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

the elat aqaba dead sea jordan subgraben system abstract the elat dead sea jordan rift zone is divided into distinct subgrabens these subgrabens are separated from one another by pivotal uplifted areas the subgrabens are usually asymmetric with the sense of asymmetry changing from west to east and vice versa along the length of the rift zone most faults are meridional n s trending or submeridional nne ssw trending transverse faulting is extremely rare thus opposing the key stone theory and also the fashionable rhomb chain model our levantine chain of subgrabens are but an infra pleistocene initial stage in the afro arabian rift system

the nature of the plate interface and driving force of interseismic deformation in the new zealand plate boundary zone revealed by the continuous gps velocity field 1 new zealand straddles the boundary between the australian and pacific plates cenozoic relative plate motion has resulted in a complex pattern of faulting and block rotation with displacements on individual faults up to hundreds of kilometers however over periods of several years gps measurements show a remarkably smooth pattern of velocities we show here using a new method of back slip analysis that almost the entire plate boundary continuous gps velocity field can be predicted within measurement error from a simple model of elastic distortion due to deep slip on a single plate interface megathrust in the hikurangi and putsegur subduction zones or fault through continental lithosphere beneath the southern alps at the relative plate motion rates this suggests that the main driving force of plate boundary deformation is slip on the deeper moving part of the plate interface without buried creep in localized shear zones beneath individual surface faults the depth at which this deep slip terminates locking point line determines the width of deformation along the hikurangi margin there is also clockwise rotation of 150 km long segment of the fore arc wairoa domain at 4 5 1 ma relative to the australian plate about a pole in western north island model residuals in the velocity field are mainly a result of incomplete averaging of the cycle of slow slip events on the plate interface downdip of the locking point

palynological evidence for the quaternary rates of accumulation along the dead sea rift and structural implications abstract continuous pollen diagrams obtained for five deep boreholes penetrating the thick quaternary sector of the dead sea rift fill have been correlated with the oceanic oxygen isotope records one of these was radiometrically dated by interfingering volcanics the quaternary sequence was subdivided into ten palynozones and the rates of accumulation are calculated for each in the three sub basins of the dead sea rift rates of accumulation in increments of 100 ky are calculated for two boreholes notera 3 in the north and amazyahu 1 in the south based on more detailed data obtained for these sequences the rates of accumulation indicate considerable subsidence of the southern dead sea at 2 3 1 8 m y during the last 250 ky the northern dead sea in the last 20 ky the central jordan valley at 2 2 2 0 m y and the hula at 1 5 1 25 m y and during the last 70 ky the regions separating these sub basins show very little accumulation and subsidence through the quaternary it is evident that the structural development of the dead sea rift sub basins is not synchronous

comparison of magsat and low level aeromagnetic data over the canadian shield implications for grm band limited magnetic anomalies over the canadian shield for wavelengths of 500 2200 km derived from the magnetometer satellite magsat data correlate peak for peak with the corresponding anomalies derived from the aeromagnetic data this suggests that the anomalies detected by magsat are physically meaningful a new potential field satellite geopotential research mission grm has been proposed to fly at about 160 km altitude the magnetic anomaly map that can be derived from the grm data is expected to have a resolution about an order of magnitude higher than the one derived from magsat data a magnetic anomaly map of the canadian shield which is expected to derive from the grm data is shown based on the aeromagnetic data the map delineates many major geological features quite clearly and illustrates the importance of the grm mission for global geological mapping

the dead sea rift from continental rift to incipient ocean abstract the dead sea rift is a 600 km long approximately 20 km wide geomorphological depression showing a topographic relief of 1 000 to 3 000 m from the axial depression to the mountainous margins in many places the rift is the northern extension of the red sea young oceanic spreading centre and it is built of a series of internal basins the rift is the product of vertical displacements that downfaulted its floor and uplifted its margins but some sinistral strike slip offset affected the rift as well the tectonic evolution of the rift started probably in the pliocene subsequent to the termination of the intensive tectonic activity in the suez rift the transition of the tectonic activity from suez rift to the dead sea rift is due to a probable clockwise jump of the northern extension of the red sea spreading centre the dead sea rift with its internal basins and faulted precipitous escarpments presents an exceptional example for the earliest stages of the evolution of continental break up and of nascent passive continental margins tectonic interpretations of the voluminous geological and geophysical data from the rift and its margins are complicated because the information is equivocal part of the data suggests that the rift is an extensional structure whereas another part indicates that the rift is a product of regional sinistral strike slip faulting however it is suggested that the equivocal data are not necessarily conflicting because the evolution of the rift is probably associated with oblique resultant displacement of combined normal and strike slip faulting the quantitative ratio between the extensional and the lateral offset processes in the dead sea rift is controversial there is ground to presume that large downfaulting of the rift floor and intensive erosion of its uplifted margins removed and obscured critical data that could have provided reliable correlation between the eastern and western flanks nevertheless reconstruction of mesozoic depositional fades zones across the rift apparently indicates that the lateral displacements are approximately 10 km and seismic reflection profiles suggest vertical offsets reaching 7 km the series of secondary internal basins in the rift that seem equivalent to the linear system of axial basins in the northern red sea support the concept that the dead sea is under a tectonic regime that is comparable to the one that affected the red sea in the miocene these findings and the 25 to 50 reduction of crustal thicknesses underneath the rift indicate an incipient oblique oceanic spreading centre

geophysical interpretation of the magnetic anomalies of china derived from magsat data the ambiguities about geophysical implications based on the correlation of scalar magnetic anomalies and geological features were investigated a method was developed to convert scalar magnetic anomalies into a map of the lateral variations of magnetic susceptibility of the lithosphere this map is directly correlated with the causative sources the method is based on spherical harmonic analysis of lateral variations seen on the scalar magnetic anomaly map and those of the lithospheric magnetic susceptibility the harmonic coefficients are related through the fundamental causality relationship governing a magnetized body and its associated scalar magnetic anomaly the main features of the resulting magnetic susceptibility anomalies are outlined

compatibility of high altitude aeromagnetic and satellite altitude magnetic anomalies over canada results from equivalent source distributions derived jointly from high altitude average 4 km aeromagnetic and magsat derived average 400 km magnetic anomalies over canada indicate that long wavelength components 500 2500 km in these fields are extremely compatible with one another with a correlation coefficient of 0 95 the jointly estimated anomaly field at the earth s surface can be used as a long wavelength adjustment surface for regional near surface magnetic anomaly compilations and in assessing the performance of other downward continuation techniques because near surface anomalies are not available over all regions of the world we compare the jointly estimated anomaly field to the results of two different downward continuation techniques the evaluation of anomalies at the earth s surface from spherical harmonic coefficients derived from satellite altitude data and the use of downward continuation methods based on harmonic splines numerical and visual comparisons of these downward conti

the motion of crustal blocks driven by flow of the lower lithosphere and implications for slip rates of continental strike slip faults geodetic measurements in actively deforming areas of the continents reveal the pattern of deformation in the lithosphere if the dominant forces acting on crustal blocks are tractions at their bases then the long term motion of each block will be given by the average velocity of the underlying lithosphere slip rates between blocks estimated in this way from recent geodetic measurements across fault zones in the south island of new zealand and southern california are in good agreement with slip rates estimated geologically

incipient spreading center in the gulf of elat northern red sea abstract the gulf of elat located at the northern red sea is a rift that forms the southern section of the dead sea rift system a recent high resolution seismic reflection survey showed that lenticular grabens and axial anticlines are the predominant structures at the rift floor structural relationships suggest that after the lenticular graben was formed at the rift floor it was filled with sediments axial uplift along the rift caused the widening of the graben and the development of axial anticlines and at a later stage a new graben started to develop between the flank of the anticline and the boundary fault of the rift the data indicate that the tectonic regime affecting the southern dead sea rift is one of uplift and extension acting simultaneously it is presumed that upwelling of magma in the upper mantle extending northwards from the red sea is the cause for these uplift and extensional phenomena and that the gulf of elat is an incipient spreading center

the canadian aeromagnetic database evolution and applications to the definition of major crustal boundaries abstract the aeromagnetic survey programme of the geological survey of canada much of which was carried out under federal provincial agreements has resulted in over 10 000 000 line kilometres of data flown at a mean elevation of 305 m and a mean line separation of 800 m except in mountainous terrain where constant barometric altitudes were maintained for given areas these data have been digitized if not originally digitally recorded and used to produce the 1 1 000 000 magnetic anomaly map series of the geological survey of canada and associated gridded data these grids were then combined with private data shipborne data from the east and west coasts and u s navy data from the high arctic to produce the first all digital version of the magnetic anomaly map of canada a study of the longer wavelength features on this anomaly map has resulted in greatly enhanced understanding of the major tectonic units and crustal boundaries within the canadian landmass important features can be delineated by data enhancement and processing techniques such as upward continuation to emphasize deep sources vertical gradients to sharply outline contacts e g the boundaries of the economically important greenstone belts in the canadian shield and shaded relief to highlight low amplitude short wavelength features an additional technique which provides interesting insights is curvature analysis which can be used to calculate the strike of an anomaly at each point when plotted with a particular colour assigned according to the strike direction the resulting patterns help to delineate trends over long distances

an assessment of long wavelength magnetic anomalies over canada the reliability of the long wavelength portion 300 km of the magnetic field over canada as represented by the national aeromagnetic anomaly database compiled by the geological survey of canada gsc is assessed by comparison with two independent data sets a high altitude country wide survey carried out by the former earth physics branch epb and data from the magsat and pogo satellite missions the different altitudes at which each data set was measured 300 m 4 km and 400 km and their different resolution and time span of observations allow a determination of the integrity of selected wavelength bands in each data set the upward continued epb and magsat pogo fields compare well for wavelengths of 300 2500 km the gsc data show significant differences to the former indicating that the levelling and merging of several hundred individual surveys has degraded the longer wavelength components of the magnetic field replacing the gsc wavelength components 300 km with those from the epb field

stromatolites in caves of the dead sea fault escarpment implications to latest pleistocene lake levels and tectonic subsidence abstract a varied assemblage of algal stromatolites was encountered in caves along the northern section of the dead sea fault escarpment the caves are situated at the lower part of the escarpment at altitudes 310 to 188 m relative to mean sea level m s l i e ca 110 230 m above the present dead sea level the cave stromatolites are mainly composed of aragonite yielding u th ages of 75 17 ka the altitude mineralogy and ages as well as comparison with previously documented stromatolite outcrops in the area ascribe the cave stromatolites to the aragonite precipitating hypersaline lake lisan the late pleistocene predecessor of the dead sea the stromatolites are used as a lake level gauge based on the algae being reliant upon the light of the upper water layer preservation of the original structure and aragonite mineralogy of the stromatolites suggests a closed system regarding the radioactive elements enabling reliable u th dating a curve of lake lisan levels is constructed based on the stromatolite ages and cave elevations the following points are noted 1 lake levels of 247 m relative to m s l are recorded at 75 72 5 ka 2 relatively high lake levels above 220 m relative to m s l are achieved at 41 5 ka and are still recorded at 17 ka 3 the peak level is 188 m relative to m s l at 35 5 29 5 ka these results indicate lake stands up to 80 m higher than previously accepted for large parts of the lake lisan time span this difference is explained by tectonic subsidence of up to 2 2 m ka within the dead sea depression since the latest pleistocene this subsidence rate is in the same order of magnitude with previously calculated subsidence rates for the dead sea depression begin z b zilberman e 1997 main stages and rate of the relief development in israel geological survey of israel report jerusalem unlike previous lake lisan level estimations the new curve is measured at the relatively stable shoulders of the dead sea depression

stress field and kinematics for diffuse microseismicity in a zone of continental transpression south island new zealand we analyze shallow 0 20 km microseismicity adjacent to the alpine fault in new zealand where there is oblique convergence of the australian and pacific plates focal mechanisms for 155 earthquakes june 2012 october 2013 are inverted to determine the orientation of the stress field this yields a principal horizontal axis of compression shmax 114 10 which cannot be explained in terms of the sum of stress from tectonic loading due to plate convergence indicated by gps observations and gravitational stresses the azimuth of slip vectors for individual focal mechanisms cluster perpendicular and parallel to the plate convergence vector these faults however strike at 45 to shmax from the stress inversion suggesting a very low coefficient of friction the earthquake slip directions may be kinematically controlled accommodating the plate convergence on a limited set of fractures similar to the segmentation for neotectonic faulting along the alpine fault which is partitioned into strike slip and thrust segments at a 1 10 km scale we suggest two possible controls on our calculated shmax azimuths firstly there may be a slight clockwise bias in the estimates of shmax from earthquakes slip may be occurring on a more limited range of fractures than assumed by the stress inversion method although this effect is likely to be relatively small 5 more importantly the components of the stress field may be relieved at different time scales during big earthquakes resulting in a residual stress field that varies significantly 15 on timescales of several large earthquakes

anatomy of the dead sea transform does it reflect continuous changes in plate motion a new gravity map of the southern half of the dead sea transform offers the first regional view of the anatomy of this plate boundary interpreted together with auxiliary seismic and well data the map reveals a string of subsurface basins of widely varying size shape and depth along the plate boundary and relatively short 25 55 km and discontinuous fault segments we argue that this structure is a result of continuous small changes in relative plate motion however several segments must have ruptured simultaneously to produce the inferred maximum magnitude of historical earthquakes

mechanical modeling and insar measurements of mount sedom uplift dead sea basin implications for effective viscosity of rock salt we present a mechanical model for the growth of an emerging salt diapir in a tectonically active basin the analytical model is applied to and serves to constrain the effective viscosity of rock salt and strain rates during diapirism of the wall shaped mount sedom rock salt diapir dead sea basin the model is based on one dimensional flow of newtonian viscous fluid salt in a vertical channel that has been driven by the load of the overburden and affected by shear along the channel walls because the poiseuille channel flow profile is parabolic and the couette shear flow profile is linear a one dimensional model provides three sets of predicted profiles topography uplift rate and shear strain the present topography of mount sedom represents the shape of the sedom diapir and hence the effective viscosity of rock salt can be constrained by a model that best fits the present topography of the mountain the resulting sedom rock salt viscosity is determined to be between 2 and 3 1018 pa s and the associated strain rate is between 5 and 6 10 13 s 1 geological structures indicate strain rates of 9 10 13 s 1 and 3 10 14 s 1 during the holocene emerging stage and at the plio pleistocene pre emergent stage of the sedom diapir respectively the uplift history of mount sedom predicted by the model and the current topography are compared to interferometric synthetic aperture radar insar measurements of salt uplift the maximum uplift rates of mount sedom are 8 3 and 5 5 mm yr for its northern and southern parts respectively the insar uplift profiles resemble topographic profiles obtained along the same traverses implying that the uplift history during the last 14 000 years is stable steep uplift gradients observed by insar along the western margin of the diapir are higher than predicted by modeling of newtonian viscous flow this could imply that flow of power law viscous fluid may be more suitable than that of newtonian viscous fluid for the sedom rock salt at high strain rates above 8 10 13 s 1

the structure and morphotectonics of the gesher benot ya aqov area northern dead sea rift israel abstract geological geomorphological and morphotectonic studies at the gesher benot ya aqov acheulean site northern jordan valley provide 1 a unique opportunity to establish the ecological background of hominid behavior during the early stages of widespread human occupation 2 crucial data for understanding the paleo environment and the various processes that affected the area near the gesher benot ya aqov site and 3 a basis for further comprehensive research in the region quaternary tectonic activity near the acheulean archeological site has produced a complex local setting that controls the surrounding landscape tectonic activity formed the benot ya aqov embayment which attracted hominids and a variety of other fauna sediments of the benot ya akov formation deposited in the embayment facilitated excellent preservation of the remnants of acheulean hominid activities and of abundant floral and faunal remains the formation was subsequently affected by faulting and folding local uplift ended the deposition of lacustrine sediments in the embayment of hula valley basin and caused erosion and vertical incision of the jordan river that resulted in the capture of the rosh pinna river and the exposure of the benot ya akov formation these deposits are found in different structural positions along the north south oriented morphotectonic embayment the outcrops contain numerous archeological sites giving the study area an unusually high potential for future hominid discoveries

the tectonics of the timna region in southern israel and the evolution of the dead sea rift abstract the timna region is located in the western margin of the southern arava valley at a junction between two regional orthogonal fault systems the dead sea rift and the temed fault the dead sea rift trends n s and extends from the northern red sea to southern anatolia and the temed fault trends e w from the gulf of suez to the arava valley structural analysis of the timna region showed the effects of two tectonic phases that were active there since the miocene the first tectonic phase formed the dextral strike slip temed fault and two systems of secondary faults trending nw se and ne sw the second tectonic phase downfaulted the rift floor and uplifted the rift shoulders simultaneously forming a regional n s trending joint system along the rift shoulder subsequent sinistral strike slip faulting along the rift caused a drag on the eastern part of the timna region and the resulting 2 5 km northward displacement reactivated pre existing faults and formed several rifts and uplifted blocks a correlation of the structural data of the timna region with recently acquired geophysical structural and stratigraphic findings from various places along the dead sea rift indicates that the first tectonic phase in timna is the erythrean phase this phase formed systems of e w trending faults in the negev and northern sinai as well as nw se trending faults in saudi arabia jordan israel and egypt this tectonic phase was active in the miocene and is associated with the first evolutionary phase of the red sea spreading center during this phase the spreading center extended northwards towards the suez rift the second tectonic phase in timna is the levantine phase that formed the dead sea rift and its uplifted shoulders this phase has been active since the pleistocene and is associated with the second tectonic phase of the red sea spreading the structural and geophysical data suggest that the dead sea rift is an incipient spreading center extending from the red sea whereas the suez rift was not reactivated during this phase the change of trend of the northern red sea spreading center from nw se to n s deformed the east shoulder of the southern dead sea rift so that a limited sinistral strike slip displacement occurred recent seismic activity indicates that the evolution of the dead sea rift is presently active

palynological evidence for the age and rate of sedimentation along the dead sea rift and structural implications abstract pollen diagrams obtained for eight deep boreholes penetrating the thick sequences of the dead sea rift fill correlated with dated marine sequences of the coastal plain in israel enable stratigraphie assignment of the continental deposits to be made the sedimentary units of the rift valley are of two main provenances those deposited in troughs within the rift limits of predominantly lacustrine environment attaining thicknesses in the order of 1 2 km for which the trough is the final erosion base level and those not limited to the rift boundaries but known from wide areas in israel mostly laid down in river systems that crossed the rift region on their way to the sea these fluviatile formations are in the order of hundreds of meters thick in the rift valley region which acted as an intermediate basin the first group of rock units of late miocene through early middle pliocene to glacial pleistocene ages indicate phases of considerable subsidence the earlier termed the erythrean and the later the levantine phase these are predated in the late oligocene through middle miocene by gentle subsidence and separated during the late pliocene preglacial pleistocene by another period of relative quietness in tectonic activity