the eastern termination of the zagros fold and thrust belt iran structures evolution and relationships between salt plugs folding and faulting 1 the zagros mountains result from the ongoing collision between the arabian and central iran plates the main features of the eastern zagros are 1 numerous emerged or buried salt diapirs made up of late precambrian hormuz salt and 2 the irregular along strike shape of the collision related detachment folds with frequent bending to understand this layout four geological cross sections have been constructed from the persian gulf foreland basin to the inner part of the zagros fold and thrust belt shortening in the deformed parts of the sections is less than 10 and is mainly accommodated by detachment folding we show that late cenozoic folding occurred in a region that was already punctuated by salt domes and diapirs in fact almost continuous halokinesis developed since the earlier paleozoic i e just short time after the deposition of the hormuz salt and continued up to the present these preexisting salt structures and their relevant local thickening strongly influenced both the localization and the direction of folds

central zagros fold thrust belt iran new insights from seismic data field observation and sandbox modeling 1 we present five generalized cross sections across the central zagros fold and thrust belt iran these sections show that the fold geometry varies significantly both horizontally and vertically the style is closely related to the changes in the mechanical behavior of the lithostratigraphic horizons and in particular to the presence of intermediate decollements within the sedimentary pile restoration of the sections shows amounts of shortening of the same order from one section to the other however it appears to be unequally distributed suggesting variations in basal decollement shear strength analogue modeling has been performed to systematically investigate the effect of an intermediate decollement level at different depths on the style of folding the models demonstrate that the position of intermediate decollements is an important factor controlling both structural style and fold wavelength models with shallow intermediate decollement show regularly and widely spaced anticlines in these models the fold wavelength depends directly on the thickness of the dominant competent layer and short wavelength superficial structures mask broad anticlines at depth models with deep intermediate decollement are characterized by the rapid propagation of deformation with small rate of shortening along this decollement influencing localization of forthcoming anticlines in the upper levels such propagation favors the development of duplexes and multiwavelength folds on this basis fold kinematics in central zagros is discussed using the variation of structural style along different folds as an indicator of the sequence of deformation detachment folding is the main folding style at least for the initial stages of deformation and thrust faults developed only at later stages some of these faults branched on decollement levels express the progression of folding whereas others are linked to late basement faults cutting through early structures in general the decollement levels are activated sequentially from deeper horizons to shallower ones however in one case gachsaran decollement a shallow decollement is activated during the early stages of folding and then abandoned during the subsequent evolution

dense shelf water formation along the south west australian inner shelf 1 hydrological data from a repeated cross shore transect obtained using teledyne webb research slocum electric gliders offshore two rocks in south western australia over 13 months are presented the data revealed that formation of dense water inshore and its transport across the shelf as a near bed gravity current defined as dense shelf water cascade dswc was a regular occurrence particularly during autumn and winter months in autumn the dense water is mainly formed through changes in salinity resulting from evaporation whilst in winter temperature change through surface cooling was the dominant factor the mean wind speeds also decrease during the transition during autumn the speed of the dswc was estimated to be 0 01 0 02 m s 1 and similar to that measured in other selected regions globally the offshore transport from the shelf is a significant component of the alongshore wind driven transport

seasonal cross shelf flow structure upwelling relaxation and the alongshelf pressure gradient in the northern california current system abstractmoored observations are used to investigate the seasonal change in vertical structure of the cross shelf circulation at a midshelf location in the northern california current system a streamwise normal coordinate system is employed to eliminate meander and eddy induced biases in the cross shelf flow that are unaccounted for with an alternative commonly applied approach the resulting flow structure develops an organized pattern midway through the upwelling season in particular under upwelling favorable conditions an onshore return layer occurs just beneath the offshore surface flow and a third offshore directed layer exists at depth that does not appear to satisfy ekman dynamics to within 9 m of the bottom both subsurface layers strengthen in time over the upwelling season mechanisms to explain the mean structure are evaluated and it is suggested that the timing of the development and strengthening of both the interior onshore return flow and the offshore near bottom layer are consisten

satellite remote sensing reveals coastal upwelling events in the san matias gulf northern patagonia abstract coastal upwelling events are effective in fluxing nutrients upward to the euphotic layer thus promoting the growth of marine phytoplankton satellite data may provide useful information to detect and characterize upwelling events in regions of sparse in situ observations we analyze the coastal upwelling process on the western san matias gulf on the northern continental shelf of argentina based on the analysis of remote sensing and in situ data upwelling events are characterized by their frequency of occurrence and magnitude during the austral summer we found roughly 6 upwelling favorable wind events per year satellite derived sea surface temperature sst data provide evidence of upwelling in 85 of the cases between 2000 and 2008 analysis of specific events provides clues on the wind forcing characteristics required to generate upwelling and on characteristic space and time scales of the process on february 2005 sst data reveal a narrow coastal band 10 km of relative cold water extending 100 km along the west coast of smg the sst in this band was 1 5 c lower than further offshore near bottom temperature fluctuations from in situ daily observations collected at two near shore locations are significantly correlated with along shore wind stress suggesting that coastal upwelling is a dominant process controlling high frequency temperature fluctuations near shore a simple quantitative estimate reveals a volume of upwelled water reaching the sea surface of about 10 10 m 3 during one relatively intense upwelling event

salinity tolerance or marine organisms deduced from red sea quaternary record abstract the oxygen isotopic record and microfossils from deep sea cores raised in the hypersaline 41 salinity gulf of aqaba indicate that during late quaternary glacial time salinity rose considerably due to sea level fall and strait dynamics reaching values of more than 50 during the last glacial maximum about 18 ka b p the salinity dependent sequence of disappearance of various species of foraminifera pteropods and coccolithophorids can be used to determine upper salinity tolerance limits of different taxa only the pteropod creseis acicula and various benthonic foraminifera are able to withstand high salinities like those during the last glacial maximum

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

the 5500 km long boundary flow off western and southern australia 1 the path of the shelf edge flow off southwestern australia is documented using results from satellite altimetry and sea surface temperature sst and a climatogical in situ analysis during austral winter a continuous current is shown to extend from its origin at north west cape to the southern tip of tasmania a distance of 5500 km satellite sst observations and surface buoy tracks confirm the location and continuity of the current trajectory while the leeuwin current is forced by the strong alongshore pressure gradient associated with the meridional portion of the western australian coastal boundary our results suggest that the essentially zonal shelf edge flow along the southern australian coast arises from the setup of coastal sea level by onshore ekman flow driven by the winter westerly wind and possibly a further alongshore pressure gradient the timing of these two different forcing mechanisms means that the west coast pressure gradient delivers the leeuwin current to the south coast just as the winds reverse and are thus able to maintain the eastward passage of the current the shelf edge flow consists of two main water masses a low salinity warm water type of tropical origin associated with the leeuwin current and a high salinity warm water inflow formed on the western end of the great australian bight continental shelf a naming convention is proposed the leeuwin current representing flow from north west cape to the great australian bight gab the south australian current between the eastern gab and western bass strait and the zeehan current off western tasmania

on the global estimates of geostrophic and ekman surface currents surface currents in oceanic environments are of crucial importance because they transport momentum heat salt and tracers over large distances that regulate both the local and large scale climate conditions and because they contribute to the lagrangian displacement of floating material ranging from living resources to marine pollution in recent decades the understanding of surface currents has benefited from the opportunity of observing sea level and wind stress via satellite derived measurements combining these parameters into geostrophic and wind driven components provides an estimate of surface currents with a quarter degree horizontal resolution at a global scale and at a daily time scale in the present study improvements are made on the consideration of the time dependence of the main parameters implied in the determination of the ekman wind driven component and on the treatment of the equatorial singularity the resulting geostrophic and ekman current observatory gekco estimates were validated with independent observations from both lagrangian and eulerian perspectives the statistics of comparison were significant over the globe for the 2000 2008 period the only exception was the estimation of meridional current along the equator which requires further developments of the dynamic model and probably more accurate measurements applications using our gekco surface current estimates in cross disciplinary approaches from physical oceanography to marine ecology are presented and discussed

the combined effect of transient wind driven upwelling and eddies on vertical nutrient fluxes and phytoplankton dynamics along ningaloo reef western australia we investigate the influence of wind stresses stratification and coastal mesoscale eddies on upwelling intensity vertical nutrient fluxes and phytoplankton biomass on the continental shelf off ningaloo reef in northwestern australia during an austral spring summer period a three dimensional 3 d hydrodynamic model roms regional ocean modeling system was coupled with a four component nitrogen based biogeochemical npzd model nitrogen phytoplankton zooplankton detritus to resolve the shelf circulation as well as the coupled nutrient and phytoplankton dynamics within a broad shelf region surrounding ningaloo reef the simulated currents temperatures and chlorophyll a concentrations generally agreed well with both the remotely sensed satellite images and observational data collected during a field experiment from september to november 2010 scenario tests for an individual wind driven upwelling event under a variety of hypothetical physical forcing conditions showed that shelf currents and biogeochemical variables were largely a function of wind stress and stratification however the functional relationships derived from this single wind event could not be extrapolated to other periods of the upwelling season due to the additional influence of 3 d mesoscale processes on the shelf the presence intensification and propagation of a coastal anticyclonic eddy during the study period strongly influenced the spatial and temporal variations in nutrient profiles which in turn caused fluctuations in vertical nutrient fluxes that were largely independent of wind stress these results emphasize that it is necessary to fully capture the 3 d details of the mesoscale and submesoscale coastal dynamics to properly predict upwelling induced coastal phytoplankton dynamics in eddy intensive shelf regions such as ningaloo reef

on the factors influencing the development of sporadic upwelling in the leeuwin current system cumulates the highest number of upwelling 140 days per year and is characterized by longer events the intensity of intermittent upwelling is influenced by the upwellingfavorable winds the characteristics of the leeuwin current e g onshore geostrophic flow mesoscale eddies and meanders stratification and nitracline and the local topography this suggests that short living nutrient enrichment of variable magnitude may occur at any time of the year at many locations along the wa coast

numerical modelling of the mean flow characteristics of the leeuwin current system abstract the oceanic circulation of the region between carnarvon 25 s and jurien bay 31 s was examined using observational and remotely sensed data in conjunction with a detailed numerical modelling study the model was validated using in situ adcp and ctd data and the horizontal eddy viscosity parameterization was tested against field observations the results generated using the regional ocean model roms v1 8 simulated the observed mean surface flow s spatial and temporal scales particularly those of the eddy features the modelled results also provided insight into the leeuwin current lc s annually averaged alongshore transport and the leeuwin undercurrent luc s mean flow characteristics analysis of the model results between 26 8 s and 30 8 s revealed the annually averaged alongshore transport across the lc s southern boundary was 5 7 sv of which the northern boundary contributed 3 60 sv or 63 the inflow of water through the western boundary due to geostrophic balance was estimated at 2 1 sv or 37 and found to vary meridionally a geopotential gradient estimated at 1 9 10 7 and acting towards the equator drives the luc located at depths between 250 and 600 m the modelled undercurrent is characterized as an energetic flow with mesoscale variability that is strongly influenced by the more energetic surface current coupling was evident in the region adjacent to the abrolhos islands western boundary 29 s where the offshore movement of lc waters by a surface meander caused the vertical scale of the undercurrent to increase inducing an anticlockwise vorticity response at a depth of 180 m the resulting subsurface eddy grew preferentially downwards before a surface response was observed the model showed that the eddy increased its vertical scale before splitting into two forming a surface and subsurface eddy with a vertical scale characteristic of the two currents the surface eddy intensified detached and moved offshore while the subsurface eddy remained attached to the topography

spatiotemporal evolution of upwelling regime along the western coast of the iberian peninsula 1 the spatial and temporal variability of upwelling regime along the western coast of the iberian peninsula ip has been analyzed by means of two different but complementary databases quikscat satellite database which is available from mid 1999 with a high spatial resolution 0 25 0 25 and pacific fisheries environmental laboratory pfel database with a coarser spatial resolution 1 1 but extending back to 1967 the combined use of both databases allows determination of the spatial variability of ekman transport and pumping and identification of temporal trends in upwelling signal upwelling favorable conditions are observed during spring and summer apart from this well known seasonality on upwelling regime along the western coast of the ip some other features have been identified 1 upwelling occurs simultaneously along the entire western coast of the ip but is undoubtedly more complex closer to particular features of the shoreline 2 positive ekman pumping is more intense near capes sao vicente and rocha during spring summer and near cape finisterre all over the year 3 more favorable upwelling conditions have been observed in february and november during the last decade this result is corroborated by sea level pressure composites which show the existence of abnormally high pressures close to the ip during the last decade compared to the historical records 1948 2006 4 the decadal variability of ui is higher in autumn winter than in spring summer 5 monthly upwelling trends indicate a weakening in upwelling intensity during most of the year with the exception of february june and july

convergence history across zagros iran constraints from collisional and earlier deformation the zagros orogen provides a unique opportunity within the alpine system to evaluate the interplay between a young tertiary collision and earlier subduction obduction processes within the crush zone and the sanandaj sirjan internal zone separating the zagros fold belt from central iran we document several major tectonic events taking place at the end of the cretaceous of the eocene and from the mio pliocene onwards ca 20 15 ma contrary to recent interpretations our data cross sections and description of the overall deformation style strongly suggest that the main zagros thrust mzt is deeply rooted possibly to moho depths and that the suture zone effectively runs along the mzt field observations show that the final resorption of the oceanic domain took place slightly after 35 ma and that collision must have started before ca 23 25 ma in northern zagros the shortening rate across the crush zone since the mid miocene 20 15 ma is estimated at a minimum 3 4 mm year shear movements in the crush zone during the eocene oligocene period and extensional strike slip movements in the internal zones during the late cretaceous point to an oblique setting early in the convergence history a geotectonic scenario for convergence from the time of obduction to the present is finally proposed

seasonal circulation and temperature variability near the north west cape of australia 1 the circulation and temperature variability on the inner shelf near the north west cape of australia off ningaloo reef was investigated using field data obtained from two moorings deployed from 2004 to 2009 the results revealed that alongshore currents on the inner shelf were on average only weakly influenced by the offshore poleward southward leeuwin current flow i e monthly averaged alongshore current velocities were 0 1 m s 1 or less the presence of a consistent summer time wind driven equatorward northward counter flow on the inner shelf referred to in the literature as the ningaloo current was not observed instead the shelf waters were strongly influenced year round by episodic subtidal current fluctuations time scale 1 2 weeks that were driven by local wind forcing analysis of the current profiles showed that periods of strong equatorward winds were able to overcome the dominant poleward pressure gradient in the region leading to upwelling on the inner shelf contrary to prior belief these events were not limited to summer periods the forcing provided by these periodic wind events and the associated alongshore flows can explain much of the observed temperature variability with timescales 1 month that influences ningaloo reef

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

linking synoptic forcing and local mesoscale processes with biological dynamics off ningaloo reef 1 a hydrographic survey offshore ningaloo reef north west australia in austral autumn 2010 revealed relatively stable subsurface water masses in the region despite the influence of interannual variability of the leeuwin current lc the surface water mass seems slightly more variable at seasonal time scale probably due to various contributions of the geographically distinct source waters of the lc a subsurface nitrate maximum 110 230 m a prominent feature of the ningaloo area during autumn was consistently observed within different water masses tightly coupled variations of subsurface nitrate and oxygen at small vertical scale suggest it is due to local in situ remineralization of organic matter likely to accumulate along sharp physical interfaces and possibly favored by injections of oxygenated subsurface waters offshore enhanced levels of surface chlorophyll a within the downwelling favorable lc are associated with deeper mixed layer depth eroding the shallow source of nutrients close to the continental shelf these nutrients are observed to be efficiently uplifted within the core of quasi persistent topographically trapped submesoscale cyclonic eddies dominated by nonlinear effects a wind driven coastal upwelling event occurred in autumn and was characterized by a relatively deep source 100 150 m coinciding with the subsurface maximum of nutrients thus promoting coastal productivity locally and farther north by alongshore advection within the ningaloo current

seasonality of sporadic physical processes driving temperature and nutrient high frequency variability in the coastal ocean off southeast australia physical processes forced by alongshore winds and currents are known to strongly influence the biogeochemistry of coastal waters combining in situ observations moored platforms hydrographic surveys and satellite data sea surface wind and sea surface height we investigate the transient occurrence of wind driven upwelling downwelling and current driven upwelling events off southeast australia remote sensed indices are developed and calibrated with multiannual time series of in situ temperature and current measurements at two shelf locations based on archives up to 10 years long climatological analyses of these indices reveal various latitudinal regimes with respect to seasonality magnitude duration of events and their driving mechanisms wind or current generally downwelling favorable winds prevail in this region however we demonstrate that up to 10 wind driven upwelling days per month occur during spring summer at 28 33 5 degrees s and up to 5 days in summer further south current driven upwelling upstream of the east australian current separation zone approximate to 32 degrees s occurs twice as often as downstream using independent in situ data sets we show that the response of the coastal ocean is consistent with our climatology of shelf processes upwelling leads to a large range of temperatures and elevated nutrient concentrations on the shelf maximized in the wind driven case while downwelling results in destratified nutrient poor waters the combination of these sporadic wind and current driven processes may drive an important part of the high frequency variability of coastal temperature and nutrient content our results suggest that localized nutrient enrichment events of variable magnitude are favored at specific latitudes and seasons potentially impacting coastal ecosystems key points multisensor analysis of shelf processes combining in situ and satellite data spatio temporal variability of transient wind and current driven up downwelling cold nutrient rich water intrusions favoured at specific locations seasons

eddy formation through the interaction between the leeuwin current leeuwin undercurrent and topography abstract the surface and subsurface circulation off south west australia was simulated using the regional ocean modelling system roms a primitive equation ocean model with terrain following s coordinates the major currents in this region the leeuwin current and leeuwin undercurrent were reproduced by specifying only temperature and salinity distributions from climatology the application of wind stress subsequent to the model reaching a quasi steady state resulted in the generation of the seasonal capes current a northward flowing current on the continental shelf associated with coastal upwelling the simulated currents compared well with the observed current patterns including the location and maximum current speeds shelf topography variations and bottom shear which generated vorticity influenced eddy formation eddies separated from the leeuwin current and the leeuwin undercurrent migrated westward and exited the model domain through merging dissipating or through an open boundary in the model simulations the undercurrent produced mostly cyclonic eddies due to strong negative vorticity where the current flowed against the continental slope the leeuwin current produced anticyclonic warm core eddies initiated from the formation of meanders which were strongest at the surface the eddy field was dominated by anticyclonic eddies at the surface and cyclonic eddies at 500 m the interaction between the leeuwin current and leeuwin undercurrent led to the formation of eddy pairs

environmental drivers of growth in massive porites corals over 16 degrees of latitude along australia s northwest shelf sustained calcification is fundamental for maintaining tropical coral reef ecosystems which are under increasing pressure from global and local changes to the marine environment annual density bands in massive corals provide a robust means to retrospectively monitor growth and identify the environmental drivers we present porites growth characteristics for 60 coral cores from 18 reef sites and five environmental regions off western australia wa over the period 1950 2008 this remote region encompasses diverse coral reef ecosystems and is an economically important natural resource hub despite high variability average calcification is highest in the offshore shelf reefs and lowest in the most southerly reefs the primary environmental drivers of these spatial variations are annual and winter minimum sea surface temperature sst and annual winter minimum photosynthetically active radiation average growth characteristics for wa reefs are comparable to those of australia s great barrier reef calcification rates at the two most southerly wa reefs are anomalously high which may be due to the unusual environmental conditions generated by the leeuwin current variable rates of sst warming across the 18 reefs are however changing the strength of the relationship between sst and calcification we found no evidence to support the contention that annual density banding is driven by environmental seasonality retrospective monitoring of growth rates provides a critical tool for both assessing coral growth responses to ongoing rapid climate change and possible responses to increasing anthropogenic pressures related to natural resource development in the region