present day kinematics of the mediterranean a comprehensive overview of gps results i combine recently published gps results to derive a geodetic horizontal velocity field consistent at the scale of the mediterranean and the surrounding alpine belts the velocity field is then used to discuss the boundary conditions around each major deforming area in the mediterranean to describe the main patterns of motion and deformation to critically review the existing kinematics models and to finally point out the main unresolved kinematics questions strain rate in europe north of the alpines belt is dominated by the signature of the glacial isostatic adjustment and tectonic strain remains below the current accuracy of gps results in the western mediterranean deformation is restricted to the betics the alboran and the morrocan rif with west to southwestward motion with respect to iberia which is part of stable europe shortening consistent with the relative nubia eurasia plate motion is found throughout the maghrebides but the distribution of deformation in northern africa remains largely unknown the central mediterranean is dominated by the counter clockwise rotation of the adriatic the junction between the southern adriatic domain and nubia has yet to be firmly established the deformation over a wide area east of the maghrebides in tunisia and the gulf of sirte in libya still remains to be quantified in the eastern mediterranean the velocity field is dominated by a general anti clockwise rotation and a general trend towards the hellenic trench with velocity magnitude increasing with decreasing distances from the trench this trend is observed not only in the aegean and anatolia but also in the southern balkans geodetic results emphasize that the convergence of the nubia and arabia plates towards eurasia directly controls the deformation across only very few segments along the plate boundary zone additional processes are therefore required to explain the observed velocity field and deformation pattern

the messinian event on the margin of the mediterranean sea in the nice area southern france abstract seismic reflection profiles have been used to map the messinian erosion surface and associated basin margin deposits on the continental margin off nice a palaeovalley extends seaward from the incised var palaeovalley mapped on land the lower part of this valley is filled by an acoustically incoherent unit with a flat top and steep slope into the basin this unit is interpreted as a coarse grained deltaic deposit that accumulated synchronously with the upper messinian evaporites in a ponded lake basin two submersible dives on strategic outcrops supported the interpretation of the seismic profiles we examined and sampled outcrops of probably early tertiary sandstones underlying the messinian erosion surface and of a fining up predominantly conglomeratic sequence that fills messinian channels on the continental slope and probably overlies the deltaic deposits these conglomerates pass up into early pliocene marls and have turbidite sedimentary structures these are prodeltaic deposits formed during the transgression at the end of the messinian based on seismic facies mapping sampling and submersible observations a palaeogeographic reconstruction of the area is proposed a basal erosion surface including the var palaeovalley represents extreme dessication of the western mediterranean and was followed by accumulation of the main messinian salt following this a lake was ponded in the ligurian basin with accumulation of evaporites and shales a gilbert type delta prograded into the basin from the var palaeovalley relative sea lake level lowering is estimated to be about 1200 m at this time there has been little faulting on the margin since the early pliocene transgression but there is estimated to have been about 800 m of flexural subsidence due to both thermal subsidence and water loading

intra annual variation of wave number 4 structure of vertical e b drifts in the equatorial ionosphere seen from rocsat 1 1 this paper studies the intra annual variation of the wave number 4 structure in the equatorial vertical e b drifts at high solar flux level based on of the rocsat 1 observations during the interval from 1999 to 2004 it is found that the daytime longitudinal structure is significant in northern summer and early autumn but weak in northern winter this is consistent with the intra annual variations of the tidal mode de3 at night the intra annual variation of the wave number 4 structure shows some differences from that in daytime which may relate to different dynamo mechanisms operating in different local time we also found that the wave number 4 structure mainly shifts eastward during daytime in most of months which is coincident with the eastward propagation of the de3 tide however it is largely disturbed near sunrise and sunset we attribute this disturbance as the jumping of the main dynamo region between e and f layers as well as the different dynamo mechanisms in different dynamo regions

tension gash like back arc basin opening and its control on subduction rollback inferred from tertiary faulting in sardinia 1 the tertiary reactivation of the paleozoic basement in ne sardinia is shown to reflect transtensional back arc tectonics related to the western mediterranean subduction rollback during the algero provencal basin opening the left lateral nuoro fault which is the prevailing structure in central sardinia operated as radial transfer between the west sardinian rift and northern tyrrhenian basin subsequently it contributed to a tension gash like opening of the southern tyrrhenian basin as conjugate fault to a right lateral fault set in se sardinia resulting antithetic rotations with respect to the arc are revealed by reoriented dikes in the basement the tension gash like opening of the southern tyrrhenian basin determined the gulf shape of the east sardinian margin and the arc shape of its calabrian counterpart this structural control on the southern tyrrhenian rollback scenario suggests that tension gash like opening of back arc basins represents an intrinsic aspect of subduction rollback

messinian erosional and salinity crises view from the provence basin gulf of lions western mediterranean abstract though the late miocene messinian salinity crisis has been intensely researched along the circum mediterranean basins few studies have focused on the central part of the mediterranean basin and especially the pre salt deposits to improve our knowledge of the messinian events it is imperative to better understand this domain in this study we provide a more complete understanding of this central domain in the provence basin we were able to recognize a thick marine detrital series up to 1000 m derived from the messinian subaerial erosion which is partly prolongated in the distal part by b a thick unit of deep marine deposits up to 800 m prior to the evaporites c a thick presumed alternation of detritals and evaporites 1500 m below the mobile halite and d a two step transgression at the end of the messinian spatially we document the eroded shelf to the deep basin and from the western to the eastern parts of the gulf of lions and temporally we extend the interpretations from the early deposition of detritic sediments to the final sea level rise the results provide a new basis for discussion not only for the development of the messinian salinity crisis but also for the reconstruction of the subsidence history of the provence basin

crustal features along a w e tyrrhenian transect from sardinia to campania margins central mediterranean abstract the tyrrhenian sea is a neogene back arc basin formed by continental extension at the rear of the eastward migrating apennine subduction system its central part generated from tortonian to pliocene includes the sardinia rifted margin to the west an area with large volcanoes in the deep central sector and the campania rifted margin to the east a reprocessing of some 2000 km of mcs lines a new swath bathymetric map and a review of previous geological and geophysical data allow to analyse the nature and distribution of continental vs oceanic crust in this area which evolved in a short time span the central portion of the southern tyrrhenian sea is characterized by moho at about 10 km depth north of magnghi and vavilov smts this thinned crustal domain include a wide continent ocean transition with the occurrence of extensional allochthons and of serpenitinzed sub continental mantle recalling other well known rifted margins as the iberia one sectors floored by oceanic crust should occur mainly in the southern part of the study area but they do not appear related to discrete spreading ridges the continent ocean boundary cannot be drawn unequivocally in the area due also to the occurrence of widespread and huge magmatic manifestations not related to oceanic spreading these portions of the southern tyrrhenian sea represents therefore a complex oceanic back arc basin surrounded by magma rich rifted continental margins the abundant igneous manifestations and the very high stretching rates observed in the area may be related to the fact that the present tyrrhenian area was occupied by an orogenic domain affected by shortening until middle miocene times which is just before the late miocene onset of back arc extension the lithosphere in the region had then to be rheologically weak abundant generation and ascent of magmas mostly of ocean island basalt type was favoured by the large lithospheric permeability induced by strong extensional deformations

simultaneous mesosphere lower thermosphere and thermospheric f region observations using middle and upper atmosphere radar simultaneous mlt mesosphere lower thermosphere and thermospheric f region upper thermosphere and ionosphere together observations conducted using the middle and upper atmosphere mu radar 35 degrees n 136 degrees e in alternate meteor and incoherent scatter modes in october 2000 and march 2001 are presented the continuous observations each lasting more than a week provide simultaneous zonal and meridional wind velocities at mlt altitudes 80 95 km meridional wind velocity in the upper thermosphere 220 450 km and electron density and peak height in the ionosphere with a time resolution of 1 5 hours the data seem to suggest that the upper atmospheric regions could be dynamically coupled through mean winds tides and waves diurnal 24 hour and semidiurnal 12 hour tides and waves of periods 16 20 hours and 35 55 hours coexist at mlt and upper thermosphere altitudes and the waves become stronger than tides at mesopause approximate to 88 km in both october and march the data in these equinoctial months also show large differences in mean winds tides and waves in the mlt region the amplitudes and phases of the 24 hour and 12 hour tides at mlt altitudes are compared with those predicted by the global scale wave model gswm the model qualitatively predicts the observed growth of the tides with altitude but does not predict the 12 hour tide becoming stronger than the 24 hour tide at altitudes above mesopause in october

regional scale morphological pattern of the tyrrhenian sea new insights from emodnet bathymetry abstract a large body of literature exists on the morphology of the tyrrhenian sea the youngest back arc basin of the eastern mediterranean however most of these studies are focused on local areas without considering the broad regional setting in this paper we consider the morphology of the entire tyrrhenian sea at a regional scale based on a dem analysis of middle resolution bathymetry downloaded from the emodnet website based on these data a first morpholineaments map has been created identifying 500 features 10 km in length without considering their tectonic settings and age furthermore a tyrrhenian regional tectonic map has been digitized from literature and the faults divided in pre pliocene pliocene and plio quaternary morpholineaments and tectonic lineaments have been grouped in six tyrrhenian sea areas plotted in rose diagrams in order to obtain the main trends in each region and to detect relationships between morphology and tectonics rose diagrams show that most of the identified morpholineaments have a tectonic origin although they are not coeval as they developed during different phases of the opening of the tyrrhenian back arc basin moreover morpholineaments data suggest that some regions of the tyrrhenian sea may be dominated by a single main trend whereas in other regions the occurrence of more trends testifies a major tectonic complexity

diurnal nonmigrating tides from timed doppler interferometer wind data monthly climatologies and seasonal variations 1 timed doppler interferometer tidi measurements of zonal and meridional winds in the mesosphere lower thermosphere are analyzed for diurnal nonmigrating tides june 2002 to june 2005 climatologies of monthly mean amplitudes and phases for seven tidal components are presented at altitudes between 85 and 105 km and latitudes between 45 s and 45 n westward propagating wave numbers 2 3 and 4 the standing diurnal tide and eastward propagating wave numbers 1 2 and 3 the observed seasonal variations agree well with 1991 1994 uars results at 95 km comparisons between the tidi results and global scale wave model gswm and thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm tidal predictions indicate that the large eastward propagating wave number 3 amplitude is driven by tropical tropospheric latent heat release alone in contrast latent heating and planetary wave migrating tidal interactions are equally important to westward 2 and standing diurnal tidal forcing there is good quantitative agreement between tidi and the model predictions during equinox but the latter tend to underestimate the westward 2 and standing diurnal tide during solstice neither model reproduces the observed seasonal variations of the eastward propagating components

structure and present day compression in the offshore area between alicante and ibiza island eastern iberian margin abstract this study deals with the structure and recent deformation of the eastern iberian margin extending from basement to seafloor and including the south western margin of the valencia basin the alicante shelf the ibiza channel and its southern margin descending into the algerian basin this area underwent a complex tectonic evolution linked to the back arc opening of the north western mediterranean and the concomitant contraction of the betic belt due to the collision with blocks located between africa and europe this oligo miocene structural heritage gave rise to a complex and continuous deformation through times including late miocene post orogenic extension and pliocene to quaternary compression in the western balearic area and coeval extension in the valencia basin this study presents maps of the depth to basement and base of the pliocene as well as bathymetry data and seismic lines which provide a precise integrated 3d study of the offshore domain it reveals a major reactivation of the area represented by the n80 to n60 trending structures small discontinuous folds and thrusts in the ibiza channel and a large flexure on the alicante shelf the structures are picked out by erosion surfaces or deposits linked to the messinian salinity crisis msc these markers are ubiquitous in the seismic sedimentary sequences and record the lateral and vertical deformation active from the messinian salinity crisis to the present the contraction in the western iberian margin and concomitant extension in the southern valencia basin are consistent with the regional stress field as determined from the focal mechanisms of offshore earthquakes or recent gps measurements the tectonic compression of the studied area casts doubt on the eventual propagation of the present day compressive stress from the algerian margin to the western balearic promontory

high resolution ultrasonic measurements as proxies to resolve clastic reservoir heterogeneity in a salt cemented gas reservoir petrophysical properties and their heterogeneity within sandstone bodies are key parameters in the evaluation of hydrocarbon and geothermal reservoirs however common tools applied to constrain the porosity distribution pattern in borehole cores are commonly time consuming and destructive or suffer from a resolution limited to the meter to decimeter scale we examine the applicability of nondestructive high resolution sonic hrs logging of well core sections in the ultrasonic frequency range as a method providing porosity proxy data at the centimeter scale in a clastic sedimentary sequence the middle solling sandstone member a gas bearing reservoir offshore from the netherlands is used as a test sample it consists almost entirely of clean cross bedded to massive eolian dune and dry sand flat deposits that are salt plugged to variable degrees plots of hrs logging data versus core plug porosity values show a positive linear relationship that develops the highest coefficient of determination r2 0 86 in structureless eolian dune sands most probably caused by the lack of bedding related anisotropies there once calibrated for a particular facies type this correlation enables the calculation of porosity proxy data from sonic transit time values acquired at centimetric steps high resolution sonic logging thus contributes a reliable and time efficient highly spatially resolving quantification of reservoir heterogeneities at centimeter scale and turns out to be a suitable tool for the nondestructive in situ detection of high porosity zones in otherwise uniform sandstone successions moreover plots of closely spaced hrs logging derived porosity proxy data significantly improve interpolation between single wider spaced core plug porosity data points

fluid geochemistry of the sardinian rift campidano graben sardinia italy fault segmentation seismic quiescence of geochemically active faults and new constraints for selection of co2 storage sites abstract sardinia is typically seismically quiescent displaying an almost complete lack of historical earthquakes and instrumentally recorded seismicity this evidence may be in agreement with the presence of a ductile layer in the northern sector of the island as suggested by the he isotopic signature in fluids rising to the surface through quiescent fault systems the fault systems have been found to be segmented and therefore isolated in fluid circulation the study of fluid behaviour along fault systems becomes strategically important when applied to solve some geological risk assessments such as rn indoor or to define geological structures like potential co 2 storage sites both of these have been recently requested by the exploitation in italy of the euratom directive and the evolution of the kyotoprotocol policy four water dominated hydrothermal areas of sardinia located along regional fault systems were considered campidano graben tirso valley logudoro and casteldoria a fluid geochemical survey was carried out taking into account physical chemical and environmental parameters major elements within gaseous and liquid phases a few minor and trace elements selected isotope ratios 2 h 18 o 13 c 3 he 4 he 222 rn concentration and some dissolved gases two different fluids have been recognised as regards both water chemistry and dissolved gases i co 2 rich gases poor in he and rn with a relatively high 3 he 4 he ratio up to r r a 2 32 associated with na hco 3 cl thermal and cold groundwater ii gases rich in he and n 2 poor in co 2 and rn with a low 3 he 4 he ratio associated with alkaline thermal and cold waters the distribution of these two groups of fluids characterises the sardinian tectonic systems in fact gas fluxes are not homogeneous being mainly related to the different fault segments and to the areas where quaternary basalts crop out the underground geochemical evolution of the sardinian fluids as a function of the geological and tectonic systems provides some suggestions for solving one of the most important problems co 2 geological sequestration in order to reduce the co 2 excess produced by human activity the best geological disposal sites are reservoirs with low hydraulic conductivity sealed to fluid movement or aquifers characterised by maximum ph buffering capacity of their mineralogical matrix the knowledge of the role of faults as permeability barriers or as deep fluid uprising pathways is prerequisite

ultrasonic logging across unconformities outcrop and core logger sonic patterns of the early triassic middle buntsandstein hardegsen unconformity southern germany abstract the recognition of unconformities in thick and monotonous sandstone successions of consistent grain size is often difficult in locally exposed surface outcrop sections and also poorly constrained by changes of petrophysical properties across the boundary surfaces here a mobile ultrasonic device is tested as a time efficient handheld logging tool to investigate relative changes in sandstone cementation and porosity across the early triassic middle buntsandstein hardegsen unconformity in southern and central germany a persistent offset of 18 20 sonic transit time occurs in all tested sections across the unconformity this offset is not restricted to single peaks but clearly separates the different sonic patterns of the hardegsen and solling formations below and above the unconformity integrated thin section analysis porosity permeability measurements and gamma density logging suggest that these changes in sonic transit time are due to major variations in sandstone cementation and the formation of secondary porosity associated with the unconformity field based ultrasonic measurements thus provide a useful addition to established outcrop logging methods and may help in the non destructive in situ identification of porosity cementation heterogeneities in sandstones in the localization of unconformities and in the correlation of borehole measured sequence boundaries to outcrop analogs

on the origin of the strait of gibraltar most interpretations of the early pliocene opening of the strait of gibraltar involve a tectonic process however no tectonic structure of this age has been unequivocally documented that could account for such a hypothesis on the other hand the sea level drop of the mediterranean during the messinian salinity crisis has dramatically enhanced continental erosion and in particular regressive fluvial erosion we show that such erosional process inevitably developed in the gibraltar area we finally propose that regressive fluvial erosion was at the origin of the opening of the strait of gibraltar

acoustic behavior of sedimentary rocks geologic properties versus poisson s ratios velocity transforms are essential for the extraction of geologic information from seismic reflection data sets and or predicting porosity from wireline logging data most commonly used transforms like the wyllie time average equation the raymer modified time average equation and the gardner equation are all based on empirical relationships extracted from relatively small clean mono and bimineral and mostly siliciclastic data sets and generally fail to explain the acoustic relationships within multimineral data sets to extract globally significant relationships between geologic and acoustic parameters more than 2800 plug measurements were collected more than two thirds of the data were our own measurements the others were from the literature this data set covers nearly all sedimentary environments and mixtures of those as well as the entire range in petrophysical properties

the nile deep sea fan an example of interacting sedimentation salt tectonics and inherited subsalt paleotopographic features abstract structural analysis of the nile deep sea fan ndsf indicates that post miocene deformation is largely controlled by down slope movement above a messinian salt layer in contrast to other similar systems the ndsf shows significant lateral asymmetry and three distinct provinces can be recognized regional variations in salt thickness and base salt geometry within the system have led to the presence of structures typical of both gravity gliding and gravity spreading trends of structures within the western and central parts of the ndsf are consistent with forming due to gravity gliding processes this pattern contrasts with that in the eastern ndsf that seem to be much more consistent with deformation due to gravity spreading observed differences in structural style across the ndsf can be related directly to the paleomorphological evolution of the nile cone during messinian time which is perhaps partly related to features that have been inherited from early mesozoic evolution of the north egypt passive margin in the east part of the ndsf the structural evolution has been significantly influenced by the proximity of eratosthenes seamount this large topographic buttress has served to both limit and deflect northeastward allochthonous advance of the messinian evaporites and has thus severely complicated deformation of the overlying plio quaternary sedimentary cover within the broad corridor that runs nnw sse and cuts obliquely across the modern bathymetry of the nile cone

a review on the driving mechanism of the tyrrhenian apennines system implications for the present seismotectonic setting in the central northern apennines abstract the formation of the tyrrhenian apennines system has been characterized by a complex distribution of major tectonic events such as opening of basins migration and distortion of orogenic belts retreat of trench zones stopping of consuming processes and starting of new subductions the various aspects of each event such as timing location dimension and deformation style impose important constraints on the genetic mechanism in this work we argue that the numerous constraints implied by all events together may be plausibly and coherently explained as effects of the convergence of the confining africa arabia and eurasia plates crucial evidence for discriminating among the various geodynamic hypotheses so far advanced is provided by the structural tectonic information recently provided by crop seismic sections in the study area the proposed evolutionary history is illustrated by several paleogeographic maps which provide a more detailed reconstruction than previous attempts particular attention is paid to describing the tectonic setting developed since the middle pleistocene in the apennines belt and its connection with seismic activity

longitudinal variation of the e region electric fields caused by atmospheric tides 1 polarization electric fields created by the e and f region dynamos cause the uplift of f region plasma the subsequent redistribution of that plasma along the magnetic field lines creates the equatorial ionospheric anomaly eia observations of the post sunset eia made by the image and timed satellites are compared here with champ orsted and sac c observations of the noontime equatorial electrojet eej during magnetically quiet periods around equinox the eia and eej show a remarkably similar four peaked wave like longitudinal variation its structure is consistent with the longitudinal variation in the strength of diurnal tides that drive the e region dynamo this indicates a strong vertical coupling between the ionosphere and troposphere because the four peaked tidal structure is driven by tropospheric weather furthermore the dayside ionospheric conditions are found to perform the global scale longitudinal structure of the post sunset ionosphere at low latitudes

midlatitude ionospheric plasma temperature climatology and empirical model based on saint santin incoherent scatter radar data from 1966 to 1987 ionospheric plasma temperature variations have recently been studied based on incoherent scatter radar isr observations at a lower midlatitude site shigaraki in east asia otsuka et al 1998 and millstone hill a typical subauroral midlatitude site in north america zhang and holt 2004 the french saint santin isr with a geographic latitude slightly higher but an apex latitude 14 lower than millstone collected bistatic and quadristatic measurements for over two solar cycles beginning in september 1965 a database of these data containing observations between 1966 and 1987 has been used in this study in order to establish the midlatitude ionospheric climatology in particular that of the upper atmosphere thermal status as well as empirical models for space weather applications this paper presents in comparison with the millstone hill results variations of ion and electron temperatures ti and te with solar activity season time of the day and altitude the f2 region te at st santin is found to be lower than at millstone between march and july when the st santin electron density ne is relatively higher the midday te below 300 km increases with f10 7 as at millstone hill above 300 km it tends to decrease with f10 7 at st santin while it increases in summer at millstone hill ti between 250 and 350 km peaks midway between spring and summer we have also created st santin ionospheric models for ne te and ti using a bin fit technique similar to that used for the millstone hill models comparisons with corresponding iri predications indicate good agreement in ti at high solar activity and above the f2 peak te from the iri tends to be higher than both the st santin and millstone hill models

tidal variability in the ionospheric dynamo region 1 the seasonal and interannual variability of migrating sun synchronous and nonmigrating solar atmospheric tides at altitudes between 100 and 116 km are investigated using temperature measurements made with the saber instrument on the timed spacecraft during 2002 2006 quasi biennial variations of order 10 15 in migrating diurnal and semidiurnal tidal amplitudes are found presumably due to modulation by the quasi biennial oscillation qbo as the tides propagate from their troposphere and stratospheric sources to the lower thermosphere a number of nonmigrating tidal components are found that have the potential to produce significant longitudinal variability of the total tidal fields the most prominent of these i e those that appear at amplitudes of order 5 10 k in a 5 year mean climatology include the zonally symmetric s 0 diurnal tide d0 the eastward propagating diurnal and semidiurnal tides with zonal wave numbers s 2 de2 and se2 and s 3 de3 and se3 and the following westward propagating waves diurnal s 2 dw2 semidiurnal s 1 sw1 s 3 sw3 and s 4 sw4 and terdiurnal s 5 tw5 these waves can be plausibly accounted for by nonlinear interaction between migrating tidal components and stationary planetary waves with s 1 or s 2 or by longitudinal variations of tropospheric thermal forcing additional waves that occur during some years or undergo phase cancellation within construction of a 5 year climatology include dw5 se1 se4 sw6 te1 tw1 and tw7 it is anticipated that the winds that accompany all of these waves in the 100 170 km region will impose longitudinal variability in the electric fields produced through the ionospheric dynamo mechanism thereby modulating vertical motion of the equatorial ionosphere and the concomitant plasma densities in addition to the wave 4 modulation of the equatorial ionosphere that has recently been discovered and replicated in modeling studies the waves revealed here will generate wave 1 sw1 sw3 d0 dw2 wave 2 sw4 tw1 wave 3 de2 se1 wave 4 de3 se2 dw5 sw6 te1 tw7 wave 5 se3 and wave 6 se4 components of this ionospheric variability depending on year and time of year however the absolute and relative efficiencies with which these waves produce electric fields remains to be determined

record of the messinian salinity crisis in the sw mallorca area balearic promontory spain the current interpretation of the messinian salinity crisis msc involves the deposition of the so called peripheral or marginal evaporites in onshore basins as well as the erosion of the margins and the formation of thick evaporites in the deep parts of the basins the present study focuses on intermediate depth basins i e located between the onshore outcrops and the deep basins indeed the balearic promontory shows small stepped basins filled with msc deposits between its western extremity on the alicante shelf and its eastern end around the menorca block new and already available seismic reflection profiles and onshore data allow us to investigate the nature and geometrical relationships of these deposits in the area between the islands of ibiza and mallorca our observations suggest the existence of three msc related units in this area the lowermost transparent seismic unit can be interpreted as a 100 to 200 m thick salt layer deposited in the deepest part of the central mallorca depression these evaporites pass laterally and upward into a thin bedded seismic unit which could be lithologically equivalent to the upper evaporites of the deep basins all around the borders of the central mallorca depression this bedded seismic unit onlaps a slope unit which shows bedded to chaotic and rafted facies the messinian continental shelf is eroded and incised by a valley extending from the palma onshore area to the mallorca downslope domain our results suggest the presence offshore of at least two generations of diachronous msc deposits the observation of salt on a continental high and the widespread msc deposits on the margins of the central mallorca depression call into question the location of halite preferentially in the deep abyssal basins and the significance of the deep basin msc units that onlap onto the margin erosional surface mes as observed all around the passive margins of the northwest mediterranean basin the dual terminology used for peripheral deep msc evaporites cannot be applied to any of the msc units found in the study area

salt tectonics and crustal tectonics along the eastern sardinian margin western tyrrhenian new insights from the metyss 1 cruise abstract the tyrrhenian sea is usually interpreted to be a neogene back arc basin that opened by continental rifting and oceanic spreading caused by the eastward migration of the apennine subduction system during miocene and pliocene times rifting of the southern tyrrhenian sea started first along the eastern sardinian margin during the middle to late miocene times including the messinian the metyss project aims at better constraining the relationships between crustal tectonics salt tectonics and sedimentation from messinian times to present day the metyss 1 cruise 2009 allowed to acquire about 1200 km of hr seismic reflection profiles along the eastern sardinian margin western tyrrhenian sea this data set clearly illustrates that this area has been highly dissected during the rifting stage by n s trending normal faults delineating ridges and basins as previously described the messinian seismic markers uu and mu locally display fan shaped stratal geometries but the mechanism responsible for such geometries salt tectonics or rifting has yet to be carefully deciphered we also mapped the spatial distribution of the mobile salt the highly variable thickness of the small confined salt basins may be related to the initial pre messinian basin geometry to the fact that salt deposition was syn rift or to salt movement southeastward salt tectonics is vigorous in unconfined basins and appears to have started early during the uu deposition more surprisingly our data demonstrate that some of the major faults have been significantly reactivated during the post rift period up to late quaternary time as shown by bathymetric scarps and associated debris flows moreover some of this post rift deformation can be evidenced within the plio quaternary sequence by a regional unconformity the post miocene deformation style varies greatly between different areas of the margin and can also be strongly influenced by the presence or absence of mobile messinian salt

structural evolution of the 41st parallel zone tyrrhenian sea the present study is based on the interpretation of more than 1300 km of 16 kj sparker seismic profiles recorded in july 1990 during the cruise t 41 of the geological institute of urbino the investigated area extends along the 41st parallel in the central tyrrhenian sea between the northern sardinian margin to the west and the latium campanian margin to the east this zone situated on continental crust marks the boundary between the northern tyrrhenian and the southern tyrrhenian domains a kinematic reconstruction is presented based on the age dating of the recognized structures i e normal faults reverse faults anticline and flower structures the evolution of the 41st parallel zone can be described in terms of polyphase tectonics characterized by different orientations of the stress field during time the direction of the normal fault trends turned clockwise striking ne sw in the late tortonian messinian e w in the early pliocene nnw sse in the late pliocene and n s during the quaternary the concurrence of compressional and strike slip deformations suggests oblique shear motions across the 41st parallel the occurrence of late pliocene quaternary tectonic activity in the northern tyrrhenian sea locally characterized by inversion tectonics suggests active mechanisms intraplate compression superimposed on the post rift subsidence

wavenumber 4 patterns of the total electron content over the low latitude ionosphere 1 the global ionospheric maps gims produced by jpl are used to investigate the longitudinal structure of the low latitude ionosphere as a proxy of the ionization parameter at low latitudes the latitudinally integrated total electron content itec is first extracted from low latitude gims and then fourier filtered to obtain the wavenumber 4 components we then study in detail the diurnal seasonal and solar cycle variations of the wave patterns it is found that the wavenumber 4 patterns are intense and well developed in boreal summer and early boreal autumn but quite weak in boreal winter this seasonal variation is consistent with that of the zonal wind of the non migrating tide mode de3 we also found that the wavenumber 4 patterns shift eastward with a shifting speed that is smaller in daytime than at night this is attributed to the contribution of both the eastward propagation of de3 in e region and the zonal e b ion drifts in f region our results support the suggestion that the longitudinal wavenumber 4 structure of the low latitude ionosphere should be originated from the non migrating tide mode de3

high resolution vertical e b drift model derived from rocsat 1 data 1 the measurements of vertical ion velocity from the first republic of china satellite rocsat 1 provide a unique database for the development of an annually and longitudinally high resolution vertical plasma drift model in the equatorial ionosphere currently the rocsat 1 based empirical vertical drift models are available for three seasons equinox and solstices however the vertical drift patterns are not precisely divided by the three seasons a monthly vertical drift model with high longitudinal resolution is desirable to accurately model the low latitude ionosphere and to identify the coupling between the ionosphere and atmospheric tide here we introduce an empirical vertical drift model derived by using the rocsat 1 data in three solar flux conditions f 10 7 180 under k p 3 the local time day of the year and longitude of the model are binned by 15 min 1 month and 10 respectively under each solar flux condition our vertical drift model is validated by comparing the model with the measurements of the vertical drift velocity at the jicamarca radio observatory the characteristics and variability of the vertical drift are briefly discussed

the western tyrrhenian sea revisited new evidence for a rifted basin during the messinian salinity crisis abstract in the last fifty years the messinian salinity crisis msc has been widely investigated in the mediterranean sea but a major basin remains fewly explored in terms of msc thematic the western tyrrhenian basin the rifting of this back arc basin is considered to occur between the middle miocene and the early pliocene thus including the msc giving a unique opportunity to study the crisis in a context of active geodynamics however the msc seismic markers in the western part of the tyrrhenian sea have only been investigated in the early eighties and the msc event in the western tyrrhenian basin remains poorly studied and unclear in this study we revisit the msc in the western tyrrhenian basin i e along the eastern sardinian margin we present results from the interpretation of a 2400 km long hr seismic reflection dataset acquired along the margin during the metyss research cruises in 2009 and 2011 the maps of the msc seismic markers reveal that the eastern sardinian margin was already dissected in structurals highs and lows during the msc we also demonstrate that the msc markers constitute powerfull time markers to refine the age of the rifting which ended earlier than expected in the east sardinian basin and the cornaglia terrace these results allow us to discuss the palaeo water depth of the western tyrrhenian basin during the msc as well as implications for possibles scenarios of the messinian salinity crisis across the eastern sardinian margin

the italian cmt dataset from 1977 to the present abstract the ingv harvard european mediterranean regional centroid moment tensor rcmt catalog collects solutions routinely computed since 1997 for earthquakes with moderate magnitude 4 5 m 5 5 in the mediterranean region the database represents an extension to smaller magnitudes of the harvard global cmt catalog based on analysis of seismograms recorded at regional distance and modeling of intermediate period surface waves the catalog includes about 600 events 200 of which in the italian region this study extends the catalog back in time for the italian region as long as made possible by available digital data i e since 1977 with the same analysis and inversion method used for current seismicity as a result we present here 65 new moment tensors for years between 1977 and 1997 these solutions represent 45 of the total number of events analyzed the existing seismograms being often too scarce to allow a stable solution the new dataset includes events in many seismic zones where moderate seismicity had previously been scarcely documented e g the po plain the central to southern apennines and the adriatic sea the complete dataset including previously determined rcmts and cmts represents the seismic deformation in the italian area during the last 25 years

constraints on mantle circulation around the deforming calabrian slab 1 combining tectonics with seismological and geochemical data we reconstruct the deformation history of the presently narrow calabrian slab and the path of mantle circulation during the last 10 ma we show that during the slab deformation the mantle laterally flowed inside the back arc region permitting its retrograde motion and giving a seismological and volcanological record after 1 2 myr

extension and compression related basins in central italy during the messinian lago mare event abstract during the messinian lago mare event in the central mediterranean area compression and extension related basins developed as a consequence of the post tortonian evolution of the tyrrhenian apennines system all these syn tectonic sedimentary basins were characterized by different subsidence rates and sedimentary processes several sections located in different tectonic domains from the tyrrhenian to the adriatic margin of the apennine chain have been investigated s valentino in abruzzo citeriore roccamorice penscosansonesco roccacaramanico and le vicenne sections are located in compression related basins foreland basin system while the tolfa blera sections and the sedimentary succession of mondragone 1 well drilled in the garigliano coastal plain are located in extension related basins hinterland or back arc basins the recognition of ostracod assemblages with paratethyan affinities allows them to be referred to the messinian lago mare event loxoconcha djaffarovi zone this result allows us to consider the tyrrhenian rifting the accretion of the apennine thrust belt and the increase in subsidence rate during the flexuration of the foreland domain as synchronous processes due to the same geodynamical process taking into account the thicknesses of the analysed sedimentary basins different total subsidence rates have been computed for both the compression and extension related basins the syn rift basins that developed on the eastern margin of the northern tyrrhenian basin volterra val di fine and tolfa blera basins recorded a mean total subsidence rate of 1 25 mm a whereas higher subsidence rates affected the eastern margin of the central tyrrhenian basin 5 mm a garigliano coastal plain the differences in horizontal stretching and total subsidence rates that affected the tyrrhenian extensional area correspond to different migration rates of the apennine orogenic system in the northern 10 mm a and central apennines 40 mm a this difference in the total syn rift subsidence rate fits in well with the segmentation model of the tyrrhenian apennines system along a nne ssw lithosphere discontinuity which crosses the system from ancona northern apennines to the r selli lineament in the tyrrhenian basin

sardinia coastal uplift and volcanism the low variability of mis 5 5 sea level m i s marine isotopic stage with respect to the present day sea level allows the sardinian coast to be used as an eustatic reference for the entire mediterranean region this level is generally at 7 2 m above current sea level along the sardinian coast one sector along the orosei gulf eastern sardinia includes a characteristic and well conserved tidal notch that changes in elevation from 7 6 to 11 5 m over only 30 km tilting upwards towards the north generally height deviations of such a tidal notch would be due to tectonic or volcanic activity the sardinia coast however is considered to have too little tectonic activity and also too small post glacial rebound in order to explain the anomaly the remaining possibility is neogene quaternary continental and or submarine volcanic activity which we investigate as a possible cause for the observed anomalies in this paper our goal is to explain the anomaly by modelling recent volcanic loading or updoming related to magmatic intrusion emplacement we review the literature on the recent volcanic deposits both on shore and off shore and investigate to what extent volcanic loads can influence the coastline from a theoretical standpoint using the isostatic flexure model and a range of loads we find that the observed notch height anomaly cannot be explained by volcanic loading but must be produced by an upward welling due to the emplacement of volcanic material as produced for instance by a laccolith or batholith the upward movement could be related to the submarine volcano only recently detected or to a source located on the eastern sardinia coast near orosei

a proposal for the kinematic modelling of w dipping subductions possible applications to the tyrrhenian apennines system in w dipping subduction zones there is a general eastward progression of the back arc basin accretionary wedge foredeep complex with the forward progression early stages of the complex are revealed by slices of upper crust and sedimentary cover abandoned to the west left floating above a new section of mantle a major shear zone should form at the new moho separating upper crust slices of earlier accretionary stages and the eastward flowing mantle the mantle wedging at the top of the subduction plane could be responsible for the uplift of the central parts of the belt the retreating of the subduction hinge is interpreted as due to the push generated by the eastward mantle flow detected in the hot spot reference frame the foredeep depth is mainly a function of the radius of curvature of the subduction hinge the frontal wedge is constructed from the stacking of the upper layers of the subducting plate and the syntectonic clastics that fill the foredeep which are progressively involved in thrusting and later by extension in order to preserve volume balance the lithosphere of the eastern plate before subduction has to be the same size as that which has been subducted due to the longer length of the arc with respect to the original length of the linear margin between the two converging plates laterally stretched subducted lithosphere is predicted at depth w dipping subductions usually have a short life probably due to their inherent capability to produce new lateral heterogeneities of the lithosphere the thin back arc which are a key factor in controlling and generating new subductions both e and w dipping this model is applied to the apennines tyrrhenian sea system

on the asymmetry of turtle back growth anticlines turtle back anticlines are common structures that develop between facing listric growth faults rooted in a flat lying decollement seismic examples from the south atlantic margins show that whereas their external shape can by symmetric their internal structure is more generally asymmetric laboratory experiments on layered sand silicone models designed to study gravity gliding are used to examine the mode of development of turtle back anticlines the results provide information on the ways turtle back asymmetry develops the comparison between nature and experiments leads to the following conclusions the fact that turtle back anticlines often start symmetric and progressively become asymmetric is due to an increase in coupling between overlying brittle sediments and ductile salt layers the increase in coupling is also responsible for the transition in time and space from dominant seaward faulting to landward faulting for the turtle back anticlines which never pass through a symmetric stage the salt diapirs which separate blocks of the sedimentary cover rafted above the basal decollement at early stages of gravity gliding can play a significant role in the development of turtle back anticlines as suggested by previous authors the diapirs first rise and then fall our experiments confirm that diapir fall favours the wrapping of rafted blocks by synkinematic layers

the messinian salinity crisis past and future of a great challenge for marine sciences forty years after the image of the mediterranean transformed into a giant salty lake was first conceived the fascinating history of the messinian salinity crisis msc still arouses great interest across a large and diverse scientific community early outcrop studies which identified severe palaeoenvironmental changes affecting the circum mediterranean at the end of the miocene were followed by investigations of the marine geology during the 1950s to 1970s these were fundamental to understanding the true scale and importance of the messinian event now after a long period of debate over several entrenched but largely untested hypotheses a unifying stratigraphic framework of msc events has been constructed this scenario is derived mainly from onshore data and observations but incorporates different perspectives for the offshore and provides hypotheses that can be tested by drilling the deep mediterranean basins the msc was an ecological crisis induced by a powerful combination of geodynamic and climatic drivers which had a great impact on the subsequent geological history of the mediterranean area and on the salinity of the global oceans these changed the mediterranean s connections with both the atlantic ocean and the freshwater paratethyan basins causing high amplitude fluctuations in the hydrology of the mediterranean the msc developed in three main stages each of them characterized by different palaeoenvironmental conditions during the first stage evaporites precipitated in shallow sub basins the msc peaked in the second stage when evaporite precipitation shifted to the deepest depocentres and the third stage was characterized by large scale environmental fluctuations in a mediterranean transformed into a brackish water lake the very high resolution timescale available for some late miocene intervals in the mediterranean makes it possible to consider environmental variability on extremely short time scales including in some places annual changes despite this fundamental questions remain some of which could be answered through new cores from the deepest mediterranean basins improvements in seismic imaging and drilling techniques over the last few decades make it possible to plan to core the entire basinal messinian succession for the first time the resulting data would allow us to decipher the causes of this extreme environmental change and its global scale consequences

longitudinal variations in the equatorial vertical drift in the topside ionosphere 1 the vertical ion drift is important for understanding and modeling the electrodynamics at low latitudes measurements from the ion drift meter on the defense meteorological satellite program dmsp f15 are used to examine longitudinal variations in the vertical ion drift at the dip equator in the topside ionosphere local time was restricted to 0930 and the data were organized by month for 2001 and 2002 two features were found contributing to the longitudinal variations in the electrodynamics meridional winds contribute to the equatorial vertical ion drift at the 830 km magnetic apex due to their dynamo action at the foot points of the magnetic field lines in the f region at magnetic latitudes near 15 electric fields producing a downward perturbation drift at 0930 are produced by hemispheric differences in the dynamo current due primarily to the different orientation of the magnetic meridian relative to the terminator this produces the seasonally dependent variation as a function of longitude that is observed a wavenumber 4 longitudinal variation also appears to be present throughout the year but is more influential during equinox conditions this variation also shows a seasonal cycle shifting east during northern summer and west during northern winter further analysis would be required to isolate the characteristics of a wavenumber 4 driver from the wavenumber 4 component of the fourier series used here to fit the data

acoustic properties of ancient shallow marine carbonates effects of depositional environments and diagenetic processes middle jurassic paris basin france abstract examination of petrophysical properties acoustic velocity porosity permeability and density and petrographical characteristics texture facies composition and diagenesis of more than 250 core plugs from the middle jurassic carbonates of the eastern paris basin provides insights into the parameters controlling acoustic velocities in relatively low porosity carbonate rocks 20 the pore type observations reveal distinct acoustic velocities in samples with intergranular macropores and samples with micropores in subhedral micrite such that velocities in microporous mudstone wackestone lagoonal deposits are greater than in macroporous grainstone shoal samples at a given porosity range 15 20 the standard wyllie and raymer transforms fit very well with the linear regression between acoustic velocity and porosity from mudstone or lagoonal facies marls and fine grained deposits interpreted as lagoonal facies include statistically significant correlation r 0 9 between velocity and porosity however the data suggest that the wide scatter in velocity porosity relationship from grainstones are not the result of different sorting grain size pore type dolomite content or clay content instead early cementation greatly influences acoustic properties during diagenesis and are interpreted to account for the high variability of velocities over a given porosity range specifically at a given porosity acoustic velocities in compacted grainstone that did not undergo early cementation are higher than in early cemented grainstone petrographic observations suggest that early cementation limits mechanical compaction creating a heterogeneous medium from the earliest stages of diagenesis non touching grains preservation of intergranular macropores that are partially to totally filled by later blocky calcite cement the abundant interfaces between micritized ooids early cement fringes and blocky calcites in grainstones may induce significant wave attenuation as a result the standard time average equations fail to predict the effect of diagenetic features such as early cementation on sonic velocity conversely an absence of early cementation favors mechanical compaction grain to grain contact and suturing the result is a homogeneous micritized grain supported network that may facilitate wave propagation through demonstration of the key role of early cementation in the explanation of variability in acoustic properties the results of this study illustrate the complicated factors influencing velocity transforms in carbonates wyllie and raymer i e classical tools for predicting reservoir properties these insights on the interpretation of vp and the refinement of velocity porosity transforms in grainstone units may be broadly applicable to enhancing seismic based exploration in carbonate successions

history of subduction and back arc extension in the central mediterranean summary geological and geophysical constraints to reconstruct the evolution of the central mediterranean subduction zone are presented geological observations such as upper plate stratigraphy hp lt metamorphic assemblages foredeep trench stratigraphy arc volcanism and the back arc extension process are used to define the infant stage of the subduction zone and its latest back arc phase based on this data set the time dependence of the amount of subducted material in comparison with the tomographic images of the upper mantle along two cross sections from the northern apennines and from calabria to the gulf of lyon can be derived further the reconstruction is used to unravel the main evolutionary trends of the subduction process results of this analysis indicate that 1 subduction in the central mediterranean is as old as 80 myr 2 the slab descended slowly into the mantle during the first 20 30 myr subduction speeds were probably less than 1 cm year x1 3 subduction accelerated afterwards producing arc volcanism and back arc extension and 4 the slab reached the 660 km transition zone after 60 70 myr this time dependent scenario where a slow initiation is followed by a roughly exponential increase in the subduction speed can be modelled by equating the viscous dissipation per unit length due to the bending of oceanic lithosphere to the rate of change of potential energy by slab pull finally the third stage is controlled by the interaction between the slab and the 660 km transition zone in the southern region this results in an important re shaping of the slab and intermittent pulses of back arc extension in the northern region the decrease in the trench retreat can be explained by the entrance of light continental material at the trench

troposphere thermosphere tidal coupling as measured by the saber instrument on timed during july september 2002 1 coupling between the troposphere and lower thermosphere due to upward propagating tides is investigated using temperatures measured from the saber instrument on the timed satellite the data analyzed here are confined to 20 120 km altitude and 40 latitude during 20 july to 20 september 2002 apart from the migrating sun synchronous tidal components the predominant feature seen from the satellite frame during this period is a wave 4 structure in longitude with extrema of up to 40 50 k at 110 km amplitudes and longitudes of maxima of this structure evolve as the satellite precesses in local time and as the wave s responsible for this structure vary with time the primary wave responsible for the wave 4 pattern is the eastward propagating diurnal tide with zonal wave number s 3 de3 its average amplitude distribution over the interval is quasi symmetric about the equator similar to that of a kelvin wave with maximum of about 20 k at 5 s and 110 km de3 is primarily excited by latent heating due to deep tropical convection in the troposphere it is demonstrated that existence of de3 is intimately connected with the predominant wave 4 longitude distribution of topography and land sea difference at low latitudes and an analogy is drawn with the strong presence of de1 in mars atmosphere the predominant wave 2 topography on mars and the wave 2 patterns that dominate density measurements from the mars global surveyor mgs spacecraft near 130 km additional diurnal semidiurnal and terdiurnal nonmigrating tides are also revealed in the present study these tidal components are most likely excited by nonlinear interactions between their migrating counterparts and the stationary planetary wave with s 1 known to exist in the southern hemisphere during this period just prior to the austral midwinter stratospheric warming of 2002

messinian subaerial erosion of the proto nile delta abstract the evaporitic drawdown and subsequent dessication of the mediterranean basins during the messinian salinity crisis has been confirmed by detailed seismic mapping of the ensuing erosion surface in the nile delta region the basal messinian unconformity determined by seismic analysis and borehole correlation extends from almost sea level in the southern delta area to depths of at least 5 km in the nile cone the onlap of the contemporaneously deposited fluvio deltaic clastics of the qawasim formation occurs at between 2 5 to 4 km below present gradual initial drawdown of the mediterranean sea with occasional sudden sporadic falls is implied by the presence of entrenched meanders and impaired rejuvenation terraces in the nile canyon formed as the proto nile river cut down into the pre existing tortonian delta complex the former tortonian delta slope became an extensive linear erosional front with over 3 km of vertical relief the uppermost levels of which were protected by tabular oligocene basalt flows preserved as mesas and buttes the lower slopes were the site of coalescing piedmont fans fed by upper slope wadi systems the piedmonts merged into the qawasim fluvio deltaic deposits of the proto nile fluvial flood plain the subcrop beneath the basal messinian unconformity reveals a remarkable diversity of rock type each with its own distinctive control on the geomorphology and geometry of the ensuing messinian erosional surface fracture patterns within the oligocene basalts produced a trellis drainage network which became later captured by a dendritic system developed on less resistant prodelta shales of the former tortonian delta slope close study of seismic profiles clearly demonstrates that the basal messinian erosional disconformity can be traced northwards to depths of at least 2 5 3 0 km before becoming affected by later pliocene faulting this validates a deep dessication model for the evolution of the messinian evaporites

influences of geomagnetic fields on longitudinal variations of vertical plasma drifts in the presunset equatorial topside ionosphere on the basis of the measurements from the ion drift meter on the defense meteorological satellite program f13 satellite from 2000 to 2002 the relative longitudinal variations of e x b vertical plasma drifts in the presunset equatorial topside ionosphere at 1745 lt are examined obvious influences of geomagnetic fields on longitudinal variations of e x b vertical plasma drifts which also show a seasonal dependence have been found during the june solstice the relative vertical plasma drifts is most significantly influenced by the geomagnetic field declination however the relative vertical plasma drifts during the december solstice more strongly correlates with the geomagnetic field strength although the relative vertical plasma drifts during equinox are also influenced by the geomagnetic field declination an underlying dependence on magnetic field magnitude as seen in december is also present

miocene rotation of sardinia new paleomagnetic and geochronological constraints and geodynamic implications the miocene rotation of sardinia western mediterranean remains poorly constrained despite a wealth of paleomagnetic data primarily due to poor chronostratigraphic control however this rotation is contemporaneous with the opening of the liguro provencal back arc oceanic basin and its history is key to understanding the kinematics of opening of the western mediterranean we address this issue through paleomagnetic and 40ar 39ar geochronological investigations of miocene volcanic sequences in sardinia precise age control allows secular variation of the geomagnetic field to be evaluated these data provide constraints on the rotational history of this continental microplate sardinia rotated 45 counterclockwise with respect to stable europe after 20 5 ma aquitanian which is a marked increase over the estimate of 30 derived from prior paleomagnetic studies rotation was essentially complete by 15 ma about 30 of rotation occurred between 20 5 and 18 ma burdigalian corresponding to the period of maximum volcanic activity in sardinia the observed rotation validates palinspastic models derived from a morphological fit of basin margins and indicates high rates of opening up to 9 cm yr 1 in the southern part of the basin between 20 5 and 18 ma

quiet time equatorial f region vertical plasma drift model derived from rocsat 1 observations 1 we have used five years of measurements on board the rocsat 1 satellite to develop a detailed quiet time global empirical model for equatorial f region vertical plasma drifts this model describes the local time seasonal and longitudinal dependence of the vertical drifts for an altitude of 600 km under moderate and high solar flux conditions the model results are in excellent agreement with measurements from the jicamarca radar and also from other ground based and in situ probes we show that the longitudinal dependence of the daytime and nighttime vertical drifts is much stronger than reported earlier especially during december and june solstice the late night downward drift velocities are larger in the eastern than in the western hemisphere at all seasons the morning and afternoon december solstice drifts have significantly different longitudinal dependence and the daytime upward drifts have strong wave number four signatures during equinox and june solstice the largest evening upward drifts occur during equinox and december solstice near the american sector the longitudinal variations of the evening prereversal velocity peaks during december and june solstice are anti correlated which further indicates the importance of conductivity effects on the electrodynamics of the equatorial ionosphere

monthly tidal temperatures 20 120 km from timed saber 1 the saber instrument on the timed satellite provides unprecedented geographical coverage for the determination and study of atmospheric tides however the slow local time precession rate of timed can cause longer term temperature variations to alias into the tidal signals a new method of analyzing satellite data for tides has been developed to circumvent this difficulty but at the expense of temporal resolution of the tidal fields i e 120 day mean tidal structures are obtained in this work we apply this method to saber temperature data to derive a series of 120 day mean tidal structures extending between 20 and 120 km altitude 50 s 50 n latitude and centered on each month from september 2003 to september 2004 in addition to the migrating sun synchronous diurnal and semidiurnal tides a number of nonmigrating tides are revealed in the saber measurements some of these waves are thought to originate via nonlinear coupling between the migrating tides and the stationary planetary wave with zonal wave number s 1 other nonmigrating tidal components appear to be forced by latent heating due to deep tropical convection of the latter the eastward propagating diurnal tide with s 3 is dominant and is as large as the migrating diurnal tide during some months of particular interest is the wave 4 structure with respect to longitude that characterizes both the diurnal and semidiurnal total tidal fields this feature is a result of the predominant wave 4 topography land sea longitude dependence at the surface which is reflected in the diurnal and semidiurnal components of the latent heating rates due to deep tropical convection the ability of the global scale wave model gswm to approximate the observed tidal fields including the wave 4 total tidal structures is also assessed

salt tectonics driven by sediment progradation part i mechanics and kinematics using conceptual reasoning and results from physical models we describe the mechanical and kinematic characteristics of sediment wedges spreading seaward above a viscous evaporitic layer spreading can occur if the distal sediment overburden is thin and weak or if it comprises preexisting salt bodies spreading is accommodated by proximal extension and an associated rise of diapiric ridges by midslope seaward translation and by distal shortening rapid sediment progradation can lead to the reactivation of older distal folds by later extension either retrogradation or renewed sedimentation following a long depositional hiatus can reactivate older grabens and diapirs in shortening

neogene evolution of the southwestern tyrrhenian sea sardinia basin and western bathyal plain abstract the reprocessing of mcs reflection lines and sampling data across the sw tyrrhenian basin from the sardinia tunisia strait sts to the orosei canyon line ocl show that the acoustic basement of the area is made by variscan crystalline metamorphic rocks covered by a thick sequence of sediments including the messinian interval the pre messinian sequence can be subdivided into three seismic intervals or subunits largely calibrated by sampling data the oldest pre messinian subunit is strongly deformed by compressional and or transpressional structures and the recovered samples are deep water arkosic sediments aquitanian in age however the whole interval may encompass a wider time span probably from late oligocene to langhian this subunit was laid down in a fore arc basin located between a volcanic arc sardinia and an accretionary wedge calabrian peloritanian kabilide or ck units prior to the collision of the latter elements with the continental margin of africa in sicily and tunisia along the so called drepano thrust front dtf coeval to collision the generation of the main sardinia thrust mst occurred carrying the sardinia basement rocks over the ck units and deforming the fore arc basin sediments the intermediate pre messinian sedimentary subunit spans from part of serravallian to part of tortonian it is post tectonic with respect to the underlying subunit but it represents a pre rift succession if related to the overlying one it consists of terrigenous deposits prograding from sardinia to the ene into a basin some hundreds of meters deep which was left in the area after collision the youngest pre evaporitic subunit late tortonian early messinian in age displays wedge shaped reflectors in the sardinia basin and forms the lower portion of a syn rift complex including the messinian and part of the pliocene sediments this succession records the onset of extensional tectonics in the area as also testified by the tortonian age of exumation of the basement while in the tyrrhenian basin north of the ocl intra tortonian to intra pliocene rifting was strong but discontinuous and migrating with time to the east in the sw tyrrhenian basin in contrast rifting was less severe but continuous during the same time interval this emphasizes the role played by the ocl a inherited mesozoic discontinuity reactivated as a transfer zone during the neogene these new data allow correlation of the main miocene deformational events observed in the study area to those of the adjacent emerged areas namely the peloritani and maghrebian units in sicily prior to the pliocene quaternary full development of the southern tyrrhenian sea

erosional processes and paleo environmental changes in the western gulf of lions sw france during the messinian salinity crisis abstract current interpretation of the messinian salinity crisis msc involves partial desiccation of the mediterranean sea coupled with the deposition of thick evaporites in the deep basins new sets of seismic reflection profiles in the western part of the gulf of lions confirm the basinward extension of the messinian erosion and enable the mapping of distinctive seismic markers indicating the messinian erosional surface or messinian unconformity the basin margin detrital deposits and the deep evaporite sequence the geometrical relationship between these three elements and their relationship to the paleogeography of the margin during the msc provide new information about the evolution of the study area during the messinian the messinian erosional surface mes commonly correlated with the desiccation phase and the deposition of deep evaporites during the apogee of the event is generally interpreted as a subaerial feature in the gulf of lions it is a complex diachronic polygenic erosional surface observed at the base of the prograding plio quaternary sequence beneath the shelf and slope it extends downslope beneath the deep basin upper evaporites and the salt and possibly correlates conformably with the base of the so called deep lower evaporites the whole morphology of the mes reflects a buried drainage pattern supporting the interpretation of fluvial erosion driven by a substantial drop in sea level our results also suggest that large submarine gravity flows occurred prior to any significant accumulation of salt in the basin and prior to the upper evaporites consequently interbedded clastic deposits may partly account for the parallel reflectors of the lower evaporites since river erosion persisted throughout the msc the salt and upper evaporite units may also contain a large amount of detrital sediments the good quality of the new seismic data clearly reveals fan shaped messinian deposits in the downstream part of the main messinian valleys i e the nile var and spanish rivers the depositional scenarios generally involve a substantial sea level fall coupled with deltaic prodeltaic accumulations a chaotic seismic unit unit d filling messinian lows and extending beneath the salt within the study area is interpreted as a messinian clastic unit we propose a polyphase scenario of detrital fan deposition involving pre syn and post salt deposition in subaqueous subaerial environments in the gulf of lions a late miocene tectonic phase that affected the western shelf also played an important role in controlling a the pattern of the messinian fluvial network b the location of maximum erosion on the shelf and c the location of the detrital fan depocentre downslope

variations in petrophysical properties along a mixed siliciclastic carbonate ramp upper jurassic ricla ne spain abstract a multi scale petrophysical study was performed on an upper jurassic siliciclastic carbonate ramp system near the village of ricla spain a combination of textural field observations thin section and grain size analysis chemical mineralogical thermo gravimetric analysis and physical porosity gamma ray and velocity measurements properties was used to capture the heterogeneity of this mixed sedimentary system subsequently synthetic seismic sections with varying resolution were created to show the characteristics of the internal ramp structures the translation from the measured petrophysical properties to a synthetic seismic section helps to better understand subsurface seismic although upscaling problems are a recurring issue the homogeneity of the samples and the continuity of the outcrop and facies reduce the number of uncertainties acoustic properties are generally controlled by the amount and type of pore spaces due to the low porosities the ramp geometry is characterized by an overall lateral homogeneity and vertical heterogeneity textural sedimentological and stratigraphic transitions in the outcrop are related to the defined facies each has its own unique mineralogical signature amplitude variations in the synthetic seismic profile are primarily caused by changes in mineral composition thus facies transitions

offshore evidence of polyphase erosion in the valencia basin northwestern mediterranean scenario for the messinian salinity crisis the messinian salinity crisis at the end of the miocene strongly affected the physiography of the mediterranean margins and in particular that of the valencia basin and its margins the valencia basin which is an aborted tertiary rift related to the opening of the oceanic provencal basin shows evidence of two major messinian erosion surfaces a basal erosion surface bes and a top erosion surface tes bracketing the messinian evaporite succession the basin s margins show only a single erosion surface here termed the margins erosion surface mes in examining the geometrical relationships of these erosion surfaces with the deep basin facies deposited in the abyssal provencal basin during the messinian salinity crisis we have been able to establish a chronology for the messinian in the valencia basin briefly the basal erosion surface extends the margins erosion surface into the central valencia basin and records an early and important sea level fall at the beginning of the messinian salinity crisis the miocene basin series were incised by canyons while the exposed margins underwent substantial subaerial erosion the basin s detrital products linked to this basal erosion grade laterally into the massive messinian salt layer of the provencal basin the overlying upper evaporites unit appears to be widely transgressive beyond the edge of the messinian salt and onlaps the basal erosion surface in the valencia basin this disposition suggests a progressive sea level rise during the deposition of the upper evaporites possibly due to the rapid accumulation of thousands of metres of shallow water evaporite facies in the provencal basin the top erosion surface at the top of the upper evaporites shows a network of incisions and we suggest that this final erosion was

elastic properties of continental carbonates from controlling factors to an applicable model for acoustic velocity predictions we have provided new insights into the controlling factors of elastic properties in continental carbonate rocks and introduced an applicable model for acoustic velocity predictions in such a medium petrophysical properties porosity permeability p and s wave velocities from laboratory measurements have been coupled with thin section observations and characterizations and x ray diffraction xrd analyses a major achievement is the establishment of the link between the mineralogical composition and the p and s wave velocity dispersion at a given porosity this reflects the subtle interplay between physico chemical and biological precipitation of continental carbonates which can also be associated with a strong influence of detrital mineralogical inputs the result is a mineralogical commixture coupled to a wide array of pore types inherited from the strong ability of carbonate rocks to undergo diagenetic alteration the proposed model takes into account the elastic moduli of the minerals porosity and pore shape and it is based on the effective medium theory we have considered the case in which the medium contained randomly oriented pores with different aspect ratios overall the fit between the predicted trends and the experimental data is fairly good especially for calcite and quartz matrix mineralogy the results are even better when considering mineralogy inferred from xrd data although in some case and despite the aspect ratio variation in both simulations the model fails to accurately predict the p wave velocities this probably means that another factor is at stake beside mineralogy this can be explained by the limitation of the effective medium approach which oversimplifies the reality and fails to account for the variability of some aspect ratio from one inclusion to another

post messinian evolution of the florence ridge area western cyprus arc part i morphostructural analysis abstract the florence ridge part of the western cyprus arc is a compressional relief that was eroded during the messinian salinity crisis while deposition of salt occurred north antalya basin and south herodotus abyssal plain in order to better assess the impact of salt tectonics in the florence ridge region deformations we conducted a morpho structural analysis of available multibeam and seismic data simed and prismed ii campaigns it is indeed a crucial issue to distinguish crustal and gravity driven structures in the compressional to strike slip belts of the eastern mediterranean along the antalya basin we mainly observed multi directional tectonic rafts typical of gravity gliding above salt on the florence ridge itself the base of salt evolves laterally to a messinian erosional surface that erodes a series of stacked nappes this surface is involved in recent faulting south of the florence ridge a nearly 100 km wide fold belt characterizes the herodotus abyssal plain three different zones parallel to the florence ridge appear within this fold belt those are respectively from north to south zones a b and c zone a is characterized mainly by small wavelength folding and faulting approaching zone b a long extensional graben deforms the seafloor zone b stands 100 to 200 m higher than zones a and c there salt welding seems common in the easternmost zone b deep sub circular bathymetric depressions are associated with extremely thick and fan shaped depocenters probably emplaced in relation with active sub salt thrusts many evidences suggest post messinian uplift in this zone zone c shows medium to high wavelength salt cored folds wavelength of those folds increase approaching the distal nile deep sea fan within zone c a nearly undeformed domain exists approaching the eratosthenes seamount en echelon folds bound this flat domain suggesting lateral salt extrusion at the junction between zone c and the distal nile deep sea fan to conclude numerous evidences argue for a post messinian reactivation of the pre messinian florence ridge accretionary wedge numerous folds uplifted zones the salt as on the nearby mediterranean ridge decouples deep and surface deformations and even allow the development of isolated grabens and associated salt ridges in the heart of the florence compressional zone we propose in this case that local basal slope of salt increase related to basement fault activity triggered gravity gliding and thus extensional deformation despite the regional compressional regime finally this study shows that the eastern nile deep sea fan submitted to extremely vigorous salt tectonics seems to have collided with the florence ridge fold belt and to have generated a salt extrusion zone

acoustic properties of carbonates effects of rock texture and implications for fluid substitution more than 250 plugs from outcrops and three nearby boreholes in an undisturbed reef of miocene tortonian age were quantitatively analyzed for texture mineralogy and acoustic properties we measured the p and s waves of carbonate rocks under dry humidified and brine saturated conditions at 10 mpa effective pressure with an ultrasonic pulse transmission technique 1 mhz the data set was compared with an extensive database of petrophysical measurements of a variety of rock types encountered in carbonate sedimentary sequences two major textural groups were distinguished on the basis of trends in plots of compressional wave velocity versus poisson s ratio a specific ratio of p wave over s wave velocity in granular rocks the framework of depositional grains is the main medium for acoustic wave propagation in crystalline rocks this medium is provided by a framework of interlocking crystals formed during diagenesis rock textures are connected to primary depositionalparameters and a diagenetic ov

longitudinal variation of f region electron density and thermospheric zonal wind caused by atmospheric tides 1 simultaneous observations of the electron density and the zonal wind obtained by the champ satellite at 400 km are used to study systematic longitudinal variations the time period selected is august september 2004 allowing observations at pre noon and post sunset hours the equatorial ionization anomaly eia and the zonal delta wind deviation from zonal average show a persistent and dominant 4 peaked longitudinal variation we interpret this structure as caused by the wavenumber 3 nonmigrating diurnal tide de3 the eia and the zonal delta wind exhibit extrema at about the same longitudes but while the intensifications of the eia and the delta wind are in phase during the evening hours they are out of phase in the morning possible coupling mechanisms are investigated

heterogeneities and diagenetic control on the spatial distribution of carbonate rocks acoustic properties at the outcrop scale abstract carbonate rocks are characterized by a high heterogeneity of their properties at the outcrop scale that results from complex interactions between sedimentary diagenetic and fracturing processes here we show acoustic p wave velocity measurements conducted step by step on three decameter scale outcrop surfaces in cretaceous carbonate rocks with contrasted heterogeneities two shallow water highly fractured cassis and low fractured calissanne carbonates and one basin highly compacted grignantes p wave measurements were compared to outcrop geology and with plug porosity p wave velocity laboratory measurements and a thin section study results show a strong scale dependence of p wave velocities which always are lower at the decimeter scale than at the plug scale vp in situ versus vp plug large discrepancies 2000 m s highlight the signature of large heterogeneities open fractures stylolithes and lower discrepancies in situ distribution follows the dip of the ripple foresets which are controlling grain sorting and porosity in calissanne outcrop the near isotropic vp are explained by an early intense fracturing and cementation in cassis outcrop and the strong horizontal anisotropy with a hole effect behavior on variograms highlights the late re opening of multiple intervals of compaction bands in grignantes these results illustrate that the early diagenesis coupled to fracture or stylolithe reactivation opening are two key processes that explain the outcrop scale p wave velocity distribution anisotropy in carbonates

using salt tectonic structures as proxies to reveal post rift crustal tectonics the example of the eastern sardinian margin western tyrrhenian sea abstract the metyss project messinian event in the tyrrhenian from seismic study is based on high resolution seismic data acquired along the eastern sardinian margin western tyrrhenian sea the main aim is to study the messinian salinity crisis msc in the western tyrrhenian basin but we also investigated the thinning processes of the continental crust and the timing of crustal vertical movements across this backarc domain our first results shown that rifting ended before the msc but that crustal activity persisted long after the end of the rifting this has been particularly observed on the proximal margin the east sardinia basin where the mobile unit mu mobile messinian salt is thin or absent in this study we examined the distal margin the cornaglia terrace where the mu accumulated during the msc and acted as a decollement thus potentially decoupling the basement from the sedimentary cover our observations provide evidence for lateral flow and gravity gliding of the salt and its brittle sedimentary overburden along local basement slopes generated by the post msc tilting of some basement blocks formerly generated during the rifting we also investigated an intriguing wedge shaped body of mu located in a narrow n s half graben bounded to the west by a major east dipping crustal normal fault classically one could think that this salt wedge is related to the syn tectonics deposition of the mu but we propose an original scenario in which the post rift vertical motion of the major fault has been cushioned by lateral flow of an initially tabular salt layer leaving the supra salt series apparently unaffected by the crustal motions of the basement we tested this scenario by comparing natural data and physical analogue modelling data our results reveal that salt tectonics provides a powerful tool to understand the deep crustal tectonics of the margin and to constrain the timing of vertical motions in the western tyrrhenian basin results that can be applied to rifted salt bearing margins worldwide

salt tectonics driven by sediment progradation part ii radial spreading of sedimentary lobes prograding above salt experimental models indicate that sedimentary lobes deposited above mobile evaporites deform gravitationally by spreading outward radially radial spreading forms both concentric and radial families of thin skinned grabens that are then pierced diapirically by salt ridges the overburden blocks located between the ridges become subsiding depocenters later continued spreading after depletion of the salt layer forces salt ridges and diapirs to fall forming rapidly subsiding bathymetric lows that channel or trap younger sediments spreading causes large horizontal overburden movements whose distribution and orientation change when the locus of regional deposition shifts

active tectonics of the adriatic region from gps and earthquake slip vectors 1 to investigate the kinematics of the adriatic region we integrate continuous and episodic gps measurements with mw 4 5 earthquake slip vectors selected from the regional centroid moment tensor catalogue coherent motion of gps sites in the po valley in apulia and in the hyblean plateau allows us to estimate geodetically constrained angular velocities for these regions the predictions of the gps inferred angular velocities are compared with the earthquake slip vectors showing that the seismically expressed deformation at the microplate boundaries is consistent with the observed geodetic motion the remarkable consistency between geodetic seismological and geological evidence of active tectonics suggests that active deformation in the central adriatic is controlled by the relative motion between the adria and apulia microplates the microplates angular rotation rates are then compared with the rotation rates calculated with a simple block model supporting the hypotheses 1 that apulia forms a single microplate with the ionian sea and possibly with the hyblean region and 2 that adria and apulia rotate in such a way as to accommodate the eurasia nubia relative motion we suggest that the present day microplate configuration follows a recent fragmentation of the adriatic promontory that during the neogene rigidly transferred the africa motion to the orogenic belts that now surround the adriatic region

microstructures and physical properties in carbonate rocks a comprehensive review abstract carbonate rocks are well known to be tremendously heterogeneous they mainly consist of component particles from biological and non biological origin embedded in a lime mud matrix and or in a cement composed of even smaller particles the size shape density and spatial arrangement of those particles alongside with natural fractures and cracks although those are certainly not exclusive to carbonate rocks define a microstructural pattern that is known to have a great influence on rock physical properties thus to understand carbonate rock systems at large scales formation reservoir geophysicists have to study them at the pore scale hoping to resolve the so called upscalling problem with this in mind unravelling and identifying the relations between physical properties and carbonate rock microstructures is paramount for a global comprehension of a carbonate rock system since the late nineties several research groups and authors have worked on documenting and providing significant insights into the microstructural parameters controlling the physical response of several rock properties porosity permeability electrical conductivity elastic seismic and mechanical properties in carbonates this article proposes a review of this specialized literature from the early and recent contributions in rock physics with emphasis on the recent studies on carbonate rocks from the paris basin

large scale boudinage of late miocene platform series triggered by margin collapse during the messinian salinity crisis ibiza island spain abstract in ibiza island we show for the first time that the post tectonic late miocene deposits are locally deformed in synsedimentary large scale boudinage structures the late miocene series is composed of a carbonate rich unit 1 that is overlaid by a clastic unit 2 and a unit 3 in which a basal oolite rich deposit is distinguished from an upper stromatolite rich part the oolite rich and competent layers of unit 3 are dissected into large rectangular to barrel shape boudins that indicate a multidirectional extension the separation of the blocks develops significantly northward revealing a stretching increase in a seaward direction that could have been favored by sliding of the distal part of the underlying marly unit over the clays along and in between the boudins the laminated layers form soft sediment syncline folds the progressive bending of these laminated layers created spaces that were filled with calcite crystal wedges providing evidence for large fluid circulation during deformation microthermometry on fluid inclusions in these calcite crystals revealed growth temperatures ranging from 190 to 260 c this high recrystallization rate is an indication of important fluid circulation during deformation processes besides the progressive infill of paleosols over some of the synsedimentary synclines indicates that deformation was a slow process during the emersion of the series and the subaerial messinian channels location in the topographic depressions formed by the boudinage of the late miocene series confirms that the deformation and sliding occurred during the relative emersion associated with the messinian salinity crisis we thus interpret the boudinage as resulting from the destabilization of a still soft carbonate platform whose sliding has been helped substantially by the injection of relatively hot fluids this work provides an onland evidence for extensional collapse during the messinian sea level drawdown

odp leg 107 in the tyrrhenian sea insights into passive margin and back arc basin evolution leg 107 of the ocean drilling program drilled a west northwest east southeast transect of seven sites across the tyrrhenian sea the youngest of the sub basins of the mediterranean sea sites 654 653 652 and 656 document the rifting and subsidence of the sardinia passive continental margin on the upper margin site 654 we cored a classic transgressive sequence subaerial conglomerates overlain by oyster bearing sands overlain by marine marl comparison between the recovered lithologies and seismic reflection profiles suggests that the synrift sediments on the upper margin are tortonian late miocene to messinian latest miocene in age whereas synrift sediments on the lower margin are messinian to pliocene in age during the messinian desiccation of the mediterranean sites 654 and 653 now on the upper sardinian margin apparently occupied a basinal setting where they received nannoplankton bearing clays interbedded with laminated gypsum sites 656 and 652 now on the lower sardinia margin were apparently higher standing during the desiccation event their messinian facies are subaerial and lacustrine respectively we infer from these lines of evidence that tilting and subsidence occurred more than a million years earlier on the upper margin than on the lower margin such diachroneity can be interpreted in terms of migration of the zone of maximum extension above a rolling back subduction zone or in terms of extension of continental crust by shear along a deep detachment fault sites 655 651 and 650 were drilled into two small basalt floored basins of the central and eastern tyrrhenian emplacement of basaltic crust in the central tyrrhenian vavilov basin apparently began more than a million years before emplacement of basaltic crust in the eastern tyrrhenian marsili basin this observation is compatible with previous suggestions that the tyrrhenian has grown southeastward in response to rollback of the down going slab that currently dips northwestward under the toe of italy at the easternmost site high vesicularity of the basalt and benthic foram assemblages in the oldest sediments imply that the basalt erupted in water shallower than 2 500 m it has apparently subsequently subsided to its present depth of 4 100 m below sea level nearly three times as fast as normal subsidence of crust formed at a mid ocean ridge

experiment study of pore structure effects on velocities in synthetic carbonate rocks abstractcarbonate rocks have a complex pore structure show strong heterogeneity and have a wide range of velocities that lead to more complicated velocity porosity relationships compared with sandstones we designed and prepared 72 carbonate synthetic cores with known pore structures according to the control variate principle we measured the p and s wave velocities of these cores by an ultrasonic pulse transmission method analyzed the effects of the pore aspect ratio ar and pore size d on velocities and compared the experimental results with predictions of effective medium theories emts the matrix of our synthetic cores was consolidated mixture of carbonate cuttings and epoxy we randomly imbedded predesigned penny shaped silicone disks or expandable polystyrene balls into the matrix during the core preparation process to simulate secondary pores the experimental results indicated that han s empirical linear velocity porosity relation was a good prediction for cores with only interparticle por

simulated equinoctial asymmetry of the ionospheric vertical plasma drifts 1 this paper studies the influence of the lower thermospheric tidal winds below 105 km on the equinoctial asymmetry of the equatorial vertical e b plasma drifts v using theoretical ionospheric dynamo model ii of the institute of geology and geophysics chinese academy of sciences tidm iggcas ii and tidal winds below 105 km from thermosphere ionosphere mesosphere energetics dynamics satellite doppler interferometer tidi observations although a series of other nonmigrating tides also affect the v asymmetry the simulated equinoctial asymmetry in v are mainly driven by the migrating diurnal tide dw1 migrating semidiurnal tide sw2 de3 and dw2 nonmigrating tides the asymmetry in daytime v varies with local time and longitude and mainly shows three features first the simulated daytime v during the march equinox is larger than that during the september equinox in most of longitudinal sectors this asymmetry is mainly driven by the semiannual oscillation sao of the migrating diurnal tide in the tropical mesosphere lower thermosphere mlt region and the equinoctial asymmetry of the migrating semidiurnal tide also plays an important role in the generation of this asymmetry second the daytime v asymmetry in the eastern hemisphere is more significant than that in the western hemisphere our simulation suggests that the longitudinal variations of the geomagnetic fields and dw2 tides play important roles in the generation of this hemisphere difference third there is an obvious wave number 4 longitudinal structure in the v asymmetry our simulation suggests that this wave number 4 structure is mainly driven by the equinoctial asymmetry of the de3 tide

the equivalent pore aspect ratio as a tool for pore type prediction in carbonate reservoirs the equivalent pore aspect ratio provides a tool to detect pore types by combining compressional and shear wave velocities porosity bulk density and mineralogical composition of carbonate rocks the integration of laboratory measurements well logs and petrographic analysis of carbonate rocks from various depositional and diagenetic settings lower cretaceous presalt nonmarine carbonates from offshore brazil lower cretaceous shallow water platform carbonates from southeast france and upper cretaceous deep water carbonate from the gargano peninsula italy allowed the acoustic signature of a wide range of pore types to be quantified the equivalent pore aspect ratios are shown to be independent of pore volume and mineralogy they can therefore be regarded as relevant parameters for discriminating selected pore network architectures in carbonate reservoirs interparticle and intercrystalline microporosity and macroporosity may include a variety of distinct pore network structures and a wide range of acoustic signatures depending on particle shape nature of contacts packing and cementation intergranular macroporosity in a densely packed granular sediment secondary pseudofenestral etc the acoustic response of moldic pores appears to be mainly controlled by the shape of the dissolved allochems the present work reveals also that correct pore type detection from acoustic and porosity measurements is highly dependent on the pore type classification used a selection of petrographic and diagenetic features to be considered for the construction of a suitable pore type classification is proposed to improve the detection of the pore type effect on the acoustic properties of carbonate reservoirs at plug and well log scale

active thrust faulting offshore boumerdes algeria and its relations to the 2003 mw 6 9 earthquake 1 we investigate the active seismogenic fault system in the area of the 2003 mw 6 9 boumerdes earthquake algeria from a high resolution swath bathymetry and seismic survey a series of 5 main fault propagation folds 20 35 km long leave prominent cumulative escarpments on the steep slope and in the deep basin fault activity creates plio quaternary growth strata within uplifted areas such as a rollover basin on the slope and piggyback basins in the deep ocean most thrusts turn to fault propagation folds at the sub surface and depict ramp flat trajectories we find that the two main slip patches of the 2003 mw 6 9 boumerdes earthquake are spatially correlated to two segmented cumulative scarps recognized on the slope and at the foot of the margin the overall geometry indicates the predominance of back thrusts implying underthrusting of the neogene oceanic crust

global structure and seasonal and interannual variability of the migrating diurnal tide seen in the saber timed temperatures between 20 and 120 km 1 the present paper is focused on the global spatial altitude and latitude structure and seasonal and interannual variability of the migrating diurnal tide derived from the sounding of the atmosphere using broadband emission radiometry thermosphere ionosphere mesosphere energetics and dynamics saber timed temperature measurements for 6 full years january 2002 to december 2007 the tidal results are obtained by a new analysis method where the tides migrating and nonmigrating and the planetary waves zonally traveling and stationary are simultaneously extracted from the satellite data it has been found that above 70 km height the saber migrating diurnal tide reflects mainly the distinctive features of the first symmetric propagating 1 1 mode while below this height it reflects the features of the first symmetric trapped 1 2 mode the trapped component amplifies near 50 km and its phase is close to 1600 lt the seasonal behavior of the diurnal tide over the equator is dominated by semiannual variation with a primary maximum in february march 18 k average amplitude for 6 years and a secondary maximum in august september 15 k the tidal amplitude grows rapidly in the mesosphere lower thermosphere however it undergoes some decay near 90 km defining ubiquitous double peaked vertical structure a very rapid reduction in amplitude is detected at heights near 115 km however above this level the diurnal tide amplifies again the vertical wavelength of the propagating diurnal tide is 20 km over the equator at middle latitudes it is not very different from that over the equator but its magnitude depends on the season in the winter it is longer than that in summer the interannual variability of the diurnal tide indicates a clear correlation with the stratospheric quasi biennial oscillation

new imaging of the salinity crisis dual messinian lowstand megasequences recorded in the deep basin of both the eastern and western mediterranean through several examples we show that following sea level fall and marginal erosion during the messinian salinity crisis msc clastic inputs into the eastern and western mediterranean sea are not distributed evenly in space and time but are mainly limited to the lower section of the messinian salinity crisis depositional megasequence significant similarities around the basin allow us to propose a mediterranean messinian salinity crisis depositional episode that can be divided into two seismic megasequences the messinian lower megasequence mlm and the messinian upper megasequence mum their distinctive seismic facies correspond to systems tracts deposited during three main stages that represent a complete sea level cycle 1 a falling stage systems tract including mass transport deposits and forced regressive clinoforms deposited in in the early part of the falling stage and related to the increasing rate of relative sea level fall this stage is characterized by a marked shift in the depocenter towards the deep basins 2 an early lowstand characterized by massive clastic inputs from major messinian rivers the rhone nile and antalya gulf rivers or smaller river systems offshore south lebanon these clastics were deposited in an oversaturated basin as evidenced by the interfingering chaotic and transparent seismic facies of the messinian lower megasequence mlm 3 a late lowstand starting with rapid deposition of massive halite with no detrital inputs into the deep basin the upper part of the evaporites clearly onlaps the messinian erosional surface at the margins and is evidence for a transition between a late lowstand stage and an early transgressive stage these deposits belong to the messinian upper megasequence mum we interpret the transition between the two megasequences as the peak of the salinity crisis the end of the relative sea level fall and the maximum dispersal of sands into the deep mediterranean basins

european mediterranean regional centroid moment tensor catalog solutions for years 2001 and 2002 abstract we present regional centroid moment tensor rcmt solutions for 168 moderate magnitude earthquakes that occurred in the european mediterranean region during 2001 and 2002 events with moment magnitudes as low as 4 0 were successfully analyzed although this low threshold is only achievable in regions with the best azimuthal coverage and with stations at a few hundred kilometers distance earthquakes with focal depths from 10 to more than 200 km were analyzed comparison with standard harvard cmts when available shows good agreement the solutions shown in this paper represent an addition to the european mediterranean rcmt catalog that we are maintaining the rcmt catalog now spans 6 years from 1997 to 2002 and contains 420 solutions we also outline the main seismic sequences that occurred in the european mediterranean region during 2001 2002

crustal shear s velocity and poisson s ratio structure along the indepth iv profile in northeast tibet as derived from wide angle seismic data summary from the s wave data collected along a 270 km long profile spanning the kunlun mountains in ne tibet 14595 sg phase arrivals and 21 sms phase arrivals were utilized to derive a whole crustal s velocity model and together with a previously derived p velocity model a poisson s ratio model beneath the profile the final tomogram for the upper 10 15 km of the crust reveals the lower velocities associated with the predominantly neogene quaternary sediments of the qaidam basin to the north and the higher velocities associated with the predominantly palaeozoic and mesozoic upper crustal sequences of the songpan ganzi terrane and kunlun mountains to the south this study finds no evidence that the kunlun mountains are involved in large scale northward overriding of the qaidam basin along a shallow south dipping thrust the in the upper 10 15 km of the crust are often lower than 0 25 indicating a preponderance of quartz rich rocks in the upper crust beneath the profile below 10 15 km depth the remainder of the crust down to the moho has an average of 0 24 beneath the songpan ganzi terrane and kunlun mountains and 0 25 below the qaidam basin these low are similar to other low found along other profiles in the northeastern part of the plateau assuming an isotropic situation and no significant variation in between 10 15 km depth and the moho then the lower crust between 25 30 km depth below sea level and the moho with p velocities varying from 6 6 km s 1 at the top to around 6 9 km s 1 at the base and of 0 24 0 25 should comprise intermediate granulites in the upper part transitioning to granulite facies metapelites in the lower part as the pre cenozoic qaidam basin crust has probably not lost any of its lower crust during the present himalayan orogenic cycle in the cenozoic and only has a of 0 245 0 25 then it appears that the pre cenozoic qaidam basin crust involved in the collision is more felsic and thus weaker and more easily deformable than normal continental crust with a global average of 0 265 0 27 and the tarim and sichuan basin crusts this situation then probably facilitates the collision and promotes the formation of new high plateau crust at the ne margin of tibet south of the qaidam basin the crust of the songpan ganzi terrane and kunlun mountains has an even lower average crustal of 0 23 0 24 and is thus presumably even weaker and more easily deformable than the crust beneath the qaidam basin this then supports the hypothesis of karplus et al that the high tibetan plateau may be thickening northward into south qaidam as its weak thickened lower crust is injected beneath stronger qaidam crust

seismic markers of the messinian salinity crisis in an intermediate depth basin data for understanding the neogene evolution of the corsica basin northern tyrrhenian sea the messinian salinity crisis msc which widely affected the whole mediterranean basin induced rapid and spectacular palaeoenvironmental changes it led to a major erosion of the onshore areas and the upper parts of the continental shelves and slopes as well as important evaporitic deposits in the offshore deep basins the corsica basin belongs to the so called intermediate depth basin type because of its location between the coastal plain shelf area of east corsica and deeper marine basins in the northern tyrrhenian sea the msc event took place in the corsica basin during a period of active regional tectonics contemporaneous with the opening of the tyrrhenian sea as well as during the development of the corsica basin and the elba pianosa ridge based on the interpretation of high resolution seismic reflection profiles and a new 1 250 000 scale synthetic geological map we establish that the msc is recorded in the corsica basin through the occurrence of two sedimentary formations bounded by three remarkable surfaces these seismic markers suggest local and temporal variations in relative water level and associated depositional environments that differ between the north and south of the corsica basin during the msc the northern sector golo basin was emerged whereas the southern sector orbo basin was often flooded or submerged in the orbo basin the deposits record both an episode of intra msc climate change and regional tectonic events during the msc the corsica basin was a perched lake isolated from the deeper tyrrhenian basins the connection with the tyrrhenian basins was re established during the final stages of the msc before the catastrophic pliocene reflooding initiated by retrogressive erosion during a relative lowstand an extensive network of incised valleys was thus established in the orbo basin allowing the drainage of the corsica basin southwards into the deeper tyrrhenian basins these markers record the active regional tectonic context throughout the msc the orbo basin was strongly subsident along its western rim while its eastern rim was uplifted in turn the golo basin subsided from middle pliocene times onwards while the northern eastern and southern edges of the corsica basin were deformed and uplifted

nonmigrating diurnal tides in the thermosphere 1 horizontal wind measurements from the hrdi and windii instruments on the upper atmosphere research satellite are analyzed to reveal the most prominent nonmigrating diurnal tidal components at 95 km the eastward propagating diurnal tide with zonal wave number s 3 de3 the standing s 0 diurnal oscillation d0 and the westward propagating diurnal tide with s 2 dw2 the strongest de3 occurs primarily during northern hemisphere summer fall with maximum eastward winds near the equator of order 15 ms 1 and is a vertical extension of the s 3 kelvin wave the first antisymmetric mode of de3 dominates during october april with maximum meridional winds near the equator of order 8 ms 1 d0 exists during nearly all months and is nonsymmetric about the equator with maximum northward wind amplitudes in the southern hemisphere of order 7 10 ms 1 dw2 closely resembles the first symmetric propagating mode from classical tidal theory with maximum northward wind amplitudes of order 10 12 ms 1 during september through february the combination of de3 d0 and dw2 with dw1 gives rise to significant longitude variations in the diurnal tide between 40 latitude forcing in the global scale wave model gswm is calibrated according to the above observations thus enabling global estimates of nonmigrating tidal temperatures and other fields for instance it is estimated that the temperature and eastward wind perturbations associated with de3 may be as large as 20k and 35 ms 1 at 145 km and 115 km respectively over the equatorial region during july

effect of atmospheric tides on the morphology of the quiet time postsunset equatorial ionospheric anomaly longitudinal wave number four pattern in the magnetic latitude and concentration of the f region peak ion density when measured at a fixed local time in a new comparison of two data sets with observations made by the ogo 4 satellite this pattern is seen to be persistent over many days around equinox during magnetically quiet conditions close to solar maximum but can be dominated by other processes such as cross equator winds during other periods it is found that the longitudinal variability is created by a processes occurring in the dayside ionosphere a longitudinal modulation of the dayside equatorial fountainisthemostlikelydrivingmechanism throughcomparisonwithgwsm 02model it isshownthatthepredictedmodulationofthedaysidethermosphericwindsandtemperaturesat e region altitudes created by non migrating diurnal tides can explain the modulation in the dayside equatorial fountain this result highlights the importance of understanding the temporal variability of tropospheric weather systems on our understanding and possible predictability of the development of the f region ionosphere it may also provide a possible further means of testing our understanding of atmospheric tides on a global scale

strong evidence for the tidal control on the longitudinal structure of the ionospheric f region this paper presents for the first time the global latitude structure and seasonal variability of the ionospheric response to the forced from below de3 and de2 tides during the period of time january 2008 march 2009 the cosmic hmf2 and saber temperature data have been utilized in order to define the ionospheric de3 and de2 tidal response to the de3 and de2 temperature tides propagating from below the cosmic de3 and de2 hmf2 tidal oscillations are derived by the same method as the tides seen the saber temperatures it has been shown that the longitude wave 4 and wave 3 hmf2 structures observed respectively in september and may 2008 are forced mainly by de3 wave 4 and de2 wave 3 temperature tides coming from below the longitude wave 3 hmf2 structure observed in january 2008 however is forced by the combined action of the de2 temperature tide coming from below and the spw3 probably generated in situ

spacing of consecutive normal faulting in the lithosphere a dynamic model for rift axis jumping tyrrhenian sea we propose that the flexure of a broken elastic plate can determine the spacing of consecutive and localized zones of shearing on a lithospheric scale the model provides a dynamic explanation for rift axis migration and as a consequence for a wide rift mode of extension calculated values for rift axis shifting are consistent with the available observations and kinematic modelling results in the tyrrhenian basin the quantitative relation obtained between lithospheric fault spacing and the effective elastic thickness t of the lithosphere can be used in an inverse modelling approach in which paleo t e e values are calculated for a basin where the diachronous and spaced nature of rifting is known

messinian salinity crisis deposits widespread over the balearic promontory insights from new high resolution seismic data abstract the current interpretation of the messinian salinity crisis msc involves the deposition of peripheral or marginal evaporites in onshore basins as well as the erosion of the margin and the deposition of thick evaporites in deep basins the so called intermediate basins are formed in domains between the onland outcrops and the deep basins the balearic promontory is a bathymetric high located between the deep algerian and liguro provencal basins and the onland spanish basin the simbad project aims to investigate the spatial variability of the msc related deposits and to assess the extent of post msc reactivation over the balearic promontory we present here the first results of the simbad high resolution seismic survey january 2013 which imaged for the first time a thin msc related unit widely distributed in small sub basins over the balearic promontory borehole analyses have shown that this unit could be correlated with primary gypsum formations linked to the peripheral evaporites locally in the central depression between mallorca and ibiza islands a thicker msc unit is observed whose lowermost transparent part could correspond to a salt layer geometrical relationships suggest that the msc in the central depression could postdate the primary gypsum the occurrence of a halite layer in the central depression at depths of 1000 to 1500 m favours the hypothesis that the evaporites precipitated passively in closed or partially closed perched sub basins possibly as a result of evaporative drawdown at different depths and possibly diachronously at least with respect to the deep basin evaporites

on the post 25 ma geodynamic evolution of the western mediterranean during the neogene and quaternary western mediterranean geodynamics were dominated by the eastward migration of the apenninic arc and associated back arc basins the migration was controlled by retreat of the apenninic slab and was associated with boudinage of the lithosphere in the back arc area palaeo reconstruction of the kinematics of the arc suggests about 775 km of migration from the late oligocene to present along a transect from the gulf of lions to calabria a maximum of 135 km of n s converge occurred between africa and europe during the same time span the western mediterranean was thus mainly shaped by the migration of the slab related to west directed subduction it is hypothesized that minor n s convergence deformed the arc but was not the cause of its formation 1998 elsevier science b v all rights reserved

global distribution and interannual variations of mesospheric and lower thermospheric neutral wind diurnal tide 1 migrating tide 1 using the timed doppler interferometer tidi mesospheric and lower thermospheric neutral wind multiyear data set 2002 2007 and ncar time general circulation models gcm 1 2 annual run results 2002 2005 at the tidi sampling points we study the migrating diurnal tide s global distribution interannual and seasonal variations in connection with the mean zonal wind interannual variations a strong quasi biennial oscillation qbo effect on the diurnal tide was observed in the tidi data and reproduced to a lesser degree in the time gcm run the migrating diurnal tide amplitude is larger during the eastward phase of the stratospheric qbo and weaker during the westward phase westward mesospheric equatorial mean zonal winds appeared during the eastward phase of the stratospheric qbo in 2002 2004 and 2006 the strongest qbo effect on both the migrating diurnal tide and mean zonal winds was observed during the march equinox the stronger tides may be related to the weaker gravity wave filtering in the stratosphere during the eastward phase stratospheric qbo the tidi data also exhibit large interhemispheric asymmetry the westward mean zonal winds in the mesosphere appeared to be associated with the enhanced diurnal tide the time gcm 1 2 diurnal tide amplitudes are in general smaller than those observed by the tidi instrument limited vertical spatial resolution for the time cgm 1 2 is suggested as the cause future improvements are expected with a higher spatial resolution in the model