experimental study on the critical triggering condition of soil failure in subsidence sinkholes subsidence sinkholes in karst terrain are a common geological hazard which can lead to natural disasters in the natural and built environment groundwater ingress is the main factor leading to subsidence previous research has focused on the qualitative analysis of the influence of groundwater although limited research into critical triggering conditions of groundwater has been undertaken quantitatively water seepage into soil is the starting condition in the development of subsidence sinkholes this paper focuses on testing the anti permeability strength as the critical triggering condition in the formation of subsidence sinkholes and develops a design and methodology to test its value quantitatively the methodology is applied in an industrial park of guilin china to assess the probability of forming subsidence sinkholes results indicate that there is a low susceptibility to the formation of subsidence sinkholes under current conditions in the ground truth investigation

biochronology and paleoclimatic implications of middle eocene to oligocene planktic foraminiferal faunas abstract planktic foraminiferal assemblages have been analyzed quantitatively in six dsdp sites in the atlantic site 363 pacific sites 292 77b 277 and indian ocean sites 219 253 in order to determine the nature of the faunal turnover during middle eocene to oligocene time biostratigraphic ranges of taxa and abundance distributions of dominant species are presented and illustrate striking similarities in faunal assemblages of low latitude regions in the atlantic pacific and indian oceans a high resolution biochronology based on dominant faunal characteristics and 55 datum events permits correlation between all three oceans with a high degree of precision population studies provide a view of the global impact of the paleoclimatic and paleoceanographic changes occurring during middle eocene to oligocene time planktic foraminiferal assemblage changes indicate a general cooling trend between middle eocene to oligocene time consistent with previously published oxygen isotope data major faunal changes indicating cooling episodes occur however at discrete intervals in the middle eocene 44 43 ma p13 the middle late eocene boundary 41 40 ma p14 p15 the late eocene 39 38 ma p15 p16 the eocene oligocene boundary 37 36 ma p18 and the late oligocene 31 29 ma p20 p21 with the exception of the e 0 boundary faunal changes occur abruptly during short stratigraphic intervals and are characterized by major species extinctions and first appearances the eocene oligocene boundary cooling is marked primarily by increasing abundances of cool water species this suggests that the e 0 boundary cooling which marks a major event in the oxygen isotope record affected planktic faunas less than during other cooling episodes planktic foraminiferal faunas indicate that the e 0 boundary event is part of a continued cooling trend which began during the middle eocene two hiatus intervals are recognized in low and high latitude sections at the middle late eocene boundary and in the late eocene p15 p16 these hiatuses suggest that vigorous bottom water circulation began developing in the middle eocene consistent with the onset of the faunal cooling trend and well before the development of the psychrosphere at the e 0 boundary

nature of the red sea crust a controversy revisited whether the red sea floor is underlain mostly by oceanic or extended continental crustal material is a controversial topic to test between the two hypotheses we used a digital color mosaic of 23 landsat thematic mapper tm scenes with field geochemical and geochronological data to identify and correlate crosscutting geologic features on the african and arabian sides faults shear zones sutures granitic complexes volcano sedimentary units and dike swarms align if arabia is rotated relative to africa by 6 7 around a pole at lat 34 6 n long 18 1 e this solution implies that the amount of continental crust underlying the red sea is small because the restored red sea coasts are typically juxtaposed

crustal structure variations and transcurrent faulting at the eastern and western margins of the eastern mediterranean abstract crustal structure variations within the crust of the eastern mediterranean as well as within the continental crust of the land areas east and west of the basin have caused segmentation of the collision zones which extend from sicily through the calabrian arc the hellenic arc and the cyprian arc to the taurus chain on both sides of the eastern mediterranean in southeastern sicily and in the levant similar tectonic features have developed hinge faults exist along both continental margins due to the different modes of collision between the land areas and the adjacent oceanic areas landward of the margins two large transcurrent fault systems the scicli fault zone and the dead sea rift have developed due to the existence of unique crustal units within the continental crust adjacent to the margins on both sides these units are more buoyant than the adjacent crust and resist underthrusting the initial faulting along both transcurrent fault systems probably started at the collision zone in the north and propagated to the south where large extensional areas the pantelleria rift and the red sea exist

seismic evidence for neogene and active shortening offshore of lebanon shalimar cruise 1 lebanon located on a 160 km long transpressional bend of the left lateral levant dead sea fault system lfs has been the site of infrequent but large earthquakes including one submarine tsunamigenic event the main objective of the shalimar marine survey was to characterize and map active deformation offshore of lebanon using a range of geophysical techniques particularly seismic reflection profiling the cruise results clearly establish the presence of young submarine thrust faults and folds and clarify the structure of this part of the levant margin a submarine fold belt bounded by thrusts and lateral ramps and extending up to 30 km from the shoreline is interpreted as the foreland thrust system of the actively growing mount lebanon range there is no large fault extending into the levant basin toward cyprus which indicates that thrusting only absorbs local transpression resulting from the lebanese restraining bend both the miocene and plio quaternary sedimentary sequences are affected by shortening with landward dipping blind thrusts and associated growth strata the presence of the messinian evaporites creates complex deformation patterns including normal faults due both to folding accommodation and to gravity spreading all well imaged in the seismic reflection profiles because the evaporite layer acts as a decollement level shortening extends farther out seaward through a series of thrust imbricates or duplexes the strongest shortening observed between beirut and batroun decreases toward the south between saida and tyre north of tripoli the passive margin is not affected by neogene deformation and is well preserved we propose that since the miocene the northward propagating lfs interacted with margin structures inherited from the mesozoic rifting phase and was deviated along the more rigid oceanic crust flooring the levant basin a process which led to the formation of the lebanese restraining bend of the lfs and consequently to the offshore shortening we document here such coastal transpression has resulted in local 100 km inversion of the passive margin which might eventually evolve into a new subduction zone

geophysical prediction and following development sinkholes in two dead sea areas israel and jordan geophysical methods seismic refraction srfr electrical resistivity tomography ert and microgravity were applied to the dead sea ds sinkhole problem in the ein gedi area at the earlier stage of the sinkhole development 1998 2002 they allowed determining the sinkhole formation mechanism and localizing the sinkhole hazardous zones the srfr method permitted to delineate the underground edge of a salt layer at the depth of 50 m the salt edge was shaped like the sinkhole line on the surface it was concluded that the sinkhole development is linked to the salt edge geoelectrical quasi 3d mapping based on the ert technique detected large resistivity anomalies with 250 300 m2 diameter and 25 35 m deep the ein gedi area has been also mapped by the use of microgravity method the residual bouguer gravity anomaly map shows negative anomalies arranged along the edge of the salt layer those gravity anomalies overall are very similar in plan to the resistivity distribution in this area the results of forward modeling indicate that both high resistivity and residual gravity anomalies are associated with a subsurface decompaction of the soil mass and deep cavity at the sinkhole site following monitoring of the sinkhole development carried out by the geological survey of israel confirmed our suggestions the drilling of numerous boreholes verified the location of the salt edge geographical information system gis database testifies that during 2003 2009 new sinkholes are continuing to develop along the salt edge within a narrow 50 100 m wide strip oriented approximately in north south direction slightly parallel to the shoreline no promotion in west east direction perpendicularly to the ds shoreline was observed in israel collapse of sinkholes and their clustering have been occurred within the area of high resistivity anomaly and negative residual gravity anomaly similar studies carried out at the ghor al haditha area jordan have shown that sinkholes there are also arranged along the winding line conforming to the salt edge in this area sinkholes are slowly moved to the dead sea direction results of geophysical studies in numerous ds sites indicate similar sinkhole development it allowed generating of the sinkhole formation model based on ancient 10 000 11 000 year old salt belt girding the dead sea along its shores

paleogene calcareous nannofossil magnetobiochronology results from south atlantic dsdp site 516 abstract the detailed study of an expanded paleogene section with abundant moderate to well preserved calcareous nannofossils from south atlantic dsdp site 516 has resulted in a precise correlation of most calcareous nannofossil markers with the magnetostratigraphy many nontraditional datums have also been documented and correlated to the magnetostratigraphy comparison of the results from site 516 with those of previous studies from other areas enables a critical evaluation of the accuracy synchroneity or diachroneity of the species events over geographically long distances of special significance is the correlation for the first time of the stratigraphic ranges of chiasmolithus gigas and rhabdosphaera gladius with the magnetostratigraphy other important results include the following first occurrence fo of cruciplacolithus primus 66 3 ma fo chiasmolithus danicus 65 6 66 0 ma fo prinsius martinii 65 5 66 0 ma fo heliolithus kleinpellii 59 8 61 6 ma probably diachronous last occurrence lo of tribrachiatus orthostylus 51 0 54 8 ma unreliable fo chiasmolithus gigas 47 4 ma fo reticulofenestra umbilica 44 6 ma lo chiasmolithus gigas 44 4 46 8 ma diachronous lo nannotetrina fulgens 44 2 ma lo chiasmolithus grandis 40 0 41 6 ma probably diachronous fo chiasmolithus oamaruensis 39 8 40 4 ma unreliable fo isthmolithus recurvus 39 5 ma lo reticulofenestra reticulata 37 6 ma lo discoaster saipanensis 36 4 ma end acme of ericsonia subdisticha diachronous fo and lo sphenolithus distentus unreliable and lo reticulofenestra bisecta 24 0 ma

the lowest place on earth is subsiding an insar interferometric synthetic aperture radar perspective since the early 1990s sinkholes and wide shallow subsidence features wssfs have become major problems along the dead sea shores in israel and jordan sinkholes are readily observed in the field but their locations and timing are unpredictable wssfs are often difficult to observe in the field however once identified they delineate zones of instability and increasing hazard in this study we identify characterize and measure rates of subsidence along the dead sea shores by the interferometric synthetic aperture radar insar technique we analyze 16 sar scenes acquired during the years 1992 to 1999 by the european remote sensing ers 1 and ers 2 satellites the interferograms span periods of between 2 and 71 months wssfs are observed in the lisan peninsula and along the dead sea shores in a variety of appearances including circular and elongate coastal depressions a few hundred meters to a few kilometers in length depressions in ancient alluvial fans and depressions along salt diapir margins phase differences measured in our interferograms correspond to subsidence rates generally in the range of 0 20 mm yr within the studied period with exceptional high rates that exceed 60 mm yr in two specific regions during the study period the level of the dead sea and of the associated ground water has dropped by 6 m this water level drop within an aquifer overlying fine grained marly layers would be expected to have caused aquifer system consolidation resulting in gradual subsidence comparison of our insar observations with calculations of the expected consolidation shows that in areas where marl layers are known to compose part of the upper 30 m of the profile estimated consolidation settlements are of the order of the measured subsidence our observations also show that in certain locations subsidence appears to be structurally controlled by faults seaward landslides and salt domes gradual subsidence is unlikely to be directly related to the sinkholes excluding the use of the wssfs features as predictable precursors to sinkhole formation

seismic refraction profiles between cyprus and israel and their interpretation summary a long seismic refraction profile was carried out between southern israel and cyprus the seismic energy was generated by 33 sea shots each of 0 8 t explosives and was recorded by land stations in israel and cyprus and by ocean bottom seismographs deployed along the profile the results showed that the continental crust of southern israel thins towards the mediterranean underneath a northward thickening sedimentary cover cyprus is underlain by a 35 km thick continental crust thinning south wards and extending to mt eratosthenes between mt eratosthenes and the israel continental shelf the crystalline crust is composed of high velocity 6 5 km s 1 material and is about 8 km thick it is covered by 12 14 km of sediments and may represent a fossil oceanic crust

structural control of sinkholes and subsidence hazards along the jordanian dead sea coast for about four decades the dead sea ds level and the surrounding water table has been dropping dramatically at least from the eighties the direct vicinity of the lisan peninsula lp jordan has been facing high rates of subsidence and sinkhole hazards between 2000 and 2002 the arab potash company apc lost two salt evaporation ponds resulting in a loss of 70 million in the fertile plain of ghor al haditha gah three deep and wide bowl shaped subsidence areas threaten human activities and infrastructures over the part of the lisan peninsula that emerged before the 1960s relict fossil sinkholes occurred everywhere whereas new collapses constantly appear in the southern area only in this paper we have integrated 15 years of field observations related to sinkholes and subsidence with interpretation of space borne radar interferometric outputs aerial photographs and satellite images this has helped to place hazardous areas in their geological context and to clarify them within the framework of the general tectonic setting of the area

on the relation between seismic wave velocity and stress in a solid summary the paper considers a model comprised of variable moduli elastic solids incorporating fracturing caused by tectonic stress the model gives us a possibility to calculate the seismic velocities and crack distribution around density variations the results of numerical simulations are shown

modern tectonic stress field in the mediterranean region evidence for variation in stress directions at different scales summary a compilation of more than one thousand stress indicators which include in situ stress measurements focal mechanisms microtectonic and other geological data allowed us to reconstruct the modern stress field in the mediterranean region and the surrounding area average stress directions at different scales have been reconstructed by means of a linear interpolation method this method takes into account the distribution scale and quality of stress data the results of the interpolation at plate scale allow us to recognize slightly deformed regions such as the northwestern european platform where average maximum horizontal stress direction is oriented roughly nnw sse subparallel to absolute and relative plate velocity directions other regions such as the caucasus alps and pyrenees where recent tectonic deformation and seismicity are present display important variations of stress directions the reconstruction of the average stress directions at different scales within the french alps pointed out that the average stress field pattern may vary from one scale to another nevertheless variations of stress directions at a given scale are consistent with the kinematics of faults of the same scale

faulting processes along the northern dead sea transform and the levant margin the northern dead sea transform is markedly different from the southern segments of the transform the strike of the transform changes in this area that forms a restraining bend and the displacement on it is much less than that on the southern and central dead sea transform the structure and evolution of the northern dead sea transform was simulated using a rheological model of a visco elastic material that takes into consideration the crustal structure variations in this area and the proximity to the collisional belts along the cyprean arc and the taurus mountains the simulation can explain the formation of the restraining bend known in this area as the yammuneh fault and the faulting along the northern levant continental margin providing that a simultaneous propagation of the dead sea transform from the north and south took place this suggests that restraining bends in general which are common features along continental transform faults are formed when two segments of a transform propagate toward each other

dynamics of extensional basin formation and inversion introduction this volume contains a cohection of papers on the dynamics of extensional basin formation and inversion presented at the 3rd annual workshop of the international lithosphere program task force origin of sedimentary basins in sundvollen norway 18 23 august 1992 previous workshops of the ilp task force had been in rueil malmaison france 1990 and in matrahaza hungary 19911 on the rim of the pannonian basin the task force also organized a number of sessions during the 1992 european geophysical society and the 1993 european union of geosciences conferences reports of these meetings have been published in a number of special volumes and papers cloetingh et al 1993a b stephenson 1993 cloetingh sassi and task force team 1994 the 4th task force meeting focusing on the interplay of extension and compression was held in benevento southern italy in october 1993 a selection of papers presented at that task force workshop will be published in a forthcoming special volume of tectonophysics the emphasis of the 5th workshop of the task force taking place in the dead sea rift israel is on rifting and strike slip tectonics the 1995 workshop will be organized in the southern pyrenean foreland basin with the aim of examining the relationships between tectonics and eustasy in foreland fold and thrust belts the emphasis of the sundvollen workshop was on modelling studies as well as observational approaches to the dynamics of basin extension and inversion important elements of the meeting were the discussion of extensional tectonics rifting in passive margin settings and volcanism and magmatism in rifts and basins following the task force strategy to link subsurface data to field analogues an important part of the meeting was devoted to a thematic excursion in the oslo rift field guides have been published separately larsen et al 1992a

leaching of lisan marl and its consequences on the engineering behavior of dikes studied by finite elements modeling leaching of lisan marl dead sea jordan increased the soil compressibility and cohesion intercept back analysis using the plaxis finite element code was successfully implemented the finite element modeling of dike construction showed a significant increase of total settlement and negligible effect on the strength as calculated by the c reduction method the height of dikes to be constructed on lisan marl as foundation material should be optimized to account for the effect of soluble salts leaching for this to take place an accurate calculation of settlement is crucial

dinoflagellate cysts and mid oligocene chronostratigraphy in the central mediterranean region two new dinoflagellate cyst zones are proposed linking previously established zonal schemes for the eocene oligocene and oligocene miocene successions in the central mediterranean region the hystrichokolpoma pusillum hpu and chiropteridium lobospinosum clo interval zones are based on the contessa quarry and monte cagnero sections central italy and are correlated with previously established magnetostratigraphical and biostratigraphical schemes the base of the chattian is considered to correlate with chron cl0n in central italy the most distinct dinoflagellate cyst event associated with this chron is the first occurrence of distatodinium biffii marking the base of the distatodinium biffii dbi zone indirect evidence also suggests that the first occurrence of distatodinium biffii is above but close to the base of the chattian stage in its type area in northwest germany thus making it an important marker other possible markers for the base of the chattian are the last occurrence of areosphaeridium pectiniforme and the lowest acme of chiropteridium spp the latter may be related to the major mid oligocene sea level fall ta tb exxon supercycle boundary also considered to represent the base of the chattian and previously correlated with chron cl0n however in the contessa quarry section this dinoflagellate cyst event is associated with the older chron c11

compressibility and collapse characteristics of arid saline sabkha soils abstract arid saline soils are well distributed over the globe with a variety of nomenclature along the seaboard of the arabian gulf these soils exist widely and are known as sabkhas despite the cemented and saline characteristics of the sabkha matrix a recent investigation indicated that flooding the saline sabkha with distilled water in the conventional oedometer apparatus was incapable of producing a sudden reduction in volume and or a significant collapse this study proposes a modification to the conventional oedometer on undisturbed sabkha specimens to consolidating specimens under a constant head tests were therefore conducted on undisturbed sabkha specimens to assess their compressibility and collapse potential whereby percolation of water was commenced under two pressures to evaluate the role of sustained pressure on the collapse mechanisms despite the low compressibility of sabkhas results of these tests indicated that these arid saline soils possess a high collapse potential attributable primarily to dissolution of sodium chlorides leaching of calcium ions and soil grain adjustment the collapse potential increases with an increase in the acting pressure at which percolation of water takes place in contrast to other typical soils the collapse of arid saline soils is not instantaneous but requires sufficient volume of water to percolate in order to enhance the dissolution of the cementing agents

stable and unstable damage evolution in rocks with implications to fracturing of granite summary we address the relation between the rock rigidity and crack density by comparing predictions of a viscoelastic damage rheology model to laboratory data that include direct microscopic mapping of cracks the damage rheology provides a generalization of hookean elasticity to a non linear continuum mechanics framework incorporating degradation and recovery of the effective elastic properties transition from stable to unstable fracturing and gradual accumulation of irreversible deformation this approach is based on the assumption that the density of microcracks is uniform over a length scale much larger than the length of a typical crack yet much smaller than the size of the entire deforming domain for a system with a sufficiently large number of cracks one can define a representative volume in which the crack density is uniform and introduce an intensive damage variable for this volume we tested our viscoelastic damage rheology against sets of laboratory experiments done on mount scott granite based on fitting the entire stress strain records the damage variable is constrained and found to be a linear function of the crack density an advantage of these sets experiments is that they were preformed with different loading paths and explicitly demonstrated the existence of stable and unstable fracturing regimes we demonstrate that the viscoelastic damage rheology provides an adequate quantitative description of the brittle rock deformation and simulates both the stable and unstable damage evolution under various loading conditions comparison between the presented data analysis of experiments with mount scott granite and previous results with westerly granite and berea sandstone indicates that granular or porous rocks have lower seismic coupling this implies that the portion of elastic strain released during a seismic cycle as brittle deformation depends on the lithology of the region hence upper crustal regions with thick sedimentary cover or fault zones with high degree of damage are expected to undergo a more significant inelastic deformation in the interseismic period compared to intact crystalline rocks

a rheological model of a fractured solid abstract experiments to study the behavior of various materials point to the relation that exists between elastic properties and the type of stress the influence of the state of stress on the elasticity of a fractured material will be discussed for a physically non linear model of an elastic solid the strain dependent moduli model of material presented in this paper makes it possible to describe this feature of a solid it also permits to simulate a dilatancy of rocks a damage parameter introduced into the model using a thermodynamical approach allows to describe a rheological transition from the ductile regime to the brittle one and to simulate the rock s memory narrow fracture zone creation and strain rate localization additionally the model enables the investigation of the final geometry of fracture zones and also to simulate their creation process taking into account pre existing fracture zones the process of narrow fracture zone creation and strain rate localization was simulated numerically for single axis compression and shear flow

recognition of stratigraphic sequences in carbonate platform and slope deposits empirical models based on microfacies analysis of palaeogene deposits in southeastern spain abstract the functional morphology and life style of foraminifers can be used to determine their former position on the platform and to detect upwards shallowing and deepening trends in sedimentary sequences the sequential analysis of the palaeogene platform deposits of alicante proved to be greatly enhanced by the use of the palaeoecology of foraminifers on the basis of this analysis three different empirical models for platform accommodation cycles could be designed a ramp model distinctive for the lower eocene a combined ramp rimmed model characteristic for the middle and upper eocene and a rimmed model representative for oligocene cycles the change in platform type through time is thought to be a response to climate related changes in growth potential of hermatypic corals possible criteria to distinguish systems tracts in slope deposits on their foraminiferal and clast content are put to the test in a slope section with positive results from the correlation of the southern spanish palaeogene cycles with eurasian african plate boundary events along the pyrenees and with antarctic glaciations it can be concluded that the majority of the cycles are tectonically controlled with glacio eustatic contributions since the middle late eocene boundary

simulation of foreland basin stratigraphy using a diffusion model of mountain belt uplift and erosion an example from the central alps switzerland foreland basin stratigraphy can be considered as the result of three interacting processes thrust deformation which builds the tectonic load sedimentary and erosional processes which redistribute that load and the flexural response of the lithosphere the resultant stratigraphy of foreland basins is commonly composed of a small number of shallowing and coarsening upward cycles bounded by regional unconformities to understand the development of these unconformities we present a simple model of these three processes coupling an evolving thrust wedge on a linear elastic plate with erosion and sedimentation defined by the diffusion equation applied to topography our model demonstrates the development of regional unconformities without recourse to either eustasy or complex viscoelastic models for the continental lithosphere the model describes the thrust wedge foreland basin system in terms of four parameters 1 the effective elastic thickness of the foreland plate te 2 the sediment transport coefficient k 3 the thrust wedge advance rate 4 the surface slope of the thrust wedge the model is applied to the oligocene miocene north alpine foreland basin nafb of eastern switzerland the stratigraphy of the nafb can be simplified into two large scale shallowing upward cycles separated by an unconformity at the base of the burdigalian 22 ma geological information is taken from the nafb to estimate suitable values for the parameters listed above assuming a linear elastic lithospheric rheology the te value is estimated at 10 5 km from decompacted sediment columns data to constrain the sequential development of the thrust wedge come from structural geology the early stages 40 24 ma of compression involved a relatively low angle thrust wedge with an advance rate of approximately 2 4 mm yr at about 24 ma the wedge advance slowed down and thickened by underplating crystalline basement of the foreland plate the value for the transport coefficient has been estimated from previous studies prior to attempting to simulate the broad scale geometry of the nafb the role of each parameter was assessed individually the values for te and k are held constant throughout the simulation of the nafb at 7 5 km and 500 m yr respectively the geometry of the base burdigalian unconformity is reproduced by variations in the parameters describing the thrust wedge the surface slope angle of the wedge is increased from 2 5 to 4 over 0 2 m y and the rate of thrust advance is decreased from 2 mm yr to 0 2 mm yr during the thickening event between 24 and 23 8 ma the rejuvenation of the internal parts of the thrust load causes backtilting of the foreland basin sediments and after a time lag erosion of the distal stratigraphy over the forebulge so simulating the base burdigalian unconformity

understanding basement tectonics of an interior cratonic basin southern illinois basin usa abstract although the illinois basin is one of the world s most studied interior cratonic basins little is known of its deep structure or seismotectonic framework in this study seismic reflection profiles over the major structures of the basin reveal reverse faults that penetrate the upper precambrian crust disrupt the surface of precambrian basement and accommodate folding of paleozoic sediments observations of deformation indicate concordant folding of the basement surface and overlying strata and or possible laramide style basement controlled folding most profiles show evidence of dual fold vergence and some profiles suggest transpression involving lower paleozoic strata and the basement surface the moderate seismicity in the southern illinois basin just north of the new madrid seismic zone nmsz defines an active deformation regime of interpreted nne striking dextral strike slip and reverse faulting upper crustal fault structure such as shown in this study could provide a fabric capable of reactivation by stress manifested as contemporary seismicity a tectonic framework for the possible kinematic linkage of deformation in the nmsz and the southern illinois basin is proposed on the basis of a hypothetical distribution of branched fault and or fold patterns in southern illinois that broaden northward beyond the nmsz such a dispersive deformation pattern is thought to be associated with the gradual cessation in displacement north of the nmsz i e displacement is dissipated over many faults the abrupt change in seismotectonic regime from a relatively discrete highly seismic nmsz with infrequent great earthquakes to a multi stranded fault pattern with more frequent moderate earthquakes in southern illinois is typical of active strike slip systems involving a bend or shift in direction

thermo mechanical model of the dead sea transform abstract we employ finite element thermo mechanical modelling to study the dynamics of a continental transform boundary between the arabian and african plates marked by the dead sea transform dst that accommodated ca 105 km of relative transform displacement during the last 20 myr we show that in the initially cold lithosphere expected at the dst shear deformation localizes in a 20 40 km wide zone where temperature controlled mantle strength is minimal the resulting mechanically weak decoupling zone extends sub vertically through the entire lithosphere one or two major faults at the top of this zone take up most of the transform displacement these and other modelling results are consistent with geological observations and lithospheric structures imaged along the desert seismic line suggesting that the arava valley segment of the dst is an almost pure strike slip plate boundary with less than 3 km of transform perpendicular extension modelling suggests that the location of the arava valley segment of the dst has been controlled by the minimum in lithospheric strength possibly associated with margin of the arabian shield lithosphere and or by regionally increased crustal thickness models also show that heating of the arabian shield mantle adjacent to the dst inferred independently by petrological and seismological studies is required to explain asymmetric late cenozoic uplift in the area

flip convergence across the phoenician basin through nucleation of subduction abstract modern examples of active subduction nucleation are scarce hence knowledge is derived from reconstructions of old subduction zones and numerical modeling here we present a rare analog of induced subduction nucleation occurring today along the northeastern mediterranean continental margin geological evidence gathered here suggests that plate convergence between africa sinai arabia and eurasia anatolia since the pliocene led to fragmentation of the northern sinai plate into the phoenician and northern levant micro plates currently convergence is in the process of shifting from subduction cessation beneath the eastern cyprus arc to reactivation of the northern levant margin this shift induces the nucleation of an embryonic subduction zone through polarity reversal it re defines the front of plate convergence

lithospheric strength variations as a control on new plate boundaries examples from the northern red sea region abstract the complex plate boundary between arabia and africa at the northern end of the red sea includes the gulf of suez rift and the gulf of aqaba dead sea transform geologic evidence indicates that during the earliest phase of rifting the red sea propagated nnw towards the mediterranean sea creating the gulf of suez subsequently the majority of the relative movement between the plates shifted eastward to the dead sea transform we propose that an increase in the strength of the lithosphere across the mediterranean continental margin acted as a barrier to the propagation of the rift a new plate boundary the dead sea transform formed along a zone of minimum strength we present an analysis of lithospheric strength variations across the mediterranean continental margin the main factors controlling these variations are the geotherm crustal thickness and composition and sediment thickness the analysis predicts a characteristic strength profile at continental margins which consists of a marked increase in strength seaward of the hinge zone and a strength minimum landward of the hinge zone this strength profile also favors the creation of thin continental slivers such as the levant west of the dead sea transform and the continental promontory containing socotra island at the mouth of the gulf of aden calculations of strength variations based on changes of crustal thickness geotherm and sediment thickness can be extended to other geologic settings as well they can explain the location of rerifting events at intracratonic basins of backarc basins and of major continental strike slip zones

the dead sea rift lateral displacement and downfaulting phases abstract a sinistral strike slip of 105 km along the dead sea rift is confirmed by the continuity in the restored trend of eocene sedimentary belts yet the similar characteristics on either side of the rift between the upper miocene conglomerates mudstones and lithographic limestones particularly the kefar gil adi fm and the pliocene marls oolitic limestones and basalts e g bira fm gesher fm cover basalt raise doubts as to whether a major lateral slip occurred after the end of the upper miocene or even during that epoch the master fault along which motion took place runs through the middle of the jordan valley on the western side of the hula valley through the metulla saddle and the ayoun valley and merges with the yammunneh fault major phases mainly of downfaulting occurred 1 during the middle and at the beginning of the upper miocene hordos fm and post hordos 2 subsequent to deposition during the upper miocene and pliocene and 3 towards the end of the lower pleistocene post ubediye and mishmar hayarden fms when tilting and folding within the rift marked the last significant stage of its formation

the role of hydrogeology in solution subsidence development and its environmental impacts a case study for sazlica nigde turkey solution subsidence and other types of collapse failures developed in the vicinity of sazlica have been a major source of environmental problems such as groundwater pollution soil erosion and foundation failures extensive pumping of water from the lake dipsiz during irrigation seasons creates landslide developments at the shores of the lake five stages of landslide development were observed in the unconsolidated soils around lake dipsiz bowl shaped solution subsidence features with depths from 1 to 3 m and diameters between 1 and 60 m were formed due to excess pumping and recharge and discharge features of unconfined aquifer the pumping activities must be controlled to prevent further environmental problems lake dipsiz and other subsidence developments are the groundwater exposure areas highly vulnerable to contamination the proposed remedies for overcoming the environmental problems are the establishment of conservation areas around such natural features ceasing the removal of top soil controlling the urbanization and keeping the livestock farming away from the areas susceptible to pollution

response of sabkha to laboratory tests a case study abstract sabkha is a saline evaporative flat soil that forms under and climates it is generally associated with saturated watertables that are very close to the ground surface there are typically two major types of sabkhas coastal and continental or inland the presence of brines in the sabkha matrix and the crystallization of diagenetic minerals therein can lead to the highly variable mechanical properties of such a soil this investigation was carried out to evaluate the engineering properties of this salt laden and water sensitive sabkha soil several laboratory tests were conducted including compaction permeability unconfined compression direct shear triaxial cbr specific gravity measurements and grain size distribution analysis the investigation also focussed on the effect of distilled water and or sabkha brine on the properties of this unusual type of soil

the dead sea earthquake of 23 april 1979 the dead sea earthquake of 23 april 1979 mb 5 1 was felt throughout israel and in parts of the neighboring countries the epicentral distribution of this earthquake its aftershocks two of the largest dead sea earthquakes during the last 50 yr and recent microearthquake data suggest that an active segment of the dead sea rift fault system lies along the eastern part of the dead sea a detailed intensity study shows a pronounced dependence of seismic intensities on ground characteristics strong motion seismograph measurements were obtained for the first time in the levant countries and they suggest that peak ground accelerations are not significantly different from worldwide data

collapse sinkholes and radar interferometry reveal neotectonics concealed within the dead sea basin 1 the dead sea ds pull apart basin is one of the more seismically active segments of the ds transform plate boundary in the last decade hundreds of collapse sinkholes have been formed along the ds coastlines in israel and jordan causing severe damage to the regional infrastructure the formation of these sinkholes is attributed to the dissolution of a buried salt layer by fresh groundwater due to the drop of the ds and the associated groundwater levels here we show that the sinkhole distribution combined with gradual land subsidence measured by radar interferometry insar track young fault systems suspected as active concealed within the fill of the ds rift this notion is supported by 1 sinkholes clustering along discrete lineaments with a striking trend similarity to that of the exposed rift margin faults 2 prominent discontinuities in seismic reflection profiles offsetting young sediments several kyrs old below sinkhole lines and 3 straight boundaries of gradual subsidence features that coincide with or parallel sinkhole lines combined the sinkhole lineaments and the insar measurements reveal a zigzag pattern of buried faults within the ds rift fill

oligocene through palaeogene neogene boundary foraminifera of the northern mesohellenic basin macedonia greece biostratigraphy and palaeoecologic implications abstract foraminifera of the oligocene and early miocene siliciclastic units from the northern part of the mesohellenic basin macedonia northern greece provide good biostratigraphic potential taxa identified from a number of sections cropping out in the study area indicate that these deposits fan in zones p20 upper part p21 p22 and most of zone n4 of blow s zonal scheme the occurrence within the lowest part of the pendalofos formation of abundant globigerinoides primordius together with other earliest miocene planktonics defines the base of the miocene although a remarkable planktonic foraminiferal turnover occurred close to the palaeogene neogene boundary the benthic populations do not show any clear change except in relation to palaeoecologic conditioning analysis of benthic foraminifera led to the definition of a palaeodepth curve indicating that the deposition during the late oligocene and early miocene occurred in a middle to upper mostly bathyal and outer neritic conditions the distribution of selected benthic foraminifera is compared with sedimentologically derived depositional environments the correlation between the major global unconformities predicted by the exxon coastal onlap chart and the mesohellenic succession is based on the joint use of biochronologic and biostratigraphic palaeoecologic tools

the rotation of arabia and the levant fault system abstract we establish the kinematics of the rotation of arabia with respect to africa and show that the rotation rate of africa increased by a factor of about four in late serravallian time about 12 13 ma ago we discuss evidence that oceanic accretion started simultaneously in the gulf of aden and in the red sea at this time it is also at this time that the levant and anatolian fault systems were initiated our initial reconstruction of the red sea rift in late oligocene early miocene time approximately superposes the present shore lines which coincide with the mid point of the zones of rapid crustal thinning the future continental slopes the amount of extension during the early phase of continental rifting is obtained by assuming that the total volume of continental crust is conserved during extension and by checking these estimates through closure around the sinai triple junction in the late miocene the southern evant fault zone was a zone of distributed shear deformation through counterclockwise block rotation extending soul h ward within the northernmost red sea since the early pliocene the shear motion has been localized within the gulf of aqaba changing the tectonic pattern in the northern red sea

use of ground penetrating radar for assessment of potential sinkhole conditions an example from ghor al haditha area jordan sinkholes are near surface indicators of active karst features at depth such as cavities conduits and solutionally enlarged fractures this study tests the usefulness of ground penetrating radar gpr to identify and locate buried sinkholes as a means of interpreting the existence of these subsurface hydraulically active karst features gpr survey was made at the ghor al haditha area west of the jordan dstf in the jordan valley escarpment at the eastern dead sea shoreline gpr profiles 100 mhz made along the eastern dead sea shoreline showed a trough like pattern of radar reflections outlining a series of possible filled sinkholes this feature is about 38 m wide and about 12 m deep its width is consistent with the width of the feature obtained from the topographic map of the area the gpr survey suggests that this feature has been filled with relatively dense and resistive materials this structure lies almost directly above a major water bearing zone

preferential rifting of continents a source of displaced terranes lithospheric rifting while prevalent in the continents rarely occurs in oceanic regions to explain this preferential rifting of continents we compare the total strength of different lithospheres by integrating the limits of lithospheric stress with depth comparisons of total strength indicate that continental lithosphere is weaker than oceanic lithosphere by about a factor of 3 also a thickened crust can halve the total strength of normal continental lithosphere because the weakest area acts as a stress guide any rifting close to an ocean continent boundary would prefer a continental pathway this results in the formation of small continental fragments or microplates that once accreted back to a continent during subduction are seen as displaced terranes in addition the large crustal thicknesses associated with suture zones would ironically make such areas likely locations for future rifting episodes this results in the tendency described as the wilson cycle of new oceans to open along the suture where a former ocean had closed

basin sedimentation and the growth of prograding deltas a theoretical model is developed for the infilling of a basin by the progradation of a delta the model simulates four mechanisms for the transfer of sediment from the land to the sea 1 bed load dumping along the delta front 2 hemipelagic sedimentation under the seaward flowing river plume 3 proximal slope bypassing by turbidity currents and 4 the combined effects of both short term wave and tidal action and long term creep and small slides downslope diffusion of the accreting sediment mass the general model is of relatively low precision useful for predicting basin infilling on time scales greater than a few hundred years the river plume portion of the model can predict sedimentation on time scales of less than a year and is designed to reflect the dynamics of a free two dimensional buoyant jet that transports a composite size population of suspended particles the general model allows the prediction of lithologies changing with time and space the model has been used to simulate infilling processes for knight and bute inlets two grabenlike fjord basins along the coast of british columbia model simulations of delta progradation over the last 10 000 years favorably predicted the modern seafloor bathymetry and sediment accumulation rates to within a factor of 2 of measured 210pb 137cs and sediment trap rates

displaced terranes and crustal evolution of the levant and the eastern mediterranean geophysical data from the levant and the eastern mediterranean suggest that this area can be divided into distinct crustal units of different origins for example a marked difference in crustal structure and structural style exists in the levant between samaria and judea south of the carmel structure and the galilee and lebanon north of it on the other hand several microcontinental fragments such as cyprus and the eratosthenes and anaximander seamounts are embedded within the oceanic crust of the eastern mediterranean the present location of these units has resulted from complex tectonic processes which were active during the mid paleozoic mesozoic evolution of this area during this period several crustal units were accreted to the northern margin of africa while others were detached away from it the crustal evolution of the eastern mediterranean and the levant is intimately linked with the closure of the paleo tethys the formation of the neo tethys and its subsequent closure

sinkholes subsidence and subrosion on the eastern shore of the dead sea as revealed by a close range photogrammetric survey abstract ground subsidence and sinkhole collapse are phenomena affecting regions of karst geology worldwide the rapid development of such phenomena around the dead sea in the last four decades poses a major geological hazard to the local population agriculture and industry nonetheless many aspects of this hazard are still incompletely described and understood especially on the eastern dead sea shore in this work we present a first low altitude our analysis reveals a kilometer scale sinuous depression bound partly by flexure and partly by non tectonic faults the estimated minimum volume loss of this subsided zone is 1 83 106 m3 with an average subsidence rate of 0 21 m yr 1 over the last 25 years sinkholes in the surveyed area are localized mainly within this depression the sinkholes are commonly elliptically shaped mean eccentricity 1 31 and clustered nearest neighbor ratio 0 69 their morphologies and orientations depend on the type of sediment they form in in mud sinkholes have a low depth to diameter ratio 0 14 and a long axis azimuth of nne ne in alluvium sinkholes have a higher ratio 0 4 and are orientated nnw n from field work we identify actively evolving artesian springs and channelized sediment laden groundwater flows that appear locally in the main depression consequently subrosion i e subsurface mechanical erosion is identified as a key physical process in addition to dissolution behind the subsidence and sinkhole hazard furthermore satellite image analysis links the development of the sinuous depression and sinkhole formation at ghor al haditha to preferential groundwater flow paths along ancient and current wadi riverbeds

quantitative assessment of in situ salt karstification using shear wave velocity dead sea abstract the dead sea ds coastal areas have been dramatically affected by sinkhole formation since around 1990 such sinkholes along both israeli and jordanian shores are linked to karst cavities that form through slow salt dissolution a quantitative estimate of such in situ salt karstification would be an important indicator of sinkhole hazard one of the indications of salt karstification is its increased hydraulic conductivity caused by the development of dissolution cavities forming conducting channels within the salt layer we measured the hydraulic conductivity k versus shear wave velocity vs of ds salt in situ for estimating the actual salt karstification in areas of sinkhole development these parameters were measured with the magnetic resonance sounding mrs and multichannel analysis of surface waves masw methods respectively understanding of the field relationships was augmented by similar inter relations obtained in the laboratory on samples of ds salt in situ salt velocities vs vary from 750 m s to over 1650 m s while hydraulic conductivity k in the same zones varies between about 10 4 m s to slightly over 10 8 m s both field and laboratory k and vs values fit the exponential function ln k 0 0045 vs 5 416 with a determination coefficient r2 of 0 88 a classification based on vs and k was generated for salt conditions and the corresponding degrees of sinkhole hazard which was verified in the mineral beach sinkhole development area the mapping of sinkhole sites shows that they form within highly conductive zones with k 5 5 10 5 it is suggested that this methodology with some modification can be used for evaluating the conductive properties of karstified rock and associated sinkhole hazards

tracing pluvial periods in an ancient desert environment depositional surfaces of early miocene sediments are preserved in the coastal cordillera atacama desert northern chile dunai et al 2005 measurement of cosmogenic ne in clasts from erosion sensitive sediment surfaces show that these surfaces have been barely affected by erosion since 25 ma predominantly hyperarid conditions since 25 ma are required to create and preserve these oldest continuously exposed surfaces on earth dunai et al 2005 subsequent to deposition these sediment surfaces have been slightly altered by erosion and deposition during a resampling campaign aimed at constraining the timing of erosion and deposition eighty quartz pebbles were collected at the inlet of the first in a series of salt carst depressions at the bottom of a wide valley on the sediment surface dunai et al 2005 the ne ages of these clasts show distinct clusters at 3 5 4 ma 8 10 ma 13 15 ma 17 18 ma 24 ma 33 35 ma the ages that are younger than the deposition age give the timing of pluvial phases in which the runoff was strong enough to incise hardrock channels into the surrounding hill slopes and deposit material onto the sediment surface that had little to no pre exposure to cosmic rays ages concordant to the deposition age probably represent laterally dislocated material of the original sediment surface ages greater than the deposition age indicate that portions of the local source region of the clasts were very slowly eroding stable prior to the pluvial episode that eroded and transported them onto the sediment surface the inferred pluvial phases are age concordant with episodes of supergene enrichment in porphyry copper deposits of the pre cordillera and the andes to the east of the study area sillitoe and mckee 1996 the timing of all inferred pluvial phases is age concordant with periods global and or regional climate change global cooling regional wet phases vasconcelos et al 1994 zachos et al 2001

localisation and temporal variability of groundwater discharge into the dead sea using thermal satellite data the semi arid region of the dead sea heavily relies on groundwater resources this dependence is exacerbated by both population growth and agricultural activities and demands a sustainable groundwater management yet information on groundwater discharge as one main component for a sustainable management varies significantly in this area moreover discharge locations volume and temporal variability are still only partly known a multi temporal thermal satellite approach is applied to localise and semi quantitatively assess groundwater discharge along the entire coastline the authors use 100 landsat etm band 6 2 data spanning the years between 2000 and 2011 in the first instance raw data are transformed to sea surface temperature sst to account for groundwater intermittency and to provide a seasonally independent data set t maximum sst range per pixel within biennial periods is calculated subsequently groundwater affected areas gaa are characterised by t 10 c this allows the exact identification of 37 discharge locations clusters along the entire dead sea coast which spatially correspond to available in situ discharge observations tracking the gaa extents as a direct indicator of groundwater discharge volume over time reveals 1 a temporal variability correspondence between gaa extents and recharge amounts 2 the reported rigid ratios of discharge volumes between different spring areas not to be valid for all years considering the total discharge 3 a certain variability in discharge locations as a consequence of the dead sea level drop and finally 4 the assumed flushing effect of old dead sea brines from the sedimentary body to have occurred at least during the two series of 2000 2001 and 2010 2011

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

major calcareous nannofossil and foraminiferal events between the middle eocene and early miocene abstract the more significant biostratigraphic events during the time interval from beginning middle eocene to beginning miocene with special emphasis on the eocene oligocene boundary are discussed the microfossils considered are calcareous nannofossils planktic foraminifera and smaller and larger benthic foraminifera areas taken into account include particularly the caribbean trinidad barbados dsdp south atlantic sections cape basin site 360 walvis ridge sites 362a 363 angola basin site 364 the equatorial north atlantic dsdp site 354 and the southern alps possagno in the larger foraminifera the treatment is somewhat different with selected families and genera being considered for their distribution in the eastern and western hemisphere

the east anatolian fault an oblique collisional belt abstract the tectonic setting for the area around the arabia africa anatolia triple junction is described from combined landsat spot satellite image analysis and field observations since the late miocene the motion along the east anatolian fault generated major structures corresponding to shortening with a sinistral slip component the 150 km wide area of the triple junction is highly deformed by folding and thrusting distributed mainly on the border of the anatolian block in addition kinematic reconstructions confirm that the arabia anatolia relative motion is both sinistral and convergent the sinistral strike slip faults of the east anatolian fault zone are of second order and local consequences of the n s arabia anatolia collision

drop down formation of deep basins along the dead sea and other strike slip fault systems summary we address the mechanism of sedimentary basin formation along strike slip fault systems with 3 d numerical simulations based on a continuum damage rheology model the formation of these basins is usually explained by a pull apart mechanism that predicts a rhomb shaped basin geometry bounded by two longitudinal strike slip faults and two transverse listric faults significant ductile deformation of the lower crust and upper mantle associated with basin growth requires normal or elevated heat flux the dead sea continental transform is associated with some of the larger and unusually deep basins among which the southern dead sea is the deepest the heat flow in the dead sea basin is anomalously low and it is associated with deep seismicity moreover the basin is bounded by deep transverse normal faults rather than the listric faults required by the pull apart model hence the formation of the basin cannot be explained by the existing pull apart model ben avraham and schubert proposed an alternative conceptual model for the formation of the deepest basin at the southern dead sea they suggested that an isolated block of lithosphere has dropped into the mantle we simulate the formation of this and other deep basins along the dead sea fault and demonstrate that the drop down mechanism of the dead sea basin formation suggested by ben avraham schubert is possible density heterogeneities formed in the crust or upper mantle during a previous stage of regional magmatism drop into the upper mantle when strike slip faults are created and detach them from the surrounding lithosphere the simulations indicate that the resulting basin is rhomb shaped and that with time it grows by the addition of distinct segments to its edges the proposed mechanism could account for the formation and evolution of large sedimentary basins along other strike slip fault systems such as the san andreas fault and other continental transform faults

a thin viscous sheet model for continental deformation summary for the purposes of describing its large scale and long term deformation the continental lithosphere is regarded as a continuum obeying a newtonian or a power law rheology the flow of a thin sheet of power law material overlying an inviscid substrate is studied under the assumption that vertical gradients of the horizontal velocity are negligible a numerical model is used to investigate the deformation of such a sheet under conditions approximating those of continent continent collision the material flows in response to forces applied to its boundaries for example the indenting of one continent by another and to forces in its interior arising from gradients in crustal thickness the horizontal divergence of the flow produces changes in the crustal thickness and hence a time dependent form to the flow itself for a given set of boundary conditions the flow depends on the stress exponent in the power law rheology n and on the argand number which is a measure of the ratio between the stress arising from crustal thickness contrasts and the stress required to deform the material at the ambient strain rates when the effective viscosity of the medium is very high ar o crustal thickness variations do not influence the flow if the material is newtonian n l the deformation associated with an influx of material approximating an indenter is of much greater lateral dimension than the width of the indenter whereas when material has a power law rheology n 3 5 are used the deformation is confined to a region of lateral extent comparable to that of the indenter as ar increases the forces arising from crustal thickness contrasts exert more influence on the flow and the maximum crustal thickness that can be sustained by a given influx of material is related by a simple expression to the effective viscosity of the medium at the ambient strain rates in the limit of a very weak medium ar 10 the lithosphere is unable to sustain appreciable crustal elevation contrasts the results of these numerical experiments show that systems in which the effective viscosities are such that the maximum deviatoric stresses are between 1 kbar

groundwater chemistry of strike slip faulted aquifers the case study of wadi zerka ma in aquifers north east of the dead sea wadi zerka ma in catchment area is located to the north east of the dead sea it has two types of aquifers a an upper unconfined aquifer and b a lower confined aquifer the two aquifers are separated by a marl aquiclude a major strike slip fault passes perpendicularly through the two aquifers and the aquiclude layer with embedded normal faults the aim of the study was to specify the effect of the major strike slip fault on the groundwater chemistry the spatial variability of the hydrochemical compositions and physiochemical parameters of the groundwater were investigated it was found that the embedded normal faults of the strike slip fault form conduits that allow groundwater to flow from the lower aquifer to the upper aquifer resulting in mixed groundwater the ratio of mixing was estimated to be 94 groundwater from the upper aquifer and 6 from the lower aquifer since groundwater in the lower aquifer is around three times more saline than the upper aquifer water mixing into the upper water aquifer generates a salinity hazard

salt diapirs in the dead sea basin and their relationship to quaternary extensional tectonics abstract regional extension of a brittle overburden and underlying salt causes differential loading that is thought to initiate the rise of reactive diapirs below and through regions of thin overburden we present a modern example of a large salt diapir in the dead sea pull apart basin the lisan diapir which we believe was formed during the quaternary due to basin transtension and subsidence using newly released seismic data that are correlated to several deep wells we determine the size of the diapir to be 13 10 km its maximum depth 7 2 km and its roof 125 m below the surface from seismic stratigraphy we infer that the diapir started rising during the early to middle pleistocene as this section of the basin underwent rapid subsidence and significant extension of the overburden during the middle to late pleistocene the diapir pierced through the extensionally thinned overburden as indicated by rim synclines which attest to rapid salt withdrawal from the surrounding regions slight positive topography above the diapir and shallow folded horizons indicate that it is still rising intermittently the smaller sedom diapir exposed along the western bounding fault of the basin is presently rising and forms a 200 m high ridge its initiation is explained by localized e w extension due monoclinal draping over the edge of a rapidly subsiding basin during the early to middle pleistocene and its continued rise by lateral squeezing due to continued rotation of the amazyahu diagonal fault

tectonic consequences of the collision of the arabian and eurasian plates finite element models abstract the tectonic consequences of northward motion of the arabian plate and its push against the anatolian plate are modeled using a two dimensional plane stress finite element scheme interaction of four plates african arabian anatolian and eurasian and rupture of major faults inside and around anatolia are investigated by assigning northward motions to the arabian 5 cm yr and the african 3 cm yr plates a number of boundary conditions are used to match the known fault motions with theoretical models the faults are modeled as weak zones which could fail by slip strike slip faulting and or separation normal faulting numerical models show that northward convergence of the arabian and african plates alone cannot explain movements on all known faults an additional driving force that would produce about 2 cm yr westward motion of the anatolian plate is required with such a boundary condition added the finite element models produce movements along five major faults north anatolian east anatolian dead sea or levant fracture tuz golu and ecemis with current magnitudes and directions

late neogene erosion of the agulhas moat and the oligocene position of subantarctic surface water abstract the agulhas ridge moat is a scoured depression up to 100 m deep and over 20 km wide flanking the northern side of the agulhas ridge in the southeastern atlantic a core from the moat has been assigned a late oligocene age zone np 24 based on the nannoplankton present scouring was probably caused by westward flowing antarctic bottom water moving in excess of 15 20 cm s 1 possibly during the middle to late pleistocene oxygen isotope analyses indicate a late oligocene surface water temperature between 6 9 and 16 6 c over the core site these paleotemperatures suggest that the subantarctic surface water mass extended farther north during the oligocene modern sea surface temperatures over the site are about 21 c

fracturing process of granite inferred from measurements of spatial and temporal variations in velocity during triaxial deformations fracturing in fine grained homogeneous granite during triaxial deformation was investigated by measuring the spatial and temporal variations of elastic wave velocities velocities along 20 ray paths were measured with 12 piezoelectric transducers attached to a sample under confining pressures up to 400 mpa systematic velocity differences observed among the 20 paths apparently indicate the formation of a dilatant region near the surface of a sample the damaged region formed near the surface due to asymmetric development of dilatancy seemed to play an important role in controlling ultimate failure no evidence of the formation of a crack concentration zone adjacent to the ultimate fracture plane could be found before failure insofar as could be estimated from the velocity variations of elastic waves propagating along its plane however a highly concentrated region of cracks in which the fracture nucleated was generated in the damaged region at stresses of more than 97 99 of the ultimate strength in all the specimens based on tomographic images computed using an algebraic reconstruction technique the elastic waves were strongly affected by the damaged region even under the high confining pressures at which cracks are considered to close

conrad deep a new northern red sea deep origin and implications for continental rifting a previously unknown deep here called conrad deep was discovered during an extensive geophysical survey of the northern red sea in june 1984 conrad deep is located at 27 03 n 34 43 e only 90 km south of the gulf of suez and is the most northern deep yet discovered in the red sea it is located within a well developed axial depression which also contains charcot deep 100 km to the south the axial depression is associated with abundant recent deformation and is situated at the peak of a regional heat flow high extending across the rift conrad deep is typical of the small northern type red sea deep it is 10 km long 2 km wide and has a maximum depth of 1460 m it is associated with high and variable heat flow values and large magnetic anomalies there is no evidence of a dense brine layer detailed analysis of the geophysical data implies that the deep probably results from a very recent

dinoflagellate cyst stratigraphy of the eocene oligocene transition in central italy abstract eight dinoflagellate cyst zones based on the massignano and monte cagnero sections in central italy provide high resolution control for the eocene oligocene e o transition most of these zones have been recognized in the time equivalent contessa highway section and are calibrated against previously established magneto and biostratigraphies the invasion of the mediterranean area by several higher latitude dinoflagellate taxa marks the e o boundary as characterized by the last occurrence of the hantkeninids planktic foraminifers calibrated against a horizon just above the youngest normal polarity event within chron c1 3r quantitative and qualitative dinoflagellate events across the e o boundary allow the recognition of warmer and cooler successive intervals of sea surface temperature in addition to apparent sea level fluctuations our data indicate that latest eocene warm conditions and a sea level highstand were rapidly replaced by short term cooler conditions and a lowstand across the e o boundary horizon following a shortterm warmer interval and a highstand during the earliest oligocene a second cool and lowstand episode occurred this cool interval was of greater magnitude and duration than the one at the e o boundary horizon and may correspond to the globally recognized cooling event reported from the basal part of chron c1 3n

active faulting in the dead sea rift abstract manifestations of late quaternary and holocene faulting were studied in a 500 km long segment of the dead sea transform rift most prominent are left slip faults whose characteristic physiographic features are recognizable along most of the studied segment where these faults bend or are stepped to the left rhomb shaped grabens or pull aparts are produced forming depressions in the reverse situation compressional features such as pressure ridges domes and folds form positive topographic features such structures are combined on a variety of scales ranging from a few hundred meters long to tens of kilometers normal faults sub parallel to the left slip faults produce a trough like valley along much of the dead sea transform but are most prominent along the margins of the large rhomb grabens e g the dead sea trough they apparently record a small component of transverse extension generally their motion is slow young slip did not occur along some segments during the last few 10 4 y elsewhere throws of 10 20 m at least occurred in this period the dead sea transform is seismically active the instrumental and historic records indicate a seismic slip rate of 0 15 0 35 cm y during the last 1000 1500 y while estimates of the average pliocene pleistocene rate are 0 7 1 0 cm y either much creep takes place or the slip rate varies over periods of a few 10 3 y

direct dating of weathering phenomena by 40ar39ar and k ar analysis of supergene k mn oxides abstract potassium bearing manganese oxides cryptomelane k1 2 mn3 mn4 8 o16 xh2oand hollandite k ba 1 2 mn3 mn4 8 o16 xh2o are often authigenically precipitated in weathering profiles the presence of structural potassium in manganese oxides makes these minerals datable by the k ar and 40 ar 39 ar methods dating of these phases allows us to time the progression of oxidation fronts during weathering and pedogenic processes detailed age resolution of the weathering history allows us to use deep weathering profiles as land based stratigraphic records of past climatic and geomorphic events complementing evidence from the marine sedimentary and paleontological record potential problems in manganese oxide dating such as ar and or k losses excess argon 39ar loss by recoil during neutron irradiation contamination by primary minerals resistant to weathering the presence of multiple generations of manganese oxides and proportionately low radiogenic ar yield due to adsorbed atmospheric gases are addressed the k ar and 40 ar 39 ar analytical results indicate that ar and or k losses excess 40ar and 39ar recoil seem not to pose problems in manganese oxide dating this investigation suggests that fine scale laser probe 40 ar 39 ar technique is most appropriate for dating of weathering phenomena because this technique permits us to identify contaminating phases and the presence of multiple generations of weathering minerals in the inherently complex mineral assemblage characteristic of weathering profiles k ar and 40 ar 39 ar dating of supergene k bearing manganese oxides formed during lateritization of archean and proterozoic bedrocks in the caraj s region amazonia brazil indicates that weathering started before 72 6 ma petrographic electron microscope and electron microprobe investigation reveal multiple generations of manganese oxide precipitation k ar and 40 ar 39 ar laser probe step heating results independently confirm the presence of these various generations of manganese oxides age clusters at 65 69 51 56 40 43 33 35 20 24 12 17 ma and zero age 0 2 0 2 ma suggest episodic precipitation of k mn oxides resulting from changing weathering conditions in the amazon throughout the cenozoic k ar and 40 ar 39 ar dating of supergene cryptomelane from weathering profiles in eastern minas gerais southeastern brazil suggests continuous weathering from 10 to 5 6 ma ago possibly reflecting local climatic conditions due to the proximity with the atlantic ocean

effects of a temperature dependent rheology on large scale continental extension the influence of a temperature dependent rheology on large scale continental extension is investigated using a thin viscous sheet model a vertically averaged rheology is used that is consistent with laboratory experiments on power law creep of olivine and that depends exponentially on temperature the behavior of the model depends principally on two parameters the peclet number which describes the relative rates of advection and diffusion of heat and a dimensionless activation energy which controls the temperature dependence of the rheology numerical calculations of such a thin sheet subjected to an extensional boundary condition show the following results at short times following the beginning of extension deformation occurs with negligible change in temperature so that only small changes in lithospheric strength occur due to attenuation of the lithosphere and maximum rates of deformation are located close to the extensional boundary however after a certain time interval thermal diffusion results in lowered temperatures in the lithosphere strongly increasing lithospheric strength and slowing the rate of extension this critical time depends principally on the peclet number and is short compared with the thermal time constant of the lithosphere the changes in strength cause the locus of high extensional strain rates to shift with time from regions of high strain to regions of low strain results of the calculations are compared with observations from the aegean where maximum extensional strains are found in the south near crete but the largest present day extensional strain rates occur about 300 km further north the comparisons support the hypothesis that the observed separation of the loci of maximum strain and maximum present day strain rates in the aegean may be the consequence of changes in lithospheric strength arising from the temperature dependent mechanical properties of lithospheric materials

a braided strike slip model for the northern continuation of the dead sea fault and its implications for levantine tectonics abstract the assumption that the 100 110 km sinistral displacement on the dead sea fault is transmitted northwards along a single structure the yammouneh fault which runs ne sw across lebanon is here reviewed a number of valid objections to this concept exist a more attractive model supported by the limited data available from the area is that the motion is transmitted along a number of faults on this basis the temporary rightward flexure of the levant fracture through lebanon has given rise to a braided strike slip fault complex the yammouneh serrhaya fault system this model overcomes the objections against the older concept and allows the explanation of the mt lebanon bekaa valley anti lebanon complex in terms of transpressive and transtensive blocks a tentative outline of the cenozoic structural evolution of the area in terms of two or more phases of motion along the levant fracture is presented

landslides along the jordanian dead sea coast triggered by the lake level lowering the level of the dead sea lowers 1 m year and this rate is in acceleration the decline is causing one of the major environmental disasters of the twenty first century the freshwater resources management policy of israel jordan and palestine controls the phenomenon since the 1960s the level of this terminal lake dropped by 28 m and its surface shrunk by one third in the 1990s international builders created major tourist resorts and industrial plants along the jordanian shore while during the same period geological hazards triggered by the level lowering spread out from the very beginning of the year 2000 sinkholes subsidence landslides and river erosion damaged infrastructures more and more frequently dikes bridges roads houses factories pipes crops etc until present scientific articles about this ongoing disaster concerned only sinkholes and subsidence phenomena this paper focuses on the landslides issue along the jordanian coast based on a set of ground observations collected since 1999 the dynamics of the triggering factors in relation to the evolution of the hydro geological setting is discussed it is inferred that the recent industrial and tourist infrastructures never took into consideration the very important geotechnical constraints resulting from the dead sea lowering

subsidence and sinkhole hazard assessment in the southern dead sea area jordan the dead sea area is increasingly facing serious subsidence and sinkhole hazards on march 22 2000 the dyke of a two month old major salt evaporation pond located along the shore of the lisan peninsula jordan collapsed over almost two kilometers the pond was set up over unstable new lands that have been progressively emerging during the last three decades in one hour 56 millions m 3 of brine poured out into the northern natural part of the sea here we present data suggesting that the drop of the water level in conjunction with the particular tectonic setting of this area is at least one of the factors that led to the disaster we focused our study over the northern part of the lisan peninsula and ghor al haditha which are two places undergoing the most intense deformations along the jordanian dead sea coast we used the results of a static high precision gravimetric survey to detect subsurface cavities in ghor al haditha we analyzed a interferometric digital terrain model of the recent emerged platform of the lisan peninsula and interpreted radar differential interferograms contemporary with gravity measurements for the peninsula we discuss the possibilities to detect assess and monitor areas prone to collapse on the jordanian side of the southern dead sea coast

rift propagation along the southern dead sea rift gulf of elat abstract the gulf of elat is located at the southern part of the dead sea rift and at the northern part of the red sea geophysical data suggest that it can be divided into three distinct segments northern central and southern on the basis of shallow and deep structures the shallow structure of the gulf of elat as well as of other parts of the dead sea rift is dominated by the presence of grabens which are usually interpreted as pull apart basins formed by the horizontal motion on faults along the dead sea rift this rift is considered to be a plate boundary of the transform type various geophysical data including heat flow gravity magnetics and seismic refraction indicate systematic changes along the length of the gulf of elat the rifting activity is probably more advanced in the southern portion of the gulf this advanced rifting activity propagate from south northward within the southern portion of the gulf of elat the transition from the structure of the red sea to that of the dead sea rift actually takes place of the entire length of the dead sea rift only in the southern part and possibly also in the central part of the gulf of elat is actual mantle upwelling now taking place this upwelling is also associated with a widening of the rift zone at depth the two processes the transform motion and the propagation of rifting activity probably proceed independently

the origin of the dead sea rift abstract the dead sea rift is considered to be a plate boundary of the transform type several key questions regarding its structure and evolution are does sea floor spreading activity propagate from the red sea into the dead sea rift did rifting activity start simultaneously along the entire length of the dead sea rift or did it propagate from several centres why did the initial propagation of the red sea into the gulf of suez stop and an opening of the gulf of elat start using crustal structure data from north africa and the eastern mediterranean and approximating the deformation of the lithosphere by a deformation of a multilayer thin sheet that overlies an inviscid half space the regional stress field in this region was calculated using this approach it is possible to take into account variations of lithospheric thickness and the transition from a continental to an oceanic crust by application of a strain dependent visco elastic model of a solid with damage it is possible to describe the process of creation and evolution of narrow zones of strain rate localization corresponding to the high value of the damage parameter i e fault zones mathematical simulation of the plate motion and faulting process suggests that the dead sea rift was created as a result of a simultaneous propagation of two different transforms one propagated from the red sea through the gulf of elat to the north the other transform started at the collision zone in turkey and propagated to the south

the dead sea transform fault system abstract a new map showing the major features of the dead sea transform fault system based on seismicity satellite imagery geological maps and bathymetric charts is presented special attention is given to the possible northward continuation of the transform system beneath the mediterranean sea near ed damur south of beirut the map shows the dead sea transform system to be a series of offset overlapping left lateral transform faults with a rhombochasm between each pair the system has similarities with the equatorial fracture zones in the atlantic ocean throughout the dead sea transform system is considered in its regional setting i e as extending from the red sea spreading centre in the south to the eurasian collision zone in the north it is suggested that it may intersect the latter somewhere east of cyprus making that area the northernmost termination of the dead sea transform system

late eocene to early oligocene dinoflagellate cysts from the priabonian type area northeast italy biostratigraphy and paleoenvironmental interpretation abstract marginal marine late eocene through early oligocene dinoflagellate cyst successions have been studied from the type area of the priabonian stage northeast italy the results allow the recognition of dinoflagellate zones previously defined in bio and magnetostratigraphically well calibrated pelagic sequences from central italy thus providing a first order correlation of the priabonian stage to the standard chronostratigraphic scale with unprecedented precision within this detailed biostratigraphic framework successive shifts in the composition of the dinoflagellate cyst assemblages are interpreted in terms of sea level and sea surface temperature sst fluctuations the evaluation of ecologically and sedimentary controlled changes in the composition of dinoflagellate cyst assemblages in combination with sequence stratigraphic analysis allows the reconstruction of third and fourth order sea level fluctuations the third order sea level fluctuations appear to correspond to exxon cycles ta4 1 4 5 the stratigraphically and palaeoenvironmentally important late eocene dinoflagellate cyst species glaphyrocysta priabonensis sp nov is formally described

fault dissolution front relations and the dead sea sinkhole problem abstract there are two conflicting models of sinkhole development along the dead sea ds the first one considers structural control on sinkholes constraining them to tectonic lineaments this hypothesis is based on seismic reflection studies suggesting that sinkholes are the surface manifestations of active neotectonic faults that may serve as conduits for under saturated groundwater enabling its access across aquiclude layers another hypothesis based on results of multidisciplinary geophysical studies considers the salt edge dissolution front as the major site of sinkhole formation this hypothesis associates sinkholes with karstification of the salt edge by deep and shallow undersaturated groundwater our recent seismic reflection and surface wave studies suggest that salt formed along the active neotectonic faults sinkholes form in a narrow strip 60 100 m wide along a paleo shoreline constrained by faults and alluvial fans which determined the edge of the salt layer this scenario reconciles the two major competing frameworks for sinkhole formation

similarities between planktonic and larger foraminiferal evolutionary trends through paleogene paleoceanographic changes abstract the paleogene evolutionary records of planktonic foraminifera and larger benthic foraminifera show parallel patterns in development that may in part reflect changes in nutrient flux to surface waters following the terminal cretaceous extinctions faunas were dominated by a few cosmopolitan opportunistic species more specialized k strategists in both groups diversified during the paleocene dominating into the early eocene consistent with he globally mild climatic regime and probable limited rates of nutrient flux to surface waters high latitude cooling intensified in the middle eocene promoting diversification of less specialized taxa characteristic of cooler and deeper waters higher latitudes meridional upwelling zones and boundary currents geographic ranges of warm water taxa diminished and fragmented yet many species survived thus global diversities during the middle eocene were the highest in the cenozoic as cooling and increased rates of nutrient flux further intensified in the late eocene extinction rates of warm water planktonic and larger benthic species exceeded origination rates of cooler water and less specialized forms so diversity dropped to intermediate levels where it remained through the late eocene and oligocene previous observations that planktonic foraminiferal faunas dominated by warm water taxa are often replaced by cool water faunas even though oxygen isotopes only recorded relatively minor cooling can be reconciled by the explanation that the biotic communities responded to changes in trophic resources and euphotic habitats that accompany the temperature reduction as well as to temperature change itself

internal structure of the dead sea leaky transform rift in relation to plate kinematics abstract the structures along the dead sea transform rift are related to the motions of the sinai and arabia plates which border it and to the irregularities of their boundaries the total slip was 105 km left lateral but the present structures were formed mainly during the last 40 km of slip which probably occurred in the plio pleistocene along the southern half of the transform the strike slip motion takes place on en echelon faults this produces rhomb shaped grabens or pull aparts which are sometimes composite and in which there is local crustal separation thus much of the transform is leaky these structures occur in a morpho tectonic rift valley delimited by normal faults which express a small component of transverse extension along a few segments the shape of the transform is such that lateral motion produces local transverse compression the geometric relations of the structures along the transform define an eulerian pole of relative plate motions at 32 8 n 22 6 e 0 5 the older motion was somewhat different and is described by a pole located about 5 west of the above then the component of transverse extension and crustal separation was much smaller than now while local transverse compression was more important the northern half of the dead sea transform has an irregular shape and the bordering plates did not remain rigid as lateral motion continued here transverse compression is often important

deep drop down basin in the southern dead sea abstract the large dead sea graben is located within the dead sea fault a plate boundary of the transform type the graben is composed of two basins the northern one is occupied by a lake about 300 m deep and has a sedimentary fill of about 6 km the southern dead sea basin however is unusually deep with about 14 km of sedimentary fill the geometry of the southern dead sea basin is anomalous along the entire dead sea fault we suggest that the southern dead sea basin was formed during the first stage of the formation of the dead sea fault when the tips of propagating faults one from the collision front in the north and one from the red sea in the south met in this area the fault tips overlapped and curved towards each other isolating a block of crust and lithosphere that dropped into the mantle geophysical data indicate that the basin is probably bordered on all sides by vertical faults that cut deep into basement the deep part of the southern dead sea basin is not a pull apart but instead a drop down basin the salton trough in california is probably another example of such a basin

eocene and early oligocene micropaleontology and paleoenvironments in se umbria italy a detailed study based on calcareous nannofossils and planktonic and benthic foraminifera has been carried out on five sections in the scaglia group of the umbrian region visso and cascia areas central italy these sections are characterized by continuous pelagic sedimentation and are constituted mainly of marls marly limestones and limestones of early eocene to early oligocene age calcareous turbidites with shallow water skeletal debris discharged from the latium abruzzi carbonate platform are interbedded within the pelagic sequences the biostratigraphic study based on calcareous nannofossils and planktonic foraminifera confirmed the continuous succession of standard events and revealed some new ones these results allow us to refine the biostratigraphic resolution with a very good correlation between calcareous nannofossil and planktonic foraminiferal zonations the major features and events recognized are the early middle eocene boundary zones p9 p10 is characterized by the first occurrence fo of hantkeninids by abundant thick walled globigerinatheka g senni and by spinose acarininids a decrease has been noted in planoconvex morozovellids and an increase of low spired subbotinids the benthic assemblage shows a great variability with an increase in the zone p11 of the large heterolepa and cibicidoides this is an event of worldwide significance in the calcareous nannofossils the fo of nannotetrina sp was used to define the lower boundary of zone cp13 instead of n fulgens because poor preservation prevented identification at the specific level the fo of reticulofenestra umbilica marking the lower boundary of zone cp14 occurs in the upper part of zone p11 the zone p13 was recognized indirectly because of the absence of the index species orbulinoides beckmanni the base of the zone is close to the fo of turborotalia cerroazulensis and is defined by an increase of catapsydrax sp and by the last occurrence lo of acarinina bullbrooki the top of the zone is defined by an increase of the high spired subbotinids of the s corpulenta group and the disappearance of morozovella spinulosa the middle late eocene boundary zones p14 p15 is characterized by the extinction of the spinose acarininids and of the smooth walled planorotalites from zone p13 to zone p15 there is a replacement in the benthic assemblages in fact pleurostomella heterolepa and anomalinoides capitata characterize these zones bolivinids become abundant and uvigerinids appear around the p14 p15 boundary the late eocene is characterized by an increase of subbotinids with abortive chambers and of the turborotalia cerroazulensis lineage hantkeninids and cribohantkeninids are rare particularly c inflata the fo of istmolithus recurvus has been noted at the base of zone p16 within this zone globigerinatheka index and turborotalia cunialensis coexist the lo of g index is associated with a strong decrease of representatives of the genus globigerinatheka at the same level of the lo of g index the coeval extinctions of discoaster barbadiensis and discoaster saipanensis are noted just above this level within zone p17 the lo of t cerroazulensis lineage t cocoaensis and t cunialensis has been recognized the eocene oligocene boundary is defined by planktonic foraminifera at the extinction level of hantkeninids and cribrohantkeninids shortly following that of the t cerroazulensis group

correction to a thin viscous sheet model for continental deformation summary the governing equation derived by england mckenzie for the deformation of a thin viscous shell contains an error we give the correct derivation here and correct those figures where the change makes a visible difference the correct results differ quantitatively from those of england mckenzie but their conclusions are not affected

distributed damage faulting and friction we present a formulation for mechanical modeling of geological processes in the seismogenic crust using damage rheology the seismogenic layer is treated as an elastic medium where distributed damage modifying the elastic stiffness evolves as a function of the deformation history the model damage rheology is based on thermodynamic principles and fundamental observations of rock deformation the theoretical analysis leads to a kinetic equation for damage evolution having two principal coefficients the first is a criterion for the transition between strength degradation and recovering healing and is related to friction the second is a rate coefficient of damage evolution which can have different values or functional forms for positive degradation and negative healing evolution we constrain these coefficients by fitting model predictions to laboratory data including coefficient of friction in sawcut setting intact strength in fracture experiments first yielding in faulting experiments under three dimensional strain onset and evolution of acoustic emission and dynamic instability the model damage rheology accounts for many realistic features of three dimensional deformation fields associated with an earthquake cycle these include aseismic deformation gradual strength degradation development of process zones and branching faults around high damage areas strain localization brittle failure and state dependent friction some properties of the model damage rheology e g cyclic stick slip behavior with possible accompanying creep are illustrated with simplified analytical results the developments of the paper provide an internally consistent framework for simulating long histories of crustal deformation and studying the coupled evolution of regional earthquakes and faults this is done in a follow up work

active tectonics of the alpine himalayan belt between western turkey and pakistan summary over 80 new fault plane solutions combined with satellite imagery as well as both modern and historical observations of earthquake faulting are used to investigate the active tectonics of the middle east between western turkey and pakistan the deformation of the western part of this region is dominated by the movement of continental material laterally away from the lake van region in eastern turkey this movement helps to avoid crustal thickening in the van region and allows some of the shortening between arabia and eurasia to be taken up by the thrusting of continental material over oceanic type basement in the southern caspian mediterranean makran and black sea thus central turkey bounded by the north and east anatolian strike slip faults is moving west from the van region and overrides the eastern mediterranean at two intermediate depth seismic zones one extending between antalya bay and southern cyprus and the other further west in the hellenic trench the motion of northern iran eastwards from the van region is achieved mainly by a conjugate system of strike slip faults and leads to the low angle thrusting of iran over the southern caspian sea the seismicity of the caucasus shows predominantly shortening perpendicular to the regional strike but there is also some minor elongation along the strike of the belt as the causcasus overrides the caspian and black seas the deformation of the eastern part of this region is dominated by the shortening of iran against the stable borders of turkmenistan and afghanistan the north east direction of compression seen in zagros is also seen in north east iran and the kopet dag where the shortening is taken up by a combination of strike slip and thrust faulting large structural as well as palaeomagnetic rotations are likely to have occurred in ne iran as a result of this style of deformation north south strike slip faults in southern iran allow some movement of material away from the collision zone in ne iran towards the makran subduction zone where genuinely intermediate depth seismicity is seen within this broad deforming belt large areas such as central turkey nw iran azerbaijan central iran and the southern caspian appear to be almost aseismic and therefore to behave as relatively rigid blocks surrounded by active belts 200 300 km wide the motion of these blocks can usefully be described by poles of rotation the poles presented in this paper predict motions consistent with those observed and also predict the opening of the gulf of iskenderun ne of cyprus the change within the zagros mountains from strike slip faulting in the nw to intense thrusting in the se and the relatively feeble seismicity in se iran baluchistan this description also explains why the north south structures along the iran afghanistan border do not cut the east west ranges of the makran within the active belts surrounding the relatively aseismic blocks a continuum approach is needed for a description of the deformation even though motions at the surface may be concentrated on faults the evolution of fault systems within the active zones is controlled by geometric constraints such as the requirement that simultaneously active faults do not in general intersect many of the active processes discussed in this paper particularly large scale rotations and lateral movement along the regional strike are likely to have caused substantial complexities in older mountain belts and should be accounted for in any reconstructions of them

age of supergene oxidation and enrichment in the chilean porphyry copper province twenty five samples of supergene alunite collected from deeply developed supergene profiles in porphyry copper deposits and prospects between latitudes 20 degrees and 27 degrees s in northern chile yield k ar ages ranging from about 34 to 14 ma therefore supergene oxidation and enrichment processes were active from the early oligocene to the middle miocene a minimum of 20 m y supergene activity at individual deposits lasted for at least 0 4 to 6 2 m y the early oligocene supergene activity affected deposits in the paleocene porphyry copper belt whereas early and middle miocene supergene processes are documented in the early cretaceous paleocene and late eocene to early oligocene porphyry copper belts middle miocene oxidation also affected the oldest epithermal gold silver deposits in the maricunga belt farther east supergene activity commenced no less than 11 m y after generation of each porphyry copper deposit because of the time required to unroof the copper bearing parts of the system supergene activity throughout northern chile ceased at approximately 14 ma the geologic features of deposits and prospects and their morphotectonic positions present latitudes and present elevations display no obvious correlations with the supergene chronology exploration for major cumulative enrichment blankets should not be carried out either beneath thick sequences of piedmont gravels or ignimbrites of oligocene through middle miocene age unless their accumulation is demonstrably late in the documented history of supergene activity or in porphyry copper provinces such as those of central chile and northwestern argentina which formed after approximately 14 ma the uplift responsible for efficient cumulative copper enrichment is difficult to correlate convincingly with the brief pulses of compressive tectonism postulated for northern chile and contiguous areas unless their effects were much more prolonged intensifying aridity is confirmed as the likely reason for the cessation of supergene activity in northern chile and tectonic uplift was its most probable cause however more fundamental global controls producing a period of chemical weathering followed by worldwide dessication also may have played a role

hierarchic three dimensional structure and slip partitioning in the western dead sea pull apart 1 rifted basins are bounded by marginal belts with fault networks and flexures we analyze the internal structure of such a belt the western margins of the dead sea basin this basin is 150 km long 15 20 km wide with more than 10 km of sediment fill and it is currently subsiding due to slip of the dead sea pull apart the western margin of the dead sea basin is an elongated n s belt with an intricate three dimensional 3 d pattern of zigzag faults flexures and joints the dominant structures are four sets of oblique normal faults arranged in orthorhombic symmetry the faults are steep with prevalent strike directions of nnw and nne large flexures developed along and above these faults forming tilted blocks and localized asymmetric folds two sets of subvertical joints that dominate the area trend nne and nnw subparallel to the strikes of the dominant fault sets the parallel relations between these structures at all scales suggest that they formed during a single tectonic phase three dimensional fault modeling reveals a 3 d strain field with a large vertical shortening a minor horizontal shortening in n s direction belt parallel and a large horizontal e w extension basinward the calculated stress fields associated with the zigzag fault segments are compatible with the observed fault parallel flexures further the calculations predict the formation of local tensile belts above the faults and these tensile belts could explain the penecontemporaneous development of the two joint sets architecture similar to the western margins of the dead sea basin is likely to develop on rifted margins wherever 3 d deformation is required by the rifting kinematics

a synthetic stratigraphic model of foreland basin development the processes of erosion and deposition must be included in foreland basin models to predict correctly basin geometry and stratigraphy we present a synthetic stratigraphic model of the development of nonmarine foreland basins that predicts progressive geometry topography and facies patterns in the model steady crustal shortening occurs according to a wedgethickening model erosion and deposition follow a diffusive process and the lithosphere is compensated elastically erosion and deposition are controlled by the transport coefficients r of the diffusion equation for a range of thrust velocities and lithospheric rigidities transport coefficients are of order 102 103 m yr in the mountain belt these values are much higher than those derived from the study of scarp degradation in the sedimentary basin transport coefficients of order 104 m2 yr are appropriate and are compatible with previous studies of fluvial and deltaic deposition rapid thrusting results in a narrow underfilled basin while slow thrusting results in a wide overfilled basin in addition by varying the erosional and depositional transport coefficients while holding other parameters constant we generate both overfilled and underfilled basins these results suggest that changes in the rate of thrust loading the climate or the source rock lithology can create stratigraphic signatures that have been interpreted to record viscoelastic relaxation of the lithosphere clearly to understand either the long term behavior of the lithosphere or to interpret orogenic history from preserved foreland strata the manner in which a basin was filled must be considered we apply the model to the evolution of the modern sub andean foreland and find that an erosional transport coefficient of 3000 m2 yr and a depositional transport coefficient of 20 000 m2 yr successfully predict the observed basin geometry

lake levels and sequence stratigraphy of lake lisan the late pleistocene precursor of the dead sea lake lisan the late pleistocene precursor of the dead sea existed from 70 000 to 15 000 yr b p it evolved through frequent water level fluctuations which reflected the regional hydrological and climatic conditions we determined the water level of the lake for the time interval 55 000 15 000 cal yr b p by mapping offshore nearshore and fan delta sediments by application of sequence stratigraphy methods and by dating with radiocarbon and u series methods during the studied time interval the lake level fluctuated between 340 and 160 m below mean sea level msl between 55 000 and 30 000 cal yr b p the lake evolved through short term fluctuations around 280 290 m below msl punctuated at 48 000 43 000 cal yr b p by a drop event to at least 340 m below msl at 27 000 cal yr b p the lake began to rise sharply reaching its maximum elevation of about 164 m below msl between 26 000 and 23 000 cal yr b p then it began dropping and reached 300 m below msl at 15 000 cal yr b p during the holocene the lake corresponding to the present dead sea stabilized at ca 400 m below msl with minor fluctuations the hypsometric curve of the basin indicates that large changes in lake area are expected at above 403 and 385 m below msl at these elevations the lake level is buffered lake lisan was always higher than 380 m below msl indicating a significantly large water contribution to the basin the long and repetitious periods of stabilization at 280 290 m below msl during lake lisan time indicate hydrological control combined with the existence of a physical sill at this elevation crossing this sill could not have been achieved without a dramatic increase in the total water input to the lake as occurred during the fast and intense lake rise from 280 to 160 m below msl at 27 000 cal yr b p

geology and evolution of the southern dead sea fault with emphasis on subsurface structure the dead sea fault is an active transform fault linking opening in the red sea with collision in the taurus zagros mountains motion is left lateral and estimated at approximately 5 7 mm year 1 the fault is seismically active and can be divided into two distinct structural segments this study focuses on the southern segment based mainly on the wealth of geophysical data owing to transtention caused by oblique slip and the overlapping of en echelon fault strands a series of pull apart basins were formed along the fault s length these basins are long and deep reaching in places more than 10 km deep they are characterized by extensional compressional and asymmetrical structures varying in size from large scale defining the general structure of the dead sea fault valley to small scale defining the internal structure this study examines the internal structure of these basins from south to north and summarizes the state of knowledge to date

dead sea sinkholes an ever developing hazard sinkhole development along the western shore of the dead sea became a major concern in 1990 with the appearance of a series of holes 2 15 m diameter and up to 7 m deep in the newe zohar area one of these sinkholes below the asphalt surface of the main road along the western shore of the dead sea was opened by a passing bus repeated infilling and collapse of these holes indicated the extent of this ongoing process and the significance of this developing hazard since then sinkholes have developed in other areas including qalia ein samar ein gedi and mineral beach

oligocene miocene age of aridity in the atacama desert revealed by exposure dating of erosion sensitive landforms the age of onset of hyperaridity in the atacama desert chile which is needed to validate geological and climatological concepts has been heretofore uncertain measurement of cosmogenic 21 ne in clasts from erosion sensitive sediment surfaces in northern chile shows that these surfaces have been barely affected by erosion since 25 ma surface exposure ages of sediment clasts give replicate values at 25 20 and 14 ma and individual values at 37 and 9 ma predominantly hyperarid conditions are required to preserve these oldest continuously exposed surfaces on earth our findings are compatible with the hypothesis that the onset of aridity in the atacama desert could be the reason for rather than the consequence of uplift of the high andes

sinkhole hazards along the eastern dead sea shoreline area jordan a geological and geotechnical consideration for the last four decades the level of the dead sea has been subjected to continual variation which among other important factors has led to the occurrence of much subsidence and many sinkholes in the southern dead sea area sinkhole activities occurred repetitively and were observed in open farms across roads near dwellings and near an existing factory thus causing a serious threat to the locals and farmers of the area and their properties this paper presents the main results from detailed geological and geotechnical studies of this area aerial photo interpretation and borehole drilling aided these studies parallel geophysical investigations vertical electrical sounding and seismic refraction and hydrological and hydrogeological studies were made by others in the same area to also investigate this phenomenon it was found that sinkholes are aligned to and follow old water channels and are concentrated parallel to the recent shoreline of the dead sea the development of subsurface cavities is associated mainly with the variation in the level of the dead sea over the four past decades the presence of regional salt intrusion under the surface of salt beds the fluctuation of the water table and continuous dissolution and the active tectonism of the area moreover this work showed that the area is still under active sinkhole hazards and other parts of the area will be inevitably affected by sinkholes in the future no practical engineering solution to this problem is feasible

deformation along the yammuneh the restraining bend of the dead sea transform paleomagnetic data and kinematic implications a simple geometrical model shows that the plate margin along the restraining bend segment of the transform plate boundary be deformed in order to accommodate overlap of the crust this model predicts both the maximum width of the deformed zone and the magnitude of deformation when the general geometry of the plate margin is known as well as the plate slip vector and the amount of cumulative displacement this idea has been tested along the plate margin of the yammuneh restraining bend of the dead sea transform the plate margin has been deformed by nne folding parallel to the restraining bend and by east west trending right lateral strike slip faults paleomagnetic measurements yield counterclockwise rotation of r r 61 0 9 6 and f f 23 4 17 2 the paleomagnetic rotational data and fault kinematic suggest that the mechanism which accommodates regional left lateral shear is simultaneous right lateral strike slip faulting on secondary faults and block rotation the magnitude of deformation is the same as that predicted by the model which is 100 shortening in a direction parallel to the plate slip vector and negligible deformation in a direction parallel to the transform the large amount of rotation implies that probably more than one fault set is involved and present day seismic activity is the current manifestation of this crustal deformation process if this prediction is correct then the current deformation of the plate margin is accommodated by more favorable newly formed nnw right lateral strike slip faults