ice flux divergence anomalies on 79north glacier greenland 1 the ice flux divergence of a glacier is an important quantity to examine because it determines the rate of temporal change of its thickness here we combine high resolution ice surface velocity observations of nioghalvfjerdsfjorden 79north glacier a major outlet glacier in north greenland with a dense grid of ice thickness data collected with an airborne radar sounder in 1998 to examine its ice flux divergence we detect large variations up to 100 m yr in flux divergence on grounded ice that are incompatible with what we know of the glacier surface mass balance basal mass balance and thinning rate we examine the hypothesis that these anomalies are due to the three dimensional flow of ice around and atop bumps and hollows in basal topography by comparing the flux divergence of three dimensional numerical models with its surface equivalent we find that three dimensional effects have only a small contribution to the observed anomalies on the other hand if we degrade the spatial resolution of the data to 10 km the anomalies disappear further analysis shows that the source of the anomalies is not the ice velocity data but the interpolation of multiple tracks of ice thickness data onto a regular grid using a scheme here block kriging that does not conserve mass or ice flux this problem is not unique to 79north glacier but is common to all conventional ice thickness surveys of glaciers and ice sheets and fundamentally limits the application of ice thickness grids to high resolution numerical modeling of glacier flow

present day south american climate abstract this paper documents the main features of the climate and climate variability over south america on the basis of instrumental observations gathered during the 20th century it should provide a modern reference framework for paleoclimate research in south america targeting high resolution proxies over the past few centuries several datasets suitable for present day climate research are first described highlighting their advantages as well as their limitations we then provide a basic physical understanding of the mean annual cycle of the precipitation and atmospheric circulation over the continent and the adjacent oceans in particular the diversity of precipitation temperature and wind patterns is interpreted in terms of the long meridional extent of the continent and the disruption of the large scale circulation caused by the andes cordillera the contrasting oceanic boundary conditions and the landmass distribution similarly the intensity and timing of the interannual and interdecadal climatic fluctuations exhibit considerable geographical dependence as some regions are more influenced by large scale phenomena rooted in the tropical oceans while others are more influenced by high latitude phenomena the impact of these large scale phenomena over south america is documented by a regression analysis between selected atmospheric indices and the precipitation and temperature fields we have included a discussion on the seasonality and long term stability of such impacts and complemented our general description by an updated review of the literature on climate variability over specific regions

structural variation within the himalayan fold and thrust belt a case study from the kohat potwar fold thrust belt of pakistan abstract the kohat and potwar fold thrust belts kp ftb in pakistan exhibit structural variations over 250 km along strike within the himalayan fold and thrust system our 3d deformation model shows that kohat surface structures evolved above an active roof thrust in eocene evaporites the ramp forming duplexes in the kohat were stacked and passively transported toward the foreland above new ramps resulting in up to 5 km of thickening between the two decollements ramps from the kohat extend into the potwar as thrust tips of fault propagation folds the basement slope changes from flat 1 below the southern part corresponding to the change in structural style and complexity of the kp ftb the kalabagh fault zone linking the two belts is interpreted as a zone of complex dextral strike slip rotational faulting salt expulsed from the hanging walls of normal faults and under synclines in the kalabagh fault zone moved toward the footwall of normal faults accumulated in the cores of anticlines and formed lobe structures at the deformation front the fundamental reasons for the variable structural styles are changes in decollement strength basement slope preexisting normal faulting presence of a secondary decollement and spatially variable salt mobility and accumulation

accelerating shrinkage of patagonian glaciers from the little ice age ad 1870 to 2011 davies b j glasser n f 2012 accelerating shrinkage of patagonian glaciers from the little ice age similar to ad 1870 to 2011 journal of glaciology 58 212 1063 1084

late pleistocene rise of the sedom diapir on the backdrop of water level fluctuations of lake lisan dead sea basin abstract during the last glacial between 70 and 15 kyr b p large parts of the dead sea rift were inundated by lake lisan we use the established history of lake lisan water level fluctuations as a tool for determining the rates and styles of the salt tectonic uplift of the sedom salt diapir our reconstruction is based on new accurate mc icpms u th ages of lake lisan deposits overlying the top of mount sedom the surface expression of the sedom diapir these sediments range in age between 46 4 and 15 5 kyr b p comparison of the present elevations of the studied lisan sediments to the lake lisan level curve indicates that these sediments were uplifted to their present elevations due to the diapiric rise of mount sedom during the late pleistocene lisan sediments older than 46 4 kyr b p were not found yet on mount sedom suggesting that it was exposed prior to that time we correlate the exposure phase of mount sedom with the lowest stand of lake lisan between 48 and 43 kyr b p during which previously deposited sediments were eroded the age of the top of the lisan formation on mount sedom is 15 5 kyr b p and it has been uplifted by 75 m since then

emplacement of a fold nappe betic orogen southern spain the aguilon nappe sierra alhamilla southeast spain is a north closing recumbent isoclinal fold with a greatly thinned lower limb this large scale geometry can be demonstrated using small scale structures the fold nappe is detached along the lower limb and lies on a carpet of mylonitic schist mylonite and cataclasite formation of the nappe must have involved northward relative transport a point of current controversy in the betic zone during emplacement the nappe underwent extensive ductile deformation accomplished partly by pressure solution of silica in the highly deformed footwall rocks however quartz was deformed by crystal plastic processes the change in deformational mechanism suggests a downward increase in deviatoric stress which is compatible with a gravitational mechanism of nappe emplacement the core of the low grade nappe is occupied by medium grade schist the abrupt change in grade suggests that the schist contact is an extensional fault that excised part of the original metamorphic zonation and was subsequently refolded in the nappe such relations are common in the betic zone and suggest extension by listric normal faulting a characteristic feature of nappes emplaced by gravity spreading

analysis of folding and deformation within layered evaporites in blocks bm s 8 9 santos basin brazil the sao paulo plateau in the deepwater santos basin is the site of numerous recent pre salt petroleum discoveries the area is characterized by a thick sequence of layered evaporites comprising primarily halite with subordinate anhydrite and carnalite and trace amounts of other minerals the sequence is divided into six stratigraphic packages three relatively competent beams containing the bulk of the stronger anhydrite and three relatively weak detachment layers observed structural styles range from the simple to the complex including upright open folds inclined thrusted folds recumbent isoclinal folds sheath folds and superposed folds mul tiple detachments lead to polyharmonic folding disharmonic folding and overtightened folds major anticlinal structures contain acoustically transparent material surrounding disrupted highly deformed pieces of the lower two beams the deformation is non coaxial with anticlines forming a polygonal pattern and fold hinges that are highly curvilinear the sao paulo plateau is a contractional province that formed in response to proximal extension at the albian gap during convergent gravity gliding spreading of the margin shortening possibly began during the waning stages of evaporite deposition but the bulk of the movement occurred during the santonian mid eocene the evaporite sequence shortened much more than the cover because of extreme updip attenuation and consequent basinwards flow beneath the cover deeper levels of evaporite exhibit more shortening due to strain partitioning across internal detachments

a detailed look at diapir piercement onto the ocean floor new evidence from santos basin offshore brazil abstract diapir piercement through the ocean floor marks the final stages of a dynamic migration path once exhumed a diapir extrudes from the seafloor placing an obstacle for the flow of ocean bottom currents while the hydrodynamic response of the flow has been previously studied the detailed depositional and weathering modifications involved in the piercement process are less understood to bridge this gap we gathered already available multibeam bathymetric data multichannel 2d seismic reflection profiles and collected new single channel chirp profiles acoustic doppler current profiler data and sediment samples across santos basin offshore brazil in this region the processes connecting the uppermost subsurface with the lowermost section of the water column are unknown data show three main stages of diapir exhumation pre syn and post piercement into the seafloor extensional faults crown the pre exposed diapir before its piercement through the seafloor ocean bottom currents rework the top of the faults to form elongated depressions the bottom currents tightly detour the diapir during and after its exposure at the seafloor this interaction forms a drift and moat contourite depositional pattern our high resolution data allow relating these morphologies to seafloor processes and distinguishing them from other reflector geometries related to diapir flank deformation such as outward dipping of reflections we further use this geometrical distinction to suggest a key for interpreting the exposure versus burial history of other diapirs worldwide

a promising location in patagonia for paleoclimate and paleoenvironmental reconstructions revealed by a shallow firn core from monte san valentin northern patagonia icefield chile the study of past climate variability from ice core investigations has been largely developed both in polar areas over the past decades and more recently in tropical regions specifically along the south american andes between 0 and 20 s however a large gap still remains at mid latitudes in the southern hemisphere in this framework a 15 3 m long shallow firn core has been extracted in march 2005 from the summit plateau of monte san valentin 3747 m 46 35 s 73 19 w in the northern patagonia icefield to test its potential for paleoclimate and paleoenvironmental reconstructions the firn temperature is 11 9 c at 10 m depth allowing to expect well preserved both chemical and isotopic signals unperturbed by water percolation the dating of the core on the basis of a multi proxy approach combining annual layer counting and radionuclide measurements shows that past environment and climate can be reconstructed back to the mid 1960s a mean annual snow accumulation rate of 36 3 cm year 1 i e 19 2 g cm 2 year 1 is inferred with a snow density varying between 0 35 and 0 6 g cm 3 which is much lower than accumulation rates previously reported in patagonia at lower elevations here we present and discuss high resolution profiles of the isotopic composition of the snow and selected chemical markers these data provide original information on environmental conditions prevailing over southern patagonia in terms of air masses trajectories and origins and biogeochemical reservoirs our main conclusion is that the san valentin site is not only influenced by air masses originating from the southern pacific and directly transported by the prevailing west winds but also by inputs from south american continental sources from the e ne sometimes mixed with circumpolar aged air masses the relative influence of these two very distinct source areas changing at the interannual timescale thus this site should offer a wealth of information regarding south pacific argentinian ne e areas and antarctic climate variability

internal structure kinematics and growth of a salt wall insights from 3 d seismic data the detailed kinematics of natural salt walls remain elusive because such structures are typically poorly exposed at outcrop only partly exposed in mine workings and diapiric salt is typically poorly reflective in seismic data we use three dimensional seismic and borehole data from offshore brazil to investigate how structural styles vary along strike within a spectacularly well imaged salt wall deformed layering in the salt allows us to map complex seismic scale structures in the wall within the wall s relatively simple external shape is a range of previously undocumented structural styles produced by 1 initial upwelling and formation of a wall parallel anticline due to regional extension and differential overburden load 2 breaching of the anticline rayleigh taylor overturn and emplacement of an intrasalt allochthonous sheet driven by a density inversion and 3 internal thrusting of the mature diapir caused by regional compression this study is arguably the first detailed documentation of the internal structure and kinematics of a natural salt wall highlighting the presence of abruptly varying intrasalt structural styles the structures identified and the inferred kinematics suggest that given specific mechanical stratigraphy density driven overturn within salt diapirs can play a key role in their growth

diapiric growth within an early jurassic rift basin the tazoult salt wall central high atlas morocco the central high atlas morocco constitutes a diapiric province that hosts a complex array of elongated diapirs and minibasins that formed during the lower jurassic rift of the atlas basin this paper aims to study the structure and growth evolution of the tazoult diapiric wall located in the central high atlas by means of structural and sedimentological fieldwork integrated with remote sensing mapping the tazoult salt wall is a 20 km long x 3 km wide ne sw trending ridge that exposes upper triassic red beds and basalts along its core the succession flanking the salt wall ranges from hettangian to bajocian ages displaying spectacular sedimentary wedges in the se and nw flanks the hettangian early sinemurian carbonates mainly crop out as blocks embedded in the core rocks the 1 km thick pliensbachian platform carbonates display large subvertical flap structures along the flanks of the tazoult salt wall with unconformities bounding tapered composite halokinetic sequences in contrast the 2 5 km thick late pliensbachian aalenian mixed deposits form tabular composite halokinetic sequences displaying small scale hook halokinetic sequences passive diapirism resulted in the lateral extrusion of the evaporite bearing rocks to form an allochthonous salt sheet towards the adjacent se amezrai minibasin the bajocian platform carbonates partially fossilized the tazoult salt wall and thus constitute a key horizon to constrain the timing of diapir growth and discriminate diapirism from alpine shortening the pliensbachian carbonate platform evolved as a long flap structure during the early growth of the tazoult salt wall well before the onset of the alpine shortening

ice loss from the southern patagonian ice field south america between 2000 and 2012 1 a time series composed of 156 aster derived digital elevation models dems and a radar penetration bias corrected version of the shuttle radar topography mission srtm dem is used to derive ice surface height and volume changes at the southern patagonian ice field spi in southern south america the observations made between february 2000 and march 2012 indicate that the ice field is rapidly losing volume at many of the largest outlet glaciers and in most cases thinning extends to the highest elevations of the ice field mass loss is occurring at a rate of 20 0 1 2 gt a 1 which when summed with mass loss at the adjacent northern patagonian ice field results in a combined rate of 24 4 1 4 gt a 1 equivalent to 0 067 0 004 mm a 1of sea level rise our decade long mass loss rates are substantially higher than those derived during the last three decades of the 20th century but are in good agreement with recent grace observations our volume loss estimate is sensitive to constraints applied to the amount of thickening in the accumulation zone new field measurements and a continued dem time series will be required to refine our estimates

unraveling rift margin evolution and escarpment development ages along the dead sea fault using cosmogenic burial ages abstract the dead sea fault dsf is one of the most active plate boundaries in the world understanding the quaternary history and sediments of the dsf requires investigation into the neogene development of this plate boundary dsf lateral motion preceded significant extension and rift morphology by 10 ma sediments of the sedom formation dated here between 5 0 0 5 ma and 6 2 2 1 inf ma yielded extremely low 10be concentrations and 26al is absent these reflect the antiquity of the sediments deposited in the sedom lagoon which evolved in a subdued landscape and was connected to the mediterranean sea the base of the overlying amora formation deposited in the terminal amora lake which developed under increasing relief that promoted escarpment incision was dated at 3 3 0 8 0 9 ma burial ages of fluvial sediments within caves 3 4 0 2 ma and 3 6 0 4 ma represent the timing of initial incision initial dsf topography coincides with the earliest red sea morb s and the east anatolian fault initiation these suggest a change in the relative arabian african plate motion this change introduced the rifting component to the dsf followed by a significant subsidence margin uplift and a reorganization of relief and drainage pattern in the region resulting in the topographic framework observed today

soft sediment deformation within seismogenic slumps of the dead sea basin abstract the late pleistocene lisan formation preserved next to the dead sea provides exceptional 3 d exposures of folds and faults generated during soft sediment slumping and deformation it is possible to generate a range of four different scenarios associated with overprinting in a single slump event the progressive evolution of slump systems may be broadly categorised into initiation translation cessation relaxation and compaction phases thrust packages typically define piggyback sequences during slump translation with back steepening of imbricate faults leading to collapse of folds back up the regional palaeoslope detailed evaluation of slumped horizons may also permit structures to be traced across apparently separate and distinct slumped units the recognition that slumps may be reworked by younger seismically triggered events suggests that in some cases the seismic recurrence interval may be shorter than previously anticipated

anatomy of mushroom shaped diapirs we produced more than 100 mushroom shaped diapirs in eight centrifuged models under acceleration of 1200 g the modelling results allow natural examples to be recognized mushroom diapirs have an overhanging bulb fringed by one or more skirts which can curl inward to form vortices capable of entraining cover material to various degrees most of the internal folds are downward facing the oldest buoyant unit occurs in the skirt and in the diapiric core younger buoyant units or their immediate cover are infolded in crescentic patterns external mushroom diapirs have skirts that infold cover material with greater maturity the skirts can curl inward to form an external vortex entraining cover in contrast internal mushroom diapirs have skirts confined entirely within the intrusion again with greater maturity these confined skirts may curl inward but they entrain only diapiric material internal mushroom structure results from toroidal circulation confined within the diapir where isoviscosity prevails external mushroom structure results where source and entrained cover have similar effective viscosities entrained inclusions of more permeable country rock threaten the integrity of a mined cavern by creating a plumbing system

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

contribution of the patagonia icefields of south america to sea level rise digital elevation models of the northern and southern patagonia icefields of south america generated from the 2000 shuttle radar topography mission were compared with earlier cartography to estimate the volume change of the largest 63 glaciers during the period 1968 1975 2000 these glaciers lost ice at a rate equivalent to a sea level rise of 0 042 0 002 millimeters per year in the more recent years 1995 2000 average ice thinning rates have more than doubled to an equivalent sea level rise of 0 105 0 011 millimeters per year the glaciers are thinning more quickly than can be explained by warmer air temperatures and decreased precipitation and their contribution to sea level per unit area is larger than that of alaska glaciers

annular modes in the extratropical circulation part i month to month variability the leading modes of variability of the extratropical circulation in both hemispheres are characterized by deep zonally symmetric or annular structures with geopotential height perturbations of opposing signs in the polar cap region and in the surrounding zonal ring centered near 458 latitude the structure and dynamics of the southern hemisphere sh annular mode have been extensively documented whereas the existence of a northern hemisphere nh mode herein referred to as the arctic oscillation ao has only recently been recognized like the sh mode the ao can be defined as the leading empirical orthogonal function of the sea level pressure field or of the zonally symmetric geopotential height or zonal wind fields in this paper the structure and seasonality of the nh and sh modes are compared based on data from the national centers for environmental prediction national center for atmospheric research reanalysis and supplementary datasets the structures of the nh and sh annular modes are shown to be remarkably similar not only in the zonally averaged geopotential height and zonal wind fields but in the mean meridional circulations as well both exist year round in the troposphere but they amplify with height upward into the stratosphere during those seasons in which the strength of the zonal flow is conducive to strong planetary wave mean flow interaction midwinter in the nh and late spring in the sh during these active seasons the annular modes modulate the strength of the lagrangian mean circulation in the lower stratosphere total column ozone and tropopause height over mid and high latitudes and the strength of the trade winds of their respective hemispheres the nh mode also contains an embedded planetary wave signature with expressions in surface air temperature precipitation total column ozone and tropopause height it is argued that the horizontal temperature advection by the perturbed zonal mean zonal wind field in the lower troposphere is instrumental in forcing this pattern a companion paper documents the striking resemblance between the structure of the annular modes and observed climate trends over the past few decades

sedimentary and structural controls on seismogenic slumping within mass transport deposits from the dead sea basin abstract comparatively little work has been undertaken on how sedimentary environments and facies changes can influence detailed structural development in slump sheets associated with mass transport deposits mtds the nature of downslope deformation at the leading edge of mtds is currently debated in terms of frontally emergent frontally confined and open toed models an opportunity to study and address these issues occurs within the dead sea basin where six individual slump sheets s1 s6 form mtds in the late pleistocene lisan formation all six slumps which are separated from one another by undeformed beds are traced towards the ne for up to 1 km and each shows a change in sedimentary facies from detrital rich in the sw to more aragonite rich in the ne the detrital rich facies is sourced predominantly from the rift margin 1 5 km further sw while the aragonite rich facies represents evaporitic precipitation in the hyper saline lake lisan the stacked system of mtds translates downslope towards the ne and follows a pre determined sequence controlled by the sedimentary facies each individual slump roots downwards into underlying detrital rich layers and displays a greater detrital content towards the sw which is marked by increasing folding while increasing aragonite content towards the ne is associated with more discrete thrusts the mtds thin downslope towards the ne until they pass laterally into undeformed beds at the toe the amount of contraction also reduces downslope from a maximum of 50 to

numerical modeling on progressive internal deformation in down built diapirs a two dimensional finite difference code fdcon is used to estimate the finite deformationwithin a down builtdiapir the geometry of the down built diapir is fixed by using two rigid rectangular o

seismically triggered soft sediment deformation structures close to a major strike slip fault system in the eastern alps hirlatz cave austria abstract we investigate episodic soft sediment deformation structures cross cut by normal faults preserved in unlithified finely laminated calcite rich sediments in the hirlatz cave in the northern calcareous alps austria these sediments comprise varve like alternations of brighter carbonate quartz rich layers and darker clay mineral rich layers the deformed sediments contain abundant millimeter to centimeter scale soft sediment structures load casts ball and pillow structures sheet slumps thrust faults and folds erosive channels filled with slides and chaotic slumps after deposition and soft sediment deformation normal faults developed within the entire sedimentary succession an event that probably correlates with an offset of c 10 cm of the passage wall above the outcrop our major conclusions are i the sediments have a glacial origin and were deposited in the hirlatz cave under phreatic fluvio lacustrine conditions the deposition and the soft sediment deformation occurred most likely during the last glaciation i e around 25 ka ago ii the liquefaction and formation of the soft sediment structures in water saturated stratified layers was triggered by episodic seismic events iii the internally deformed sediments were later displaced by normal faults iv a possible source for the seismic events is the active sinistral salzach ennstal mariazeller puchberger semp strike slip fault which is located about 10 km south of the outcrop and plays a major role in accommodating the extrusion of the eastern alps towards the pannonian basin to our knowledge the described structures are the first report of liquefaction and seismically induced soft sediment deformations in quaternary sediments in the eastern alps

formation and dating of a salt pillar in mount sedom diapir israel the formation of a 20 m high salt pillar in mount sedom dead sea area was analyzed and dated and these results were complemented by measurement of present uplift rate because the pillar is a part of the actively rising sedom diapir contrary to earlier assumptions which stated that the salt pillar was formed by direct rainfall the observed solutional notches and morphology of the neighboring chasm indicate that the salt pillar is due to a karstic cave that collapsed the uppermost part of the cave still carried an underground ephemeral stream 4000 yr ago as indicated by six 14c dates of wood washed into the highest cave level the sudden collapse that left the isolated salt pillar was probably triggered by a catastrophic earthquake the measured uplift rate 9 3 3 5 mm yr shows that when the pillar formed it was much closer to the base of mount sedom

determining the exposure age of a karst landscape an extensive salt karst system has developed in mount sedom salt diapir israel during the holocene multilevel vadose caves were14c dated using wood fragments embedded in alluvial deposits the oldest date of each cave is used to constrain the age of the salt exposure the upper portion of the southeastern escarpment was the first to rise above base level 7100 yr b p caves in the surrounding area indicate gradual landscape exposure around this initial karstified area between 7000 and 4000 yr b p the northern part of the mountain experienced a similar exposure history lagging some 3000 yr after the southern part this lag may be attributed to the narrow width of the diapir in the north which increases viscous drag at the borders of the rising diapir

u series and oxygen isotope chronology of the mid pleistocene lake amora dead sea basin abstract this study establishes for the first time the chronology and limnological history of lake amora dead sea basin israel whose deposits the amora formation comprise one of the longest exposed lacustrine records of the pleistocene time the amora formation consists of sequences of laminated primary aragonite and silty detritus ca sulfate minerals halite and clastic units this sedimentary sequence was uplifted and tilted by the rising sedom salt diapir exposing 320 m of sediments on the eastern flanks of mt sedom the arubotaim cave ac section the chronology of the ac section is based on u disequilibrium dating 230th 234u and 234u 238u ages combined with floating 18 o stratigraphy and paleomagnetic constraints the determination of the 230th 234u ages required significant corrections to account for detrital th and u these corrections were performed on individual samples and on suites of samples from several stratigraphic horizons the most reliable corrected ages were used to construct an age elevation model that was further tuned to the oxygen isotope record of east mediterranean foraminifers based on the long term similarity between the sea and lake oxygen isotope archives the combined u series 18 o age elevation model indicates that the exposed amora sequence was deposited between 740 and 70 ka covering seven glacial interglacial cycles marine isotope stages mis 18 to 5 taking the last glacial lake lisan and the holocene dead sea lacustrine systems as analogs of the depositional limnological environment of lake amora the latter oscillated between wet glacial and more arid interglacial conditions represented by sequences of primary evaporites aragonite and gypsum that require enhanced supply of freshwater to the lakes and clastic sediments respectively the lake evolved from a stage of rapid shifts between high and low stand conditions during 740 to 550 ka to a sabkha like environment that existed at the ac site between 550 and 420 ka this stage was terminated by a dry spell represented by massive halite deposition at 420 ka mis12 11 during mis10 6 the lake fluctuated between lower and higher stands reaching its highest stand conditions at the late glacial mis6 after which a significant lake level decline corresponds to the transition to the last interglacial mis5 low stand lake represented by the uppermost part of the formation 18 o values in the primary aragonite range between 6 0 and 1 3 shifting cyclically between glacial and interglacial intervals the lowest 18 o values are observed during interglacial stages and may reflect short and intense humid episodes that intermittently interrupted the overall arid conditions these humid episodes expressed also by enhanced deposition of travertines and speleothems seem to characterize the negev desert and in contrast to the overall dominance of the atlantic mediterranean system of rain patterns in the dead sea basin some humid episodes during interglacials may be traced to southern sources

fold and thrust systems in mass transport deposits abstract improvements in seismic reflection data from gravity driven fold and thrust systems developed in offshore mass transport deposits mtds reveal a number of significant features relating to displacement along thrusts however the data are still limited by the resolution of the seismic method and are unable to provide detail of local fold and thrust processes investigation of exceptional gravity driven contractional structures forming part of mtds in lacustrine deposits of the dead sea basin enables us to present the first detailed outcrop analysis of fold and thrust systems cutting unlithified soft sediments we employ a range of established geometric techniques to our case study including dip isogons fault propagation fold charts and displacement distance diagrams previously developed for investigation of thrusts and folds in lithified rocks fault propagation folds in unlithified sediments display tighter interlimb angles compared to models developed for lithified sequences values of stretch which compares the relative thickness of equivalent hangingwall and footwall sequences measured along the fault plane may be as low as only 0 3 which is significantly less than the minimum 0 5 values reported from thrusts cutting lithified rocks and reflects the extreme variation in stratigraphic thickness around thrust related folds we suggest that the simple shear component of deformation in unlithified sediments may modify the forelimb thickness and interlimb angles to a greater extent than in lithified rocks the average spacing of thrust ramps and the thickness of the thrust sequence display an approximate 5 1 ratio across a range of scales in mtds in general thicker hangingwall and footwall sequences occur with larger thrust displacements although displacement patterns on thrusts cutting unlithified yet cohesive sediments are more variable than those in lithified rocks line length restoration of thrust systems in mtds reveals 42 shortening which reduces to 35 in overlying beds a 23 reduction in shortening by folding and thrusting along individual thrusts suggests that heterogeneous lateral compaction may increase by 10 towards the sediment surface thrust systems cutting unlithified sediments display distinct steps in cumulative displacement distance plots representing increased rates of slip along the floor thrust while displacement distance plots along individual thrusts also reveal horizontal steps relating to lithological variation competent units cut by thrust ramps may display the greatest displacement which then progressively reduces both upward and sometimes downward along the ramp this relationship demonstrates that ramps do not necessarily propagate upwards from the underlying flat as in some traditional models but rather initiate by offset of competent horizons in the hangingwall of the detachment critical taper angles in mtds may be an order of magnitude less than in accretionary complexes or lithified rocks overall thrusts cutting unlithified sediments in mtds display more variable displacement and more pronounced displacement gradients toward fault tips compared to thrusts cutting lithified sequences

insar mapping and modelling of an active iranian salt extrusion abstract interferometric synthetic aperture radar insar imaging is a powerful technique that is increasingly used to extract detailed 3d information on earth surface structures including exposed diapiric surfaces we have used insar to map for the first time the cumulative surface deformation in a 6 km 6 km region surrounding an active salt diapir syahoo and its associated surface salt flow or namakier exposed in the zagros mountains of southern iran images provided by the european space agency were acquired in 12 increments ranging in length between 35 and 1248 days over a 14 year interval between july 1992 and may 2006 the deformation of the salt surface is non steady with extrapolated rates of displacement varying between surficial uplifts of 1 4 mm day 1 511 mm a 1 and subsidence of 2 2 mm day 1 803 mm a 1 growth of a central topographic dome occurs following short wet intervals to create a salt fountain morphology which then slowly decays during the intervening long dry periods salt associated with dynamic bulging9 of the central dome during wet intervals may flow laterally via gravity spreading into the surrounding salt sheet resulting in deflation and subsidence of the dome which is counteracted by growth and inflation of the adjacent namakiers salt bulges9 that migrate down the namakier resulting in local inflationary and deflationary cycles of the surface may be regarded as episodic pulses of gravity spreading areas of inflation and deflation are also observed to commonly reverse during dry to wet periods as the overall salt system effectively self regulates as it continually strives for dynamic equilibrium as long as the source of salt remains undepleted gravity spreading of the dome ultimately results in more buoyancy driven salt flowing up the diapiric neck to replenish and feed the extrusion and maintain the gross fountain morphology

exploring the relative contribution of mineralogy and cpo to the seismic velocity anisotropy of evaporites we present the influence of mineralogy and microstructure on the seismic velocity anisotropy of evaporites bulk elastic properties and seismic velocities are calculated for a suite of 20 natural evaporite samples which consist mainly of halite anhydrite and gypsum they exhibit strong fabrics as a result of tectonic and diagenetic processes sample mineralogy and crystallographic preferred orientation cpo were obtained with the electron backscatter diffraction ebsd technique and the data used for seismic velocity calculations bulk seismic properties for polymineralic evaporites were evaluated with a rock recipe approach ultrasonic velocity measurements were also taken on cube shaped samples to assess the contribution of grain scale shape preferred orientation spo to the total seismic anisotropy the sample results suggest that cpo is responsible for a significant fraction of the bulk seismic properties in agreement with observations from previous studies results from the rock recipe indicate that increasing modal proportion of anhydrite grains can lead to a greater seismic anisotropy of a halite dominated rock conversely it can lead to a smaller seismic anisotropy degree of a gypsum dominated rock until an estimated threshold proportion after which anisotropy increases again the difference between the predicted anisotropy due to cpo and the anisotropy measured with ultrasonic velocities is attributed to the spo and grain boundary effects in these evaporites

reply to charrach 2019 comment on internal deformation and uplift rate of salt walls detected by a displaced dissolution surface dead sea basin by zucker et al 2019

committed sea level rise for the next century from greenland ice sheet dynamics during the past decade we use a three dimensional higher order ice flow model and a realistic initial condition to simulate dynamic perturbations to the greenland ice sheet during the last decade and to assess their contribution to sea level by 2100 starting from our initial condition we apply a time series of observationally constrained dynamic perturbations at the marine termini of greenland s three largest outlet glaciers jakobshavn isbrae helheim glacier and kangerdlugssuaq glacier the initial and long term diffusive thinning within each glacier catchment is then integrated spatially and temporally to calculate a minimum sea level contribution of approximately 1 0 4 mm from these three glaciers by 2100 based on scaling arguments we extend our modeling to all of greenland and estimate a minimum dynamic sea level contribution of approximately 6 2 mm by 2100 this estimate of committed sea level rise is a minimum because it ignores mass loss due to future changes in ice sheet dynamics or surface mass balance importantly 75 of this value is from the long term diffusive response of the ice sheet suggesting that the majority of sea level rise from greenland dynamics during the past decade is yet to come assuming similar and recurring forcing in future decades and a self similar ice dynamical response we estimate an upper bound of 45 mm of sea level rise from greenland dynamics by 2100 these estimates are constrained by recent observations of dynamic mass loss in greenland and by realistic model behavior that accounts for both the long term cumulative mass loss and its decay following episodic boundary forcing

large scale control on the patagonian climate abstractpatagonia located in southern south america is a vast and remote region holding a rich variety of past environmental records but a small number of meteorological stations precipitation over this region is mostly produced by disturbances embedded in the westerly flow and is strongly modified by the austral andes uplift on the windward side leads to hyperhumid conditions along the pacific coast and the western slope of the andes in contrast downslope subsidence dries the eastern plains leading to arid highly evaporative conditions the authors investigate the dependence of patagonia s local climate precipitation and near surface air temperature year to year variability on large scale circulation anomalies using results from a 30 yr long high resolution numerical simulation variations of the low level zonal wind account for a large fraction of the rainfall variability at synoptic and interannual time scales zonal wind also controls the amplitude of the air temperature annual cycle by changi

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

cycles of passive versus active diapirism recorded along an exposed salt wall abstract although it has long been recognised that passive salt diapirism may encompass sub ordinate cycles of active diapirism where sedimentary overburden is periodically shed off the roof of the rising salt there has been very little study of this process around exposed salt halite diapirs however the late miocene pliocene sedom salt wall on the western side of the dead sea basin presents an opportunity for detailed outcrop analysis of diapiric salt and the associated depositional and deformational record of its movement during both passive and active phases of diapirism the sub seismic scale record of diapirism includes sedimentary breccia horizons interpreted to reflect sediments being shed off the crest of the growing salt wall together with exceptional preservation of rotated unconformities and growth faults areas of more pronounced dips directed towards the salt wall are capped by unconformities and interpreted to represent withdrawal basins within the overburden that extend for at least 1500 m from the salt margin elsewhere broad areas of upturn directed away from the salt extend for up to 1250 m and are marked by a sequence of rotated unconformities which are interpreted to bound halokinetic sequences the margins of the salt wall are defined by steep extensional boundary faults that cut upturned strata and have enabled rapid and active uplift of the salt since the holocene the sedom salt wall therefore charts the transition from passive growth marked by withdrawal basins growth faults and unconformities to more active intrusion associated with major boundary faults that enable the rapid uplift of overburden deposited on top of the salt to 100 m above regional elevations in the past 43 ka individual cycles of passive and active diapirism occur over timescales of

upslope verging back thrusts developed during downslope directed slumping of mass transport deposits acknowledgements sm acknowledges the israel science foundation isf grant no 1436 14 and the ministry of national infrastructures energy and water resources grant 214 17 027 rw was supported by the israel science foundation isf grant no 1245 11

regional trends in active diapirism revealed by mountain range scale insar time series 1 we construct an orogen wide insar time series over the zagros mountains and eastern markan subduction zone in southern iran from 19 envisat tracks spanning 2003 2010 we observe active salt diapirism of the infra cambrian hormuz salt at 20 locations and identify several diapirs that are not moving all active diapirs reach the surface within the asmari limestone or older rock units while we do not observe any active diapirism occurring within younger exposures reflecting a complex vertical accumulation of the basal salt and reactivation of diapirs by erosion diapir reactivation of this sort may be a critical factor affecting the feasibility of sequestering nuclear waste and co2 in evaporite sequences over geologic time scales the distribution of active diapirism is indifferent to increases in mean elevation suggesting a relatively uniform thickness of the zagros fold belt above the basal salt with steps in topography driven by basement thickening we do not observe aseismic uplift of anticlines because rates are likely below the detection threshold of our time series this suggests that uplift is accommodated at small rates 2 3 mm yr over numerous structures instead of focused at the deformation front

internal kinematics of salt diapirs the internal structure of intrusive and extrusive salt bodies elucidates their external shape and the mechanism and history of diapiric emplacement information relevant to petroleum exploration trace amounts of brine can act like heat to weaken salt and promote geologic creep by solution transfer mechanisms we compare natural strain markers in salt with the artificial markers used by fluid dynamicists stream lines are the smooth flow paths followed by fluid particles stream surfaces separate flow laminae and contain the stream lines grain shape fabrics in salt anneal readily and have strain memories so short that lineations map the stream lines and foliations map the stream surfaces of the last stages of deformation by contrast larger structures like folded beddi g have much longer strain memories as a result multiple generations of tonguelike recumbent flow folds formed by unsteady flow in the mother source layer rotate to upright sheath folds or spines in the stems of diapirs here they are constricted and refolded into steep curtain folds to form crescentic and other interference patterns visible in the roofs of salt mines mature diapirs can form crestal bulbs which may be balloon or mushroom shaped and which potentially form larger petroleum traps than previously supposed screens of country rock may be entrained between the stem and peripheral overhanging lobes caused by episodic sedimentation

deformation of intrasalt beds recorded by magnetic fabrics funding information israel science foundation isf grant number 868 17 israeli government grant number 40706 israel science foundation grant number 868 17

dependence of century scale projections of the greenland ice sheet on its thermal regime observations show that the greenland ice sheet has been losing mass at an increasing rate over the past few decades which makes it a major contributor to sea level rise here we use a threedimensional higher order ice flow model adaptive mesh refinement and inverse methods to accurately reproduce the present day ice flow of the greenland ice sheet we investigate the effect of the ice thermal regime on 1 basal sliding inversion and 2 projections over the next 100 years we show that steady state temperatures based on present day conditions allow a reasonable representation of the thermal regime and that both basal conditions and century scale projections are weakly sensitive to small changes in the initial temperature field compared with changes in atmospheric conditions or basal sliding we conclude that although more englacial temperature measurements should be acquired to validate the models and a better estimation of geothermal heat flux is needed it is reasonable to use steady state temperature profiles for short term projections as external forcings remain the main drivers of the changes occurring in greenland 2014 publishing technology

3d seismic study of complex intra salt deformation an example from the upper permian zechstein 3 stringer western dutch offshore mostoftheinformationonsubsurfaceevaporiticstructurescomesfrom3dseismicdata however this data only provide limited information about the internal structure of the evaporites which is known from salt mines and salt diapir outcrops brittle intra salt layers carbonate anhy drite clay ofatleast 10 m thicknessform goodreflectors inevaporites but the structure and dynam ics of such stringers in the salt movement are poorly understood in this study we investigate the intra salt zechstein 3 z3 stringer from 3d seismic data in an area offshore the netherlands observations show complex deformation including boudinage folding and stacking reflections from thin and steep stringer parts are strongly reduced and we present different structural models andtestsofthese wecompareourobservationstostructuralmodelsfromsaltminesandanalogue numerical models of intra salt deformation a smoothed representation of the upper surface of the stringer fragments follows the shape of top salt but smaller scale stringer geometries strongly differ from this and imply boudinage the imaged disharmonic patterns of constrictional folds pro vide evidence for the complexity of the intra salt in agreement with observations in salt mines this may be explained by interaction of the layered salt rheology complex three dimensional salt flow different phases and styles of basement tectonics and movement of the overburden

fracture pattern analysis as a tool for constraining the interaction between regional and diapir related stress fields poza de la sal diapir basque pyrenees spain during diapir evolution the local stress field results from the interaction between diapirrelated and remote regional stress fields the fracture pattern hosted in the overburden can register this evolving interaction providing significant insights for the unravelling of the diapir kinematics in this work we present the example of the poza de la sal diapir which is a salt diapir that pierces the synorogenic deposits of the basque pyrenees the integrated analysis of mesostructural data which includes field collected faults joints and fracture traces digitalized on high resolution orthophotos allowed us to establish an evolutionary model for the stress field around diapirs the presented data support the idea that during diapir evolution stress fields evolve from mostly regional related to mostly diapir related contrasting with other geological data seismic data geological map and cross section we observe that different methods provide complementary information coherent with the proposed evolutionary model of the poza de la sal diapir the study of fracture development associated with the growth of salt diapirs is of interest for both academic and industrial purposes in fact fractures play an important role in fluid flow and its accumulation in salt diapir related reservoirs johnson bredeson 1971 koestler ehrmann 1987 davison et al 2000a b on the other hand the analysis of fracture patterns is useful to constrain the host structure evolution thorbjornsen dunne 1997 tavani et al 2008 and accordingly can provide useful information for understanding diapir kinematics alsop 1996 stewart 2006 yin groshong 2007 yin et al 2009 the fracture pattern associated with salt diapirs and in general with doming structures is characterized by two classes of elements radial and concentric fig 1a b e g parker mcdowell 1955 withjack 1979 squyres et al 1992 branney 1995 malthe sorenssen et al 1999 rowan et al 1999 2003 davison et al 2000a b freed et al 2001 stewart 2006 this pattern is documented in simple structures where the remote stress field is negligible in relation to the diapir related stress fields when such a condition is not verified the interaction of these two stress fields leads to the development of more complex patterns ode 1957 withjack scheiner 1982 studies of interacting regional and punctual stress fields e g ode 1957 indicate that the influence of diapir induced stress progressively reduces away from the dome i e the punctual structure as a consequence far from the diapir the fracture pattern responds to the remote stress field and approaching the diapir the fracture pattern tends to be radial and concentric fig 1c although these patterns have been observed by several authors in different structures withjack scheiner 1982 mege masson 1996 ernst et al 2003 there are no detailed field studies focusing on this topic in this work we present a simple 2d theoretical stress field model where the stress tensor resulting from the interaction between remote and diapirrelated stress fields is assumed to be for a fixed distance from the diapir centre a 2 2 matrix provided by the sum of the horizontal components of the two stress tensors the eigenvectors associated with this matrix are assumed to be the principal axes of the local stress field the working hypothesis is that if the stress field changes the azimuth of fractures joints developed under these stress fields also change by understanding interactions between diapir related and regional stress fields we can predict the azimuth of the developed fractures to test the validity of this theoretical model we have applied it to a well exposed salt diapir located at the western pyrenees poza de la sal diapir this is a near circular diapir with a mainly carbonate overburden affected by a complex pattern of fractures results of this comparison indicate that despite its simplicity the provided stress model is a useful tool for understanding the kinematics of salt diapirs accordingly in this paper we provide from alsop g i archer s g hartley a j grant n t hodgkinson r eds 2012 salt tectonics sediments and prospectivity geological society london special publications 363 521 532 http dx doi org 10 1144 sp363 25 the geological society of london 2012 publishing disclaimer www geolsoc org uk pub ethics guidelines to obtain a fracture pattern using the theoretical model presented to complement other techniques of investigation such as field work or 3d seismic interpretations

syn to post rift diapirism and minibasins of the central high atlas morocco the changing face of a mountain belt the atlas mountains are classically regarded as a failed mesozoic rift arm subject to alpine inversion folding and thrusting here we present new integrated structural and sedimentological studies that have revealed numerous early middle jurassic diapiric ridges and minibasins characterized by distinctive halokinetic structures diachroneity in halokinesis is observed across the central high atlas waning first in the sw during the early middle jurassic jbel azourki and tazoult ridges and continuing to late middle jurassic towards the ne imilchil region the halokinetic structures are readily differentiated from the effects of later alpine deformation allowing a new picture of the central high atlas to emerge the most pervasive deformation in the central high atlas is associated with early middle jurassic diapirism whereas the impact of alpine inversion is mostly focused at the basin margins this new understanding helps explain previously problematic aspects of the atlas mountains which we now recognize as an exceptionally well exposed natural laboratory for understanding the interactions between halokinesis tectonics and sedimentation

ice flow modelling to constrain the surface mass balance and ice discharge of san rafael glacier northern patagonia icefield we simulate the ice dynamics of the san rafael glacier srg in the northern patagonia icefield 46 7 s 73 5 w using glacier geometry obtained by airborne gravity measurements the full stokes ice flow model elmer ice is initialized using an inverse method to infer the basal friction coefficient from a satellite derived surface velocity mosaic the high surface velocities 7 6 km a 1 near the glacier front are explained by low basal shear stresses 1 km a 1 we force the model using different surface mass balance scenarios taken or adapted from previous studies and geodetic elevation changes between 2000 and 2012 our results suggest that previous estimates of average surface mass balance over the entire glacier were likely too high mainly due to an overestimation in the accumulation area we propose that most of srg imbalance is due to the large ice discharge 0 83 0 08 gt a 1 and a slightly positive 0 08 0 06 gt a 1 the committed mass loss estimate over the next century is 0 34 0 03 gt a 1 this study demonstrates that surface mass balance estimates and glacier wastage projections can be improved using a physically based ice flow model

submarine salt glacier of northern tunisia a case of triassic salt mobility in north african cretaceous passive margin stratigraphical sedimentological and structural data and a bouguer gravity map of medjez el bab meb in northern tunisia are used to illustrate a cretaceous example of salt extrusion on a passive continental margin located just south of the teboursouk thrust front a preferential decollement surface used by the continuous tertiary shortening in this area the meb structure is a simple n40 e box anticline removing the two tertiary foldings eocene and miocene leads to the exposure of the original feature of a simple submarine salt glacier the triassic salt rocks appear as an albian interstratified body between two cretaceous series with stratigraphic normal polarity suggesting a bedding parallel extrusion at the sediment water interface of the triassic salt in cretaceous times the formation of such salt extrusions are associated with extensional faulting probably both in the cover and basement the presence of a slope and basinwards salt flow this scenario is similar to the allochthonous salt described in other salt provinces characterizing passive margins

further evidence for early lunar magnetism from troctolite 76535 the earliest history of the lunar dynamo is largely unknown and has important implications for the thermal state of the moon and the physics of dynamo generation the lunar sample with the oldest known paleomagnetic record is the 4 25 billion year old ga troctolite 76535 previous studies of unoriented subsamples of 76535 found evidence for a dynamo field with a paleointensity of several tens of microteslas however the lack of mutual subsample orientation prevented a demonstration that the magnetization was unidirectional a key property of thermoremanent magnetization here we report further alternating field demagnetization on three mutually oriented subsamples of 76535 as well as new pressure remanent magnetization experiments to help rule out shock magnetization we also describe new 40ar 39ar thermochronometry and cosmogenic neon measurements that better constrain the rock s thermal history although the rock is unbrecciated unshocked and slowly cooled its demagnetization behavior is not ideal due to spurious remanence acquisition despite this limitation all three subsamples record a high coercivity magnetization oriented in nearly the same direction implying that they were magnetized by a unidirectional field on the moon we find no evidence for shock remanence and our thermochronometry calculations show no significant reheating events since 4249 12 million years ago ma we infer a field paleointensity of approximately 20 40 t supporting the previous conclusion that a lunar dynamo existed at 4 25 ga the timing of this field supports an early dynamo powered by thermal or thermochemical core convection and or a mechanical dynamo but marginally excludes a dynamo delayed by thermal blanketing from radiogenic element rich magma ocean cumulates

salt tectonics sediments and prospectivity an introduction salt is a crystalline aggregate of the mineral halite which forms in restricted environments where the hydrodynamic balance is dominated by evaporation the term is used non descriptively to incorporate all evaporitic deposits that are mobile in the subsurface it is the mobility of salt that makes it such an interesting and complex material to study as a rock salt is almost unique in that it can deform rapidly under geological conditions reacting on slopes 0 58 dip and behaving much like a viscous fluid salt has a negligible yield strength and so is easy to deform principally by differential sedimentary or tectonic loading significant differences in rheology and behavioural characteristics exist between the individual evaporitic deposits wet salt deforms largely by diffusion creep especially under low strain rates and when differential stresses are low basins that contain salt therefore evolve and deform more complexly than basins where salt is absent the addition of halokinetic processes to the geodynamic history of a basin can lead to a plethora of architectures and geometries the rich variety of resultant morphologies have considerable economic as well as academic interest historically salt has played an important role in petroleum exploration since the spindletop dome discovery in beaumont texas in 1906 today much of the prime interest in salt tectonics still derives from the petroleum industry because many of the world s largest hydrocarbon provinces reside in salt related sedimentary basins e g gulf of mexico north sea campos basin lower congo basin santos basin and zagros an understanding of salt and how it influences tectonics and sedimentation is therefore critical to effective and efficient petroleum exploration within rift basins in particular salt is seen to orchestrate the petroleum system through halokinesis it creates structural traps counter regional dips on continental margins and it can carry or entrain adjacent lithologies via rafting salt influences synand post kinematic sediment dispersal patterns and reservoir distribution and can therefore be important for the creation of stratigraphic traps it can also form top and side seals to hydrocarbon accumulations and act as a seal to fluid migration and charge at a more regional scale salt may also dramatically affect the thermal evolution of sediments due to its high thermal conductivity a thick layer of salt cools sediments that lie below it while heating sediments above it this effect cannot be underestimated as it helps provide the favourable conditions for source rock maturation in the deepwater gulf of mexico and santos basins even though sedimentary overburden may be 5 km or more in thickness salt can also impact reservoir quality the role of salt in the diagenetic history of reservoirs through its control on hydrothermal pore waters is a crucial element in the risking of the deepwater palaeogene play of the gulf of mexico for example salt continues to kinetically evolve through time not only by the classical roller diapir pedestal canopy collapse progression but also with varying rates of deformation in response to changing sedimentation rates and patterns the relative timing of salt movement and its impact on source reservoir trap seal and timing often governs the prospectivity in saltrelated basins beyond the realm of petroleum salt is also used as a resource for potash gypsum and nitrates and has the potential to be employed as a repository for radioactive waste or a top seal to sequestered co2

velocities and driving pressures of clay rich sediments injected into clastic dykes during earthquakes summary we studied the velocities and driving pressures associated with clastic dyke formation in the ami az plain where hundreds of clastic dykes cross cut the soft rock of the late pleistocene lacustrine lisan formation within the seismically active dead sea basin flow of clastic material into fractures and opening of the fractures are two mechanisms that occur during earthquake induced clastic dyke emplacement two analytic models were established based on field observations and experimental viscosity tests to estimate the velocities and driving pressures that were associated with dyke emplacement a a channel flow for upward injection of a clay water mixture and b a profile of fracture dilation based on the elastic theory analysis the two models predict that pressures between 1 and 10 mpa are generated in the source layer and dykes in the last stage of the injection process in addition the channel flow model predicts that the injection velocity reaches metres to tens of metres per second and the emplacement time of the clastic dykes is on a scale of seconds it is suggested that the high pressure values represent the static stress drop during earthquake events or represent dynamic stresses resulting from the seismic waves which passed through the soft lacustrine rocks in both cases the predicted high pressure values indicate that the clastic dyke was emplaced in close proximity of an active segment of the dead sea fault during the late pleistocene holocene

internal deformation and uplift rate of salt walls detected by a displaced dissolution surface dead sea basin abstract despite numerous studies examining salt tectonics relatively little is known regarding the internal movements of salt units that build diapirs such as the mount sedom salt wall in this study we focus on the recent deformation processes of southern mount sedom we choose a fossilized dissolution surface known as the salt mirror of mount sedom as a structural datum in order to understand and resolve the deformation processes during the last 14 ka surveying the salt mirror surface from outcrops and natural dissolution chimney caves sets constraints for the structural map our results indicate that the salt wall rises as a telescopic antenna with the internal salt units sliding across each other along bedding plane slip faults influenced by the subsiding dead sea basin the flow of the rising salt forms an elongated ridge distinctly asymmetric across its short dimension the uplift rate of the southern part of mount sedom throughout the last 14 ka is at least 11 mm yr this result is somewhat higher but in a fair agreement with the results of previous studies that assessed the rates in a variety of methods the telescopic behavior of the salt wall represents a mode of internal deformation that might be applicable to other salt diapirs worldwide

mapping of glacial motion and surface topography of hielo patagonico norte chile using satellite sar l band interferometry data the first topographic and ice motion maps of the northwestern flank of hielo patagonico norte hpn northern patagonia icefield in chile were produced using satellite synthetic aperture interferometric radar data acquired by nasa s spaceborne imaging radar c instrument in october 1994 the topographic map has a io m vertical precision with a 30 m horizontal spacing which should be sufficient to serve as a reference for monitoring future mass changes of the icefield the ice motion map is accurate to within 4 mm d or 1 ma the radar derived surface topography and ice velocity are used to estimate the ice discharge from the accumulation area of four outlet glaciers and the calving flux and mass balance of glaciar san rafael the results demonstrate the use of sar interferometry for monitoring glaciological parameters on a spatial and temporal scale unattainable by any other means

global sea level contribution from the patagonian icefields since the little ice age maximum the melting of mountain glaciers and ice caps is expected to contribute significantly to sea level rise in the twenty first century 1 3 although the magnitude of this contribution is not fully constrained glaciers in the patagonian icefields of south america are thought to have contributed about 10 of the total sea level rise attributable to mountain glaciers in the past 50 years 3 however it is unclear whether recent rates of glacier recession in patagonia are unusual relative to the past few centuries here we reconstruct the recession of these glaciers using remote sensing and field determinations of trimline and terminal moraine location we estimate that the north patagonian icefield has lost 103 20 7 km 3 of ice since its late holocene peak extent in ad 1870 and that the south patagonian icefield has lost 503 101 1 km 3 since its peak in ad 1650 this equates to a sea level contribution of 0 0018 0 0004 mm yr 1 since 1870 from the north and 0 0034 0 0007 mm yr 1 since 1650 from the south the centennial rates of sea level contribution we derive are one order of magnitude lower than estimates of melting over the past 50 years 3 even when we account for possible thinning above the trimline we conclude that the melt rate and sea level contribution of the patagonian icefields increased markedly in the twentieth century

structural micro structural and kinematic analyses of channel flow in the karmostaj salt diapir in the zagros foreland folded belt fars province iran abstract one of the main characteristic of the zagros foreland fold and thrust belt and the zagros foreland folded belt are wide distributions of surface extrusion from the hormuz salt diapirs this study examines the structure and kinematic of channel flow in the karmostaj salt diapir in the southwestern part of the zagros foreland folded belt this diapir has reached the surface as a result of the channel flow mechanism and has extruded in the southern limb of the kuh gach anticline which is an asymmetric decollement fold with convergence to the south structural and microstructural studies and quantitative finite strain rs and kinematic vorticity number wk analyses were carried out within this salt diapir and its namakier this was in order to investigate the structural evolution in the salt diapiric system the characteristics and mechanism of the salt flow and the distribution of flow regimes within the salt diapir and interaction of regional tectonics and salt diaprism the extruded salt has developed a flow foliation sub parallel to the remnant bedding recorded by different colors a variety of internal folds including symmetrical and asymmetrical folds and interference fold patterns shear zones and boudins these structures were used to analyze mechanisms and history of diapiric flow and extrusion the microstructures reveal various deformation mechanisms in various parts of salt diapir the measurements of finite strain show that rs values in the margin of salt diapir are higher than within its namakier which is consistent with the results of structural studies mean kinematic vorticity number wm measured in steady state deformation of diapir and namakier is wm 0 45 0 48 0 13 the estimated mean finite deformation wm values indicate that 67 8 pure shear and 32 2 simple shear deformation were involved the implications of which are discussed the vorticity of flow indicates that in the early stage of growth poiseuille flow was the dominate mechanism especially in the core of diapir with higher pure shear component relative to simple shear component whilst a couette flow at the margins of diapir is the dominate mechanism with higher simple shear component relative to pure shear component the obtained kinematic vorticity number reflects spatial partitioning of dominantly poiseuille flow in core and couette flow along edges of diapir these two mechanisms reflect a persistent flow governed by a simultaneous combination of pure shear and simple shear in a hybrid poiseuille coutte flow

distinguishing the effect of diapir growth on magnetic fabrics of syn diapiric overburden rocks basque cantabrian basin northern spain

paleomagnetic reconstruction of a diapir emplacement a case study from sedom diapir the dead sea rift reconstructing the emplacement path of a diapiric sequence is relatively complex in part because the stratigraphic top versus bottom sense of the sequence can be obscured by the complex structure paleomagnetic study of the diapiric sequence may reveal simultaneously three characteristics of it 1 the stratigraphic sense 2 the three dimensional rotation path of the tilted sequence and 3 the magnetic polarity of the sequence we apply paleomagnetism to reconstruct the emplacement path of the sedom diapir in the dead sea rift israel this application resolves the ambiguity regarding the geometrical orientation of the thickest intrarift stratigraphic section 2 km exposed in the dead sea region we here report the natural remanent magnetization for 172 oriented samples mainly dolomite and siltstone from seven localities in the steeply inclined beds of the sedom diapir a fold test as well as other field and laboratory tests shows that the characteristic remanent magnetization chrm component of the rocks was acquired before the tilting of the sedom sequence whereas the low coercivity magnetic component of probably chemical remanent magnetization origin was acquired after the tilting this low coercivity secondary component likely acquired in the brunhes normal chron records up to 40 young counterclockwise rotation about a vertical axis the chrm and secondary components together with the bedding plane were restored to their expected original position by rotating them about horizontal vertical or inclined axes to get the complete three dimensional rotation path the resulting structure of the southern sedom diapir is composed of a thin western salt wall that is juxtaposed against a thick eastern salt wall in the northern part of the mountain apparently only the thick eastern salt wall is exposed

u th dating of lake lisan late pleistocene dead sea aragonite and implications for glacial east mediterranean climate change u series dating can be an effective means to obtain accurate and precise ages on quaternary carbonates however most samples require a correction for u and th in admixed detritus this complication is often addressed through generation of u th isochrons requiring analyses of several coeval samples in addition presence of water derived hydrogenous th in the carbonate can cause inaccuracies in isochron ages this study reports a high resolution u series chronology of sediments deposited by lake lisan the last glacial precursor of the dead sea the strategy employed combines multiple measurements from a few stratigraphic heights and fewer analyses from many heights in a single described and measured section the resulting chronology is based on ages at 22 heights in a 40 m thick section covering the interval of 70 14 calendar ka bp the effects of admixed detritus are evaluated using trace elements nearly pure aragonite samples indicated by very low abundances of insoluble elements such as nb and zr were found to contain hydrogenous th which causes the uncorrected u 230th age of a modern sample to be 2 5 ka nevertheless accurate ages have been obtained by correcting for the detrital and aqueous interferences the resulting ages are in stratigraphic order and their accuracy is evidenced by consistency of lisan formation u series and 14c ages with the coral based calendar radiocarbon age calibration the u th ages provide a context to unravel the limnological history of lake lisan boundaries between the lower middle and upper stratigraphic units correspond to the mis 4 3 and 3 2 transitions respectively during mis 2 and 4 the lake generally showed a stable two layer configuration and a positive fresh water balance reflected by deposition of laminated aragonite detritus dry intervals during mis 2 and 4 are indicated by thick gypsum layers and an inferred depositional hiatus which are temporally associated with heinrich events h1 at 17 ka and h6 at 65 ka respectively during mis 3 the lake level was unstable with intermittent dry periods indicated by abundant clastic layers and a significant hiatus between 43 49 ka clastic layers are associated with dansgaard oeschger events during mis 3 and indicate lake level declines during abrupt northern hemisphere warmings overall the climate of the eastern mediterranean region shows a strong linkage to the northern hemisphere climate with increasing lake size and stability during cold periods and fluctuations and dessication during warmings and heinrich events

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

a linear theory of orographic precipitation a linear theory of orographic precipitation is developed including airflow dynamics condensed water advection and downslope evaporation the formulation extends the widely used upslope model vertically integrated steady state governing equations for condensed water are solved using fourier transform techniques closed form expressions are derived for special cases for more general cases the precipitation field is computed quickly by multiplying the terrain transform by a wavenumber dependent transfer function five length scales are included in the model mountain width a buoyancy wave scale the moist layer depth and two condensed water advection distances the efficiency of precipitation in the model is sensitive to the decay of the forced ascent through the moist layer and to the advection of condensed water downwind into the region of descent the strong influence of horizontal scale on precipitation pattern and amount predicted by the model is discussed the model is illustrated by applying it to the olympic mountains in washington state

deformation within an exposed salt wall recumbent folding and extrusion of evaporites in the dead sea basin abstract despite the enormous global interest in salt tectonics which is largely driven by its importance to hydrocarbon exploration direct field based studies of salt exposed at the earth s surface are rare however mount sedom located at the western side of the dead sea basin presents one such opportunity for detailed analysis of salt and the associated sedimentary and structural record of its movement the sedom salt wall is a 10 km 1 5 km n s trending ridge comprising a range of late miocene pliocene evaporites and clastics which have penetrated the overlying pleistocene clastic sequence the salt wall displays a moderate steep west dipping western margin and an overturned west dipping eastern flank the sedimentary record of passive wall growth includes sedimentary breccia horizons that locally truncate underlying beds and are interpreted to reflect sediments having been shed off the crest of the growing salt wall structurally the overturned eastern flank is marked by upturn within the overburden extending for 300 m from the salt wall deformation within the evaporites is characterised by ductile folding and boudinage while a 200 m thick clastic unit within the salt wall forms a tight recumbent fold traceable for 5 km along strike and associated with a 500 m wide inverted limb this overturned gently dipping limb is marked by ne directed folding and thrusting sedimentary injections and a remarkable attenuation of the underlying salt from 380 m to

recent contributions of glaciers and ice caps to sea level rise satellite measurements of earth s gravity field show that the mass loss of glaciers and ice caps contributed to sea level rise by approximately 0 4 millimetres per year between 2003 and 2010 the extent to which mass loss from ice covered land areas contributes to sea level rise is not known accurately in part because previous global estimates use different techniques for glaciers ice caps and ice sheets the gravity recovery and climate experiment grace satellite has provided monthly measurements of the global gravity field since 2002 using grace data jacob et al assess regional mass loss between 2003 and 2010 and conclude that mass loss from ice covered land areas contributed almost 1 5 mm per year to the sea level rise estimated mass loss from the high mountains of asia was negligible in contrast to some other reports glaciers and ice caps gics are important contributors to present day global mean sea level rise1 2 3 4 most previous global mass balance estimates for gics rely on extrapolation of sparse mass balance measurements1 2 4 representing only a small fraction of the gic area leaving their overall contribution to sea level rise unclear here we show that gics excluding the greenland and antarctic peripheral gics lost mass at a rate of 148 30 gt yr 1 from january 2003 to december 2010 contributing 0 41 0 08 mm yr 1 to sea level rise our results are based on a global simultaneous inversion of monthly grace derived satellite gravity fields from which we calculate the mass change over all ice covered regions greater in area than 100 km2 the gic rate for 2003 2010 is about 30 per cent smaller than the previous mass balance estimate that most closely matches our study period2 the high mountains of asia in particular show a mass loss of only 4 20 gt yr 1 for 2003 2010 compared with 47 55 gt yr 1 in previously published estimates2 5 for completeness we also estimate that the greenland and antarctic ice sheets including their peripheral gics contributed 1 06 0 19 mm yr 1 to sea level rise over the same time period the total contribution to sea level rise from all ice covered regions is thus 1 48 0 26 mm 1 which agrees well with independent estimates of sea level rise originating from land ice loss and other terrestrial sources6

flow speed within the antarctic ice sheet and its controls inferred from satellite observations accurate dynamical models of the antarctic ice sheet with carefully specified initial conditions and well calibrated rheological parameters are needed to forecast global sea level by adapting an inverse method previously used in electric impedance tomography we infer present day flow speeds within the ice sheet this inversion uses satellite observations of surface velocity snow accumulation rate and rate of change of surface elevation to estimate the basal drag coefficient and an ice stiffness parameter that influences viscosity we represent interior ice motion using a vertically integrated approximation to incompressible stokes flow this model represents vertical shearing within the ice and membrane stresses caused by horizontal stretching and shearing combining observations and model we recover marked geographical variations in the basal drag coefficient relative changes in basal shear stress are smaller no simple sliding law adequately represents basal shear stress as a function of sliding speed low basal shear stress predominates in central east antarctica where thick insulating ice allows liquid water at the base to lubricate sliding higher shear stress occurs in coastal east antarctica where a frozen bed is more likely examining thwaites glacier in more detail shows that the slowest sliding often coincides with elevated basal topography differences between our results and a similar adjoint based inversion suggest that inversion or regularization methods can influence recovered parameters for slow sliding and finer scales on broader scales we recover a similar pattern of low basal drag underneath major ice streams and extensive regions in east antarctica that move by basal sliding