the influence of evaporation and rainfall on supratidal groundwater dynamics and salinity structure in a sandy beach evaporation has been recognized as a major driving force affecting coastal aquifer systems however its effects on subsurface flow and salinity structure have not been investigated in sufficient detail this paper presents field measurements and numerical simulations of pore water flow and subsurface salinity structure in the supratidal zone of a sandy beach subjected to evaporation as well as rainfall it was found that evaporation significantly increased pore water salinity up to 85 g l within a shallow layer approximately 10 cm below the beach surface the induced density gradient generated salt fingers near the beach surface which caused local groundwater circulation i e fingering flow however unlike inland aquifers the salt fingering was significantly diminished by tidal action that prompted the horizontal mixing of salt in the beach the subsequent precipitation e g rainfall diluted the evaporation induced high saline plume near the beach surface and drove the plume to migrate further downward the plume gradually dispersed and was diluted along the groundwater pathways the simulation results indicated that evaporation as well as precipitation at the beach surface induced complex driving mechanisms for supratidal groundwater flow depending on the intensity at the beach surface evaporation and rainfall significantly altered the pore water flow and associate solute transport processes in the supratidal zone of the beach

fungal proliferation at the cretaceous tertiary boundary we have found that a fungal spike occurs between the diverse late cretaceous palynoflora and the low diversity fern dominated early paleocene assemblages in a new zealand section the fungal layer is coincident with the ir anomaly marking the extinction event

estimation of evaporation from the normally dry lake frome in south australia depth profiles of deuterium composition expressed as delta values have been used to make point estimates of evaporation from the floor of the normally dry lake frome a salt lake in northern south australia values from five sites varying between 90 and 230 mm yr 1 have been used to obtain a relatively crude approximation for mean evaporation rate from the lake of 170 mm yr 1 under the assumption that this represents discharge of water from the regional groundwater system the groundwater inflow into the lake is calculated as 5 108 m3 yr 1 two possible models which describe groundwater inflow into the lake are discussed

a mechanistic study of nonlinear solute transport in a groundwater surface water system under steady state and transient hydraulic conditions two laboratory experiments were conducted to investigate the effects of tides and buoyancy on beach hydraulics in the presence of a seaward groundwater flow due to an elevated regional water table in the first experiment case 1 the difference in concentration between the salt water at sea and the water of the regional aquifer was small 2 4 g l 1 such that it did not engender density gradients the salt acts as a tracer in this case in the second experiment case 2 the difference was 32 0 g l 1 which creates a significant density gradient this case corresponds to the presence of fresh groundwater in the subsurface of the coasts of the continental united states the experiments were numerically simulated by the marine unsaturated marun model a numerical model for density and viscosity dependent flows in two dimensional variably saturated media the long term experimental and numerical results showed that the seawater plume entered the beach from the sea and occupied most of the intertidal zone the maximum depth of the seawater plume was near the midsection of the intertidal zone and it decreased near the low and high tide lines when viewed in the context of case 2 these results indicate an inverted salinity distribution in beaches subjected to tides with salt water from sea overtopping the freshwater lens for both cases water from the regional aquifer moved seaward beneath the seawater in the intertidal zone and pinched out near the low tide mark we also noted that beach hydraulics are highly two dimensional with water entering the beach at a near vertical angle and leaving it at a near horizontal angle which casts doubts on analyses of beach hydraulics based on the dupuit assumption findings from this work have direct implications within the practice of bioremediation of oil spills on beaches we found that applying dissolved nutrients on the beach surface at low tide is superior to applying them in a trench landward of the beach this is because the residence time of the nutrient plume in the bioremediation zone of the beach in the prior situation is longer than that in the latter

tide induced seawater groundwater circulation in shallow beach aquifers summary in this paper we investigated the tide induced seawater groundwater circulation in shallow beach aquifers using the finite element model marun the numerical solutions were generalized using a dimensionless formulation from a dimensionless tidal period and a dimensionless beach slope of 10 we obtained results that apply to a wide range of beach permeabilities from 10 4 m s to 10 3 m s beach slopes from 3 16 to 31 6 tidal amplitude 0 3 m 2 m and period diurnal or semidiurnal the numerical simulations demonstrated the following the maximum darcy velocity always occurs at the intersection of the watertable and the beach surface the offshore beach groundwater is almost stagnant compared with the onshore groundwater flow which may explain the previous observations that the major portion of the seaward groundwater seepage usually occurs in the shallow part of the submerged beach the outflow from the seepage face accounts for 41 97 average 55 of the outflow from the intertidal zone the amount of seawater infiltrating into the intertidal zone in a tidal cycle increases with the beach permeability and decreases when the inland recharge increases and ranges from 35 5 m 3 yr 1 m 1 to 505 8 m 3 yr 1 m 1 for all the cases considered smaller beach slopes smaller inland freshwater recharges and or greater beach permeability lead to larger saltwater plumes in the intertidal zone of the beach the results are in line with the existing results of field observations and numerical simulations by previous researchers a 2008 elsevier b v all rights reserved

variable density flow and solute transport simulation of regional aquifers containing a narrow freshwater saltwater transition zone variable density flow and solute transport simulation of aquifer systems containing narrow transition zones between freshwater and saltwater requires particular attention to certain aspects of the numerical method and its application to be successful typically only cases involving wide transition zones have been simulated with variable density transport models possibly because of inaccuracies in the modeling approaches used the major components of a successful approach are threefold first functionally consistent approximation of terms involved in fluid velocity calculations is necessary in the case of galerkin finite element methodology a significant modification is required to the standard approach in order to achieve consistency second the simulator must be verified in a particular series of tests the usual tests using henry s problem for verification of density dependent transport simulators are inadequate to check for consistency of the velocity approximations and for the accuracy of simulating flow driven by bouyancy forces third adequately fine spatial discretization is required when applying the simulator for spatial stability of the numerical transport solution and to allow accurate representation of narrow transition zones and the effects of low transverse dispersivity the effectiveness of this approach is demonstrated through simulation of the flow of fresh and saline groundwater in the layered basalt aquifer of southern oahu hawaii the transition zone in this regional flow system is narrow except near the discharge area where it is broadly dispersed simulation of this common situation with an inconsistent approximation gives grossly incorrect results while simulation with a consistent model provides a robust tool for analysis of system hydrology

the rise and demise of podozamites in east asia an extinct conifer life style abstract in the late triassic early jurassic forests dominated by podozamites an apparently deciduous shoot dropping conifer with broad multi veined leaves were extensive in what were the mid latitudes of eastern asia podozamites was the only conifer in many forests of this region and at times appeared to have formed an almost mono specific vegetation podozamites appears to have been little effected through the triassic jurassic transition but responded to climate changes later in the jurassic the chinese region progressively dried through the middle jurassic and aridity had developed in some areas by the late jurassic early cretaceous the centre of distribution of podozamites shifted north to the siberian region where conditions remained wet there it typically coexisted with conifers having a diverse range of smaller leaf morphologies by the late albian angiosperms had arrived in the siberian area and risen to dominance some time after this event podozamites became extinct this is significant as it represents the permanent extinction of a unique lifestyle a deciduous broad leaved and multi veined conifer the broad history of podozamites raises some interesting issues 1 the existence of a large dominantly deciduous vegetation at mid latitudes in the late triassic early jurassic is little discussed 2 it is unexpected that as broad leaved angiosperms took over amongst the conifers it was the broad leaved multi veined podozamites that became extinct this is the morphology that might have been expected to compete with the apparently more shade forming angiosperms instead it was the smaller leaved and single veined conifers that remained to coexist with the angiosperms

impacts of evaporation on subsurface flow and salt accumulation in a tidally influenced beach we coupled a mass transfer formulation of evaporation to the density dependent variably saturated finite element model marun to predict the salinity under realistic conditions in a beach in the gulf of mexico the results showed that evaporation almost doubled the pore water salt concentration in the intertidal zone in comparison to the case with no evaporation the results also showed that for the relatively wet atmospheric conditions the maximum evaporation did not occur from the supratidal zone rather from the intertidal zone and it was due to the difference in moisture between pore water and atmosphere the highest salinity occurred during the spring tide period and extended into the neap tide period when the atmospheric condition was assumed to be constant and conducive to large evaporation high temperature and low air humidity the maximum salinity region shifted to the supratidal zone and persisted there due to low mixing the maximum salinity value in the intertidal zone for this case was not larger than that of the variable atmospheric condition case however the maximum was more landward than the more realistic variable atmospheric condition case which suggests that accurate characterization of pore water salinity in tidally influenced beaches requires accurate knowledge of atmospheric conditions in addition to beach and hydraulic properties the constant atmospheric condition simulations suggest that antecedent extreme conditions greatly affect the salinity in the supratidal zone but they are dampened in the intertidal zone

architecture of late orogenic quaternary basins in northeastern mediterranean sea abstract in the northeastern mediterranean sea pliocene to quaternary depocentres have formed in extensional basins bounded by splays of the east anatolian transform fault this tectonic regime is superimposed on a miocene and older back arc environment that experienced late miocene compression along the misis kyrenia thrust which now lies in the middle of the extensional zone the thrust zone is now represented by a narrow horst that appears to be bounded by strike slip faults pliocene quaternary extension took place on listric fault fans that are orthogonal to the bounding transform splays and sole at a messinian evaporite horizon and on some deeper soling listric faults parallel to and near the bounding faults the rapid extension has resulted in progressive landward migration of paleoshorelines and low depositional gradients glacio eustatic fluctuations in shoreline positions strongly influenced sediment distribution most sediment dispersion was from deltaic plumes with turbidites of minor significance depocentres landward of the maximum seaward extent of paleoshorelines were formed almost entirely by tectonic subsidence minor deep water depocentres controlled by halokinesis accumulated mud turbidites during extreme low stands of sea level

faulting associated with historical and recent earthquakes in the eastern mediterranean region summary this paper summarizes evidence for surface faulting in historical and recent earthquakes in the eastern mediterranean region and in the middle east such information is particularly important for studies of active tectonics and for palaeoseismology we have found 78 cases of faulting pre 1900 and 72 post 1900 some of which show that faults that have apparently been inactive this century had already ruptured before 1900 for some cases faulting could not have been predicted from 20th century activity and in others it could have been expected but has not been observed during the instrumental period the data are suycient to allow the derivation of relationships between magnitude and rupture length

block rotation by strike slip faulting structural and paleomagnetic evidence geometric analysis shows that motion of sets of strike slip faults should cause block rotation otherwise the distorted fault domain would not fit with its surrounding the sense of the block rotation depends on the sense of fault slip and the spacing and orientation of the faults all of which can be obtained from structural data the predictions of the geometric model can then be independently tested by paleomagnetic measurements the model was tested in northern israel structural data reveal several domains of contemporaneous right and left lateral strike slip faults paleomagnetic measurements show that in a domain of nnw trending left lateral faults blocks rotated 23 3 8 2 clockwise and in a domain of right lateral faults blocks rotated 22 4 9 0 anticlockwise these results are in agreement with the prediction of the geometric analysis of the structure the combined results of the heterogenous deformation of the area resembles a pure shear which allows n s extension by about 1 3 in other domains rotations of 34 6 9 1 and 53 1 11 0 were found in their original orientation the left and right lateral faults intersected at angles of 60 70 enclosing the principal axis of shortening in accordance with theories of brittle failure as a result of block rotations this angle is now larger and may reach 110 the results demonstrate large block rotations in different senses in domains of strike slip faults the independent structural and paleomagnetic data can be interpreted within the framework of a simple geometric model northern israel is considered to be a good model for this efficient mechanism of intraplate deformation which is expected to occur in similar tectonic settings elsewhere

structure and tectonic development of the ghab basin and the dead sea fault system syria we examine the structure and evolution of the ghab basin that formed on the active yet poorly understood northern segment of the dead sea transform fault system the basin formed in plio quaternary time at a complex step over zone on the fault subsidence occurred along cross basin and transform parallel faults in two asymmetric depocentres the larger depocentre in the south of the basin is asymmetric towards the east the margin along which most active transform displacement apparently occurs the syrian coastal ranges located directly west of the ghab basin are a consequence of late cretaceous and cenozoic regional compression heavily modified by the dead sea fault system and ghab basin formation we prefer a model whereby the dead sea fault system in northwest syria developed in plio quaternary time consistent with previously proposed models of two phase dead sea fault system movement and red sea spreading

late aptian palaeoclimatic turnovers and volcanism insights from a shallow marine and continental succession of the apennine carbonate platform southern italy abstract this study reports an integrated facies analysis carried out on a new section from the upper aptian of the se matese mts civitella licinio northern campania s italy which includes several decimeter to meter scale lacustrine intervals straddling a meter scale plant rich plattenkalk these intervals are assigned to the late gargasian early clansayesian by their stratigraphic relationship with the upper salpingoporella dinarica acme as well as lithologic and biostratigraphic supra regional key markers found in the apennine carbonate platform apcp including the orbitolina level we infer that the monogeneric parautochthonous plant remains frenelopsis sp were deposited in a supratidal to paralic coastal mudflat close to a restricted shallow marine lagoon at the verge of an arid semiarid climatic phase the plattenkalk was rapidly replaced by persistent lacustrine lithofacies at the onset of a major climatic turnover glacial trigger the overlying shallow marine deposits are capped by a deeply incised palaeokarstic surface and in turn by unconformable middle clansayesian transgressive shallow marine deposits interlayering of reliable lithologic indicators of palaeoclimate and high resolution event stratigraphic hires correlation of the civitella licinio succession with the astrochronologically tuned mt faito reference section of the apcp bring evidence of rapidly fluctuating hydroclimatic conditions wet and arid phases in the short 100 ky and long 400 ky eccentricity time band hires and astrochronological age assignment to crucial key markers and humid arid phases at civitella licinio permit to further refine the detailed stratigraphy of the mt faito reference section and to assign the upper s dinarica acme of the apcp to a numerical age of 118 55 118 50 my sem and eds analyses document common to abundant windblown volcanic particles glass shards and sanidine crystals throughout the frenelopsis rich plattenkalk 118 3 to 118 2 my and the encasing units especially in the overlying brackish lacustrine deposits palaeogeographic and palaeoclimatic reconstructions suggest that the pyroclastic material was probably transported by northeasterly trade winds from orogenic volcanic centers located within the dinaridic carpatho balkan arc trench system and have been supplied to the apcp for a time span of 3 my during the late aptian a preliminary tephrostratigraphic correlation of the upper aptian volcaniclastic levels of the apcp with the bentonite levels of the vocontian basin is proposed

a new jurassic recent apparent polar wander path for south america and a review of central andean tectonic models abstract the jurassic to recent palaeomagnetic data from the stable cratonic areas of south america and africa are reviewed and evaluated from the combined data set seven mean reference pole positions are calculated for the early middle and late jurassic early and late cretaceous palaeogene and neogene most of these new palaeopoles are well defined and indicate a complex course of apparent polar wander for the south american plate comparison of the palaeomagnetic data from the andean margin with the reference poles indicates vertical axis rotations defining a broad pattern of anticlockwise rotations north of the arica deflection at approximately 19 s and clockwise rotations to the south further analysis indicates however that the distribution and magnitude of rotations is more complicated than this broad division tectonic models proposed to explain the pattern of rotations and the possible origins of the arica deflection are discussed it is suggested that the rotations probably result from localised in situ rotations controlled by strike slip fault systems or thrust sheets rather than large scale rotation mechanisms the broad rotation pattern may result from the influence of pre existing structures in the margin or variations in the flexural rigidity of the brazilian shield behind the deformation zone

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

on the computation of darcian velocity and mass balance in the finite element modeling of groundwater flow darcian velocity has been conventionally calculated in the finite element modeling of groundwater flow by taking the derivatives of the computed pressure field this results in discontinuities in the velocity field at nodal points and element boundaries discontinuities become enormous when the computed pressure field is far from a linear distribution it is proposed in this paper that the finite element procedure that is used to simulate the pressure field or the moisture content field also be applied to darcy s law with the derivatives of the computed pressure field as the load function the problem of discontinuity is then eliminated and the error of mass balance over the region of interest is much reduced the reduction is from 23 8 to 2 2 by one numerical scheme and from 29 7 to 3 6 by another for a transient problem

loading effect of water table variation and density effect on tidal head fluctuations in a coastal aquifer system 1 water table variation will result in considerable variation of the weight of the pore water which has loading effects on the groundwater flow in the underlying confined aquifer here we present an analytical solution on such a loading effect in a coastal aquifer system consisting of an unconfined aquifer a confined aquifer and an impermeable layer between them with the two lower layers extending under the sea the solution generalizes several existing ones in the literature the water table variation s loading effects tend to enhance the amplitude and to reduce the phase shift of the tide induced head fluctuation these effects become considerable when the tidal loading coefficient is large the aquifer s offshore extending length is long and the unconfined aquifer has large values of hydraulic conductivity and specific yield numerical examination indicated that the assumption of ignoring the density variation causes an error not greater than 2 5 of the tidal amplitude

convection in groundwater below an evaporating salt lake 2 evolution of fingers or plumes the downward convection of salt fingers or plumes developed from the unstable boundary layer of an evaporating dry salt lake is examined using a numerical model and hele shaw cell experiments in the convecting layer the early small waves evolve into fingerlike or plumelike formations the number of fingers or plumes decreasing with time owing to differential growth and or coalescence comparison of intermediate formational stages of this pattern with the pattern generated by a two dimensional numerical simulation shows good qualitative agreement however there is a significant mismatch of the growth rates at long times in the computer simulation the plume length develops approximately twice as rapidly as it does in the experimental case a simple numerical experiment independent of the salt lake boundary conditions is compared to previously published laboratory scale measures of plume development in hele shaw cells which confirms the retardation of hele shaw plumes by a factor of approximately 50 this departure is attributed to the differences in dimensionality between the hele shaw flow domain and the model domain the data indicated that leading plumes develop isolated behavior at long times and may not be adequately represented in hele shaw analog models and numerical simulation provides a more accurate simulation of field scale behavior

deformational behaviour of continental lithosphere deduced from block rotations across the north anatolian fault zone in turkey abstract theoretical considerations of lithosphere deformation across transform plate boundaries predict an expression in terms of 3istributed deformation the magnitude of rotation is expected to diminish away from the fault zone in a way which depends on the length of the fault the amount of displacement and the ductility of the lithosphere palaeomagnetic studies across the north anatolian transform fault zone which separates the eurasian plate and anatolian block in northern turkey show that clockwise rotations predicted from the sense of dextral motion are indeed present and have attained finite rotations of up to 270 during the 5 ma history of neotectonic deformation such rotations are however confined to narrow 10 km wide zones between system bounding faults and appear to have resulted from rotation in ball bearing fashion of equidimensional blocks a few kilometres in size outside of this zone only anticlockwise rotations are observed these are unrelated to deformation across the fault zone and record regional anticlockwise rotation of turkey which is complementing clockwise rotation of greece and accompanying neogene opening of the aegean sea the observed behaviour of continental lithosphere satisfies no plausible value of power law behaviour we therefore conclude that relative motion across this transform boundary occurs as a discrete zone of intense deformation within a brittle layer comprising the seismogenic upper crust this is presumed to be detached from a continuum deformation response to shearing in the lower crust and mantle beneath

late jurassic early cretaceous palynofloras in the lhasa block central xizang china and their bearing on palaeoenvironments abstract as a part of the qinghai xizang plateau the lhasa block has experienced a very complicated geological history since it rifted from gondwana little is known about how terrestrial ecosystems evolved on this block during this time our new materials collected from this block reveal for the first time the palaeovegetation and palaeoclimate during the late jurassic to early cretaceous three distinct palynological associations are recognized including the late jurassic cyathidites classopollis association and the early cretaceous berriasian barremian dicheiropollis and dicheiropollis peak associations an additional classopollis cooksonites association recovered from qubsang which lacks dicheiropollis is coeval with the dicheiropollis association these associations are generally similar to those on the qiangtang block southern qinghai province which indicates that these blocks had merged before the late jurassic facilitating establishment of a common palynoflora across the two blocks and adjacent regions the palaeovegetation on the lhasa block in the late jurassic was characterized by abundant tree ferns whereas during the earliest cretaceous cheirolepidiacean communities were more dominant within these communities a new cheirolepidiacean plant that produced dicheiropollis pollen emerged implying a potential increase in temperature the palaeoclimate was generally warm and semi humid during the late jurassic and early cretaceous although fluctuations of temperature and humidity occurred a reduction in precipitation from the lhasa block to the inland qiangtang block and tarim basin is reflected in the palynoflora a brief history of the vegetation and climate of the lhasa block from late jurassic to early cretaceous is provided

field study of spatial variability in unsaturated flow beneath and adjacent to playas we quantified unsaturated flow beneath playa and adjacent interplaya settings at a site in the southern high plains united states to resolve issues related to where and how water moves through the unsaturated zone this is the first study in which the data density 39 boreholes and the variety of techniques used physical chemical and isotopic were sufficient to quantify spatial variability in unsaturated flow water contents water potentials and tritium eoneentrations were much higher and chloride eoneentrations were much lower beneath playas than in interplaya settings which indicated that playas focus recharge these results refute previous hypotheses that playas act as evaporation pans or that recharge is restricted to the annular region around playas water fluxes estimated from environmental tracers ranged from 60 to 120 mm yr 1 beneath playas and were 0 1 mm yr 1 during the past 2000 5000 years beneath natural interplaya areas not subjected to ponding to evaluate the apparent inconsistency between high recharge rates and thick clay layers beneath playas we applied bromide and fd c blue dye to evaluate flow processes these applied tracer experiments showed preferential flow along roots and desiccation cracks through structured clays in the shallow subsurface in playas

numerical modeling of water flow below dry salt lakes effect of capillarity and viscosity abstract we investigate numerically the effects of capillarity and viscosity on density dependent flows below dry salt lakes the numerical model marun boufadel m c suidan m t venosa a d 1999a a numerical model for density and viscosity dependent flows in two dimensional variably saturated media j contam hydrol 37 1 20 is used to assess the combined and separate effects of capillarity and concentration engendered viscosity on the groundwater dynamics of a two dimensional system simulating a dry lake we found that accounting for concentration engendered viscosity effects under saturated water flow conditions gives totally different groundwater dynamics from the case where these effects are neglected however concentration dependent viscosity effects were minor when unsaturated water flow conditions were present under variably saturated flow conditions capillarity effects gave totally different hydraulics in the porous domain from the saturated flow case upwelling regions observed under saturated flow conditions were downwelling when capillarity effects were present a mesh orientation study revealed that density dependent flows were susceptible to the orientation of the diagonals of the triangular elements a discussion on the accuracy and the efficiency of the marun model in the context of density and viscosity dependent flows in two dimensional variably saturated media is also provided

palaeovegetation and palaeoclimate changes across the triassic jurassic transition in the sichuan basin china abstract the triassic jurassic transition interval is marked by enhanced biotic turnover rates in both marine and terrestrial realms however limited data from asia hampers the understanding of global ecosystem response to the end triassic mass extinction event here we present significant vegetation and climate changes across the triassic jurassic transition in the eastern tethys region southern china a detailed palynological study was performed from the qilixia section of the sichuan basin china spanning the upper triassic norian rhaetian xujiahe formation to the lower jurassic hettangian sinemurian lower zhenzhuchong formation five palynological assemblages reveal significant ecosystem fluctuations across the triassic jurassic transition our study indicates a lowland fern flora and a warm and humid climate in the late triassic norian to rhaetian interrupted by a cooler interval at the norian rhaetian transition and followed by a mixed mid storey forest under cooler and drier condition in the latest rhaetian this is followed by a fern dominated lowland vegetation and a warmer and drier climate during the triassic jurassic transition and a flora with abundant cheirolepid conifers in the hettangian sinemurian these long term changes in vegetation and inferred climatic conditions are comparable with records from the western tethyan realm and possibly reflect global terrestrial environmental changes associated with central atlantic magmatic province volcanism during the triassic jurassic transition

convection in groundwater below an evaporating salt lake 1 onset of instability convective groundwater motion can be generated in aquifers beneath and adjacent to saline lakes such motions strongly control the subsurface distribution of salts the formation of saline minerals and the distribution of contaminants that may be disposed of in the saline lake in particular schemes to use saline lakes as evaporation basins for irrigation waste waters must consider the groundwater dynamics associated with convection the convection is driven by the evaporative concentration of salts at the land surface leading to an unstable distribution of density however the evaporative groundwater discharge can dynamically stabilize this saline boundary layer and inhibit convection in this work we investigate the nature and onset of convection for a range of boundary conditions typically found in saline lakes processes involved in the accumulation of salt at the surface of a groundwater discharge zone and in the gravitational instability of the near surface groundwater are considered results of theoretical stability analysis are applied through laboratory and numerical experimentation to the more complex geometries typically found in the field these comparisons indicate that for large saline lakes the stability of the saline boundary layer can be parameterized by traditional rayleigh criteria in which the aquifer permeability and the evaporation rate from the lake bed are principal controlling factors for typical saline lake environments convection will dominate in sediments whose permeability exceeds approximately 10 14 m2 below this threshold permeability the boundary layer should be stabilized by the evaporative flux resulting in the accumulation of salts and evaporites at the land surface these results provide insight into the predictive behavior of groundwater dynamics and solute distributions in many natural systems

plant taphonomy and palaeoecology in the lacustrine una delta late barremian iberian ranges spain abstract plant cuticle compressions and sporomorphs were studied in coaly clays belonging to the upper barremian la huerguina formation in una south western iberian ranges cuenca spain cuticle assemblages are extremely monotonous and formed by the genera frenelopsis schenk emend watson classostrobus alvin et al and glenrosa watson and fisher sporomorphs are dominated by classopollis pflug emend srivastava the genus glenrosa is described for the first time in europe sedimentological and taphonomical analyses show that these assemblages originated by fragmentation and size selection during residence in the leaf litter and by fluvial transport final deposition occurred in crevasse splay deltaic front and pro deltaic environments our results indicate that the una delta was fed almost exclusively by remains of cheirolepidiaceous conifers living in the upper deltaic plain of a lacustrine delta a comparison with the flora found in the open lacustrine facies of las hoyas which is laterally equivalent of the beds studied shows that land plant assemblages of las hoyas are more diverse the parautochthonous matoniaceous tree fern weichselia reticulata dominated the lakeshore vegetation of las hoyas in contrast to the vegetation of the upper delta plain of una which was dominated by frenelopsis the habitats of frenelopsis and glenrosa from the upper barremian oligohaline basin of una las hoyas contrast with the habitats commonly hypothesized for both taxa in coastal marine environments or on saline edaphic profiles in conclusion frenelopsis appears to have a wider tolerance to salinities than previously thought and their adaptations to saline edaphic conditions should be considered species specific rather than genus specific

late cretaceous campanian leaf and palynoflora from southern skane sweden a late cretaceous campanian leaf megaflora from the vomb trough in southern skane sweden has been investigated on the basis of collections held at the swedish museum of natural history the mai

the structural relationship between the east anatolian and dead sea fault zones in southeastern turkey abstract the complex structural relationship between the east anatolian and dead sea fault zones is examined mostly based on field observations in southeastern turkey where the two fault zones are close together several faults previously poorly documented can be traced to connect either to the east anatolian fault zone or to the dead sea fault zone one of these faults connects the dead sea fault zone to the east to the amanos fault to the west the amanos fault a n trending normal fault is a part of the east anatolian fault zone since it is apparently a left step fault between the main and southern strands of the east anatolian fault zone the dead sea fault zone also is connected to the east anatolian fault zone northeast of the town of narli and or northeast of the hazar lake therefore we suggest that the two fault zones can be considered as one broad fault system in southeastern turkey although they are well recognized as two different fault zones this fault system is responsible for several complex neogene structural features of the western part of the southeastern turkey one of these is the hatay graben which can be divided into southern central and northern parts the graben contains down to the west normal faults in its southern part the central part of the graben is a divergent strike slip basin and the northern part is a half graben

quaternary stress regime change in the hatay region se turkey in this study we determine the plio quaternary to present day stress regime acting in the hatay region located at the northeastern corner of the east mediterranean region the modern state of stress is obtained from inversion of focal mechanism solutions of shallow earthquakes this inversion identifies a dominantly extensional stress regime with a ne trending h m i n 3 axis at the present day the stress regime determined from inversion of slip vectors measured on fault planes confirms that this regime is extensional in the studied area both the kinematics and chronologies of fault slip vectors show that the stress state changed from an earlier strike slip regime to a younger extensional stress regime with a consistent ne trending h m i n 3 axis the change from strike slip to extensional stress regimes probably occurred during the quaternary regionally both stress regimes induce sinistral displacement on the east anatolian fault and dead sea fault systems the north anatolian fault naf is a dextral strike slip fault which runs about 1400 km from east to west and has been active since collision between the eurasian and arabian plates together with the sinistral east anatolian fault the naf intracontinental deformation zone contributes to the westward extrusion of anatolia as a consequence of northward drift of arabia consequently the late cenozoic stress regimes acting in the hatay region result from the coeval influence of forces due to 1 the subduction processes in the west and southwest 2 the continental collision in the east and 3 the westward escape of the anatolian block however the timing of the temporal stress transition suggests that the quaternary stress regime change resulted from subduction processes with the extensional stress regime in the hatay region being mainly attributable to roll back of the mediterranean subducted slab along the cyprus arc

cretaceous patterns of floristic change in the antarctic peninsula cretaceous radiation of angiosperms from low to high palaeolatitudes coupled with the break up of gondwana played a major role in establishing and maintaining biogeographic patterns across the southern hemisphere uncertainties in details of plate reconstructions provide conflicting hypotheses about area relationships of gondwana fragments this has led to a number of competing proposals concerning angiosperm migration across gondwana central to this debate is the role of the antarctic peninsula a region that is often envisaged as providing the main connection between east and west gondwana the initial radiation of angiosperms into the antarctic peninsula region however postdates appearances elsewhere in east gondwana e g australia strongly suggesting that the antarctic peninsula was not the main gateway at least in the early stages of gondwana radiation a steep climatic gradient in this part of the world probably acted as an effective barrier to angiosperm radiation the peak of floristic replacement coincides with the peak of cretaceous warmth turonian which in turn suggests that climatic warming acted as a forcing mechanism by pushing latitudinal belts of vegetation southwards once into the southern high latitudes angiosperms diversified and as climates cooled during the late cretaceous a number of important groups seem to have their origins here recent investigations of antarctic macro and microfloras indicate progressive floristic replacement through the cretaceous bryophytes hepatophytes bennettites and other seed plants all show a rapid decline in diversity in contrast ferns initially decline then recover while conifers remain relatively stable the ecological preferences of the replaced groups imply that angiosperms initially occupied areas of disturbance and were understorey colonizers only later replacing fern thickets and becoming important in the overstorey this pattern is consistent with those observed elsewhere through the cretaceous

spatial variability and hydrologic evolution of australian lake basins analogue for pleistocene hydrologic change and evaporite formation abstract processes evident in basins across hydrologic gradients from humid to arid regions today provide analogues for systems that may have operated in some individual basins during periods of past hydrologic change thus lakes in humid regions today with low salinity sedimentary facies and with morphology controlled largely by wave action may closely resemble past lacustral pluvial phases experienced in zones which today are relatively arid and saline conversely playas controlled today by groundwater and in some cases subject to defletion may resemble those arid and dune building stages experienced by basins in sub humid regions today as they underwent glacial age desiccation in any such sequence of spatial or temporal gradients from humid to more arid conditions the frequency of basin filling and drying modulates the rate of evaporitive loss of interstitial waters from the exposed basin surface this in turn controls the salinity evolution of the interstitial and local groundwaters the notion of closed systems for terminal lakes while satisfactory for analysis of surface water budgets is quite inapplicable to the evolution of brines where surfacewater groundwater exchange during the high salinity drying stages becomes a controlling factor affecting all salt budgets in these systems evaporites may only be preserved when the sub surface waters have evolved to salinites near saturation for the salts concerned if sub surface waters are frequently diluted by surfacewater groundwater exchange evaporites will not be preserved in the record even though the surface system appears hydrologically closed the process of interstitial water evolution which controls efflorescence deflation and salt weathering exerts a dominating influence on basin geomorphic expression as well as on hydrochemical fractionation

late early cretaceous climate and pco2 estimates in the liupanshan basin northwest china abstract the extinct conifer family cheirolepidiaceae especially pseudofrenelopsis is commonly used to reconstruct the atmospheric palaeo co2 concentration pco2 during the cretaceous period in recent years many pseudofrenelopsis specimens have been collected from the uppermost stratum of the naijiahe formation in the liupanshan basin ningxia hui autonomous region northwest china the stomatal parameters such as stomatal density stomatal index stomatal pore length and stomatal pore depth and the stable carbon isotope composition of the present pseudofrenelopsis were analyzed the palaeo co2 levels of the liupanshan basin during the late early cretaceous late albian were reconstructed using stomatal ratio sr and mechanistic model approaches the sr method yielded a semi quantitative pco2 estimate of 620 ppmv on the basis of the recent standardization and 1030 ppmv on the basis of the carboniferous standardization which show similarities with other sr based and geochemical based reconstructions for the late early cretaceous the pco2 was about 670 ppmv on the basis of mechanistic model method similar to the estimated pco2 values recovered by the sr method corrected with the recent standardization based on comparative studies of previously published pco2 results of the early cretaceous pco2 levels varied during the early cretaceous and pco2 was relatively stable during the late early cretaceous furthermore environmental conditions of the liupanshan basin during the late early cretaceous were studied the stable carbon isotope composition of pseudofrenelopsis leaves ranged from 21 5 to 24 3 with an average of 22 8 indicating an arid semi arid and high evaporation climate during the late early cretaceous in the liupanshan basin these environmental conditions were also supported by palynological lithological and geochemical evidence

a new terrestrial plant rich fossil lagerstatte from the middle cenomanian late cretaceous of the apennine carbonate platform magliano vetere southern italy depositional and palaeoenvironmental settings abstract we describe a new terrestrial plant rich fossil lagerstatte discovered at magliano vetere campania region s italy in the middle cenomanian of the apennine carbonate platform the deposit 1 42 m thick is made up of a thin bedded interlayering of evenly laminated dolomicrites lenticular dolorudites and carbonaceous seams which contain well preserved remains of terrestrial plants yielding cuticles and minor fishes this study focuses on plant remains to provide systematical taphonomical and palaeoenvironmental considerations nevertheless a preliminary analysis carried out on fossil fishes has led to the identification of pycnodontids and teleosts the fossil lagerstatte retains sterile foliage bearing shoots with epidermal features belonging to the genus frenelopsis of the extinct conifer family of the cheirolepidiaceae plant remains possibly represent a stable biotope as floral composition displays no variation along the deposit nevertheless episodes of harsh environmental conditions occurred as demonstrated by a fish mortality event and ca sulphate evaporite precipitation taphonomical considerations and sedimentological evidence from the encasing sediments suggest a parautochthonous deposition of fossil plants in a supratidal intertidal mudflat including a salt marsh that was characterised by a restricted sea water circulation deposition of primary dolomite and episodical wildfires the presence of xeromorphic features in frenelopsis from magliano vetere could represent an adaptation to haline environment which was subjected to microtephra supply from a distant orogenic volcanism the facies evolution of the studied fossil lagerstatte records a rapid regressive and a following slower transgressive trend and constitutes the lowermost portion of a 20 m thick interval characterised by several dolomitic plattenkalk up to 1 50 m thick which are separated by cyclically stacked peritidal limestones we infer that 1 the 20 m thick plattenkalk bearing interval represents a sequence boundary zone in the stratigraphical record of the middle cenomanian apcp 2 frenelopsis thrived at the verge of an arid semiarid climatical phase during a major pulse of relative sea level fall

an experimental and numerical investigation of saltwater movement in coupled saturated partially saturated systems 1 a combined experimental and numerical analysis is used to examine the movement and interaction of saltwater and freshwater in unconfined porous media particular emphasis is placed on flow phenomena in the partially saturated region above the water table and along the interface between the saturated and partially saturated regions while some numerical models are apparently capable of simulating these phenomena there is still a significant lack of experimental data with which to verify the models here a series of laboratory scale experiments is considered to evaluate density dependent saltwater freshwater flow patterns in both the saturated and partially saturated zones the laboratory experiments demonstrate clearly that significant lateral flows and coupled density driven flow effects may take place in the partially saturated region above the water table and at the interface between the saturated and partially saturated zones in parallel a finite element numerical model is developed the model reproduces effectively the observed flow behaviors the quality of the results suggests that the numerical model has the capacity to provide realistic predictions

cheirolepidiacean foliage and pollen from cretaceous high latitudes of southeastern australia cheirolepidiaceae leaves and pollen are recorded from valanginian albian strata of southeastern australia that were deposited at high latitudes under cool moist climates in contrast to the semi arid or coastal habitats preferred by many northern gondwanan and laurasian representatives of this group leaves of this family are characterized by thick cuticles and cyclocytic stomata with randomly oriented apertures arranged in scattered or longitudinal rows or bands stomata are deeply sunken and surrounded by four to six subsidiary cells that bear one or two ranks of prominent overarching papillae which may constrict the mouth of the pit three new taxa otwayia denticulata tosolini cheirolepidiaceae cuticle sp a and sp b are distinguished based on cuticular features adding to several previously documented cheirolepid conifers in the early cretaceous of eastern australia cheirolepidiaceae foliage is preserved predominantly in fluvial floodbasin settings and is interpreted to be derived from small trees occupying disturbed or low nutrient sites the foliage is associated with classopollis corollina pollen and roots characterized by prominent mycorrhizal nodules a cenomanian classopollis type recognised from bathurst island northern australia is recorded for the first time from the early cretaceous eumeralla formation otway basin classopollis locally is rare in valanginian barremian strata of boola boola gippsland but constitutes up to 14 of the palynomorph assemblage in albian strata this indicates that the family was locally abundant in cool southern high latitude climates of the mesozoic contrary to previous reports of its rarity in this region

magnetic anomalies of lava fields in the canary islands possible consequences for paleomagnetic records abstract measurements of the total magnetic field have been performed above the surface of 12 lava flows in the canary islands of la palma and tenerife directions can differ by up to 15 and intensity changes reach 20 the mean flow directions do not coincide and the mean flow virtual dipole moments vdms differ by more than 10 the deviations are linked to topographic features at the surface of the flows and should persist during emplacement of the next overlying flow such effects can thus limit the resolution of paleomagnetic records of detailed geomagnetic features and the field intensity variations above the flows and between the mean flow values could explain a significant part of the scatter inherent to many paleointensity studies historical field variations have been recorded from the same flows and are in agreement with the european curve for the same period however there is also some correlation with the present field which suggest that the underlying magnetized bodies could have affected the paleomagnetic records biases induced by the crustal field would increase considerably during periods of reduced field intensity like during reversals and induce erroneous records samplings performed over large distances within each lava flow would provide the best way to average out the contribution of the anomalies in any case such effects should not be neglected in paleomagnetic studies

numerical modeling of water flow and salt transport in bare saline soil subjected to evaporation summary a numerical study based on a density dependent variably saturated groundwater flow model marun was conducted to investigate subsurface flow and salt transport in bare saline aquifers subjected to evaporation which was simulated using the bulk aerodynamic formulation as evaporation was assumed to depend on the pore moisture the evaporation flux evolved gradually causing a gradual increase in the pore salinity this is in contrast to prior studies where the high salinity was imposed instantaneously on the ground surface key factors likely affecting subsurface hydrodynamics were investigated including saturated hydraulic conductivity capillary drive relative humidity in the air and surrounding groundwater replenishment the simulations showed two temporal regimes where the first consists of rapid evaporation for a duration of hours followed by slow evaporation until evaporation ceases in the absence of surrounding groundwater replenishment evaporation induced density gradient generated an upward water flow initially and then the flow decreased at which time a high density salt finger formed and propagated downwards capillary properties and atmospheric condition had significant impacts on subsurface moisture distribution and salt migration in response to the evaporation the results also suggested that the presence of subsurface water replenishment to the evaporation zone tended to produce a steady evaporation rate at the ground surface

parameter estimation for determining hydraulic properties of a fine sand from transient flow measurements a cone penetrometer method for measuring hydraulic conductivity of unsaturated soils at depth is under development successful advancement of this method hinges on using parameter estimation to obtain hydraulic parameter values from pore water pressure and flow rate data a finite element model is employed to predict flow responses and objective functions describe differences between true and simulated responses contour plots in parameter space show the relative sensitivity of objective functions to field saturated hydraulic conductivity kfs field saturated moisture content fs and the van genuchten hydraulic parameters and n principal curvatures and directions in parameter space describe the nature of objective functions near true parameter values an objective function based on flow rate and pore water pressures does not provide better parameter sensitivity than one based on pore water pressures alone it appears possible to obtain estimates of kfs and but unlikely that the other parameters will be identifiable

the golbaoi basin southeastern turkey a complex discontinuity in a major strike slip fault zone we show that the 33 km long golbaoi basin on the east anatolian fault zone marks the triple junction between the african arabian and turkish plates the main strand of the turkish arabian plate boundary the goksu fault enters this basin from the ene before splaying to form faults which develop farther southwest into the turkish african and african arabian boundaries the golba i turko u fault the turkish african boundary is shown to have slipped 16 km the prevously unrecognised kirkpmar fault the african arabian boundary has slipped 17 km we propose that this fault geometry developed at c 3 ma following earlier slip starting at c 5 ma on other strike slip faults nearby which marked the start of westward motion of the turkish plate

late palaeogene neogene evolution of the triple junction region near maras south central turkey the marao region of turkey includes the anatolian arabian african triple junction the african arabian margin is marked by left lateral transtension along the dead sea kara su rift motion on the anatolian arabian boundary is partitioned between the left lateral east anatolian fault and a fold thrust belt termed the engizek zone equivalent to the bitlis suture further east the african anatolian boundary lies along the cyprus misis andirin trend and is expressed near the triple junction as the aslantao iskenderun zone now undergoing slow left lateral transtension the neogene evolution of these boundaries is largely recorded in the stratigraphy and structure of the basins that lie along the anatolian arabian lice basin and anatolian african aslantao iskenderun basin boundaries these basins appear to have developed in the early miocene along major strike slip zones large half graben in the pre neogene 9basement9 of the western misis andirin block developed contemporaneously with motion on the anatolian african boundary these extensional features evolved subsequent to the intense shattering of the mesozoic carbonate sequence in the misis andirin block and its mixing with panels of deep water palaeogene strata to form an extensionally disrupted assemblage transpression and conversion of both anatolian african and anatolian arabian boundaries to fold thrust belts occurred in the late miocene transpression continues along the anatolian arabian boundary but transtension has recurred along the anatolian african boundary since the pliocene

diversity of the woody vegetation of gondwanan southern africa abstract the flora of gondwanan southern africa is represented in the rock record by micro fossils macro fossils and petrified woods all these types of fossils are seldom preserved together in any one particular facies because of taphonomic and preservational biases in order to obtain as accurate a picture as possible of the woody vegetation both the fossil woods and other macroplant fossils such as leaf impressions fructifications and cuticle of woody plants have been correlated this was done for each formation in the karoo supergroup in order to illustrate the changes in diversity of woody vegetation over time sediments of the karoo supergroup represent the terrestrial fossil record of the period upper carboniferous to the lower cretaceous when africa finally separated from south america in the upper carboniferous to lower permian dwyka formation there are at least five described genera of woods from south africa and namibia early to middle permian woods ecca group are a little more diverse with six genera representing the glossopterids cordaitaleans and possibly other seed fern groups late permian to early triassic beaufort group woods show very little change in diversity in spite of the major floral and biotic turnover evident from the rest of the fossil record although the late triassic molteno formation macro flora has been shown to be an example of explosive diversification the generally poorly preserved woods do not reflect this lower jurassic fossils clarens formation are also poorly preserved but have araucarian characteristics early cretaceous woods represent the araucariaceae cheirolepidiaceae and podocarpaceae with a number of species the diversity of the woods has not changed as much as the rest of the floral components in southern africa from the late carboniferous to the early cretaceous possible reasons for this apparent stasis are the conservative nature of wood functional restrictions limitations of suitable conditions for petrifications and the fact that very little research has been done on southern african woods

revised and synthetic apparent polar wander paths of the african eurasian north american and indian plates and true polar wander since 200 ma we have reviewed paleomagnetic data available for the eurasian african north american and indian plates over the last 200 ma selection criteria are those generally accepted with an emphasis on evidence for lack of remagnetization accurate dating and proper structural analysis this results in 23 35 51 and 2 poles for eurasia africa north america and india respectively we believe that this limited set of higher quality data is more likely to reveal key features of apparent polar wander apw paths than averaging of larger data sets involving less stringent selection criteria we propose and describe revised apw paths but more importantly we next use relative motion models to transfer all data in a common reference frame we find good agreement between transferred data when they are averaged separately for each plate in independent 20 ma windows this is a check on consistency of paleomagnetic data kinematic models and of the geocentric dipole hypothesis transferred data from all plates are averaged in 20 ma windows to generate synthetic apw paths for all plates studied these synthetic paths are in agreement with the original revised apw paths that use only data from a single plate moreover both geographic and time resolution are improved spatial confidence intervals are of the order of 5 the synthetic paths display interesting features such as a previously ill recognized apw loop for eurasia paleomagnetic and hotspot apw are next compared and a determination of true polar wander tpw is derived we find significant tpw amounting to over 20 in the last 200 ma tpw appears to be episodic with a standstill between 180 and 110 ma there is general agreement with a previous study of livermore et al 1984 the tpw standstill appears to correlate with a time of decreasing reversal frequency ending with the cretaceous long normal superchron other periods of fast tpw would seem to correspond to increasing reversal frequency however it is suggested that the major tpw hairpin at 50 ma might correspond to the collision of india with eurasia tentative correlations with core or mantle indicators can be understood as a result of couplings between the core mantle and lithosphere we believe primarily related to episodic evolution of the d layer

hydrodynamics in a gravel beach and its impact on the exxon valdez oil 1 this paper investigated the interaction of groundwater and seawater in a tidally influenced gravel beach field observations of water table pore water salinity were performed the two dimensional finite element model marun was used to simulate observed water table and salinity based on field observations and model calibrations a two layered beach structure was identified which is characterized by a high permeability surface layer underlain by a low permeability lower layer the salt wedge seaward of the low tide line was almost invariant in comparison with the strong fluctuations of the salinity plume in the surface layer of the intertidal zone the presence of the two layers prevented the presence of a freshwater discharge tube between the upper saline plume and salt wedge this is in contrast with the previous works where freshwater discharge tube was observed the tide induced submarine groundwater discharge sgd was estimated at 9 m3 d 1 m 1 a large value that is probably due to the large tidal range of 4 8 m and the very permeable surface layer the freshwater seawater dynamics revealed here may provide new insights into the complexity intensity and time scales of mixing between fresh groundwater and seawater in tidal beaches the simulated water table of the beach was higher than the interface between the surface layer and the lower layer which prevented exxon valdez oil from penetrating into the lower layer in 1989

neotectonic deformation linking the east anatolian and karatas osmaniye intracontinental transform fault zones in the gulf of iskenderun southern turkey deduced from paleomagnetic study of the ceyhan osmaniye volcanics 1 left lateral strike slip along the dead sea fault zone dsfz between the african and arabian plates is partitioned into a complex set of motions at its northern extension where arabia impinges into the anatolian collage as a result the nature of the contemporary link between the east anatolian and dead sea transforms is unclear to quantify strike slip motion expressed as tectonic rotations along the inferred southwest continuation of the east anatolian fault zone eafz we have investigated the paleomagnetism of young 1 ma volcanics in the adana basin gulf of iskenderun region comprising the ceyhan osmaniye volcanic suite this volcanism is sited close to the intersection between the sinistral karatas osmaniye fault zone kofz and the neotethyian suture nine sites from a basaltic lava field in the vicinity of osmaniye are entirely of normal polarity and in the context of their very young morphologies are assigned to the brunhes chron declinations are mostly clockwise from the present field this age assignment identifies rapid recent 780 ka uplift at the head of the gulf of iskenderun and is linked to a diversion of the ceyhan river drainage and ongoing regional tilting eight sites yield a mean declination of 11 3 10 implying clockwise block rotation on riedel type fractures on the northwest side of the kofz seven lavas sites from a volcanic succession near botas at the southwestern extension of the volcanic lineament are of reversed polarity and rotated counterclockwise by 43 7 with respect to the present field polarity k ar and morphological evidence indicate an assignment toward the latter part of the matuyama chron and identify rapid neogene block rotation of a flake within the kofz an inferred maximum slip rate of 0 6 cm year on this fault zone is comparable with lower estimates of slip on the eafz and suggests that most strike slip on the dsfz is now being partitioned to the west of the gulf of iskenderun on a developing strike slip zone linking with the cyprus arc

recent volcanism tectonics and plate kinematics near the junction of the african arabian and anatolian plates in the eastern mediterranean abstract in the eastern mediterranean plate convergence occurs between africa arabia and anatolia the africa arabia motion is a strike slip displacement along the dead sea fault the africa anatolia motion is taken up by subduction south of cyprus the convergence between arabia and anatolia is taken up along the east anatolian fault the analysis of the regional fault surfaces reveals the presence of two major tectonic phases that affected southeastern turkey near the junction of these three plates the older deformations are related to a n s compression the more recent movements are directed mainly westward and associated with strike slip and extension tectonics near the triple junction since 2 ma a fissure volcanism produced tholeiite followed by alkali basalt along the amanos fault the northern end segment of the dead sea fault in addition reconstruction of rigid plate kinematics between arabia africa and anatolia using recent plate motion parameters and space geodesy data suggest for the east anatolian fault a slip rate of 7 8 9 mm year the maximum finite displacement recognised for this structure being around 15 km we have obtained 1 9 ma as the maximum age for the fault formation the volcanic tectonic and kinematic data converge to propose a ca 2 ma age for the change of local tectonic regime in the junction area the structural mapping the geometry of the fractures used by the magma to reach the surface and the presence of alkali basalt of mantle source suggest that the deformation along the northern end of the dead sea transform i e the amanos fault was modified by the formation of the east anatolian fault zone in this region apparition of the east anatolian fault accommodating westward motion of the anatolian plate resulted in oblique slip tension along the amanos segment of the dead sea transform giving rise to a fissure fed mantle derived alkaline volcanism at ca 2 ma which lasted until recent times 0 4 ma

taxonomic turnover and abundance in cretaceous to tertiary wood floras of antarctica implications for changes in forest ecology based on the temporal distribution abundance and taxonomic composition of wood floras four phases of vegetation development are recognized through the cretaceous to early tertiary of the antarctic peninsula 1 aptian to albian communities dominated by podocarpaceous araucarian and minor taxodiaceous cupressaceous conifers with rare extinct gymnosperms sahnioxylon 2 progressive replacement of these communities in cenomanian to santonian times by angiosperms most without modern analogues 3 increasing dominance of angiosperms becoming important both in terms of diversity and abundance towards the mid late cretaceous 4 modernization of the flora during the campanian to maastrichtian with the extinction of earlier forms appearance of the nothofagaceae and diversification of associated elements these patterns broadly follow trends seen in the leaf and palynological record but with some important differences during the cretaceous conifer composition undergoes a change whereby phyllocladoxylon type woods increase relative to the older podocarpoxylon forms during the paleocene to eocene period a marked extinction in wood types occurs associated with an increase in the abundance of nothofagaceous wood detailed examination of wood abundance and distributions from sections within maastrichtian and paleocene formations points to strong environmental control on taxonomic compositions similar differences are encountered when comparing coeval floras from different geographic regions and palaeoenvironments

studies of quaternary saline lakes iii mineral chemical and isotopic evidence of salt solution and crystallization processes in owens lake california 1969 1971 abstract as a consequence of the 1969 1970 flooding of normally dry owens lake a 2 4 m deep lake formed and 20 of the 2 m thick salt bed dissolved in it its desiccation began august 1969 and salts started crystallizing september 1970 ending august 1971 mineralogic brine composition and stable isotope data plus field observations showed that while the evolving brine composition established the general crystallization timetable and range of primary and secondary mineral assemblages it was the daily monthly and seasonal temperature changes that controlled the details of timing and mineralogy during this depositional process deuterium analyses of lake brine interstitial brine and hydrated saline phases helped confirm the sequence of mineral crystallizations and transformations and they documented the sources and temperatures of waters involved in the reactions salts first crystallized as floating rafts on the lake surface natron and mirabilite salts whose solubilities decrease greatly with lowering temperatures crystallized late at night in winter when surface water temperatures reached their minima trona nahcolite burkeite and halite salts with solubilities less sensitive to temperature crystallized during the afternoon in summer when surface salinities reached their maxima however different temperatures were generally associated with crystallization at the surface and accumulation on the lake floor because short term temperature changes were transmitted to surface and bottom waters at different rates consequently even when solubilities were exceeded at the surface salts were preserved or not as a function of bottom water temperatures halite a nearly temperature insensitive salt was always preserved monitoring the lake brine chemistry and mineralogy of the accumulating salts shows 1 an estimated 0 9 10 6 tons of co 2 was released to the atmosphere or consumed by the lake s biomass prior to most salt crystallization 2 after deposition some salts reacted in situ to form other minerals in less than one month and all salts except halite decomposed or recrystallized at least once in response to seasons 3 warming in early 1971 caused solution of all the mirabilite and some of the natron deposited a few months earlier a deepening of the lake though the lake surface lowered and an increase in dissolved solids 4 phase and solubility index data suggest that at the close of desiccation na 2 co 3 7h 2 o never reported as a mineral could have been the next phase to crystallize

a palaeomagnetic study of the sivas basin central turkey crustal deformation during lateral extrusion of the anatolian block abstract the sivas basin is a complex collage of eocene and younger rocks located within the wedge shaped eastern margin of the anatolian block between the dextral north anatolian fault zone and the sinistral eastern anatolian fault zone it has been subject to ongoing deformation by movement of the arabian block into eurasia and concomittant sideways expulsion of the anatolian block post collisional deformation since mid miocene times has been dominated by n s to nw se compression expressed by thrusting and strike slip faulting cretaceous and eocene rocks were magnetically overprinted to variable degrees during the collisional phase although these overprints have since been rotated mostly anticlockwise rocks emplaced during the neotectonic history are high fidelity palaeomagnetic recorders of subsequent block movements regional anticlockwise rotation is recognised across the basin with differential rotation of fault and thrust bounded blocks an absence of perceptible differences between group mean rotations identified from miocene pliocene and quaternary units shows that most regional rotation has been concentrated within the latest phase of the neotectonic history during quaternary times at an average rate of 10 ma commencement of this rotation postdates initiation of the north anatolian fault zone implying that compression following collision was accomodated initially by crustal thickening during late miocene and pliocene times subsequent anticlockwise rotations have resulted from sideways expulsion of blocks to the south of the central anatolian thrust along major ne sw sinistral faults to achieve the crustal shortening resulting from n s compression these fault orientations and their sense of motion are explained by a prandtl model involving deformation of a triangular plastic terrane the anatolian block between two rigid plates eurasia and afro arabia the variations in regional rotation identified by palaeomagnetism show that average contemporary anticlockwise rotation of anatolia revealed by gps data 1 2 ma is achieved by variable and locally large block rotations between major thrusts and strike slip faults

differential neotectonic rotations in anatolia and the tauride arc palaeomagnetic investigation of the erenlerdaǧ volcanic complex and isparta volcanic district south central turkey abstract in the anatolian sector of the alpine himalayan collisional belt a palaeotectonic phase of terrane accretion has been succeeded by a neotectonic phase of intracontinental deformation as the afro arabian plate has continued to impinge differentially into the accreted collage the resulting tectonic escape has during the last few million years extruded and rotated blocks in a southwesterly direction this paper reports a palaeomagnetic investigation of the erenlerda volcanic complex and isparta alkaline volcanic district undertaken to extend analysis of crustal rotation into the southwestern part of the anatolian region and investigate the interaction with the isparta angle and the extensional province of western turkey the erenlerda volcanism comprises three phases of volcanism the oldest sille volcanics 11 7 11 4 ma yield a mean d 150 i 52 rotated anticlockwise during early stages of crustal thickening and deformation before a later miocene episode c 10 9 8 9 ma d 183 i 47 and a mio pliocene episode d 179 i 51 the latter two episodes indicate that no significant rotation has resulted during the neotectonic crustal extrusion in this southwestern sector of anatolia further to the west within the isparta angle a 4 7 4 0 ma alkaline episode yields a mean of d 186 i 53 rotated slightly clockwise the pattern of palaeomagnetic declinations across anatolia shows rotations that are strongly anticlockwise in the east near the arabian pincer and diminish towards the west to become zero or slightly clockwise at the western extremity of the collage the timing of rotation also appears to become younger towards the south crustal deformation has therefore been distributed and the net effect of terrane extrusion to the west and south has been to expand the curvature of the tauride arc and by inference the cyprian arc where good age control exists in cappadocia and the sivas basin rotations are found to be concentrated within the last few million years and are up to an order higher than rates deduced from global positioning system the palaeomagnetic data imply that the neotectonic deformation following collision initially produced crustal thickening resulting in uplift of the anatolian plateau and was only subsequently accommodated by major differential block rotation during tectonic escape

the northern red sea and the dead sea rift abstract the results of geophysical measurements at sea when combined with mesostructural measurements on land demonstrate systematic extensional features in the region of the northern red sea and the dead sea rift rifts and diapirs were encountered in the northern red sea showing an arcuate trend whereas the faulted continental margins at that region are oriented nw se the rifts and the diapirs changed their trend northwards from nnw sse to n s systems of rifts and diapirs are considered to be extensional features therefore the tectonic extensional axis probably changed its orientation accordingly a series of rifts and diapirs was found also in the gulf of elat trending approximately parallel to the coastlines and is interpreted to be the northern extension of the red sea rift and diapir system mesostructural measurements that were carried out in the western flank of the dead sea rift indicated further evidence for structural extension trending e w to ene wsw in addition to measurements of left lateral offset of approximately 10 km all these data when combined with the geophysical measurements of the characteristics of the earth crust underneath the dead sea rift suggest a tectonic regime of oblique extension in the region of the red sea and the dead sea rift this tectonic regime indicates that the red sea spreading center extends northwards along the dead sea rift and the clockwise change of the axial trend imposed a sinistral offset to the tectonic extension thus it is suggested that the dead sea rift is an incipient oblique spreading center

constraints on arabian plate motion and extensional history of the red sea analysis of the geologic and geophysical data from the western and northern margin of the arabian plate combined with data from the red sea gulf of aden leads to an interpretation of arabian plate motion that supports an episodic extensional history in the red sea and gulf of aden phase 1 extension began in medial to late eocene and was caused by the nw propagation of the reoriented central indian ridge spreading center it stretched and thinned continental crust along numerous wrench and normal faults that reactivated preexisting structures first phase extension stopped when the arabian plate terminally sutured to eurasia in the medial miocene and halted northward movement of arabia relative to africa the combined african arabian plates moved north more slowly constricting and thickening continental crust in the bitlis zagros sutures while the red sea remained technically quiescent and accumulated salt by the early pliocene continued northward movement was accommodated by lateral extrusion of large continental wedges north of the bitlis zagros sutures this allowed arabia to move northward faster than africa and reopen the red sea where phase 2 extension was expressed by seafloor spreading extension within the red sea gulf of aden rift system has been controlled by the interactions and effects of two factors 1 convergent processes between the north margin of the arabian plate and the eurasian plate to the north and 2 northwest propagation of extension associated with the medial eocene reorganization of the central indian spreading center

neotectonic deformation in the transition zone between the dead sea transform and the east anatolian fault zone southern turkey a palaeomagnetic study of the karasu rift volcanism in southern turkey ongoing differential impingement of arabia into the weak anatolian collisional collage resulting from subduction of the neotethyan ocean has produced one of the most complex crustal interactions along the alpine himalayan orogen several major transforms with disputed motions including the northward extension of the dead sea fault zone dsfz meet in this region to evaluate neotectonic motion on the amanos and east hatay fault zones considered to be northward extensions of the dsfz the palaeomagnetism of volcanic fields in the karasu rift between these faults has been studied remanence carriers are low ti magnetites and all except 5 of 51 basalt lavas have normal polarity morphological polarity and k ar evidence show that rift formation occurred largely during the brunhes chron with volcanism concentrated at 0 66 0 35 ma and a subsidiary episode at 0 25 0 05 forty four units of normal polarity yield a mean of d i 8 8 54 7 with inclination identical to the present day field and declination rotated clockwise by 8 8 4 0 within the 15 km wide hassa sector of the karasu rift the volcanic activity is concentrated between the amanos and east hatay faults both with left lateral motions which have rotated blocks bounded by nw se cross faults in a clockwise sense as the arabian block has moved northwestwards an average lava age of 0 5 ma yields a minimum cumulative slip rate on the system bounding faults of 0 46 cm year according with the rate deduced from the africa arabia euler vector and reduced rates of slip on the southern extension of the dsfz during plio quaternary times estimates deduced from offsets of dated lavas flows and morphological features on the amanos fault zone tectonophysics 344 2002 207 are lower 0 09 0 18 cm year probably because they are limited to surface fault breaks and do not embrace the seismogenic crust results of this study suggest that most strike slip on the dsfz is taken up by the amanos east hatay afrin fault array in southern turkey comparable estimates of quaternary slip rate are identified on other faults meeting at an unstable fff junction dsfz east anatolian fault zone karatas fault zone a deceleration in slip rate across the dsfz and its northward continuation during plio quaternary times correlates with reorganization of the tectonic regime during the last 1 3 ma including tectonic escape within anatolia establishment of the north and east anatolian fault zones bounding the anatolian collage in mid late pliocene times a contemporaneous transition from transpression to transtension and concentration of all basaltic magmatism in this region within the last 1 ma

structure of the intraplate eastern palmyride fold belt syria the palmyride fold belt is an aulacogen within the arabian plate linked to the levantine continental margin which contains 10 km of phanerozoic sediments inversion of this mesozoic basin began during late cretaceous time although most deformation was clearly post oligocene recent field mapping shows that almost all the structures have resulted from a phase of northwest southeast compression followed by major dextral transpression early northwest southeast compression resulted in northeast southwest aligned fold axes in the central and southeast palmyrides many of which were subsequently rotated by progressive dextral simple shear during neogene to recent time the north south aligned sinistral dead sea fault is the major wrench fault aligned at 45 to the maximum compressive stress the conjugate east west striking dextral jhar fault and the northwest southeast aligned bishri fault have accommodated limited dextral shear and clockwise rotation of northeast southwest aligned folds jebels mrah ash shaer in the northern palmyrides dextral strike slip faults aligned along reidel fractures r1 cut the flanks of earlier domal structures jebel abu rajmein subordinate antithetic r2 reidel shears aligned north northeast south southwest are trans tensional sinistral strike slip faults showing minor extension that cut through the earlier domal structures for example ras al hawa depression in jebel abu rajmein northwest southeast aligned faults for example jebel bilas cross trend faults show northeast southwest extension at right angles to the palmyride shortening direction this extension parallels the major euphrates graben trend in eastern syria and northwestern iraq and also parallels some aligned pliocene pleistocene volcanic rifts south of damascus and in the jebel druze jebel arab region of southern syria and northern jordan a regional palmyride strain ellipse is presented to explain the geometry of all these structures the ad daww depression is a northeast southwest aligned transpressional basin containing around 2 km thickness of tertiary sediments the basin is bounded to the west by a sinistral shear couple along the cherrife structural trend in the central palmyrides along the north by the dextral jhar fault and along the southeast by the compressional southeast palmyrides in the southeast palmyrides structural style is one of a series of northeast southwest aligned narrow anticlines in the mesozoic platform sediments with upright to north west dipping southeast facing axial planes shortening amounts are very small in the eastern palmyrides 1 km and taken up almost entirely by folding but these increase slightly toward the west to probably 20 km in the cherrife region tight box folds and slightly asymmetric folds in the southeast palmyrides have a localized basal detachment along the triassic gypsum horizon which in some examples flows into the fold core jebel hayyan there is no evidence for a major basal detachment underlying the palmyrides all folding and faulting can be related to disharmonic folding of the mesozoic sediments above a triassic evaporite sequence and subsequent dextral transpression the lack of overthrusting explains the absence of any foreland basin caused by lithospheric flexuring on the rutbah platform the major palmyride deformation in miocene pliocene times was concomitant with the opening of the red sea with the closing of the bitlis zagros suture zone in eastern turkey and central iran and with the main sinistral strike slip motion along the dead sea fault

variably saturated modeling of transient drainage sensitivity to soil properties abstract numerical analysis of a transient two dimensional rectangular symmetry unconfined drainage problem using a variably saturated flow model shows that the location of the phreatic surface and the height of the seepage face are functions of the capillary forces exerted in the vadose zone a sensitivity analysis investigating the effects of independent variations in the saturated hydraulic conductivity and the two van genuchten parameters is compared to one performed where the saturated hydraulic conductivity is functionally related to the van genuchten parameters the relationship between these descriptive soil parameters which may be used to describe the pore size density function of a porous medium and the saturated hydraulic conductivity is surmised based upon limited empirical evidence expressing the permeability as a function of these soil properties reverses the sensitivities of the variably saturated model to the van genuchten parameters from the preliminary work performed herein consideration of the number of degrees of freedom used when performing a sensitivity analysis is shown to warrant great care if the predicted sensitivities are to have meaningful physical interpretations

steady seepage in trenches and dams effect of capillary flow steady seepage from two dimensional domains is investigated using a dimensionless formulation for variably saturated media that depends on three dimensionless parameters m n and the parameter m is the product of the anisotropy ratio and the squared ratio of the vertical length scale to the horizontal length scale the parameter n increases with the uniformity of the pore sizes and represents the ratio of the domain height to the height of the capillary fringe our modeling results show that the seepage face height in rectangular domains is always larger than the seepage face height computed from saturated flow models the results also show that the seepage face height increases with increasing m increasing n and or decreasing the outflows computed from the present model are always larger than the outflows computed by the dupuit assumption nomographs for rectangular and trapezoidal domains simulating trenches and dams are presented

structures and kinematics in the northeastern mediterranean a study of an irregular plate boundary abstract extensional structures are prominent in the northeastern mediterranean a unique sector of the africa eurasia plate convergence zone to explain this paradoxical situation we analyse here the young tectonics of this region by examining its structural elements and plate kinematics offshore multichannel seismic reflection profiles and onland geology show that the stuctural settings are different on the two sides of the northeastern mediterranean triple junction afr arb ana on the east stuctures controlled by strike slip and by compression coexist whereas on the west compression is not very conspicuous here deep basins separated by a partly submerged ridge are prominent we interpret the ridge which comprises the kyrenia misis andirin unit at its core as a large flower structure which extends from southeastern turkey to cyprus the adana cilicia and the iskenderun latakia mesaoria basins on its flanks are interpreted as due to extension this interpretation agrees with the relative motions between the africa arabia eurasia and anatolia plates in this region analysis of the local plate kinematics reveals that strike slip predominates along the southern boundary of the anatolia plate in this region as a result of anatolia s westward escape east of the triple junction this motion is associated with comparable shortening transverse to the plate boundary whereas west of the triple junction the motion transverse to the plate boundary varies between slight compression to extension depending mainly on the local strike of the plate boundaries these variations calculated from regional data correlate well with the observed structural changes along the northeastern mediterranean sector of the plate convergence zone the structural kinematic analysis explains both the lateral changes in the deformation style and the existence of local extension in the northeastern mediterranean

tectonic evolution of the niksar and tasova erbaa pull apart basins north anatolian fault zone their significance for the motion of the anatolian block abstract the tasova erbaa and niksar basins are two adjacent pull apart basins along the north anatolian fault zone nafz within the tasova erbaa basin sedimentary lithofacies of the upper pontus formation plio pleistocene are asymmetrically distributed with laterally derived alluvial fans coarse braid plain deposits and axial braided stream deposits dominating the northern and western parts of the basin the basin has gently dipping sediments locally affected by pervasive extensional t faulting isolated compressional structures are associated with master faults deformation zone width 500 m pervasive extensional faults t and r and late stage pdz parallel compressional faults are also present an additional set of extensional faults trends perpendicular to the pdz accommodating secondary pull apart stretching within the basin the distribution of sedimentary facies and structural styles is consistent with that predicted by models for pull apart basins the adjacent niksar basin is an active pull apart basin possibly as young as 0 5 1 ma its modern drainage and sedimentary facies are symmetrically arranged adding the lengths of the tasova erbaa and niksar basin suggests 80 km total displacement along the north anatolian fault which is consistent with seymen itu ph d thesis 1975 sengor j geol soc 136 1979 269 282 and armijo et al tectonophysics 243 1999 135 154 who observed about 85 5 km total displacement along the north anatolian fault the change in course of the north anatolian fault marked by the formation of the niksar ezinepazari segment and this new geometry suggest that the anatolian block is rotating anticlockwise by having two separate poles one located near damascus and the other occurring north of the sinai peninsula this change may also mark the transfer of the anatolian triple junction from erzincan to karliova about 1 ma ago furthermore it appears that while the fault shortcuts the older basin a new generation of pull apart basins is formed due to changes of boundary conditions along the fault zone

global positioning system constraints on plate kinematics and dynamics in the eastern mediterranean and caucasus we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1997 at 189 sites extending east west from the caucasus mountains to the adriatic sea and north south from the southern edge of the eurasian plate to the northern edge of the african plate sites on the northern arabian platform move 18 2 mm yr at n25 5 w relative to eurasia less than the nuvel 1a circuit closure rate 25 1 mm yr at n21 7 w preliminary motion estimates 1994 1997 for stations located in egypt on the northeastern part of africa show northward motion at 5 6 2 mm yr also slower than nuvel ia estimates 10 1 mm yr at n2 4 e eastern turkey is characterized by distributed deformation while central turkey is characterized by coherent plate motion internal deformation of 2 mm yr involving westward displacement and counterclockwise rotation of the anatolian plate the anatolian plate is de coupled from eurasia along the right lateral strike slip north anatolian fault naf we derive a best fitting euler vector for anatolia eurasia motion of 30 7 0 8 n 32 6 0 4 e 1 2 0 1 myr the euler vector gives an upper bound for naf slip rate of 24 1 mm yr we determine a preliminary gps arabia anatolia euler vector of 32 9 1 2 n 40 3 1 1 e 0 8 0 2 myr and an upper bound on left lateral slip on the east anatolian fault eaf of 9 1 mm yr the central and southern aegean is characterized by coherent motion internal deformation of 2 mm yr toward the sw at 30 1 mm yr relative to eurasia stations in the se aegean deviate significantly from the overall motion of the southern aegean showing increasing velocities toward the trench and reaching 10 1 mm yr relative to the southern aegean as a whole

block versus continuum deformation in the western united states abstract the relative role of block versus continuum deformation of continental lithosphere is a current subject of debate continuous deformation is suggested by distributed seismicity at continental plate margins and by cumulative seismic moment sums which yield slip estimates that are less than estimates from plate motion studies in contrast block models are favored by geologic studies of displacement in places like asia a problem in this debate is a lack of data from which unequivocal conclusions may be reached in this paper we apply the techniques of study used in regions such as the alpine himalayan belt to an area with a wealth of instrumental data the western united states by comparing plate rates to seismic moment release rates and assuming a typical seismogenic layer thickness of 15 km it appears that since 1850 about 60 of the pacific north america motion across the plate boundary in california and nevada has occurred seismically and 40 aseismically the san francisco bay area shows similar partitioning between seismic and aseismic deformation and it can be shown that within the seismogenic depth range aseismic deformation is concentrated near the surface and at depth in some cases this deformation can be located on creeping surface faults but elsewhere it is spread over a several kilometer wide zone adjacent to the fault these superficial creeping deformation zones may be responsible for the palaeomagnetic rotations that have been ascribed elsewhere to the surface expression of continuum deformation in the lithosphere our results support the dominant role of non continuum deformation processes with the implication that deformation localization by strain softening must occur in the lower crust and probably the upper mantle our conclusions apply only to the regions where the data are good and even within the western united states i e the basin and range deformation styles remain poorly resolved nonetheless we maintain that block motion is the deformation style of choice for those continental regions where the data are best

quaternary sedimentary history of adana cilicia and iskenderun basins northeast mediterranean sea detailed single channel airgun and 3 5 khz profiles from the northeastern mediterranean sea show that the continental shelf is formed by superimposed deltaic successions depositional sequences separated by major erosional unconformities each depositional sequence is composed of a sigmoid prograding package overlain by an oblique prograding package representing respectively delta progradation during high and low sea levels of interglacial and subsequent glacial stages during the glacio eustatic lowstands of sea level deltas prograded seaward the present day shelf break denotes the topset to forest transition at maximum progradation during the last glacial period during post glacial transgressions the deltas initially lost their dynamic equilibrium with the environment and rapidly retreated landward leading to the deposition of a thin veneer of sediments originating from reworking of formerly coastal sediments at the highstand position the deltas were re established in the ancestral adana bay and foreset progradation started chronology suggests that the cilicia and iskenderum basins are subsiding at rates of 0 38 m 1000 yr 1 and 0 33 m 1000 yr 1 respectively seismic reflection profiling shows that delta architecture in the adana cilicia and iskenderun basins is mainly controlled by glacio eustatic sea level fluctuations and continuous basin subsidence

palaeomagnetism and magnetic properties of the cappadocian ignimbrite succession central turkey and neogene tectonics of the anatolian collage abstract the cappadocian ignimbrite succession of central southern anatolia comprises at least nine major and two minor calc alkaline rhyolitic sheets emplaced at 1 2 ma intervals between 11 2 and 1 1 ma it records the last phase of neotethyan subduction during final emplacement of the tauride orogen in southern turkey this study reports magnetostratigraphy and describes associated rock magnetic properties remanence resides in ti poor titanomagnetites haematisation is locally produced by post emplacement oxidation but does not contribute significantly to the palaeomagnetic signature although secondary processes within the ignimbrite sheets have produced composite isothermal remanent magnetisation spectra and variable intensities of magnetisation weak anisotropy of magnetic susceptibility describes tensors with maximum axes close to bedding and minimum axes perpendicular to this plane directions of kmax with weak imbrication mostly suggest flow away from centres of eruption located by gravity and remote sensing older ignimbrites upper and lower goreme akdag zelve from the cardak centre are all of normal polarity later ignimbrites partly erupted from the derinkuyu centre comprise the sarimaden r cemilkoy r tahar r kizilkaya r incesu n and valibaba sofular r ignimbrites the overall reversed group mean is d i 174 51 n 10 units r 9 84 95 6 6 k 55 and all magnetisation directions from the upper goreme 9 0 ma onwards are rotated anticlockwise with respect to eurasian and african palaeofields this sense of rotation characterises most of central anatolia and averages 9 5 in this sector the rotation rate from 8 to 1 ma bp was 1 25 ma but it appears to have accelerated during the latter part of the quaternary to about an order higher than rates determined from gps rotation has resulted from extrusion of fault blocks during tectonic escape of the anatolian collage to the southwest and followed crustal thickening as the afro arabia plate has continued to impinge differentially into eurasia cenozoic magnetic inclinations are systematically shallower across anatolia than inclinations expected from the geocentric dipole model and the apparent polar wander of bordering major plates only part of this difference 400 km can be accommodated by northward movement and crustal thickening in central anatolia since mid miocene times shallow inclinations observed in the aegean region extend into turkey they are observed in young volcanics and appear to reflect a regional geomagnetic anomaly the pattern of neotectonic declinations across anatolia shows rotations that are strongly anticlockwise rotated in the east near the arabian pincer but diminish towards the west to become zero or slightly clockwise at the western extremity of the collage rotations also seem to become generally younger towards the south crustal deformation has therefore been distributed and the net effect of terrane extrusion to the west and south has been to expand the curvature of the tauride arc and by inference the cyprus arc

a global palaeoclimatic reconstruction for the valanginian based on clay mineralogical and geochemical data abstract high resolution clay mineral and 18ocarb analyses have been performed on three sections of valanginian age early cretaceous from northwestern 20 30 n and southern 53 s tethyan realms the data have been integrated in a large set of published mineralogical clays and geochemical 18ocarb 18obivalve 18olenticulina 18obelemnite and tex86 data from 17 sections situated between 45 n and 53 s based on this data set we provide new insights into valanginian climate conditions from a wide range of palaeolatitudes we highlight climate trends within specific areas and identify main climate belts in the proto north atlantic realm 15 17 n large amounts of smectite together with the occurrence of palygorskite testify for a semi arid climate belt throughout the valanginian significant variations in kaolinite content in the northwestern tethyan realm 20 to 30 n suggest that this realm has been more sensitive to changes in hydrological cycling and subsequent erosion and runoff processes during the early to early late valanginian transition interval this time interval that is coincident with the pronounced positive and globally recognized carbon isotope excursion cie the weissert episode documents the wet conditions of a humid subtropical climate belt temperature ranges derived from 18o records suggest climate warming by about 3 5 0 9 c in the northern hemisphere during the weissert episode this is followed by a global cooling of about ca 1 5 0 9 c in both hemispheres during the late valanginian we postulate that these patterns were due to interplays between tectonic and orbital factors which have controlled the distribution of regional palaeoclimate belts during the valanginian the semi arid belt expressed in the proto north atlantic realm has probably been induced by its specific palaeogeographic configuration and the existence of isolated basins which were each characterized by strong and continuous thermohaline circulation an eccentricity paced monsoon like system might have played a significant role in maintaining the subtropical belt around the northwestern tethyan realm up to the mid latitudes 35 45 n superimposed on these regional processes a widespread magmatic pulse in parana etendeka volcanic activity might have stimulated greenhouse conditions impacting marine biota and favouring the development of a dense vegetation cover on the continent an increase in sedimentary burial of 13c depleted organic carbon on the continents may have contributed to the progressive global positive carbon isotope excursion in the medium term it has also probably led to a significant decrease in atmospheric co2 as testified by the global cooling recorded during the late valanginian in both hemispheres and the probable concomitant extension of polar ice caps

observations on the complexity of the east anatolian fault turkey abstract that the east anatolian fault is made up of discrete segments of different strike and diverse structural style is well illustrated by oblique hand held photographs taken from the space shuttle linear and curvilinear faults plus major folds show the variable deformability of the collage of material that constitutes the anatolian plate now undergoing the early stages of collision tectonics