our modelling suggests that the continental margin undergoing strike slip controlled break up experiences warming due to thinning along pull apart basin systems pull apart basins eventually develop sea floor spreading ridges margins bounded by strike slip faults located among pull apart basins with these ridges first undergo cooling however spreading ridges leaving the break up trace along its strike eventually pass by these cooling margins warming them again before the final cooling proceeds as a result the structural highs surrounded by several source rock kitchens witness a sequential expulsion onset in different kitchens along the trajectory of spreading ridges

numerical analyses of subsurface flow in a steep hillslope under rainfall the role of the spatial heterogeneity of the formation hydraulic properties 1 the paper aims at analyzing subsurface flow and streamflow generation in steep hillslopes after rainfall the principal scope of the work is to assess the role played by the spatial variability of the hydraulic properties on the subsurface flow patterns and hillslope discharge we try to address this task through a three dimensional numerical model which solves the richards equation under prescribed initial and boundary conditions along an established practice the relevant hydraulic parameters are modeled as random space functions with given statistical properties realistic features of the spatially variable formation parameters and the precipitation data are incorporated into the simulation model it is found that spatial heterogeneity has a significant impact on the movement of water in the hillslope and the streamflow generation in particular the heterogeneous systems are more sensitive to rain input and display an increase of both the water table and saturation which is faster than the homogeneous case the same is for water velocity which is everywhere larger when heterogeneity is considered as a consequence the dynamics of subsurface stormflow recognized as the leading mechanism for streamflow generation in the simulations and the outflow discharge produced by the hillslope after a rain event are enhanced by heterogeneity despite of the possible lack of generality of the numerical experiments they provide useful insight into the complex dynamics occurring in hillslope systems the simulations show the importance of including realistic spatial heterogeneity in hillslope hydrology studies

dynamic response of surface water groundwater exchange to currents tides and waves in a shallow estuary 1 in shallow fetch limited estuaries variations in current and wave energy promote heterogeneous surface water groundwater mixing benthic exchange which influences biogeochemical activity here we characterize heterogeneity in benthic exchange within the subtidal zone of the delaware inland bays by linking hydrodynamic circulation models with mathematical solutions for benthic exchange forced by current bedform interactions tides and waves benthic fluxes oscillate over tidal cycles as fluctuating water depths alter fluid interactions with the bed maximum current driven fluxes 1 10 cm d occur in channels with strong tidal currents maximum wave driven fluxes 1 10 cm d occur in downwind shoals during high energy storms simulated wave pumping rates increase by orders of magnitude demonstrating the importance of storms in solute transfer through the benthic layer under moderate wind conditions 5 m s integrated benthic exchange rates due to wave current and tidal pumping are each 1 10 m3 s on the order of fluid contributions from runoff and fresh groundwater discharge to the estuary benthic exchange is thus a significant and dynamic component of an estuary s fluid budget that may influence estuarine geochemistry and ecology

structural framework of the gulf of elat aqaba northern red sea the gulf of elat aqaba occupies the southern part of the dead sea rift the rift is considered to be a plate boundary of the transform type partially leaky which connects seafloor spreading in the red sea with the sagros taurus zone of continental collision the deep water in the gulf of elat up to 1850 m provides a rare opportunity to examine the process of continental rifting by marine geophysical techniques the bathymetry alone provides much information about fault patterns in this area the fragmentation of the once continuous arabian african platform is a complicated process it shapes the structure of the gulf which has developed through continuing tectonism primarily consisting of faulting recent geophysical and geological studies of the gulf of elat including bathymetry bottom photographs continuous seismic profiles seismic refraction gravity magnetics heat flow and coring provide new information about the shallow and deep crustal structure of this important segment of the world rift system the shallow structure of the gulf is dominated by three elongated en echelon basins which strike n20 25 e undulations in the floors of the basins produce several distinct deeps these basins are interpreted as pullaparts the new data from the gulf suggest that classical models for the formation of these structures should be modified only one of the longitudinal faults of each depression is a strike slip fault while the other is predominantly a normal fault the situation with the other two sides of the basin which are supposed to be composed of normal faults may also be more complex than previously thought at least in one case one such boundary is composed of a strike slip fault while the other has no significant fault crustal models of the gulf of elat based on gravity data indicate that the basins are rather shallow and do not extend into the lower crust the fill of the basins extends to about 5 km below the seafloor in the northern and southern basins and less in the central basin most significant magnetic anomalies in the gulf of elat extend from land into the sea none of them however extends from one coast to another across the gulf this supports the geological evidence for a shear between the arabia and sinai plates the magnetic field over the southern third of the gulf is rather smooth and markedly different from that of the other parts the nature of the magnetics the crustal structure of the western margin and the heat flow values indicate a thinner crust and different tectonic processes in the southern part of the gulf overall it seems that within the southern gulf of elat a transition occurs between crustal spreading that takes place in the red sea to a rifting without spreading that takes place along the dead sea transform spreading activity propagates from south to north the most active place is the central basin which is being propagated northward into the shallow northern basin

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

modelling the influence of pre existing brittle fabrics on the development and architecture pull apart basins abstract we use new analogue modelling experiments to analyse the development of pull apart basins in an upper crust characterised by the presence of pre existing discrete fabrics as in previous models lateral movement of rigid basal plates induced strike slip deformation of a sand pack local extension allowing the formation of a pull apart basin was produced by the step over geometry of the master faults in this area a basal silicone layer was introduced to distribute deformation and reproduced a weaker crust in the basin conditions of neutral overlapping and underlapping interacting master faults were reproduced the model upper crust modelled by a sand mixture was characterised by the presence of pre existing structures the orientation of these inherited heterogeneities was systematically varied in different experiments model results indicate that depending on their orientation with respect to the strike slip displacement pre existing structures can be reactivated both within and at the margins of the pull apart basins inside the basin reactivation occurs when the pre existing structures are orthogonal or sub orthogonal to the strike slip displacement in this case the pre existing fabrics delay the development and linkage of cross basin faults and increase the complexity of the deformation pattern giving rise to a new set of faults characterised by an atypical trend pre existing fabrics oblique to the local extension direction may be partly reactivated in the central part of the basin as segments of cross basin faults at the margins of the pull apart reactivation occurs if the fabrics spatially coincide with the lateral boundaries of the silicone layer in these conditions reactivation allows a faster development of the border faults which are less segmented than in the homogenous models this also results in a more regular final geometry of the pull apart

mesoscale strike slip faults and damage zones at marsalforn gozo island malta well exposed strike slip faults in limestones in the north western part of gozo show damage zones that can be grouped into three categories based on their location along faults tip damage linking damage and distributed damage the predominant fracture types within damage zones include extension fractures and secondary faults tip damage zones usually show wedge shaped patterns formed by antithetic faults and extension fractures commonly accompanied by block rotation several fractures are combined at linking damage zones typically with the concentration of a high intensity of fractures structures in distributed damage zones are typically similar to the classical riedel shear pattern evolutionary and 3d models are proposed in terms of the geometries of damage zones for small displacement strike slip fault zones different evolutionary routes depend on fault tip modes and locations

fresh and saline groundwater discharge to the ocean a regional perspective 1 studies of groundwater flow in coastal aquifers often focus strongly on freshwater and investigate flow in a narrow 5 km zone surrounding the coastline this work was designed to place coastal flow in a regional context and to compare fresh and saline submarine groundwater discharge sgd for regional flow systems numerical flow and transport models were developed to estimate sgd associated with topography driven flow seawater recirculation and geothermal convection in a passive margin setting simulations were based on two cross sections of north carolina and sensitivity studies were used to explore the impact of varying hydraulic and transport parameters results suggest that saline flow associated with seawater recirculation and geothermal convection should be considered in studies of sgd studies limited to shallow topography driven flow may be justified in using small study areas but flow systems contributing to sgd may span at least 20 km surrounding the coast and continental slope

a two dimensional analytical solution of groundwater response to tidal loading in an estuary a two dimensional transient groundwater flow equation for a confined nonleaky aquifer is solved analytically with an estuary tidal loading boundary condition the amplitude and phase of the tide varies with position and time respectively these variations called the damping coefficient for amplitude and separation constant for phase along the coastline are considered in the analysis the solution presented is more advanced than the traditional one dimensional analytical solution with a one dimensional tidal loading boundary condition the damping coefficient and separation constant in the application study are obtained from the harmonic analysis of the observed tidal level in apalachicola bay florida the analytical solution is compared to a two dimensional finite difference solution a numerical simulation illustrates the response of piezometric head to tidal loading the piezometric head and phase from both solutions match closely the analytical and numerical solutions show that a piezometric head along both sides of the estuary can be predicted given a tidal elevation at the entry of an estuary the fluctuation of piezometric head in response to tidal loading diminishes rapidly inland and diminishes slowly along the coastline of an estuary there are also obvious phase shifts associated with spatial variations as the wave propagates

salt tectonics in pull apart basins with application to the dead sea basin the dead sea basin displays a broad range of salt related structures that developed in a sinistral strike slip tectonic environment en echelon salt ridges large salt diapirs transverse oblique normal faults salt walls and rollovers laboratory experiments are used to investigate the mechanics of salt tectonics in pull apart systems the results show that in an elongated pull apart basin the basin fill although decoupled from the underlying basement by a salt layer remains frictionally coupled to the boundary the basin fill therefore undergoes a strike slip shear couple that simultaneously generates en echelon fold trains and oblique normal faults trending mutually perpendicular according to the orientation of basin boundaries sedimentary cover deformation can be dominantly contractional or extensional at the extremities of pull apart basins forming either folds and thrusts or normal faults respectively these guidelines applied to the analysis of the dead sea basin show that the various salt related structures form a coherent set in the frame of a sinistral strike slip shearing deformation of the sedimentary basin fill

normal faults and their hanging wall deformation an experimental study we have used clay models to study the effects of fault shape and displacement distribution on deformation patterns in the hanging wall of a master normal fault the experimental results show that fault shape influences the style of secondary faulting and folding mostly antithetic normal faults form above concave upward fault bends whereas mostly synthetic normal faults form above low angle fault segments and convex upward fault bends beds dip toward the master normal fault above concave upward fault bends and away from the master normal fault above low angle fault segments and convex upward fault bends generally secondary faulting and folding are youngest at fault bends and become progressively older past fault bends hanging wall deformation patterns differ significantly when a basal plastic sheet imposes a constant magnitude displacement distribution on the master normal fault in models without a plastic sheet numerous secondary normal faults form in the hanging wall of the master normal fault most secondary normal faults propagate upward and consequently have greater displacement at depth in models with a plastic sheet few visible secondary normal faults develop most of these faults propagate downward and consequently have less displacement at depth hanging wall folding is wider and bedding dips are gentler in models without a plastic sheet than in identical models with a plastic sheet the observed particle paths displacement distributions bedding dips and orientations of the principal strain axes in our physical models with and without a basal plastic sheet are compatible with the assumption that homogeneous inclined simple shear accommodates the hanging wall deformation not all of our modeling observations however are consistent with this assumption specifically the observed variability with depth of the distribution and intensity of deformation is incompatible with homogeneous inclined simple shear as the hanging wall deformation mechanism

robust evidence for random fractal scaling of groundwater levels in unconfined aquifers this study introduces new approaches to improve the statistical robustness of techniques for quantifying the fractal scaling of groundwater levels and uses these techniques to investigate scaling of groundwater levels from a consolidated permeable carbonate aquifer six groundwater level time series and an associated river stage time series from the unconfined chalk aquifer a dual porosity fractured limestone aquifer in the pang lambourn catchment uk have been analysed surrogate data of time series with known scaling properties have been used to estimate the probability distribution of the spectral and geometric scaling exponents determined by detrended fluctuation analysis dfa and power spectral density psd respectively robust regression techniques have been used to improve estimates of the scaling exponents and robust non parametric techniques have been used to correlate scaling exponents with features of the boreholes and catchments strong statistical support has been found for temporal scaling of groundwater levels over a wide range of time scales however bootstrap estimates of the scaling exponents indicate a much larger range of exponents than found by previous studies suggesting that the uncertainty in existing estimates of scaling exponents may be too small there is robust evidence that geometrical scaling properties at each borehole can be related to the depth of the observation boreholes and distance of those boreholes from the river in the catchment but no such correlations were found for the spectral scaling exponents the results build on the body of evidence that groundwater levels as with many hydrogeological phenomena may be well modelled with mathematical concepts from statistical mechanics that do not attempt to capture every detail of these highly heterogeneous and complex systems

structure and deformation history of the northern range of trinidad and adjacent areas conflicting models have been proposed for both the evolution of northern south america and the neotectonics of the south caribbean plate boundary zone the trinidadian portion of the margin is particularly controversial but surprisingly it has been little studied we present a structural analysis of trinidad s northern range pertinent updates of the island s stratigraphy and sedimentology and new zircon fission track age determinations and use them to constrain trinidad s geologic history and to better understand the controlling tectonic processes in our interpretation trinidad s three e ene striking ranges which are separated by late neogene recent depocenters expose 1 the northern range group generally greenschist metamorphosed upper jurassic to cretaceous north facing continental slope sediments of the northern range deposited on the northern south american passive margin 200 400 km to the wnw and 2 the trinidad group cretaceous paleogene shelf slope sediments of the central and southern trinidad deposited less than 100 km wnw of their present location a small allochthon composing the sans souci group cretaceous tholeiitic volcaniclastic basaltic and gabbroic rocks sans souci formation and sediments toco formation now in the northeastern northern range has been transported hundreds of kilometers from the west with the caribbean plate despite earlier references to cretaceous orogenesis all deformation in trinidad is of cenozoic age the first deformation in the northern range d1 formed north vergent nappes and induced greenschist metamorphism probably in the late eocene or oligocene the nappes developed either by the underthrusting of the proto caribbean crust beneath south america due to convergence between north and south america or as gravity slides caused by oversteepening induced by this convergence and or the passage of the caribbean plate s peripheral bulge and arrival of its foredeep northern range d2 deformation is south vergent and represents the incorporation of northern range metasediments into the caribbean accretionary prism the transition to d3 brittle transpressive right lateral strike slip faulting is interpreted to be due to the uplift and east southeastward transpressive emplacement of northern range caribbean prism rocks onto the south american stepped shelf this emplacement formed the miocene transpressive thrust belts and foreland basin in central and southern trinidad in the final phase of northern range deformation d4 e w normal faults and shear zones and conjugate nnw sse and ne sw normal faults developed and displacement on preexisting e w right lateral strike slip faults continued the 11 ma northern range zircon fission track ages suggest rapid uplift from the late miocene to recent late miocene subsidence of the tobago platform immediately to the north of the northern range and greater than 3 km of normal down to the north displacement indicated for the north coast fault zone separating the northern range and tobago platform leads us to postulate that the rapid uplift of the northern range was in response to the northward detachment of the tobago platform from above the northern range along the north dipping transtensional north coast fault zone this late miocene change in deformation style can be explained by a change from caribbean south american right lateral transpression to right lateral strike slip generally striking 080 this has generally induced a component of extension on pre existing faults striking at greater than 080 and a component of compression on faults striking at less than 080

analogue modelling of intraplate strike slip tectonics a review and new experimental results abstract intraplate strike slip zones commonly display intricate 3 d geometries with rapid changes in structural style along strike and with depth strike slip deformation typically results in complex vertical and horizontal sections that can be difficult to interpret coherently physical modelling of strike slip fault systems is a powerful and graphic tool to help in providing a unified picture of the evolution of strike slip zones with considerable spatial and temporal detail a large number of experimental studies have investigated different aspects of strike slip tectonics using materials such as dry sand wet clay or silicone the choice of analogue material and experimental design exerts a strong control on the structures that form in the model here we present a review of different experimental setups used to investigate intraplate strike slip tectonics from the classical riedel experiment to more sophisticated setups using brittle and viscous analogue materials we review our current understanding from models of distributed shear transtension transpression pull apart basins formed in releasing stepovers and popups formed in restraining stepovers in addition we present the results of two new experimental series that investigated 1 the effect of crustal weak zones on strike slip fault zone segmentation and 2 strike slip and transpressional reactivation of extensional basins

the anatomy of a pull apart basin seismic reflection observations of the dead sea basin the dead sea basin dsb located along the african arabian plate boundary constitutes a good example of a pull apart basin because of its large dimensions its structural simplicity and its active subsidence a coherent three dimensional picture of the dsb has been constructed on the basis of analysis of seismic stratigraphy together with the interpretation of previously published geological and geophysical data despite the large known vertical offsets across the basin deformation takes place mainly along the transverse and longitudinal faults and the intervening sediments are relatively undeformed and are hardly tilted comparison between e w seismic lines indicate that the basin has widened by the collapse and tilting of arcuate blocks from the western margin but that its original shape is a full graben the southern and central parts of the basin are divided into equidistant segments 20 30 km long by transverse faults activity along these faults commenced only during the pleistocene long after the dead sea strike slip fault system was formed and migrated northward with time a likely scenario for the development of the dsb is one in which the basin grows northward with time by a simultaneous propagation of the southern strand of the dead sea fault and a retardation of the northern strand

a bottom driven mechanism for distributed faulting in the gulf of california rift abstract observations of active faulting in the continent ocean transition of the northern gulf of california show multiple oblique slip faults distributed in a 200 70 km 2 area developed some time after a westward relocation of the plate boundary at 2 ma in contrast north and south of this broad pull apart structure major transform faults accommodate pacific north america plate motion here we propose that the mechanism for distributed brittle deformation results from the boundary conditions present in the northern gulf where basal shear is distributed between the cerro prieto strike slip fault southernmost fault of the san andreas fault system and the ballenas transform fault we hypothesize that in oblique extensional settings whether deformation is partitioned in a few dip slip and strike slip faults or in numerous oblique slip faults may depend on 1 bottom driven distributed extension and shear deformation of the lower crust or upper mantle and 2 the rift obliquity to test this idea we explore the effects of bottom driven shear on the deformation of a brittle elastic plastic layer with the help of pseudo three dimensional numerical models that include side forces strain localization results when the basal shear abruptly increases in a step function manner while oblique slip on numerous faults dominates when basal shear is distributed we further explore how the style of faulting varies with obliquity and demonstrate that the style of delocalized faulting observed in the northern gulf of california is reproduced in models with an obliquity of 0 7 and distributed basal shear boundary conditions consistent with the interpreted obliquity and boundary conditions of the study area

temporal scaling of hydraulic head and river base flow and its implication for groundwater recharge 1 spectral analyses were conducted for hourly hydraulic head h data observed over a 4 year period at seven monitoring wells in the walnut creek watershed iowa the log power spectral density of the hydraulic head fluctuations versus log frequency f at all seven wells is shown to have a distinct slope or fractal dimension d indicating temporal scaling in the time series of water level fluctuations the fractal dimension of the time series varies from well to well and the spectrum for the average h over all seven wells has a fractal dimension of 1 46 and hurst coefficient of 0 54 the log power spectral density of estimated base flow in the walnut creek and four other watersheds versus log f is shown to have two distinct slopes with a break in scaling at about 30 days it is shown that the groundwater recharge process in a basin can be estimated from a head spectrum based on existing theoretical results hydraulic head in an aquifer may fluctuate as a fractal in time in response to either a white noise or fractal recharge process depending on physical parameters i e transmissivity and specific yield of the aquifer the recharge process at the walnut creek watershed is shown to have a white noise spectrum based on the observed head spectrum

multifractal analysis and modeling of rainfall and river flows and scaling causal transfer functions river flows have been known to be scaling for over 40 years and scaling notions have developed rapidly since the 1980s using the framework of universal multifractals and time series of rainfall and river runoff for 30 french catchments basin sizes of 40 km 2 to 200 km 2 from 1 day to 30 years we quantify types and extent of the scaling regimes for both flow and rain series we observed a scale break at roughly 16 days which we associate with the synoptic maximum the time scale of structures of planetary spatial extent for the two scaling regimes in both series we estimate the universal multifractal parameters as well as the critical exponents associated with multifractal phase transitions using these exponents we perform causal multifractal time series simulations and show how a simple linear scaling transfer function can be used to relate the low frequency rainfall series to the corresponding river flow series the highfrequency regime requires nonlinear transforms

the dinevar transtensional pull apart basin nw zagros mountains iran a geological study and comparison to 2d finite element elastic models the dinevar transtensional pull apart basin is a nw se trending basin located in the northwest part of the zagros mountains sanandaj sirjan tectonic zone iran this basin was formed by oblique extension in a strike slip fault system which was controlled by the pre existing sahneh and the mianrahan faults in addition to a field study we constructed a 2d finite element elastic model based on the major fault segments according to the field study various geological structures are formed around the pre existing fault segments including pencil structures with 13 aspect ratio 19 tight to open asymmetric folds oblique normal faults synthetic and antithetic faults normal and reverse fault drags and negative and hybrid type flower structure fe model results show that around the fault step is a zone of displacement gradient that indicates extension transtension within the overlapping zone consequently subsidence is predicted over the releasing fault step the modelled stress distributions within the fault step and around the fault segment tips are asymmetric elastic modelling shows that the mean normal stress within the step is tensional which would impede plastic yield while the region outside the step is characterised by compressive mean normal stress the mean normal stress pattern is characterised by a regional minimum localised inside the extensional step transtension zone and two local maximum and minimum couples formed at the advancing and retreating sides respectively in the fault segment tips the results show that two main subsidence regions depocentres or sub basins form along and in the proximity of the fault segment tips the imposed relative motion is entirely accommodated by creep on the faults which causes plastic strain to accumulate outside the faults mostly localised within the fault step this localised strain between fault segments could initiate connecting faults or reactivate earlier faults generally at high angles relative to the master fault segments as suggested by the stress and strain patterns the rotation and magnitude variation in the stress and strain trajectories reflects heterogeneous deformation in general the dinevar transtensional pull apart basin is characterised by an elongate rhomboidal to trapezoidal shaped geometry the modelled stress distribution and strain localisations within the basin are in general agreement with the locations of fault segments within the dinevar transtensional pull apart basin

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

basin formation along the bocono moron el pilar fault system venezuela within the boundary zone between the caribbean south america plates which includes the bocono moron el pilar right lateral fault system that has been active since the late tertiary there are several sedimentary basins in the venezuelan andes and the caribbean mountains these were formed in zones of crustal depression where faults diverge and as pull apart basins in zones of en echelon stepovers or along releasing bends in the faults in addition there are pull apart basins along the avila and la victoria faultzones in the caribbean mountains which are associated with the plate boundary the basins are filled with alluvial lacustrine fluvial and marine sediments mainly of quaternary age on the basis of model studies dimensions of the basins and age of their sedimentary fill it is estimated that right lateral offset necessary to form them along the bocono moron el pilar fault system varies from 2 to 125 km along the avila and la victoria fault zones this right lateral offset is estimated to range from 2 to 30 km on this basis the maximum right lateral offset along the southern caribbean plate boundary that can be documented along the bocono moron el pilar fault system has not exceeded 100 125 km if there has been larger offset it has to be documented by other means or it has taken place along other fault zones within the system

formation of sequential basins along a strike slip fault geophysical observations from the dead sea basin abstract the dead sea basin is often cited as one of the classic examples for the evolution of pull apart basins along strike slip faults despite its significance the internal structure of the northern dead sea basin has never been addressed conclusively in order to produce the first comprehensive high resolution analysis of this area all available seismic data from the northern dead sea lake lower jordan valley land were combined results show that the northern dead sea basin is comprised of a system of tectonically controlled sub basins delimited by the converging western and eastern boundary faults of the dead sea fault valley these sub basins grow shallower and smaller to the north and are separated by structural saddles marking the location of active transverse faults the sedimentary fill within the sub basins was found to be relatively thicker than previously interpreted as a result of the findings of this study the classic model for the development of pull aparts based on the dead sea is revised the new comprehensive compilation of data produced here for the first time was used to improve upon existing conceptual models and may advance the understanding of similar basinal systems elsewhere

extinction of pull apart basins numerous pull apart basins are present along the haiyuan fault zone in northwestern china detailed geological mapping of these basins reveals an evolution of faulting and subsidence that leads toward extinction of some pull apart basins the most common cause of pull apart basin extinction appears to be the development of new strike slip faults along one of the basin margin normal faults or diagonally across the basin the strike slip faults may develop together with normal faults to form a complex zone within the basin the migration of boundary strike slip faults toward the basin center can also cause the extinction of pull apart basins the extinction of these pull apart basins suggests that there is probably a tendency for a strike slip fault zone to straighten itself and the examples show how this takes place

4d analogue modelling of transtensional pull apart basins abstract scaled sandbox models were used to investigate the 4d evolution of pull apart basins formed above underlapping releasing stepovers in both pure strike slip and transtensional basement fault systems serial sectioning and 3d volume reconstruction permitted analysis of the full 3d fault geometries results show that very different pull apart basins are developed in transtension compared to pure strike slip both types of models produced elongate sigmoidal to rhomboidal pull apart systems but the transtensional pull apart basins were significantly wider and uniquely developed a basin margin of en echelon oblique extensional faults dual opposing depocentres formed in the transtensional model whereas a single central depocentre formed in pure strike slip in transtension a distinct narrow graben system formed above the principal displacement zones pdzs cross basin fault systems that linked the offset pdzs formed earlier in the transtensional models sequential model runs to higher pdz displacements allowed the progressive evolution of the fault systems to be evaluated in cross section transtensional pull aparts initiated as asymmetric grabens bounded by planar oblique extensional faults with increasing displacement on the pdzs basin subsidence caused these faults to become concave upwards and lower in dip angle due to fault block collapse towards the interior of the basin in addition strain partitioning caused fault slip to become either predominantly extensional or strike slip the models compare closely with the geometries of natural pull apart basins including the southern dead sea fault system and the vienna basin austria

role of a ductile decollement in the development of pull apart basins experimental results and natural examples abstract traditional models describe pull apart basins as graben or half graben basins with normal or normal oblique slip master faults analogous to death valley california yet many pull aparts are characterized by asymmetric basins with strike slip master faults indicating that not all pull apart basins conform to the simple death valley models we present analogue modelling results that show developmental sequences and structural styles of pull aparts are dramatically different when overburden rides over a ductile horizon and that thickness of the ductile horizon exerts control on basin development in our models synthetic and antithetic strike slip faults control basin geometries while localized normal faulting and local oblique slip on strike slip faults accommodate basin subsidence faults evolve from initial strike slip to normal oblique and normal dip slip to form a system of either isolated sub basins in the case of thick ductile layers or coalescing sub basins in the case of thin ductile layers these results demonstrate distinct differences between non ductile and ductile decollement pull apart structures basin boundaries dominated by normal faults suggest a decollement within or at the base of a non ductile layer similar to death valley california basin bounding faults dominated by strike slip and oblique slip faults indicate basin formation over a ductile layer similar to the gulf of elat aqaba or gulf of paria venezuela and trinidad

structural interpretation of hydrocarbon traps sealed by basement normal block faults at stable flank of foredeep basins and at rift basins closures sealed by basement normal block faults are most commonly formed by a grid of faults with multiple orientations and by a favorable dip of the reservoir strata hydrocarbons are trapped updip by structural upturns along the edge of the downdropped blocks or at the upthrown or downthrown edge of blocks where block tilt is away from the sealing faults closure parallel with reservoir strike is provided by 1 updip junction of primary oblique or oblique and longitudinal block bounding faults 2 internal secondary faults that trend transverse or oblique to the block boundaries 3 positive bend of reservoir strata 4 plunge of block edge folds and or 5 stratigraphic terminations of the reservoir fault seal upward along the faults is most likely where a thick section of impervious strata above the reservoir is in contact with itself across the fault or where the fault does not extend upward into shallower permeable zones seal across the fault surface is most certain where impermeable rocks are laterally juxtaposed against the reservoir impervious material within the fault zone such as shaly smear gouge cataclastic gouge mineral deposits and asphalt or tar impregnations can be effective barriers where reservoir facies are juxtaposed across the fault the traps can form a major hydrocarbon play on the stable shelves of foredeep or foreland basins as demonstrated by the san joaquin valley and eastern venezuela basins the traps provide secondary prospects in rift basins uch as the viking graben and vienna basin

quaternary tectonic evolution of the northern gulf of elat aqaba along the dead sea transform the northern gulf of elat aqaba is located in the transition between the deep marine basins of the gulf and the shallow onland basins of the arava valley interpretation of 500 km of high resolution seismic reflection data collected across the northern shelf reveals the tectonic structure and evolution of this transition six nne trending faults and one e w trending transverse fault are mapped slip rates are calculated based on measured offsets and age determination based on a radiocarbon calibrated sedimentation rate and a quaternary age model the most active fault is the evrona fault that absorbs most of the left lateral slip within the basin with an average sinistral slip rate of 0 7 0 3 mm yr through the late pleistocene and 2 3 3 4 mm yr during the holocene two intrabasin faults east of the evrona fault that have been inactive for the last several tens of thousands of years were mapped and motion from these faults has likely transferred to the evrona fault the basin is flanked on the west by the elat fault and on the east by the aqaba fault both faults are marked by large bathymetric escarpments based on displaced seismic reflectors we calculate a holocene vertical slip rate of 1 0 0 2 and 0 4 0 1 mm yr for the elat and aqaba faults respectively the geometry slip rates and slip history of the northern gulf of elat aqaba faults show that during the late pleistocene several intrabasin faults became dominant across the basin but that during the holocene the evrona fault accommodates most of the strike slip

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

three dimensional structure and evolution of an asymmetric pull apart basin the structure of a 250 m long asymmetrical pull apart basin developed in carbonate rocks at the galilee heights israel is herein analyzed the reconstruction of the basin geometry is based on detailed mapping and lidar measurements of fault scarps the architecture of faults is then used as a boundary condition for calculating the stress pattern in the vicinity of the basin using a dislocation model the basin is found to be an asymmetrical v shaped structure bordered by two longitudinal oblique right lateral strike slip faults the strike of one of the faults is bent at the eastern edge of the basin generating a transverse boundary fault which joins the second boundary fault orthogonally the overall lateral displacement is smaller than the basin length and no transverse or diagonal fault is observed in the western end of the basin the deformation around the basin is mostly displayed by fractures yet folds and fault branches are observed near the tips of the boundary faults and near kink points of fault segments stress analysis obtained by the three dimensional model is in general agreement with the orientation of fractures and location of high deformation regions in and around the basin based on our observations we present a conceptual model which demonstrates the development of asymmetric basins in releasing bends and sheds light on the structures of similar large pull apart basins

the mechanism of post rift fault activities in baiyun sag pearl river mouth basin post rift fault activities were often observed in deepwater basins which have great contributions to oil and gas migration and accumulation the main causes for post rift fault activities include tectonic events mud or salt diapirs and gravitational collapse in the south china sea continental margin post rift fault activities are widely distributed especially in baiyun sag one of the largest deepwater sag with its main body located beneath present continental slope during the post rift stage large population of faults kept active for a long time from 32 ma t70 till 5 5 ma t10 seismic interpretation fault analysis and analogue modeling experiments indicate that the post rift fault activities in baiyun sag between 32 ma 170 and 13 8 ma t30 was mainly controlled by gravity pointing to the main baiyun sag which caused the faults extensive on the side facing main baiyun sag and the back side compressive around 32 ma t70 the breakup of the continental margin and the spreading of the south china sea shed a combined effect of weak compression toward baiyun sag the gravity during post rift stage might be caused by discrepant subsidence and sedimentation between strongly thinned sag center and wing areas this is supported by positive relationship between sedimentation rate and fault growth index after 13 8 ma t30 fault activity shows negative relationship with sedimentation rate compressive uplift and erosion in seismic profiles as well as negative tectonic subsiding rates suggest that the fault activity from 13 8 ma t30 to 5 5 ma t10 might be controlled by the subductive compression from the philippine plate in the east c 2014 published by elsevier ltd

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

from infiltration to recharge use of a parametric transfer function abstract the recharge of a water table aquifer involves transfer of the infiltration effective rainfall through the unsaturated zone in certain areas the depth at which the water table lies and the properties of the unsaturated zone can vary greatly and thus the determination as a function of time of the recharge actually arriving in the saturated aquifer can be rather difficult however we need to know this recharge in order to simulate the true behaviour of the aquifer in transient state in a regional digital model of the aquifer for the purpose of calibration or prediction the resolution of the exact flow equations in the unsaturated zone is possible but seems still to be far too complex for practical applications in this paper we first propose a methodology for the identification of the spatial variability of the infiltration transfer function using common climatic and piezometric data a parametrisation of these transfer functions using gamma distributions as basic functions is then suggested two practical examples make it possible to check the applicability of the procedure

analog modeling of normal faulting above middle east domes during regional extension we study the effects of planform dome shape on fault patterns developing with and without concurrent regional extension oriented oblique to the long axis of the dome the motivation was the need to understand fault and fracture patterns in two adjacent mature hydrocarbon fields in the middle east one an elliptical dome and one an irregularly shaped dome the largest faults have throws of approximately 30 m 98 ft which is close to the resolution limit of older two dimensional seismic reflection data the known fault trends are not parallel to the highest transmissivity direction but could form compartment boundaries fault and fracture patterns developed over the modeled domes provide insight into the populations of faults and fractures that are likely to exist in the reservoirs but have been undetected because they are at or below the resolution limit of reflection seismic data major domal structural elements crestal fault systems end splay systems and radial faults are observed in modeled domes rising both with and without concurrent regional extension experimental results indicate that fault and fracture patterns are influenced by the effects of dome shape regional extension and relative timing of uplift with respect to regional extension the expression of particular sets of faults and fractures associated with concurrent doming and regional extension depends on the interaction among regional extension outer arc extension over the dome and tangential extension around the dome margins our results also indicate that the two adjacent natural domes possibly experienced different kinematic histories from those previously interpreted

a frequency domain approach to groundwater recharge estimation in karst this paper presents an alternative method for determining the values of parameters of a groundwater recharge model the phreatic zone of a karst aquifer is considered as the linear and time invariant filter that transforms the input signal of groundwater recharge rates into the output signal of spring discharges similarities between transfer functions of total rainfall rates and transfer functions of groundwater recharge rates are the basis for developing the parametric periodogram depending on parameters of a groundwater recharge model the values of parameters are estimated by minimizing the differences between the parametric periodogram and a periodogram of spring discharges the approximate whittle log likelihood function is the criterion for determining the optimal values of the parameters by using this frequency domain approach groundwater balance calculations are avoided so the method can be applied on unexplored karst aquifers when groundwater balance cannot be achieved without extensive geologic and hydrogeologic investigations the results of the applications on two springs located in the dinaric karst area in croatia are discussed

continental break up mechanism lessons from intermediate and fast extension settings continental break up mechanisms vary systematically between slow and fast extension systems slow extension break up has been established from studies of the central atlantic european and adria margins this study focuses on the intermediate and fast cases from gabon and east india and draws from the interpretation of reflection seismic gravimetric and magnetic data interpretation indicates continental break up via continental mantle unroofing in all systems with modifications produced by magmatism in faster extension systems break up of the intermediate extension gabon system involves partial upper continental crustal decoupling from continental mantle whereas in the fast east coast india system decoupled and lower crustal regimes underwent upwarping in soggy zones in the footwalls of major normal faults usually upper crustal break up is affected by pre existing anisotropies which form systems of constraining rails for extending continental crust this modifies the local stress regimes they regain a regional character as the function of constraining rails vanishes during progressive unroofing of the upper mantle different regions attain different amounts of upper crustal stretching prior to the break up the break up location is then controlled by the upper crustal energy balance principle of wound linkage by which the minimum physical work is performed for linking upper crustal wounds leading to successful upper crustal break up

the structural evolution of dilational stepovers in regional transtensional zones we propose a theoretical model supported by a field study to describe the patterns of fault fracture meshes formed within dilational stepovers developed along faults accommodating regional scale wrench dominated transtension the geometry and kinematics of the faulting in the dilational stepovers is related to the angle of divergence and differs from the patterns traditionally predicted in dilation zones associated with boundary faults accommodating strike slip displacements where 0 for low values of oblique divergence 30 and low strain the fault fracture mesh comprises interlinked tensile fractures and shear extensional planes consistent with wrench dominated transtension at higher values of strain a switch occurs from wrench to extension dominated transtension leading to the reactivation and or disruption of the early formed structures these structural processes lead to the development of a geometrically complex and kinematically heterogeneous fault pattern which may affect and or perturb the development of a through going fault linking and facilitating the slip transfer between the two overlapping fault segments as a result dilational stepover zones will tend to form long lived sites of localized extension and subsidence in regional transtensional tectonic settings cyclic increases decreases of structural permeability will be related to slip on the major boundary faults that control the distribution of fluid flow paths and consequently the long and short term structural evolution of these sites our model also predicts complex and more realistic subsurface fluid migration pathways relevant to our current understanding of hydrothermal ore deposits and hydrocarbon migration and storage

calcite and quartz microstructural geothermometry of low grade metasedimentary rocks northern range trinidad abstract the northern range of trinidad is a mountainous exposure of deformed metasedimentary rocks with mesozoic depositional ages and tertiary metamorphic ages located in the caribbean south american plate boundary zone these rocks lack precise mineralogical indicators of metamorphic grade using temperature sensitive quartz and calcite microstructures and fission track data we identify describe quantify and map a nearly continuous spectrum of relatively low l50 c to relatively high 250 400 c deformation temperatures from east to west across the range average estimated rock exhumation rates also increase systematically along this trend the analysis illuminates a sharp east west trending major thermal discontinuity i e a fault along the southern boundary of the range kinematic analysis of faults and shear bands adjacent to this boundary and modeling indicate that the fault probably dips southward at 80 85 and accommodated normal dip slip at rates that decreased from west to east earlier experimental studies at high strain rates illustrated a strong strain rate dependency for quartz microstructural transitions our work indicates a possible strong temperature control for quartz microstructural transitions at natural strain rates

3d analogue modeling of the south china sea a discussion on breakup pattern the opening of the south china sea is one of the most important cenozoic events in se asia in order to investigate its tectonic evolution three analogue modeling experiments were compared the modeling results suggest that rifting pattern and orientation change of the rift zone were related to initial theological stratification affected by the ductile flow of silicone lower crust and honey asthenosphere the faults became flattened especially close to the breakup area we conjecture that the slope area may bear relatively hotter and thinner lithosphere than the shelf area from the beginning of rifting due to stretching and mantle upwelling associated with this regional extension which in turn lead to the change in initial rheological stratification and therefore the rifting pattern from shelf to slope in the experiments breakup developed first at isolated points which grew and coalesced to become a single spreading area the conjugate boundaries were either all concave or all convex where a rigid massif was located at the divergent boundary stretching history was different in this case the northern and southern areas thinned rapidly and developed into two deep troughs which may finally evolve into spreading centers the shape of the massif controls the orientation and boundary shape of the spreading area it is interpreted that crustal breakup was more viscous in style and the nw sub sea basin developed along the northern trough of the zhongsha xisha massif macclesfield bank c 2008 elsevier ltd all rights reserved

rainfall runoff relations for karstic springs multifractal analyses karstic watersheds appear as highly as non linear and non stationary systems the behaviour of karstic springs has been previously studied using non linear simulation methods volterra expansion and non stationary analyses methods based on wavelet transforms the main issue of karstic spring behaviour consists of the presence and the identification of characteristic time scales in order to highlight more precisely the scale properties of the rainfall runoff relations for karstic springs the multifractal analysis is introduced these methods are applied daily and half hourly rainfall rates and runoffs measured on a three french karstic springs located in the pyrenees mountains ariege france aliou baget and fontestorbes they are characterised by a variable development of the drainage systems we have at our disposal long and uninterrupted series of data over period of several years which constitute a high quality bank data multifractal analyses of both daily and half hourly rainfall rates and runoffs give evident a scale dependant behaviour effectively it highlights the presence of different multifractal processes at each sampling rate using a universal class of multifractal models based on cascade multiplicative processes the identified multifractal sub processes are characterised by the classical parameters and c1 all these results should lead to several improvements in karstic springflow simulation models

forearc basin formation in the tectonic wake of a collision driven coastwise migrating crustal block the example of the north andean block and the extensional gulf of guayaquil tumbes basin ecuador peru border area trench parallel extensional strain resulting from the northward drift of the north andean block has controlled the tectonic evolution of the gulf of guayaquil tumbes basin at least for the past 1 8 1 6 ma industrial multichannel seismic and well data document that e w to ene low angle detachment normal faults the posorja and jambeli detachment systems to the north and the tumbes detachment system to the south accommodated the main subsidence step along the shelf area during late pliocene quaternary times 1 8 1 6 ma to present two tectonic regimes showing different styles and ages controlled the evolution of the southern ecuador and northern peru continental margin and shelf the n s extensional regime along the shelf area is related to north andean block drift whereas the e w extensional regime along the continental margin results from tectonic erosion at depth strain rotation takes place along a major n s trending transfer system formed by the inner domito fault and the inner banco peru fault which bound the detachment systems to the west the strike slip component along this transfer system roughly located at the continental margin shelf break evolved as a response to slip along the detachment systems bounding the basin to the north and to the south the tumbes detachment system is the master fault controlling basin evolution through time and it may represent the shallower expression of a reactivated obduction megathrust it connects landward with the continental structures assumed to be part of the eastern frontier of the north andean block for the past 2 ma the total lengthening calculated along a complete n s transect of the gulf of guayaquil tumbes basin ranges between 13 5 and 20 km this lengthening is compatible with the documented drift of the north andean block for the same period of time the gulf of guayaquil tumbes basin is not a classical pull apart basin it exemplifies a particular type of pull apart basin basically controlled by 1 detachments extending downward across the brittle crust and 2 plate coupling along the subduction decollement which controls the inward segmentation of deformation

transpression displacement partitioning and exhumation in the eastern caribbean south american plate boundary zone the caribbean south american plate boundary zone in northeastern venezuela is a transpressive orogenic belt consisting from north to south of a nascent subduction zone south caribbean deformed belt a volcanic arc leeward antilles arc a hinterland with high pressure p low temperature t metamorphic rocks cordillera de la costa belt and a southern nonmetamorphic foreland fold and thrust belt serrania del interior the geometry style and orientation of mid cretaceous to tertiary synmetamorphic deformation structures d1 in the hinterland are compatible with formation in a right oblique subduction or collision zone in which displacement partitioning has occurred late oligocene to recent right oblique convergence resulted in the emplacement of the arc and hinterland on the passive south american margin and the formation of the foreland fold and thrust belt d2 the displacements between the caribbean and south american plates are partitioned as well both d1 and d2 deformations are diachronous they are older in the west and younger in the east and related to the eastward passage of the caribbean plate with respect to south america the ascent decompression and exhumation of the high p low t metamorphic rocks occurred in two stages the first in the cretaceous by arc parallel extension d1 and the second in neogene time by thrusting d2 and subsequent erosion

pull apart basin formation and development in narrow transform zones with application to the dead sea basin contrary to other examples like death valley california and the sea of marmara turkey the dead sea type pull apart basins form within a narrow transform corridor between strike slip faults that are less than 10 km apart much smaller than the crustal thickness of 35 km in this paper we investigate the role of fault zone width versus thickness and rheology on the mechanics of pull apart basins through a series of laboratory experiments results show that pull apart basins that develop above a small step over i e smaller than the thickness of the brittle layer are narrow and elongated parallel to the overall motion this is enhanced by increased decoupling along a basal ductile layer the experiment with the highest degree of mechanical decoupling shows a striking resemblance to the dead sea basin dsb comparison with modeling results suggests that the dsb s flat basin floor is bordered over its full length by strike slip faults that control the basin geometry and temporal and spatial basin migration this is in strong contrast to death valley type pull apart basins that are highly oblique to the transform direction with transverse normal faults dominating over longitudinal strike slip faults results imply that lithosphere rheology and the ratio of basin width to crustal thickness are controlling factors in the mechanics of pull apart basin formation within transform corridors like the dead sea fault

a first deep seismic survey in the sea of marmara deep basins and whole crust architecture and evolution abstract increased source strength streamer length and dense spatial coverage of seismic reflection profiles of the seismarmara leg 1 allow to image the deep structure of the marine north marmara trough nmt on the strike slip north anatolian fault naf west of the destructive izmit 1999 earthquake a reflective lower crust and the moho boundary are detected they appear upwarped on an e w profile from the southern central basin eastwards towards more internal parts of the deformed region thinning of the upper crust could use a detachment suggested from an imaged dipping intracrustal reflector that would allow upper crustal material to be dragged from beneath it and above the lower crust accounting for the extensional component but also southwest motion of the southern margin of the nmt sections across the eastern half of the nmt crossing the cinarcik and imrali basins reveal several faults that are active reaching into the basement and have varying strike and proportions of normal and strike slip displacement they might be viewed as petals of a large scale negative flower structure that spreads over a width of 30 km at surface and is rooted deeper in the lithosphere under the central basin a very thick sediment infill is revealed and its extensional bounding faults are active and imaged as much as 8 km apart down to 6 km depth we interpret them as two deep rooted faults encompassing a foundering basement block rather than being merely pulled apart from a jog in a strike slip above a decollement the deep basin lengthening would account for only a modest part of the proposed 60 km finite motion since 4 myr along the same direction oblique to the nmt that sidesteps the shear motion from its two ends thus differential motion occurred much beyond the deep basins like subsidence involving the nmt bounding faults and the intracrustal detachments the complex partitioned motion localized on active faults with diverse natures and orientations is suggested to represent the overburden deformation induced from horizontal plane simple shear occurring in depth at lithospheric scale and in front of the north anatolian fault when it propagated through the region

extensional fault arrays in strike slip and transtension abstract sedimentary basins developed under conditions of strike slip or transtension are subject to significant rotational strains yet faults developed in such regimes are commonly explained using simplified models that ignore rotation the heaves of extensional faults developed provide a means of quantifying this rotation for ideal strike slip simple shear the apparent stretch due to fault heaves can be related simply to shear strain at shear strains above 1 0 previously formed extensional faults begin to show inversion as reverse faults becoming fully inverted at 2 0 in transtensional basins the apparent stretch is related in addition to the initial orientation of the faults which may itself be related to the incremental strain in the stellarton basin of nova scotia canada fault heaves and orientations can be measured from subsurface mine plans measurements of these quantities indicate that strain was only mildly transtensional with a small the measurement of fault heaves potentially provides detailed information on strain wherever strike slip or transtensional basins have been explored in detail by seismic or other subsurface methods

a late pliocene to middle pleistocene pluvial lake in fish lake valley nevada and california the question of whether a pluvial lake existed in fish lake valley nevada and california has been debated for more than 100 yr new stratigraphic evidence indicates that a lake did exist in this valley at intervals during late pliocene to middle pleistocene time this lake may have drained northward or it may have been periodically contiguous with a pluvial lake to the north in columbus salt marsh proof of the existence of this lake informally named pluvial lake rennie is derived from three principal outcrops of shallow water deposits two outcrops of deep water deposits and several drilling logs the deposits contain beds of silicic tephra which provide age control on the basis of thickness grain size major oxide chemistry of glass shards and paleomagnetism three of the shallow water deposits including deltaic beach and siliceous hot spring sediments consist mainly of bishop ash derived from the 0 77 ma eruption of the long valley caldera a fourth shallow water deposit is associated with 1 ma glass mountain tephra beds the exposed deep water deposits consist of green claystone siltstone and fine grained sandstone containing tephra derived from the eruptions of the 2 1 ma tuff of taylor canyon and the 2 0 ma huckleberry ridge tuff the drilling logs record numerous thick beds of clay and sandy clay inferred to be deep water lacustrine deposits pluvial lake rennie fluctuated in size and depth beginning prior to 2 ma and continuing until sometime alter 0 77 ma at about 0 77 ma the lake had a highstand at an elevation of 1 460 m covered an area of 400 500 km2 and had a maximum depth of 250 m the lake level dropped just after the eruption of the bishop ash but the lake may have persisted at a lower level until 0 5 ma no large long lived lake existed in fish lake valley in late pleistocene time probably due to the increasing rain shadow effect caused by the relative uplift of the white mountains and sierra nevada in the pleistocene these results indicate that the late middle to late pleistocene history of pluvial lake rennie is similar to that of lake tecopa but is quite different from those of lake lahontan and searles lake

temporal scaling of groundwater discharge in dual and multicontinuum catchment models this paper presents a multicontinuum approach to model fractal temporal scaling of catchment response in hydrological systems the temporal scaling of discharge is quantified in frequency domain by the transfer function h x which is defined as the ratio between the spectra of catchment response and recharge time series the transfer function may scale with frequency x as h x x2b while the classical linear and dupuit models predict exponents of b52 and b51 observations indicate scalings with noninteger exponents b such behaviors have been described by multifractal models which however often lack a relation to the medium characteristics we revisit and extend the classical linear dupuit aquifer models and discuss their physical meanings in the light of the resulting aquifer dynamics on the basis of these classical models we derive a multicontinuum approach that provides physical recharge models which are able to explain fractal behaviors with exponents 1 2 b 2 furthermore this approach allows to link the fractal dynamics of the discharge process to the physical aquifer characteristics as reflected in the distribution of storage time scales we systematically analyze the catchment responses in the proposed multicontinuum models and identify and quantify the time scales which characterize the dynamics of the catchment response to recharge

transform margins development controls and petroleum systems an introduction this paper provides an overview of the existing knowledge of transform margins including their dynamic development kinematic development structural architecture and thermal regime together with the factors controlling these this systematic knowledge is used for describing predictive models of various petroleum system concept elements such as source rock seal rock and reservoir rock distribution expulsion timing trapping style and timing and migration patterns the paper then introduces individual contributions to this volume and their focus supplementary material location table and map of specific transform examples structural elements of the romanche transform margin and glossary of terms used in this article is available at https doi org 10 6084 m9 figshare c 3276407 gold open access this article is published under the terms of the cc by 3 0 license this volume shows dynamic linkage between new transform margin research and increasing transform margin exploration it offers a critical set of predictive tools via an understanding of the mechanisms involved in the development of play concept elements at transform margins and their controlling factors our introduction to this volume reviews the current knowledge of the transform margins focusing on their dynamic development kinematic development structural architecture thermal regimes and petroleum systems the last part of this paper introduces the contributions to this volume

lithospheric scale centrifuge models of pull apart basins abstract we present here the results of the first lithospheric scale centrifuge models of pull apart basins the experiments simulate relative displacement of two lithospheric blocks along two offset master faults with the presence of a weak zone in the offset area localising deformation during strike slip displacement reproducing the entire lithosphere asthenosphere system provides boundary conditions that are more realistic than the horizontal detachment in traditional 1 g experiments and thus provide a better approximation of the dynamic evolution of natural pull apart basins model results show that local extension in the pull apart basins is accommodated through development of oblique slip faulting at the basin margins and cross basin faults obliquely cutting the rift depression as observed in previous modelling studies our centrifuge experiments suggest that the angle of offset between the master fault segments is one of the most important parameters controlling the architecture of pull apart basins the basins are lozenge shaped in the case of underlapping master faults lazy z shaped in case of neutral offset and rhomboidal shaped for overlapping master faults model cross sections show significant along strike variations in basin morphology with transition from narrow v and u shaped grabens to a more symmetric boxlike geometry passing from the basin terminations to the basin centre a flip in the dominance of the sidewall faults from one end of the basin to the other is observed in all models these geometries are also typical of 1 g models and characterise several pull apart basins worldwide our models show that the complex faulting in the upper brittle layer corresponds at depth to strong thinning of the ductile layer in the weak zone a rise of the base of the lithosphere occurs beneath the basin and maximum lithospheric thinning roughly corresponds to the areas of maximum surface subsidence i e the basin depocentre

stochastic analysis of transport in hillslopes travel time distribution and source zone dispersion 1 a stochastic model is developed for the analysis of the traveltime distribution f in a hillslope the latter is described as made up from a surficial soil underlain by a less permeable subsoil or bedrock the heterogeneous hydraulic conductivity k is described as a stationary random space function and the model is based on the lagrangian representation of transport a first order approach in the log conductivity variance is adopted in order to get closed form solutions for the principal statistical moments of the traveltime our analysis indicates that the soil is mainly responsible for the early branch of f i e the rapid release of solute which preferentially moves through the upper soil the early branch of f is a power law with exponent variable between 1 and 0 5 the behavior is mainly determined by unsaturated transport the subsoil response is slower than that of the soil the subsoil is mainly responsible for the tail of f which in many cases resembles the classic linear reservoir model the resulting shape for f is similar to the gamma distribution analysis of the f moments indicates that the mean traveltime is weakly dependent on the hillslope size the traveltime variance is ruled by the distribution of distances of the injected solute from the river the effect is coined as source zone dispersion the spreading due to the k heterogeneity is less important and obscured by source zone dispersion the model is tested against the numerical simulation of fiori and russo 2008 with reasonably good agreement with no fitting procedure

kinematics of the gondwana basins of peninsular india abstract the gondwana successions 1 4 km thick of peninsular india accumulated in a number of discrete basins during permo triassic period the basins are typically bounded by faults that developed along precambrian lineaments during deposition as well as affected by intrabasinal faults indicating fault controlled synsedimentary subsidence the patterns of the intrabasinal faults and their relationships with the respective basin bounding faults represent both extensional and strike slip regimes field evidence suggests that preferential subsidence in locales of differently oriented discontinuities in the precambrian basement led to development of gondwana basins with varying but mutually compatible kinematics during a bulk motion grossly along the present day e w direction the kinematic disparity of the individual basins resulted due to different relative orientations of the basement discontinuities and is illustrated with the help of a simple sandbox model the regional e w motion was accommodated by strike slip motion on the transcontinental fault in the north

development of asymmetric basins along continental transform faults abstract many basins associated with wrench or transform faults are asymmetrical both longitudinally and laterally the sense of basin asymmetry changes along the strike of transform faults geophysical data from the dead sea rift and other transforms indicate that wrench induced asymmetric basins are bounded on only one side by a transform fault this implies that during the evolution of such basins maximum compression was parallel to the transform the direction of extension can change during the geologic evolution of a basin a possible explanation of this observation takes the strength of the fault into into consideration in the case of a weak fault in a strong crust the horizontal principal stresses would probably rotate to orientations parallel and perpendicular to the fault thus minimizing the shear stress on the main fault basins formed by regional extension such as in the east african rift system sometimes show similar features recent studies have shown that these basins often undergo oblique extension this suggests that the asymmetry in these basins may result from simultaneous strike slip motion and fault normal extension similar to the way asymmetry is produced in large transform basins periods of oblique extension can alternate with periods of orthogonal extension the asymmetry formed during periods of oblique extension is often preserved in the stratigraphic record

intracrustal detachment within zones of continental deformation geologic mapping of active to recently active geologic structures in panamint valley western united states and in the haiyuan region and northern tibetan plateau china suggests detachment in the middle and lower crust on a scale of tens of kilometres to at least several hundred kilometres detachment occurs similarly in predominantly extensional panamint valley and in predominantly compressional china environments it involves structures with displacements of more than 10 km and displacement rates of more than 3 mm yr perhaps more than 10 mm yr the steeply dipping strike slip faults present in all three areas hunter mountain fault haiyuan fault and altyn tagh fault zone terminate in zones of extension or compression and geometric relations indicate that all structures including strike slip faults are thin skinned and restricted to the upper crust in panamint valley and in the haiyuan region deformation within these systems can be reconstructed in three dimensions displacement on the strike slip faults is absorbed by extension or compression occurring at the termination of the faults so strike slip displacement is roughly equal to and in the same direction as shortening or extension we propose that left slip on the altyn tagh fault zone in northern tibet is similarly absorbed by shortening southeast of the fault zone within the qaidam basin and the nan shan

generalized analytical model for benthic water flux forced by surface gravity waves 1 a generalized analytical model for benthic water flux forced by linear surface gravity waves over a series of layered hydrogeologic units is developed by adapting a previous solution for a hydrogeologic unit with an infinite thickness case i to a unit with a finite thickness case ii and to a dual unit system case iii the model compares favorably with laboratory observations the amplitude of wave forced benthic water flux is shown to be directly proportional to the amplitude of the wave the permeability of the hydrogeologic unit and the wave number and inversely proportional to the kinematic viscosity of water a dimensionless amplitude parameter is introduced and shown to reach a maximum where the product of water depth and the wave number is 1 2 submarine groundwater discharge sgd is a benthic water discharge flux to a marine water body the case i model estimates an 11 5 cm d sgd forced by a wave with a 1 s period and 5 cm amplitude in water that is 0 5 m deep as this wave propagates into a region with a 0 3 m thick hydrogeologic unit with a no flow bottom boundary the case ii model estimates a 9 7 cm d wave forced sgd as this wave propagates into a region with a 0 2 m thick hydrogeologic unit over an infinitely thick more permeable unit the case iii quasi confined model estimates a 15 7 cm d wave forced sgd the quasi confined model has benthic constituent flux implications in coral reef karst and clastic regions waves may undermine tracer and seepage meter estimates of sgd at some locations

temporal and spatial scaling of hydraulic response to recharge in fractured aquifers insights from a frequency domain analysis quantification of the recharge in fractured aquifers is particularly challenging because of the multiscale heterogeneity and the range of temporal scales involved here we investigate the hydraulic response to recharge of a fractured aquifer using a frequency domain approach transfer functions are calculated in a range of temporal scales from 1 day up to a few years for a fractured crystalline rock aquifer located in ploemeur s brittany france using recharge and groundwater level fluctuations as input and output respectively the spatial variability of the response to recharge characteristic response time amplitude temporal scaling is analyzed for 10 wells sampling the different compartments of the aquifer some of the transfer functions follow the linear reservoir model behavior on the contrary others display a temporal scaling at high frequency that cannot be represented by classic models large scale hydraulic parameters estimated from the low frequency response are compared with those estimated from hydraulic tests at different scales the variability of transmissivity and storage coefficient tends to decrease with scale and the average estimates converge toward the highest values at large scale the small scale variability of diffusivities which implies the existence of a range of characteristic temporal scales associated with different pathways is suggested to be at the origin of the unconventional temporal scaling of the hydraulic response to recharge at high frequency

transform normal extension and asymmetric basins an alternative to pull apart models continental transforms are commonly associated with relatively small scale pull apart basins however much larger scale basins which are not consistent with the pull apart model commonly exist adjacent to transforms structures associated with several basins along the dead sea rift and el pilar fault illustrate this these basins are remarkably asymmetric bounded by essentially linear transform segments on one side and subparallel normal faults on the other suggesting simultaneous strike slip motion and transform normal extension this observation which is incompatible with classical faulting theory can be explained along divergent plate boundaries if the transform fault is much weaker than the adjacent crust analysis of the orientation of the horizontal principal stress direction near a weak transform fault embedded in an otherwise strong crust shows that convergent and divergent plate motion results in a stress field characterized by nearly fault normal compression and extension respectively structural styles along the san andreas dead sea and el pilar transform systems show that predictable changes between these two states have occurred through time along strike of the transforms

the coso geothermal field a nascent metamorphic core complex investigation of the coso range using seismicity gravity and geochemistry of rocks and fluids supports the interpretation that the structure hosting the geothermal resource is a nascent metamorphic core complex the structural setting is a releasing bend in a dextral strike slip system that extends from the indian wells valley northward into the owens valley this tectonic setting results in nw directed transtension which is accommodated by normal and strike slip faulting of the brittle upper 4 6 km of the crust and shearing and ductile stretching below this depth accompanied by shallow igneous intrusions focal mechanisms of some small earthquakes that have occurred from 1996 to the present beneath the coso range exhibit depth dependent rotation of seismic p and t axes indicating that the local orientations of the principal stresses likely favor resolved shear stress on low angle faults these small earthquakes occur near the base of seismicity which we interpret as coincident with the brittle ductile transition geochemical results show a significant asthenospheric influence in the isotopic composition of rocks and fluids indicating that the crust is thinned within the coso structure thinned upper crust is underlain by a more dense mafic body at depths of 10 km or less this is consistent with observed gravity anomalies and models the mafic body may represent cumulates left over from the fractional crystallization of rhyolite which occurs as endogenous domes at coso or it could be a sheeted dike complex in the upper mid crustal area transtension began at 2 3 ma and continues today using a long term crustal deformation rate of 2 mm yr we infer that the basal detachment fault commonly observed in fully exhumed metamorphic core complexes will reach the surface in two to four million years