analysis of gravity anomalies of sedimentary basins by an asymmetrical trapezoidal model with quadratic density function the decrease of density contrast with depth in many sedimentary basins can be approximated by a quadratic function the interpretation of gravity anomalies over sedimentary strata can be more realistic if variable density contrasts rather than constant density contrasts are assumed i derive the equation for the gravity anomaly of an asymmetrical trapezoidal model assuming a quadratic density function and i develop methods of interpretation using the marquardt algorithm while interpreting a synthetic anomaly profile the convergence of the algorithm is shown by plotting the values of the objective function damping parameter and various parameters of the model with respect to iteration number the results are superior to those obtained when using constant density contrasts in addition i apply the method in the interpretation of gravity anomalies over the san jacinto graben and the lower godavari basin

upper mantle s velocity structure and moho depth variations across zagros belt arabian eurasian plate boundary the collision of the arabian and eurasian plates in the early miocene after the subduction of neo tethys ocean beneath eurasia formed the zagros belt a seismically active continental continental plate boundary in southwest iran the zagros suture zone is an important seismotectonic boundary indicating an abrupt cutoff between the intense seismicity of the zagros and the almost aseismic central iran plateau compared with other more evolved plate boundaries little is known about the deep lithospheric structure of the zagros belt such as the fate of subducted neo tethys plate and ambiguity in the presence of intermediate and deep earthquakes under the zagros suture zone in this study we use the partitioned waveform inversion pwi method to image the upper mantle s velocity structure and moho depth variations across zagros collisional zone the resulting moho depth along the profile shows the average moho depth value of order of 40 45 km for most parts of the profile with abrupt crustal thickening in the middle of the profile up to about 65 km as expected the derived models show that the relatively old and cold arabian plate has higher velocity at depth than the younger lithosphere farther north in central iran a sharp and steep subcrustal boundary is found roughly coincident with the surficial expression of the main zagros thrust mzt separating two different mantle domains a high velocity anomaly possibly representing a fragment of subducted lithosphere has been imaged beneath central iran at a depth between 350 and 600 km which is quite similar to the case of indo asian collision in qinghai tibetan plateau these observations as well as the sudden changes of shallow velocities along the cross section with a sharp boundary under the zagros suture zone support the idea that subducted oceanic lithosphere has broken off under the region of maximum moho depth a relatively low velocity region beneath the arabian plate is also imaged in our high resolution tomography model which is interpreted as an indication of lithospheric delamination within the arabian lithosphere

factors controlling copper solubility and chalcopyrite deposition in the sungun porphyry copper deposit iran the sungun porphyry copper deposit is hosted in a diorite granodioritic to quartz monzonitic stock that intruded eocene volcanosedimentary and cretaceous carbonate rocks copper mineralization is associated mainly with potassic alteration and to a lesser extent with sericitic alteration based on previously published fluid inclusion and isotopic data by hezarkhani and williams jones most of the copper is interpreted to have deposited during the waning stages of orthomagmatic hydrothermal activity at temperatures of 400 to 300 c these data also indicate that the hydrothermal system involved meteoric waters and boiled extensively in this work thermodynamic data are used to delineate the stability fields of alteration and ore assemblages as a function of fs2 fo2 and ph the solubility of chalcopyrite was evaluated in this range of conditions using recently published experimental data during early potassic alteration 450 c copper solubility is calculated to have been 50 000 ppm whereas the copper content of the initial fluid responsible for ore deposition is estimated from fluid inclusion data to have been 1200 3800 ppm this indicates that initially the fluid was highly undersaturated with respect to chalcopyrite which agrees with the observation that veins formed at t 400 c contain molybdenite but rarely chalcopyrite copper solubility drops rapidly with decreasing temperature and at 400 c is approximately 1000 ppm within the range estimated from fluid inclusion data whereas at 350 c it is only 25 ppm these calculations are consistent with observations that the bulk of the chalcopyrite deposited at sungun is hosted by veins formed at temperatures of 360 60 c other factors that in principle may reduce chalcopyrite solubility are increases in ph and decreases in fo2 and acl our analysis shows however that most of the change in ph occurred at high temperature when chalcopyrite was grossly undersaturated in the fluid and that the direction of change in fo2 increased chalcopyrite solubility we propose that the sungun deposit formed mainly in response to the sharp temperature decrease that accompanied boiling and partly as a result of the additional heat loss and decrease in acl which occurred as a result of mixing of acidic cu bearing magmatic waters with cooler meteoric waters of lower salinity

lithospheric structure beneath the south eastern zagros mountains iran recent slab break off integrated lithospheric modelling based on the combined interpretation of gravity geoid and topography data sets highlights a previously undocumented lithospheric thinning beneath the zagros collisional belt iran which we propose to relate to recent slab break off at the continent ocean transitional lithosphere recent published data on the distribution of seismicity at depth support this interpretation in agreement with other published models for the zagros mountains the overlying crust exhibits by contrast a noticeable thickening reaching a maximum of 52 km the consequent thermal uplift expected from slab break off is suggested to have modified the zagros wedge taper and triggered the recently documented switch from thin skinned to thick skinned deformation in the zagros fold thrust belt

deep crustal structure and flexure of the arabian plate beneath the zagros collisional mountain belt as inferred from gravity observations the zagros mountain belt region a neogene continental collisional zone between arabia and iran that is characterized by a suture a folded belt and a foreland basin is unusual among active mountain belts in that its 6 12 km thick sedimentary cover is shortening predominantly by folding while the basement is apparently thickening along numerous high angle reverse faults we have used over 9000 gravity measurements in the region in conjunction with limited seismological observations and geological cross sections of the uppermost 10 km of crust to infer the deeper crustal structure beneath the region crustal models constrained by the bouguer anomalies and other seismological and geological data are characterized by a moho that dips about 1 to the northeast beneath the folded belt and increases in dip to about 5 near the main zagros thrust mzt the moho depth increases from 40 km beneath the leading edge of the foreland basin the mesopotamian foredeep and persian gulf to as much as 65 km beneath the mzt alternative models that incorporate a subducted oceanic crust that is attached to the underthrusting arabian crust deviate little in their moho configurations from the above simpler models negative isostatic residual anomalies are interpreted to indicate local overcompensation beneath the foreland basin and near the folded belt and beneath the mzt we show that underthrust sedimentary rocks of the converging margins along the suture zone may account for the negative isostatic residual anomalies near the mzt however to explain the rest of the isostatic anomalies requires other forces to be acting on this collisional plate boundary for example elastic flexure models required a combination of topography and subsurface loads or downward force the origin of which is not clear to approximate the bouguer or isostatic residual anomalies associated with the foreland basin and the folded belt the topography load of the zagros mountain belt is insufficient to cause the required deflection of the underthrusting arabian plate a combination of isostatic elastic flexure and horizontal compression forces acting on the edge of the arabian craton and the transitional lithosphere of central iran appears to best model the crust of the zagros region we propose a model in which the lower crust of the converging arabian plate located beneath the zagros is being shortened and thickened plastically between the seismogenic rigid upper crust and a rigid uppermost mantle lid the mantle lid probably decoupled from the lowermost crust un der thrusts the iranian crustal blocks thus confined from below the horizontally compressed plastic lower crust hydraulically depresses the moho and raises the faulted and folded brittle upper crust in isostatic equilibrium

a palynological and geoarchaeological investigation into bronze age farming at belderg beg co mayo ireland abstract this contribution describes the results and interpretations of geoarchaeological and palynological analyses of a soil profile near to a 14 c dated bronze age roundhouse in a sub peat field system at belderg beg north mayo in western ireland which displayed field scale evidence of tillage in the form of cultivation ridges this evidence of arable cultivation was supported by the presence of quernstones in the roundhouse but there was no supporting evidence from other forms of socio economic analysis soil micromorphological analysis was employed to define how the ridges were created and with what tools pollen analysis was used to characterise the surface vegetation and test the purpose of the ridges the results unequivocally showed that a phase of ard cultivation was followed after a brief hiatus by ridge and furrow tillage there were tentative indications of possible amendment of the earlier ard worked soil and more definitive evidence of midden material addition to the ridged soil an ams radiocarbon assay on the base of peat overlying the ridges indicated that tillage occurred in the mid to late bronze age

reconstruction of geologic bodies in depth associated with a sedimentary basin using gravity and magnetic data summary we present a comprehensive review of the most comm on gravity and magnetic interpretation methods to in depth retrieval of the geometry of two types of geologic bodies associated with a sedimentary basin 1 sedimentary basement relief and 2 salt bodies in reconstructing a basement topography we identify three groups of methods the automatic the spectral and the nonspectral methods the reconstruction of salt bodies geometries from gravity data usually uses the interactive forward modeling but recently gravity inversion methods have been developed to interpret this kind of geological environment

estimating the mechanical anisotropy of the iranian lithosphere using the wavelet coherence method abstract we calculated anisotropic wavelet coherence between bouguer anomaly and topography in order to map the anisotropy of the effective elastic thickness of the iranian lithosphere t e an orthotropic elastic plate model is used for inverting the anisotropic wavelet coherence to compute the mechanical anisotropy through the weak axis of the t e anisotropy of the t e weak axis and the strength of the anisotropic parameter namely the anisotropic coherence effect over the study area are estimated by restricting the rotated morlet wavelet fan wavelet geometry over an azimuthal range of 90 large scale t e variations have been shown to be associated with phenomena such as mountain belts subduction zones craton boundaries fault zones and seismogenic regions although the correlation between the major tectonic features of the iranian lithosphere and the distribution of the t e weak axis is not general or precise in some regions such as the central iran blocks and the alborz kopeh dagh zagros and makran orogenic belts the weak axis has a uniform or slowly varying pattern which changes over their boundaries a perpendicular alignment between seismic anisotropy measurements in iran and the t e weak directions suggests a lithospheric origin for anisotropy the correlation between averaged stress directions and the weak axis of the t e in iran indicates that the present day stress field and the fossil strain are still related correlation between these factors suggests vertically coherent deformation of the lithosphere in iran resulting from the multiply convergent orogenic processes the complex mechanical anisotropy pattern of the iranian lithosphere results from the interaction of many pre existent structures which dominantly control the mechanical anisotropy of the lithosphere

tectonics of the zagros orogenic belt of iran new data and interpretations abstract the zagros orogenic belt of iran is the result of the opening and closure of the neo tethys oceanic realm and consists from northeast to southwest of three parallel tectonic subdivisions 1 1 the urumieh dokhtar magmatic assemblage 2 2 the sanandaj sirjan zone and 3 3 the zagros simply folded belt recent detailed and reconnaissance mapping and stratigraphie structural analyses in various parts of the belt indicate that the tectonics of the sanandaj sirjan zone is dominated by either large scale composite duplex structures or low and high angle ne dipping imbricate systems these thrust systems have transported numerous horses and sheets nappes of metamorphosed and non metamorphosed phanerozoic rocks for tens or possibly hundreds of kilometers stratigraphic evidence and synorogenic conglomerates indicate that thrusting was initiated in the late cretaceous and has continued episodically since that time shear sense indicators in various parts of the zone reveal a ne sw direction of transport thrust systems generated in each episode are superimposed upon the previous structures cutting across and displacing them and producing complicated stacks of thrust sheets southwestward transport and stacking of the thrust sheets has resulted in an increase of about 10 15 km in the thickness of the continental crust in the southwestern part of this zone the so called z main zagros thrust which has been traditionally considered as the boundary between the sanandaj sirjan zone and the zagros simply folded belt is by no means a single high angle reverse fault nor is it a narrow zone of crushed rocks but a series of low angle thrusts locally cut by normal faults these thrusts are indistinguishable from those mapped in the sanandaj sirjan zone and are geometrically part of the sanandaj sirjan zone structures there is no single thrust among them that can be singled out and referred to as the main one the boundary of the sanandaj sirjan zone with the urumieh dokhtar magmatic assemblage to the northeast is characterized by a series of structural depressions formed by compression rock sequences including ophiolite complexes exposed along this boundary are strongly dismembered sheared and mylonitized shearing planes and foliations are either subvertical or dipping at high angles to the northeast this zone is suggested to be the suture between the afro arabian and the iranian plates overall the intensity of deformation increases northeastward from the persian gulf mesopotamian basin where strata are undeformed and horizontal through the zagros simply folded belt which is characterized by en echelon doubly plunging flexural slip folds gentle to open in the southwest and close to locally sw overturned in the northeast the intensity of deformation continues to increase further northeastward through the sanandaj sirjan zone where thrust faulting is dominant this pattern suggests that the deformational front has migrated through time from the northeastern part of the sanandaj sirjan zone i e the suture zone to its present position in the central portion of the persian gulf mesopotamian foreland basin

non linear stochastic inversion of gravity data via quantum behaved particle swarm optimisation application to eurasia arabia collision zone zagros iran potential field data such as geoid and gravity anomalies are globally available and offer valuable information about the earth s lithosphere especially in areas where seismic data coverage is sparse for instance non linear inversion of bouguer anomalies could be used to estimate the crustal structures including variations of the crustal density and of the depth of the crust mantle boundary i e moho however due to non linearity of this inverse problem classical inversion methods would fail whenever there is no reliable initial model swarm intelligence algorithms such as particle swarm optimization pso are a promising alternative to classical inversion methods because the quality of their solutions does not depend on the initial model they do not use the derivatives of the objective function hence allowing the use of l1 norm and finally they are global search methods meaning the problem could be non convex in this paper quantum behaved particle swarm qpso a probabilistic swarm intelligence like algorithm is used to solve the non linear gravity inverse problem the method is first successfully tested on a realistic synthetic crustal model with a linear vertical density gradient and lateral density and depth variations at the base of crust in the presence of white gaussian noise then it is applied to the eigen 6c4 a combined global gravity model to estimate the depth to the base of the crust and the mean density contrast between the crust and the upper mantle lithosphere in the eurasia arabia continental collision zone along a 400 km profile crossing the zagros mountains iran the results agree well with previously published works including both seismic and potential field studies this article is protected by copyright all rights reserved

climate variability and storm impacts as major drivers for human coastal marsh withdrawal over the neolithic period southern brittany nw france abstract relationships between climate variations vegetation dynamics and early human activities during the neolithic have been reconstructed from high resolution pollen and foraminiferal records obtained from cores retrieved from coastal wetland located in southern brittany guidel nw france our data show that the area around guidel corresponded to a dense temperate forest locally replaced by riparian forest in the marsh without any human disturbance during the early neolithic during the mid neolithic between 6500 and 5500 cal years bp the first episode of probable human settlement is recorded as suggested by the increase of anthropogenic plants this early record of human impact is consistent with archeological studies that find a high concentration of funeral monuments around guidel during this cultural period this complex first phase is interrupted by the disappearance of anthropogenic influence coinciding with a cold humid climate period in the region characterized by recurrent major storms then at the transition between the middle to late neolithic at 5500 cal years bp a second phase of human retreat is signaled by both vegetation dynamics and archeological records this interval also coincides with a climatic deterioration marked by cold humid conditions recorded in the region sorrel et al 2012 the results of the present study imply that human settlement departure over the neolithic was probably influenced by climatic variations during the bronze age iron age and middle ages a progressive decline of the arboreal forest synchronous with an increase of anthropogenic plants confirms the high and persistent human activity around the site furthermore our results at guidel suggest a different anthropogenic trend recorded between north and south brittany the human impact is well recorded during the neolithic at guidel while in northern brittany human settlement is not recorded before the bronze age consistent with existing archeological data

3d crustal and lithospheric model of the arabia eurasia collision zone three dimensional joined inversion of topography gravity and geoid data was carried out in the collision zone between the eurasian and arabian plates comprising central and eastern anatolia the black sea basin and the caucasus region the 3d algorithm first introduced by motavalli anbaran et al 2013 is based on a bayesian approach with gaussian density functions in which the targeted area is divided into vertical columns each comprised of four layers namely water of known thickness i e bathymetry if present crust lithospheric mantle and asthenosphere the inversion results are moho depth average crustal density and depth to the lithosphere asthenosphere boundary defined here as the 1350 c isotherm existing seismic moho depths were used as a priori information in order to constrain crustal thicknesses thickest crust up to 50 km was found underneath the great caucasus mountains thinnest crust 22 25 km underneath the black sea basin the east anatolian plateau is underlain by relatively thick crust up to 45 km thinning to less than 40 km towards the central anatolian plateau eastern anatolia and the eastern part of central anatolia are underlain by strongly thinned lithosphere up to 100 km thickest lithosphere up to 200 km underlies the caspian basin and the russian platform

micromorphological evidence of soil deterioration since the mid holocene at archaeological sites in brittany france this paper presents data on the evolution of agricultural landscapes in brittany from the end of the atlantic chronozone to the mediaeval period 450 bc ad 1600 using soil micromorphology in a multidisciplinary palaeoenvironmental context buried soils and unburied sediments associated with archaeological structures in brittany were examined the study of well dated archaeological buried soils gives new information on the way the landscape of brittany was affected by human impact which has disturbed the atlantic soil balance since the start of the neolithic and has been a major factor in soil acidification in brittany deforestation of primary woodland occurred however over a long period the analysis of down slope sediment accumulation shows that colluviation of loam rich soils was stimulated by deforestation and agriculture micromorphological study of archaeological ditches shows that some microscopical features are difficult to interpret in unburied conditions especially in modern cultivated contexts but that this can be done after comparison with experimentally reconstructed or similar traditional structures such results help our understanding of the history of bocage land enclosure

subduction history of the tethyan region derived from seismic tomography and tectonic reconstructions 1 in the mantle underneath the tethyan suture zone large volumes of positive velocity anomalies have been imaged by seismic tomography and interpreted as the present day signature of subducted tethyan lithosphere we investigate the mesozoic cenozoic subduction history of the region by integrating independent information from mantle tomography and tectonic reconstructions three different subduction scenarios for the tethyan oceanic lithosphere representative for the available tectonic reconstructions are used to predict the present thermally anomalous volumes associated with the lithospheric surface subducted since the late mesozoic next these predicted thermal volumes and their expected positions are compared to the relevant anomalous volumes derived from seismic tomographic images in this analysis we include among others the possible effects of ridge subduction and slab detachment after the cenozoic continental collisions absolute plate motion and slab thickening in the mantle our preferred subduction model comprises the opening of large back arc oceanic basins within the eurasian margin the model points to slab thickening by a factor of 3 in the mantle in which case the estimated volumes allow for active oceanic spreading 1 2 5 cm yr in the tethyan lithosphere during convergence our results further indicate the occurrence of early oligocene slab detachment underneath the northern zagros suture zone followed by both westward and eastward propagation of the slab tear and diachronous eocene to miocene slab detachment below the eastern to western himalayas free sinking rates of the detached material of 2 cm yr in the lower mantle provide the best fit between the tomographic mantle structure and our tethyan subduction model

pn tomographic imaging of mantle lid velocity and anisotropy at the junction of the arabian eurasian and african plates an edited version of this paper was published by blackwell publishing in geophysical journal international copyright 2004 blackwell publishing see also http www blackwell synergy com doi abs 10 1111 j 1365 246x 2004 02355 x http atlas geo cornell edu middleeastnorthafrica publications al lazki2004 htm

large scale 3d inversion of potential field data inversion of gravity and or magnetic data attempts to recover the density and or magnetic susceptibility distribution in a 3d earth model for subsequent geological interpretation this is a challenging problem for a number of reasons first airborne gravity and magnetic surveys are characterized by very large data volumes second the 3d modelling of data from large scale surveys is a computationally challenging problem third gravity and magnetic data are finite and noisy and their inversion is ill posed so regularization must be introduced for the recovery of the most geologically plausible solutions from an infinite number of mathematically equivalent solutions these difficulties and how they can be addressed in terms of large scale 3d potential field inversion are discussed in this paper since potential fields are linear they lend themselves to full parallelization with near linear scaling on modern parallel computers moreover we exploit the fact that an instrument s sensitivity or footprint is considerably smaller than the survey area as multiple footprints superimpose themselves over the same 3d earth model the sensitivity matrix for the entire earth model is constructed we use the re weighted regularized conjugate gradient method for minimizing the objective functional and incorporate a wide variety of regularization options we demonstrate our approach with the 3d inversion of 1743 line km of falcon gravity gradiometry and magnetic data acquired over the timmins district in ontario canada our results are shown to be in good agreement with independent interpretations of the same data

late holocene land use at orstad jaeren southwestern norway evidence from pollen analysis and soil micromorphology abstract pollen analysis was combined with radiocarbon dating physical chemical and biological soil analyses and soil micromorphology to investigate the prehistoric land use at orstad in jaeren southwestern norway orstad is an early bronze age clearance cairn field in a cultural landscape with traces of land use back to the neolithic samples were mainly collected from an 84 m long excavated trench with mainly podzolic soils although pollen preservation was poor it was possible to differentiate five phases in the local vegetation and land use history human impact on the site could be traces back to about 4400 4000 bp uncal 3045 2600 cal bc wheat and barley have been cultivated at orstad during a period from ca 3600 bp uncal 1945 1750 cal bc until the older iron age when heather vegetation began to spread on the site soil micromorphology revealed different soil management practices for this time period the soils seem to have been cleared by fire prior to cultivation until ca 3200 bp uncal 1610 1455 cal bc then new cultivation fields were laid out on higher levels and seem to have been improved by adding of organic materials mainly turves taken from podzolic top soils and peats from nearby localities

east anatolian high plateau as a mantle supported north south shortened domal structure an edited version of this paper was published by the american geophysical union agu copyright 2003 agu see also http www agu org pubs crossref 2003 2003gl017858 shtml http atlas geo cornell edu turkey publications sengor et al 2003 htm

total variation regularization for depth to basement estimate part 1 mathematical details and applications we have developed an inversion approach that estimates the basement relief of a fault bounded sedimentary basin the sedimentary pack is approximated by a grid of 3d or 2d vertical prisms juxtaposed in the horizontal directions of a right handed coordinate system the prisms thicknesses represent the depths to the basement and are the parameters to be estimated from the gravity data to obtain depth to basement estimates we introduce the total variation tv regularization as a stabilizing function this approach lets us estimate a nonsmooth basement relief because it does not penalize sharp features of the solution we have deduced a compact matrix form of the gradient vector and the hessian matrix of the approximation to the tv function that allows a regularized gauss newton minimization approach because the hessian matrix of the approximation to the tv function is ill conditioned we have modified this hessian matrix to improve its condition and to accelerate the convergence of the gauss newton algorithm tests conducted with synthetic data show that the inversion method can delineate discontinuous basements presenting large slips or sequences of small slip step faults tests on field data from the almada basin brazil and from the san jacinto graben california u s a confirm the potential of the method in detecting and locating in depth normal faults in the basement relief of a sedimentary basin

seismological evidence for crustal scale thrusting in the zagros mountain belt iran summary crustal receiver functions rfs computed from the records of 45 temporary seismological stations installed on a 620 km long profile across central zagros provide the first direct evidence for crustal thickening in this mountain belt due to a rather short 14 km average station spacing the migrated section computed from radial rfs displays the moho depth variations across the belt with good spatial resolution from the coast of the persian gulf to 25 km southwest of the main zagros thrust mzt the moho is almost horizontal with slight depth variations around 45 km crustal thickness then increases abruptly to a maximum of 70 km beneath the sanandaj sirjan metamorphic zone between 50 and 90 km northeast of the surface exposure of the mzt further northeast the moho depth decreases to 42 km beneath the urumiehdokhtar magmatic assemblage and the southern part of the central iranian microcontinent the region of thickest crust is located 75 km to the northeast of the bouguer anomaly low at 220 mgals gravity modelling shows that the measured moho depth variations can be reconciled with gravity observations by assuming that the crust of zagros underthrusts the crust of central iran along the mzt considered as a crustal scale structure this hypothesis is compatible with shortening estimates by balanced cross sections of the zagros folded belt as well as with structural and petrological studies of the metamorphic sanandaj sirjan zone

soil micromorphological evidence from iron age land use at tornby and mortlosa in linkoping sweden abstract the area of linkoping sweden has a land use history of several millennia in the last two decades many archaeological investigations of different types have been conducted here they range from trial trenching to full scale excavations of large areas and are connected to the expansion of the city the early iron age landscape of the area was formed by animal husbandry and the requirements of the domesticated animals earlier research has revealed an intensification and specialization within animal husbandry in the region occurring around the birth of christ when farms seemed particularly to specialize towards milk production however this transition and its local variations is still poorly investigated arable farming is assumed to have been characterized by small intensively used and improved cultivated areas close to the settlements but there are many questions still to be answered about the specific soil management types and crops there is a need to further investigate the land use history of the area from the early iron age 2440 2010 bp until medieval times ad 1030 1536 as part of the archaeological excavations carried out by the swedish national heritage board in 2007 six samples from three localities all in the linkoping municipality were chosen for soil micromorphological analysis at the locality of tornby i traces were found of anthropogenic activities including some kind of building activities prior to a period with extensive cultivation activities nearby presumably when the settlement was established in the pre roman iron age ca 200 bc it was followed by a period with soil management on the locality interpreted as a kind of garden cultivation the locality of tornby ii was presumably used a pasture in an early period and as a cultivation field with soil improvement in a later period at the locality of mortlosa dated to the roman iron age 2010 1680 bp and the migration period bc ad 550 ad traces from two different contemporary activity areas could be differentiated within few meters of a profile a cultivated field which has been improved with different kinds of manure through time and presumably a pathway for animals

new constraints on upper mantle s velocity structure and crustal thickness of the iranian plateau using partitioned waveform inversion summary the continental collision between the african and eurasian plates resulted in a tectonically young and complex deformation in the iranian plateau the present day iranian plateau is characterized by diverse tectonic domains including the continental collisions e g zagros and alborz and the oceanic plate subduction e g makran partitioned waveform inversion method is used here to image the s velocity structure of the upper mantle and moho depth variations in the iranian plateau of nearly 3000 waveforms originally selected for the analysis we have fitted 974 waveforms from 101 events and 39 stations which result in 11 688 linear constraints on the upper mantle s velocity structure and moho depth for the region our new seismic images show seismically faster upper mantle beneath the zagros and the arabian plate compared to the central iran and alborz this high velocity anomaly has descended beneath the central iran along the main zagros thrust across the zagros collision zone the tomographic images show a slab stagnation in the transition zone at about 410 km depth in the form of a horizontal high velocity zone which does not penetrate the deeper parts of the mantle the lowest s velocities are concentrated beneath the central iran and alborz according to our velocity models a strong high velocity anomaly is resolved beneath the trapped south caspian basin with clear indication of westward underthrusting beneath the talesh and western alborz in makran southeast iran there is a clear evidence of subduction of oceanic crust of the arabian plate beneath the makran belt which is correlated with seismicity pattern across the makran zone also the inverted moho map using a priori information of crustal thickness constraints shows the large crustal thickness beneath the zagros suture zone in some places to a maximum depth of 65 km which indicates the influence of crustal thickening and shortening beneath arabian eurasian plate boundary a significantly crustal thinning is observable across the south caspian basin compared to its margins

seismic imaging of the lithospheric structure of the zagros mountain belt iran we present a synthesis and a comparison of the results of two temporary passive seismic experiments installed for a few months across central and northern zagros the receiver function analysis of teleseismic earthquake records gives a high resolution image of the moho beneath the seismic transects on both cross sections the crust has an average thickness of 43 2 km beneath the zagros fold and thrust belt and the central domain the crust is thicker beneath the hanging wall of the main zagros reverse fault mzrf with a larger maximum moho depth in central 69 2 km than in northern zagros 56 2 km the thickening affects a narrower region 170 km beneath the sanandaj sirjan zone of central zagros and a wider region 320 km in northern zagros we propose that this thickening is related to overthrusting of the crust of the arabian margin by the crust of central iran along the mzrf considered as a major thrust fault cross cutting the whole crust the fault is imaged as a lowvelocity layer in the receiver function data of the northern zagros profile moreover the crustal scale thrust model reconciles the imaged seismic moho with the bouguer anomaly data measured on the central zagros transect at upper mantle depth p wave tomography confirms the previously observed strong contrast between the faster velocities of the arabian margin and the lower velocities of the iranian micro blocks our higher resolution tomography combined with surface wave analysis locates the suture in the shallow mantle of the sanandaj sirjan zone beneath central zagros the arabian upper mantle has shield like shear wave velocities while the lower velocities of the iranian upper mantle are likely due to higher temperature but these velocities are not low enough and the low velocity layer not thick enough to conclude on a delamination of the lithospheric mantle lid beneath iran the lack of a high velocity anomaly in the mantle beneath central iran suggests that the neotethyan oceanic lithosphere is probably detached from the arabian margin

linking slab break off hellenic trench retreat and uplift of the central and eastern anatolian plateaus abstract the central and eastern anatolian plateaus are integral parts of the world s third largest orogenic plateau in the past decade geophysical surveys have provided insights into the crust lithosphere and mantle beneath eastern anatolia these observations are now accompanied by recent surveys in central anatolia and new data constraining the timing and magnitude of uplift along its northern and southern margins together with predictions from geodynamic models on the effects of various processes on surface deformation and uplift the observations can be integrated to identify probable mechanisms of anatolian plateau growth a changeover from shortening to extension along the southern margin of central anatolia that is coeval with the start of uplift can be most easily associated with oceanic slab break off and tearing this interpretation is supported by tomography deep seismicity or lack thereof and gravity data based on the timing of uplift geophysical and geochemical observations and model predictions slab break off likely occurred first beneath eastern anatolia in middle to late miocene time and propagated westward toward cyprus by the latest miocene alternatively the break off near cyprus could have occurred in late pliocene to early pleistocene time in association with collision of the eratosthenes seamount continental fragment with the subduction zone uplift at the northern margin of central anatolia appears to result from crustal shortening starting in the late miocene or early pliocene which has been linked to the broad restraining bend of the north anatolian fault the uplift history of the interior of central anatolia since the late miocene is unclear although shortening there appears to have ended by the late miocene followed by ne sw extension this change in the deformation style broadly coincides with faster retreat of the hellenic trench as well as uplift of the northern and southern margins of central anatolia these different events throughout the plateau may be linked as faster retreat of the hellenic trench has been predicted to occur after slab break off which could have induced extension of central anatolia and helped to form the north anatolian fault through accelerated westward movement of anatolia relative to eurasia correlative geochronologic evidence that we summarize here supports the hypothesis that the geodynamic activity throughout the aegean anatolian domain starting in latest miocene to early pliocene time defines a series of events that may all be linked to slab break off

crustal structure from gravity signatures in the iberian peninsula through two dimensional fi ltering and spectral analysis of gravity data we infer the density structure of the iberia peninsula s lithosphere western europe the gravity anomaly map of the iberian peninsula displays long wavelength anomaly minima related to alpine ranges these anomalies are primarily linked to a greater crustal thickness low pass filtering of the anomaly map using a cutoff wavelength of 150 km was adequate for effective separation of shallow and deep sources used for computing the three dimensional 3 d moho interface tsuboi s technique identical to the equivalent stratum theorem is used here to map the 3 d moho interface by selecting mean source depths from the results of the spectral analysis and assuming a homogeneous density contrast of 350 kg m3 the most characteristic feature of the 3 d moho geometry was the presence of several lows associated with mountain ranges created by alpine tectonics in those areas the gravity derived moho reaches a depth of up to 45 km in the pyrenees and cantabrian mountains and close to 40 km under the betics central system and iberian chain under the iberian massif the western part of the iberian peninsula composed of a variscan basement the moho was located at a depth of 30 36 km these results are consistent with existing seismic data and indicate that gravity based techniques can provide very good estimates of lithosphere structure

combined modeling and smooth inversion of gravity data from a faulted basement relief abstractwe have combined modeling and gravity inversion to estimate an overall smooth but locally discontinuous basement relief of a sedimentary basin through an initial global smoothness solution the method indicates fault positions that may be accepted or modified then the interpreter specifies the fault dip and a tentative fault slip so the fault plane is fixed on the estimated relief the segments of the current interpreted relief that are not accepted faults are estimated through smoothness inversion and the response of the current estimated relief is computed the slip of the fault being incorporated in the estimated relief is then modified interactively until the solution presents no side lobes about the fault extremes the process is repeated for all faults the iteration stops when the tentative solution becomes compatible with the geologic knowledge of the area and produces an acceptable data fit the method was applied to data produced by a simulated graben defined by step faults dipping

three dimensional gravity inversion using simulated annealing constraints on the diapiric roots of allochthonous salt structures in the northern continental slope of the gulf of mexico large oil and gas reservoirs are often found beneath sheetlike allochthonous salt structures that are laterally extensive some of these salt structures retain their diapiric feeders or roots beneath them these hidden roots are difficult to image seismically in this study we develop a method to locate and constrain the geometry of such roots through 3 d inverse modeling of the gravity anomalies observed over the salt structures this inversion method utilizes a priori information such as the upper surface topography of the salt which can be delineated by a limited coverage of 2 d seismic data the sediment compaction curve in the region and the continuity of the salt body the inversion computation is based on the simulated annealing sa global optimization algorithm the sa based gravity inversion has some advantages over the approach based on damped least squares inversion it is computationally efficient can solve underdetermined inverse problems can more easily implement complex a priori information and does not introduce smoothing effects in the final density structure model we test this inversion method using synthetic gravity data for a type of salt geometry that is common among the allochthonous salt structures in the gulf of mexico and show that it is highly effective in constraining the diapiric root we also show that carrying out multiple inversion runs helps reduce the uncertainty in the final density model

joint optimization of vertical component gravity and p wave first arrivals by simulated annealing abstractjoint seismic and gravity analyses of the san emidio geothermal field in the northwest basin and range province of nevada demonstrate that joint optimization changes interpretation outcomes the prior 0 3 0 5 km deep basin interpretation gives way to a deeper than 1 3 km basin model kirchoff prestack depth migrations reveal that joint optimization ameliorates shallow velocity artifacts flattening antiformal reflectors that could have been interpreted as folds furthermore joint optimization provides a clearer picture of the rangefront fault by increasing the depth of constrained velocities which improves reflector coherency at depth this technique provides new insight when applied to existing data sets and could replace the existing strategy of forward modeling to match gravity data we have achieved stable joint optimization through simulated annealing a global optimization algorithm that does not require an accurate initial model balancing the combined seismic gravity objective function i

3d joint inversion modeling of the lithospheric density structure based on gravity geoid and topography data application to the alborz mountains iran and south caspian basin region abstract we present a 3d algorithm to obtain the density structure of the lithosphere from joint inversion of free air gravity geoid and topography data based on a bayesian approach with gaussian probability density functions the algorithm delivers the crustal and lithospheric thicknesses and the average crustal density stabilization of the inversion process may be obtained through parameter damping and smoothing as well as use of a priori information like crustal thicknesses from seismic profiles the algorithm is applied to synthetic models in order to demonstrate its usefulness a real data application is presented for the area of northern iran with the alborz mountains as main target and the south caspian basin the resulting model shows an important crustal root up to 55 km under the alborz mountains and a thin crust ca 30 km under the southernmost south caspian basin thickening northward to the apsheron balkan sill to 45 km central and nw iran is underlain by a thin lithosphere ca 90 100 km the lithosphere thickens under the south caspian basin until the apsheron balkan sill where it reaches more than 240 km under the stable turan platform we find a lithospheric thickness of 160 180 km

seismological constraints on the crustal structure beneath the zagros mountain belt iran summary the zagros mountain belt of western iran results from the collision of the arabian and central iran continental blocks the stage of the collision is unclear and the crustal structure of the zagros is rather poorly known in this study we investigate the velocity structure of the crust and upper mantle beneath the ghir region located in the central zagros using data collected by a temporary local seismological network including a broad band instrument the structures of the sedimentary cover and the upper crystalline crust are estimated from the inversion of p and s traveltimes of local earthquakes recorded on a dense seismological network the upper crust consists of an 11 km thick sedimentary layer v p 4 70 km s 1 above a 8 km thick upper crystalline crust v p 5 85 km s 1 the velocity of the lower crust and the depth of the moho are found using receiver function analysis of teleseismic earthquakes the lower crystalline crust is unusually slow v p 6 5 km s 1 and 27 km thick the upper bound for the total crustal thickness beneath the ghir region is 46 2 km a comparison of the thickness of the crystalline crust of the zagros with available information for the thickness of the crystalline crust of the arabian platform shows that at present the zagros has a thinner crust the current crustal thickness beneath the zagros is comparable to the pre collision crustal thickness of the arabian platform suggesting that the zagros is now in a very early stage of continental collision