numerical forward modelling of fluxoturbidite flume experiments using sedsim abstract delta front fluxoturbidity deposits in rift basin margins as well as sand avalanches are influenced by topography water level fluctuation and wave action instability of prior sediments deposited on the delta front is a prerequisite for the generation of fluxoturbidity in this study sedsim a three dimensional numerical stratigraphic forward model is used to replicate and extend a set of physical flume tank experiments investigating the formation of fluxoturbidites from different initial conditions this study has investigated the influence of topographic slope relative water level change and wave action on the formation of fluxoturbidites and hopefully improves our understanding and insight into the dynamic processes of fluxoturbidity resulting from different initiation mechanisms the study also illustrates the value of numerical modelling in complementing and extending physical flume tank studies we show that at least at the scale of a flume tank there exists an optimum window of topographic slopes within which fluxoturbidites arise due to slumping this window ranging from 9 to 18 may be useful in distinguishing the effects of topographic slope from other fluxoturbidite causal mechanisms the amplitude and frequency of water level oscillation appears to be a significant control on fluxoturbidite thickness while wave attributes especially wave angles appear to affect fluxoturbidite locality relative to the sediment source

erratum to observation and prediction of dynamic ground strains tilts and torsions caused by the mw 6 0 2004 parkfield california earthquake and aftershocks derived from upsar array observations online material corrected figures and strain rotation and displacement gradient time series

3d architecture of lowstand and transgressive quaternary sand bodies on the outer shelf of the gulf of lion france abstract a restricted area 700 km 2 of the outer continental shelf in the gulf of lions western mediterranean sea has been surveyed in detail in order to reconstruct the 3d architecture of large quaternary sand bodies that are exceptionally well preserved in the western part of the rho ne delta data sources include digital very high resolution seismic swath bathymetry and some shallow cores in two dimensions the seismic data display a complex superposition of alternating seismic units consisting of high and low angle prograding clinoforms corresponding to high and low energy environments the combination of faunal and grain size analysis from shallow cores geometry of sedimentary bodies showed that these two types of seismic facies can be attributed respectively to upper shoreface and prodelta c settings despite a similar geometry in 2d it appears that the prograding sand units have very different 3d geometries lateral extent direction of progradation with respect to the paleoshorelines implying different sedimentary processes at least two major sand units have shore parallel orientations and can be mapped along the entire study area the mechanism responsible for the formation of these sand bodies seems similar to that described for many sharp based sand bodies from the stratigraphic record especially in the western interior seaway their isolated position on the shelf being related to forced regressions in contrast some other sand units have lobate shapes with divergent directions of progradation and limited lateral extent they are often overlying fluvial incisions and they pinch out landward it is still not clear whether they are related to some allocyclic or autocyclic processes like shifting of delta c lobes as observed on the texas coast the very high resolution and high quality of the seismic data have enabled us to characterise the three dimensional architecture of small scale sedimentary bodies the study has pointed out the variability of depositional processes and has given an insight on reservoir characteristics 1998 elsevier science ltd all rights reserved

source complexity of the 6 april 2009 l aquila central italy earthquake and its strongest aftershock revealed by elementary seismological analysis 1 seismic recordings are immediately available when an earthquake occurs their analysis allows the reconstruction of the rupture dynamics by means of sophisticated techniques which usually need some tests to provide robust results however immediate information on the source kinematics is required in order to imagine the fault location and extent and quickly reconstruct the areas of stress release and subsequent accumulation very simple analysis may provide useful information giving insight in source complexity right after the 6 april 2009 l aquila earthquake mw 6 3 we analyzed the seismograms recorded at broadband and strong motion stations and provided firm constraints on rupture kinematics slip distribution and static surface deformation also discriminating the actual fault plane the fracture occurred in two stages with initial updip propagation successively proceeding toward se possibly on a different plane we also analyzed the strongest aftershock mw 5 6 showing that useful indications could be retrieved for lower magnitude events

finite fault inversion of dinsar coseismic displacement of the 2009 l aquila earthquake central italy 1 we define the geometric and kinematic characteristics of the fault activated during the mw 6 3 6 april 2009 l aquila earthquake from the modeling of envisat and cosmo skymed the first ever x band interferogram inverted for a coseismic dislocation study dinsar interferograms our best fit solution for the main shock is represented by a normal fault 16 km long and 12 km wide with a small right lateral component dipping 47 sw with a maximum slip of 90 cm although the seismic dislocation probably ended at 1 km depth the updip projection of the fault plane corresponds to the northern segment of the mapped paganica s demetrio fault where alignment of surface breaks was observed in the field the absence of this fault in existing seismic source catalogues suggests that an improved approach involving detailed surface and subsurface geological and geophysical investigations is needed for a better assessment of the seismic hazard at the local scale

modelling facies belt distribution in fan deltas coupling sequence stratigraphy and geostatistics the eocene sant llorenc del munt example ebro foreland basin ne spain abstract the eocene sant llorenc del munt fan delta complex developed in the ebro foreland basin the stratigraphy of this succession about 1000 m thick has been described as made up of several transgressive regressive composite sequences each composed of a stack of fundamental sequences in turn made up of a transgressive systems tract and an overlying regressive systems tract systems tracts are composed of several facies belts proximal alluvial fan distal alluvial fan fan delta front carbonate platform and fan delta slope and prodelta a 3d facies model of a 130 m thick stratigraphic succession was built using outcrop data from one of the composite sequences the modelling followed a hierarchical approach a deterministic method was used to reconstruct the surfaces bounding fundamental sequences and their constituent systems tracts data input was outcrop traces digitized on photorealistic terrain models the stacking trend and interfingering of adjacent facies belts within each systems tract was added by means of a geostatistical algorithm and was conditioned to measured stratigraphic logs the analysis of the resultant 3d facies distributions allows revising the architectural interpretation of the studied interval leading to the conclusion that the observed arrangements are accommodation not supply driven furthermore the 3d models were flow simulated in two injector producer scenarios up depositional and down depositional dip waterflooding flow simulation results show that the depositional architecture of the studied succession controls potential recovery efficiencies in that a considerable proportion of moveable oil is trapped at the dead ends in depositional pinch outs of the main potential reservoir fan delta front deposits also that up dip waterflooding predicts better recovery efficiencies than down dip the dataset methods and results herein make the sant llorenc del munt complex a ready for application analogue for marine transitional reservoirs

miocene facies associations and sedimentary evolution of the southern transylvanian basin romania implications for hydrocarbon exploration abstract the transylvanian basin is a mature hydrocarbon province of romania characterized by two petroleum systems mesozoic thermogenic and miocene biogenic an extensive outcrop based sedimentological and micropaleontological study correlated to seismic and well data discusses the elements of the miocene petroleum system the facies associations are indicative of alluvial fandelta shallow and deep marine settings these are grouped into four different depositional systems evaporite mud carbonate sand mud and sand gravel their evolution in time and space shows large differences between various parts of the basin that have important consequences for exploration the transylvanian gas is formed by more than 99 methane of bacterial origin this is sourced by low quality the largest traps typically have multistory up to 20 pay zones with a total of 100 bcf to 1 tcf reserves exploration to date has focused on structural traps but most of the obvious structures have been drilled it is argued that significant exploration potential lies in stratigraphic plays including confined submarine fans slope channels detached lowstand prograding wedges incised valleys diapir flanks salt tectonics related unconformities and various sub volcanic plays risks of the petroleum system elements associated to these plays in different areas of the basin are discussed

depositional architecture of growth fault related wave dominated shelf edge deltas of the oligocene frio formation in corpus christi bay texas abstract growth faults within the frio formation define six subbasins on the south texas shelf and add to the complexity of the sediment dispersal along the shelf margin these growth faults influenced sediment pathways controlled sediment partition and provided increased accommodation for deltaic depocenters rollover and thickening of sediments occur on the downthrown side of growth faults with offsets of at least 150 m and up to 750 m growth strata are indicated by intervals that thicken landward by several tens of meters from anticline crests individual 4th order 100 500 ky regressive cycles expand about five to seven times across growth faults expansion ratios as great as 10 are observed the shelf edge is associated with the largest displacement expansion ratios and thickness of prograding deltaic sequences sedimentary structures and trace fossil associations identified in cores from nueces encinal and red fish bay subbasins indicate deposition on a wave dominated deltaic shoreline the cores exhibit highly bioturbated muddy sandstones alternating with decimeter thick clean sandstones with hummocky cross stratification alternation of fair weather wave deposits with sandy storm beds in two successive fault zones suggests that all subbasins developed under similar conditions during growth fault development high sediment supply conditions favored accumulation of thicker sediments on the downthrown sides of the faults wave dominance of deltas on the outer shelves in the growth compartments suggest that building of the upper slope rather lowers slope margin and decreases the likelihood of the presence of sandy deep water fans correlation of about 700 well logs integrated with seismic data provided the areal distribution and relative timing of sediment filling of the growth faulted compartments to unravel the evolution of higher order fourth and fifth sequences affected by these growth faults core data were used to recognize depositional environments to calibrate lithology to well logs and to characterize seismic amplitude anomalies within this shoreface succession the clean sandy storm beds will make attractive hydrocarbon reservoirs especially on the crest of rollover anticlines in downthrown compartments these sandstone bodies pinch out seaward into open marine shelf mudstones and are sealed by overlying shelf mudstones deposited during transgressive episodes

induced polarization detection and mapping of contaminant plumes several laboratory and scaled model investigations suggest that organic contaminants affect the surface electrical properties of exposed soils rocks and therefore produce measurable induced polarization ip signatures however there is little field evidence of an ip methodology for contaminant mapping a2d time domain ip method is developed for mapping the fs12 contaminant plume at the massachusetts military reservation mmr located in cape cod massachusetts the fs 12 plume consists of approximately 265 m 3 of fuel that erupted from a broken underground pipeline in the early 1970s benzene and ethylene dibromide edb are the primary contaminants at fs 12 with concentrations exceeding the allowed maximum concentration levels mcl while other constituents of the plume did not exceed their mcl therefore the contaminants of interest are benzene and edb partly because of their health risk and partly because they present the highest concentrations 2400 and 1000 g l respectively among the plume constituents and are therefore more likely to be related to the polarization source ip data were acquired along a survey line that partially transects the plume extending over contaminated and uncontaminated zones and were inverted to give 2d resistivity and chargeability plots to 100 m depth and a horizontal extent of 400 m by separately inverting ip data derived from time windows located at short and long decay times a timedomain gross spectral chargeability difference is produced both the chargeability and gross spectral chargeability difference show good agreement with the known location of the plume from monitoring wells with the ip chargeability section suggesting contaminant distribution detail that cannot otherwise be inferred from the sparse borehole distribution

seismic moment tensors of the april 2009 l aquila central italy earthquake sequence summary on 2009 april 6 the central apennines were hit by an mw 6 3 earthquake the region had been shaken since 2008 october by seismic activity that culminated in two foreshocks with mw 4 1 week and a few hours before the main shock we computed seismic moment tensors for 26 events with mw between 3 9 and 6 3 using the regional centroid moment tensor rcmt scheme most of these source parameters have been computed within 1 hr after the earthquake and rapidly revised successively the focal mechanisms are all extensional with a variable and sometimes significant strike slip component this geometry agrees with the ne sw extensional deformation of the apennines known from previous seismic and geodetic observations events group into three clusters those located in the southern area have larger centroid depths and a wider distribution of t axis directions these differences suggest that towards south a different fault system was activated with respect to the sw dipping normal faults beneath l aquila and more to the north

a sequence stratigraphic model for reservoir sand body distribution in the lower permian shanxi formation in the ordos basin northern china abstract the lower permian shanxi formation is the main gas bearing stratigraphic unit in the northeastern ordos basin china based on an integrated investigation of well logs seismic data cores and outcrops the lower member of the shanxi formation has been subdivided into three third order sequences from base to top namely sq1 sq2 and sq3 the three sequences consist primarily of stacked lowstand systems tracts with little deposition of transgressive systems tracts and or highstand systems tracts detailed sedimentological and stratigraphic analyses indicated that the entire sequence is characterized by a regional transgression with incised valleys and channel fills marking the bases of each retro gradational sequence and swamp or inter channel bay mudstone and coal deposits capping each sequence the three sequences retracted source ward sequentially from the sandstone dominated sq1 to the mudstone dominated sq3 the spatial and temporal distributions of the reservoir sandstones was primarily controlled by retro gradational stacking patterns channel sand bodies formed during the lowstand systems tracts of sq1 sq2 and sq3 are excellent reservoirs which form excellent reservoir cap rock assemblages with the overlying fine grained sediments the unique sequence stacking patterns control the accumulation of hydrocarbons the reservoir quality of the sq1 sq2 and sq3 sequences become worse gradually from base to top within each sequence channel or incised valley fill of the lowstand systems tracts remain potential good expiration targets

observation and prediction of dynamic ground strains tilts and torsions caused by the mw 6 0 2004 parkfield california earthquake and aftershocks derived from upsar array observationsdynamic ground strains tilts and torsions caused by the 2004 parkfield california earthquake

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

coseismic deformation of the destructive april 6 2009 l aquila earthquake central italy from gps data 1 on april 6 2009 01 32 39 gmt the city of l aquila was struck by a mw 6 3 earthquake that killed 307 people causing severe destruction and ground cracks in a wide area around the epicenter four days before the main shock we augmented the existing permanent gps network with five gps stations of the central apennine geodetic network cageonet bordering the l aquila basin the maximum horizontal and vertical coseismic surface displacements detected at these stations was 10 39 0 45 cm and 15 64 1 55 cm respectively fixing the strike direction according to focal mechanism estimates we estimated the source geometry with a non linear inversion of the geodetic data our best fitting fault model is a 13 15 7 km2 rectangular fault sw dipping at 55 3 1 8 consistent with the position of observed surface ruptures the estimated slip 495 29 mm corresponds to a 6 3 moment magnitude in excellent agreement with seismological data

early cenozoic two phase extension and late cenozoic thermal subsidence and inversion of the bohai basin northern china abstract the bohai basin is one of a family of early cenozoic extensional basins that lie along the eastern margin of asia from russia to vietnam initial extension was probably triggered by subduction roll back of the oceanic pacific plate from the asian continent there were two phases in the bohai basin s rift history the earlier paleocene early eocene phase resulted in the deposition of the kongdian formation and the fourth lowest member of the shahejie formation in a series of elongate half grabens these half grabens have master faults with a nne ssw orientation secondary normal faults are typically clockwise oblique to the master faults indicating a component of dextral transtension deposition was focused in the west and south of the present basin these rocks are mainly alluvial fan and fluvial red beds the architecture of the basin underwent an important change at ca 43 45 ma middle eocene beginning with the deposition of the third member of the shahejie formation in part these sediments were deposited in the same half grabens as the kongdian formation but the bozhong depression in the central part of the basin originated at this time and became the major depocentre the bozhong depression superficially resembles a pull apart basin it formed when continued transtension of the earlier tertiary fault systems to the east and west created an extensional overlap between them during this phase the basin as a whole had a geometry with elements typical of both pull apart and transtensional basins regional extension in many east asian basins ended at the end of the oligocene probably because of the onset of transpression within eastern asia caused by the collision of australia with the philippine sea plate dextral transpression caused minor inversion of some of the earlier normal faults in bohai but as a whole the basin began to subside in a post rift phase of thermal subsidence that has lasted until the present day

ground rotational motions of the 1999 chi chi taiwan earthquake as inferred from dense array observations 1 large rotational motions excited by the 1999 chi chi taiwan earthquake are inferred from a dense acceleration array near the northern end of the rupture fault where large surface slips along the fault are observed the estimated major frequency content is from 0 1 to 1 0 hz with a peak near 0 2 hz it is found that in the footwall region the observed strong rotational ground motions were most probably excited by the slip of the northern rupture ending segment of the chi chi earthquake fault and that its thrust slips induced a major rock motion in the radial component the analysis here indicates that during the chi chi earthquake significant rotation seismic energy was radiated from the bent northern end of the earthquake fault further analysis of rotational ground motions may provide useful constraints for its rupture mechanisms

case study a 3d resistivity and induced polarization imaging from downstream a waste disposal site in brazil a contaminated site from a downstream municipal solid waste disposal site in brazil was investigated by using a 3d resistivity and induced polarization ip imaging technique this investigation purpose was to detect and delineate contamination plume produced by wastes the area was selected based on previous geophysical investigations and chemical analyses carried out in the site indicating the presence of a contamination plume in the area resistivity model has successfully imaged waste presence 31 mv v water table depth and groundwater flow direction a higher chargeability zone m 31 mv v outside wastes placement and following conductive anomaly was interpreted as a contamination plume normalized chargeability mn m confirmed polarizable zone which could be an effect of a salinity increase contamination plume and the clay presence in the environment

haynesville and bossier mudrocks a facies and sequence stratigraphic investigation east texas and louisiana usa abstract upper jurassic haynesville and bossier shale gas plays of the northwestern gulf of mexico gom basin produce from organic rich marine transgressive to highstand mudrocks within mixed carbonate clastic depositional systems modern wireline log suites from 200 deep wells were used for detailed correlations and 10 cores throughout the upper kimmeridgian to lower tithonian basin were incorporated into detailed facies stratigraphic and lithologic analyses the haynesville shale lies within a 2nd order transgressive systems tract tst that encompasses back stepping ramp carbonates proximal and marine shales distal below a maximum flooding surface mfs this shale onlaps retrogradational carbonates and basement highs and is capped by the 2nd order mfs bossier shales and local sandstones prograde basinward above the haynesville shale and downlap the 2nd order mfs they grade upward and updip into the thick highstand systems tract hst fluvio deltaic sandstones of the cotton valley group distally organic rich facies developed in restricted bossier environments creating another productive gas shale opportunity several preexisting basement highs in the south and carbonate platforms in the northwest and west restrict and partition the basin thus influencing deposition of highly organic versus nonorganic and siliciclastic dominated versus carbonate dominated lithologies haynesville and bossier shales each compose three upward coarsening cycles that probably represent 3rd order sequences within the larger 2nd order tst and early hst respectively most of the three bossier 3rd order cycles are dominated by varying amounts of siliciclastics deposition of the haynesville mudrocks occurred below storm wave base under mostly dysoxic conditionsm allowing settlement of benthic bivalve communities and bioturbating organisms and oscillating periodically to more anoxic conditions on the seafloor however most of the sparse faunae found in these mudrocks are of planktonic origin bossier mudrocks exhibited more oxygenated and clastic rich lithologies related to progradation of the clastic shoreline and sea level highstand knowledge of lithologic stratigraphic geochemical and faunal variations across mudrock basins needs to be detailed so that shale gas basins might be successfully explored

strain tilt and rotation associated with strong ground motion in the vicinity of earthquake faults abstract in the absence of near field records of differential ground motion induced by earthquakes we simulate the time histories of strain tilt and rotation in the vicinity of earthquake faults embedded in layered media we consider the case of both strike slip and dip slip fault models and study the effect of different crustal structures the maximum rotational motion produced by a buried 30 km long strike slip fault with slip of 1 m is of the order of 3 10 4 rad while the corresponding rotational velocity is about 1 5 10 3 rad sec a simulation of the san fernando earthquake yields maximum longitudinal strain and tilt a few kilometers from the fault of the order of 8 10 4 and 7 10 4 rad these values being small compared to the amplitude of ground displacement the results suggest that most of the damage occurring in earthquakes is caused by translation motions we also show that strain and tilt are closely related to ground velocity and that the phase velocities associated with strong ground motions are controlled by the rupture velocity and the basement rock shearwave velocity

constraints of three dimensional geological modeling on reservoir connectivity a case study of the huizhou depression pearl river mouth basin south china sea abstract the z21 gas field is the only one gas field in the huizhou depression the distributions of sandstone and mudstone in the adjacent west zone control the extent of the z21 gas field making the confirmation of the reservoir connectivity between the west zone and main zone rcwm crucial in this study a practical workflow was proposed to confirm the rcwm first the sandstone and mudstone distributions were modeled by a sequential indicator simulation using the vertical proportion curves as constraints the porosity and permeability distributions were then predicted using a sequential gaussian simulation based on sandstone and mudstone models the sandstone mudstone and physical property models were treated as components of a geological embryonic model gem prior to the rcwm confirmation different hypotheses on the rcwm of the gems were drawn bringing variations to the gems and the gems turned to be different new models these new models were then applied to numerical simulations not only to perform quality checks but also to attain the simulated formation pressure coefficients pfcs and couple the study with the current formation pressure coefficients pfcc derived from the modular formation dynamics tester mdt a hypothesis is negated if the pfcs is not equal or approximately equal to the pfcc a coupled result was iteratively generated until the rcwm was confirmed this coupling study on reservoir connectivity makes use of general geological reservoir models and highlights the ingenious designs based on different hypotheses of the rcwm to generate reliable results coupling study shows that distributions of formation pressure in the west zone of z21 field are largely affected by a low permeability belt and rcwm is proved weak due to the existence of the low permeability belt

the 2009 l aquila central italy mw6 3 earthquake main shock and aftershocks 1 a m w 6 3 earthquake struck on april 6 2009 the abruzzi region central italy producing vast damage in the l aquila town and surroundings in this paper we present the location and geometry of the fault system as obtained by the analysis of main shock and aftershocks recorded by permanent and temporary networks the distribution of aftershocks 712 selected events with m l 2 3 and 20 with m l 4 0 defines a complex 40 km long nw trending extensional structure the main shock fault segment extends for 15 18 km and dips at 45 to the sw between 10 and 2 km depth the extent of aftershocks coincides with the surface trace of the paganica fault a poorly known normal fault that after the event has been quoted to accommodate the extension of the area we observe a migration of seismicity to the north on an echelon fault that can rupture in future large earthquakes

mapping oil contaminated sand and till with the spectral induced polarization sip method the laboratory and field results from an environmental application of the spectral induced polarization sip method are presented the phase spectra of the resistivity of uncontaminated glacial till silt sand and gravel were measured in the laboratory the effects of waste oil and motor oil on the phase and amplitude spectra of the resistivity were studied using artificially contaminated sand and till samples and mineral soil samples from real waste sites field ip and sip measurements were also made at the waste sites the laboratory phase spectra of sands and tills were straight or slightly concave upwards in a log log plot the phase angle varies between 0 1 and 20 mrad at 1 hz frequency and increases towards higher frequencies with a slope of 0 15 0 25 in laboratory tests motor oil and waste oil changed the phase and amplitude spectra of sand and till at first the amplitude and phase decreased due to oil contamination later during continued maturation both the amplitude and phase increased after a few days or weeks of maturation some of the contaminated samples showed a convexupwards phase spectrum the features observed in artificially contaminated samples were also detected in the sample material from real waste sites furthermore the in situ results from the waste sites were in agreement with the laboratory results in laboratory tests the phase spectra of clean sand and till remained stable with time whereas the phase spectra of oil contaminated samples changed with increasing maturation time this together with the field results suggests that differences between the spectra of clean and polluted soils and also changes occurring in the phase spectra of contaminated soils with time can be indicative of contamination

computer modeling the internal architecture of carbonate platforms a numerical computer model is described that calculates the internal architecture of carbonate platforms in response to varying values of carbonate production subaerial and submarine erosion sediment redeposition and sea level changes the computer generated sections closely resemble large scale outcrops and interpreted seismic profiles through carbonate platforms stillstand and transgressive sequences have prograding and downlapping platform geometries with lagoons developing in transgressive systems regressive sequences have downlapping clinoforms and erosional upper surfaces glacioeustatic scale cycles have a major control on platform geometry with erosional sequence boundaries developing during low stands and platform drowning occurring during transgressive periods lowstand downlapping wedges are minor features when compared with clastic systems and major progradation and downlap of slope deposits develop with transgressions and flooding of platform tops carbonate erosion rates are varied and have an important effect on the morphology of foodback surfaces which have a major control on platform top production the computer program contributes to the analysis of carbonate systems in two ways it gives a visual picture of the quantitative effects of the many parameters controlling carbonate geometries and it aids quantitative analysis of the architectures and time scales of ancient outcrop or seismic sequences

the connectivity of reservoir sand bodies in the liaoxi sag bohai bay basin insights from three dimensional stratigraphic forward modeling abstract the distribution of sand bodies is complex in small half graben rift basins influenced by differential tectonic subsidence the characterization of reservoir sand bodies remains half quantitative because the depositional processes of the sand bodies are poorly understood and quantitatively investigated based on wells and seismic data a three dimensional stratigraphic forward modeling is conducted to quantitatively characterize the depositional evolution of reservoir stratigraphy and to analyze the connectivity of sand bodies as well as its controlling elements in liaoxi sag bohai bay basin we integrate controlling factors for sequence development including initial bathymetry of basement subsidence lake level change sediment supply and sediment transport dionisos program to establish a 3d reservoir sequence model for the middle part of the third member of eocene shahejie formation the model matches the wells data of the oilfield such as lithologies gamma ray and resistivity making it credible to further predict sandstone distribution the sedimentary process of reservoir sand bodies appear four stages in stage 1 two prototypes of delta front sand bodies developed in the northwest in stage 2 both the western delta front sand bodies and eastern slope fan sand bodies were widely developed in stage 3 the delta front sand bodies developed in large scale whereas the slope fans were smaller in stage 4 only a slope fan sand body developed in the southeast whereas lacustrine shale dominated in the rift basin during the depositional evolution process the western sand bodies were not connected to the eastern sand bodies this disconnection is a function of source supply and sustained slope sinking caused by basin differential subsidence we tested the interplay of tectonic subsidence and sediment supply through the stratigraphic modeling under the conditions of bilateral source supply the limited number of sand sediments from western delta front could not be transported to the eastern structure high nevertheless under assumptions of one source supply and strong water flow the plentiful sand sediments could be carried onto the eastern structurally elevated position therefore basin differential subsidence and bilateral supply of source are the two controlling factors for the sand distribution in small half grabens in addition we found an interesting phenomenon that sand ratio in rifted basin center increases with subsidence decreasing however it will be a constant upper limit when subsidence declines to a threshold value the threshold of subsidence slope vertical subsidence divided by length of slope varied with climate and sedimentary environment in warm climate and delta environment the threshold value is 2 3

sedimentary sequences in the gulf of lion a record of 100 000 years climatic cycles abstract the wide continental shelf of the gulf of lion up to 70 km has been the object of numerous investigations since the early days of oceanography yet the question of sequences duration the mechanisms of deposition and factors implied remained unanswered a study of a very dense grid of very high resolution vhr seismic reflection sparker data associated with surficial cores both collected by ifremer between 1992 and 2001 on the outer shelf and upper slope offshore of sete in the languedoc region gives a new insight into these issues analysis of the 3d geometry of the sedimentary record reveals a basic depositional pattern consisting of a pair of horizontally juxtaposed and downlapping prisms prism pi with low angle clinoforms results obtained from integrating lithology palynology micropaleontology seismic stratigraphy stratigraphic simulation support the hypothesis that the basic depositional pattern records a 100 000 years glacioeustatic interglacial glacial cycle as previously suggested by aloisi aloisi j c 1986 sur un modele de sedimentation deltaique contribution a la connaissance des marges passive these de doctorat d etat universite de perpignan 162 pp prisms pi corresponds to deposition at high sea level and prisms pii to deposition during low sea level at glacial maxima five sequences of paired prisms capped by five major erosion surfaces have been identified and modelled showing that the corresponding glacioeustatic cycles the last five cycles at least are recorded on the shelf of the western part of the gulf of lion

seismic geomorphology architecture and genesis of miocene shelf sand ridges in the pearl river mouth basin northern south china sea abstract multiple stages of large scale shelf sand ridges including the shoreface attached and the offshore types have developed in the miocene successions on the mid shelf region of the pear river mouth basin northern south china sea utilizing a high quality 3d seismic data set accompanying 2d seismic profiles and well logs the morphology architecture and genesis of these shelf sand ridges have been systematically investigated in this study the ridges are of very large scale with the largest one having a maximum height of 64 m a width of more than 20 km and a length of 37 km within the 3d survey area being mound shaped they also display obvious asymmetry character with the ridge crest preferentially located on the se side three main internal components including the ridge front central ridge and the ridge tail have been recognized through careful anatomy analysis of the two most well imaged ridges each displaying distinct expressions on seismic amplitudes and geometries in the plan view most of the shelf sand ridges are generally ne sw oriented and widening to the sw direction scouring features can also be clearly observed along the sw direction including scour depressions and linear sandy remnants on well logs the shelf sand ridges are represented by an overall coarsening upward pattern intervals with blocky sandstones are preferentially present on higher locations due to a differential winnowing process controlled by shelf topography plenty of evidence indicates that these ridges were primarily formed by the reworking of forced regressive or lowstand deltaic deposits under a persistent southwesterly flowing current during the subsequent transgression this very current is a composite one which is speculated to consist of winter oceanic current scsbk south china sea branch of kuroshio intrusion onto the shelf and internal waves propagating from the luzon strait tidal currents might have contributed to the se growth of the ridge in response to the reglaciation of antarctic ice sheet and the closure of pacific indian ocean seaway in the middle miocene the intensification of the north pacific western boundary current was considered to have potential links to the initiation of the shelf sand ridges at 12 ma the development of shelf ridges was terminated and replaced by rapid deltaic progradation at 5 5 ma

the messinian succession of the crotone basin southern italy ii facies architecture and stratal surfaces across the miocene pliocene boundary the upper messinian to lower zanclean succession of the crotone basin a forearc basin located along the ionian side of the calabrian arc southern italy consists of a turbidite bearing succession the petilia policastro formation overlying evaporites and abruptly passing upward into coarse grained continental deposits the carvane conglomerate which are in turn overlain by distal shelf to slope mudstones the cavalieri marl the marked environmental changes from subaqueous to continental and vice versa documented by the studied succession are inferred to be the expression of basin scale tectonics leading to uplift and exposure superposed on the mediterranean scale base level rise that followed the acme of the messinian salinity crisis the upper part of the succession documents a transgressive trend probably initiated within the carvane conglomerate and further testified by the presence of a ravinement surface marked by a transgressive lag at the base of the zanclean cavalieri marl pointing to a non catastrophic deepening occurred near the end of the messinian

rotational earthquake effects in the united kingdom the united kingdom is an area of low to moderate seismicity and damaging earthquakes are uncommon however even in the limited record of damage from historical british earthquakes a number of instances can be found of rotational effects on parts of structures primarily chimneys or the tops of spires we have assembled all the instances we know of from the united kingdom record and present them here with illustrations and extracts from the original reports it is not possible to determine whether these are the effects of true rotational motion or the effects of translatory shaking interestingly this problem was considered in some detail by field investigators as long ago as the 1880s

layered seismogenic source model and probabilistic seismic hazard analyses in central italy we defined a seismogenic model for central italy based on three layers of sources and computed the relative seismic hazard maps one layer is constituted by individual structures liable to generate major earthquakes m 5 5 we defined them as seismogenic boxes by using geological information in terms of plan projec tion of active faults the seismicity rates associated with an individual source are based on the geometry and kinematics of the fault the recurrence model is controlled by the earthquake source association and when possible we defined the occurrence time of the last major event using it in a time dependent approach another layer is given by the instrumental seismicity analysis of the past two decades which allows us to evaluate the background seismicity m 5 5 using a sliding window selec tion of events we defined a model of regular adjacent cells of variable a and b values of the gutenberg richter relation the last layer utilizes all the instrumental earth quakes and the historical events not correlated to known structures 4 5 m 6 by separating them into seismotectonic provinces shaped on a geological structural basis the seismic hazard computations first use this layered model in a traditional probabilistic scheme the results indicate a narrow belt of peak ground acceleration pga higher than 0 30g with standard deviation in attenuation functions in the axial part of the apennine chain with a maximum spot of pga 0 40g southeast of the area damaged by the 1997 1998 umbria marche sequence pga expected not to be exceeded in 50 years at 90 probability level the background seismicity gives a nonnegligible contribution to the hazard at least for first damage levels then a simplified time dependent hypothesis has been introduced for the individual sources alone computing the conditional probability of occurrence of characteristic earth quakes for each source by brownian passage time distributions adopting equivalent fictitious seismicity rates we obtained maps referring to the next 50 years by using traditional codes these results show that the contribution of the recently active sources vanishes and the most hazardous sites are now located south of l aquila and in the sulmona area we consider that the methodology and results obtained are useful for seismic risk reduction strategies

sequential architecture in a fluvial succession sequence stratigraphy in the upper cretaceous mesaverde group prince canyon utah abstract five unconformity bounded sequences have been documented within a 1300 m thick succession of predominantly fluvial upper cretaceous and lower tertiary deposits in the price canyon area of the westernmost part of the book cliffs east central utah u s a this area experienced major tectonically induced changes in the paleogeography during deposition the earliest fluvial deposits in the study area were formed in a relatively simple foreland basin setting in front of the sevier orogenic belt and contain more marine influence than previously recorded following a gradual termination of thrusting sedimentation became increasingly controlled by uplift of the san rafael swell to the southeast our studies suggest that the fluvial systems in the upper part of the succession alternated bet een being confined within a valley open towards the north and being more directly eastward flowing on the basis of the observed sequences an idealized model of alluvial sequences whose internal architecture can be related to a fall rise fall cycle of the stratigraphic base level has been established upward or downward changes in the position of this base level dictate the creation and destruction of accommodation on the alluvial plain and therefore exert a direct control on the sequential architecture and sandstone body geometry of fluvial successions in our model the basal sequence boundary is overlain by an amalgamated fluvial sandstone sheet the sheet is succeeded by a fining upward more mudstone rich level with more isolated sandstone bodies and this level may culminate in a marine or lacustrine transgression the upper part of the sequence may show a coarsening upward trend heralding the next phase of base level fall and sequence boundary generation use of the suggested model has the potential to refine existing lithostratigraphic schemes and given the higher resolution and more detailed correlation may significantly improve paleogeographic reconstructions and aid in prediction of potentially hydrocarbon bearing reservoirs a revised and refined lithostratigraphy has been established on the basis of alluvial sequence analysis the lower half of the succession forms the youngest part of a major eastward prograding clastic tongue the mesaverde group and is campanian we divide this part into the blackhawk castlegate and price river formations the rest of the succession is maastrichtian to paleocene and is referred to the north horn formation this formation was deposited in an intermontane setting

sedimentary evolution of overlapped sand bodies in terrestrial faulted lacustrine basin insights from 3d stratigraphic forward modeling abstract terrestrial faulted lacustrine basins usually have large variabilities in structural subsidence and multiple river sources the facies in such basins are thus characterised by frequently changed facies and complex relationship of overlapped sand bodies e g liaoxi depression of liaodong bay bohai sea china therefore it s a great challenge to quantitatively describe evolution of sand bodies and their overlap relationship in this study a three dimensional stratigraphic forward model is used to solve this problem which is corrected according to well log data after the parameter optimization was verified against borehole strata thickness and lithology this model had a thickness error within 8 and the lithology distribution agreed with the well data as a whole four evolution phases of the shahejie 3 formation were recognised through the modeling in the first phase the lake level rose and the eastern fan delta sand developed in the second phase the fan delta sand scaled up and the braided river delta front sand developed at a small scale in the third phase the lake level shifted from falling to rising the fan delta sand further expanded the scale and the braided river delta developed at a large scale sands on both sides overlapped at a large scale in the fourth phase the lake level rose the lake basin expanded and lake shale was the main lithology in the study area from the sedimentary evolution of es3 formation sand overlapped in the third stage in 39 75 ma two parts of the sand body began to overlap and reached largest scale in 39 6 ma which was approximately 10 km 2 both then retrograded to a separation in 39 ma when the overlap ended coupling stratigraphic forward simulation with uncertainty quantification allowed us to estimate the influence of each stratigraphic parameter on sand overlap fluvial discharge appears to be the most influential parameter while the initial bathymetry and lake level variations exert a minor to moderate impact

3d seismic geomorphology of a large plio pleistocene delta bright spots and contourites in the southern north sea abstract regional 2d seismic interpretation has been integrated with high resolution 3d interpretation in dutch offshore blocks a f in the southern north sea 17 horizons mmu s1 s4 s4 1 s4 2 s5 s5 1 s6 s13 and 14 seismic units were interpreted expanding upon studies by kuhlmann and wong 2008 the study presents detailed and extensive twt structure and thickness maps of key depositional units allowing paleogeographic reconstructions detailed analysis of incisional scour marks and hypothesised iceberg scours and constructional features contourites identified initially by bright spots on seismic data linked to bottom currents was undertaken paleo paleographic reconstructions of water depth emphasise the role of hypothesised tidally generated contour currents in the late stage deltaic infill of an epicontinental basin north sea

dielectric spectroscopy of sedimentary rocks a physiochemical model for the complex dielectric response of sedimentary rocks is used to invert broadband dielectric spectra for effective grain size distributions the complex dielectric response of each grain within the water wet granular matrix is obtained by superimposing the polarization of the electrochemical double layer which is assumed to surround each grain with the complex dielectric response of the dry mineral grain the effective complex dielectric response of the water wet matrix grains and surface phase is obtained by volume averaging over the entire distribution of particle sizes the complex dielectric response of the total mixture water wet matrix and bulk pore solution is obtained using the bruggeman hanai sen effective medium theory studies of berea sandstone show that the grain size distribution obtained by inverting the real part of the complex dielectric spectra is similar to the grain size distribution obtained from optical images of the sample in thin section the current model however does not account for surface roughness effects or the polarization of counterions over multiple grain lengths therefore the grain size distribution obtained by dielectric spectroscopy is broader than the image derived distribution the dielectric derived grain size distribution can be fit with two separate power laws that crossover at r 1 m which corresponds to a relaxation frequency of 2 khz the low frequency dielectric response f 2 khz is primarily controlled by the clay size grains and surface roughness which has a fractal dimension of d 2 48 0 07 at very low frequencies f 0 1 hz the dielectric response appears to be controlled by the electrochemical polarization of counterions over multiple grain lengths a more general model should account for the effects of surface roughness and grain interactions on the dielectric response it would also be useful to develop a simplified version of this model perhaps similar in form to the empirically derived cole cole response which could be more easily used to model and interpret electrical geophysical field surveys e g induced polarization ground penetrating radar and time domain reflectometery measurements

contamination indications derived from electrical properties in the low frequency range1 electrical measurements are an important and integrated component of geophysical investigations connected with environmental problems as a result of an analysis of the electrical conductivity basic experiments on sandstones at frequencies below 10 khz show that the complex behavior of conductivity is caused exclusively by a complex interface conductivity its value is determined mainly by the internal rock interface to porosity ratio the composition of the pore fluid and connected matrix water interactions resulting in a specific microstructure of the interface therefore it can be expected that the interface region of a soil or rock material is very sensitive to changes in composition caused by contamination contaminated sandstone and clay samples were investigated using a low frequency measurement system the investigations are directed at the influence of different contaminants and their concentration results show that the complex electrical conductivity real and imaginary parts is influenced by properties of the pore filling contaminant this influence results in a change of the level of both parts and the shape of their frequency dependence the imaginary part in particular seems to provide important secondary information in some cases this part alone allows a differentiation of the various contaminants the different behavior of various rock types showsmore that the effects observed are the result of interactions between pore fluid properties and the internal pore surface structure less

a three dimensional high resolution reservoir model of napo formation in oriente basin ecuador integrating sediment dynamic simulation and geostatistics abstract with the rapid development of computer hardware and software technology 3d modeling technology of reservoirs has been widely applied in the exploration of oilfields however when modeling the reservoir with few wells due to the absence of efficient constraints in interwell areas the accuracy of the resulting 3d model is usually lacking in this paper we study the issue of model accuracy under the conditions of oil reservoir with few wells and propose a new 3d geological modeling method that is constrained by the multiple parameters based on sedimentary dynamics we carry out a series of sediment dynamic simulation by considering a number of key processes and parameters affecting the deposition of m1 member of napo formation in t oilfield oriente basin from 79 8 ma to 76 ma to constrain the lithofacies and properties models the proposed modeling method comprises two steps first the lithology distribution is obtained from a petrologic 3d model through the forward modeling of sedimentary processes second geostatistical method is applied to build the reservoir geological model with the constraints of sedimentary dynamics and logging information from work areas the distribution of sedimentary characteristics by using a coordination kriging modeling method as a result a high degree fit is obtained between the actual characteristics of the strata and the reservoir model with relative error of 4 6 indicating future application of this method for geological modeling of reservoirs with few wells

facies heterogeneity at interwell scale in a carbonate ramp upper jurassic ne spain abstract the well exposed upper kimmeridgian carbonate ramp near arroyo cerezo iberian basin eastern spain provides an excellent analog to stratigraphically equivalent subsurface reservoirs such as the carbonate ramps of the arab d of the middle east and the smackover of the gulf of mexico critical questions regarding interwell scale heterogeneity and correlation motifs for low angle ramp systems can be addressed using continuous exposures that encompass a full range of inner to outer ramp facies outcrops in this area provide a complete exposure of the ramp succession in depositional dip direction at arroyo cerezo a 40 m thick and 1 3 km long dip oriented continuous outcrop has been studied lithofacies and bounding surfaces have been mapped on a continuous photomosaic to build a detailed 2d cross section complemented by five stratigraphic sections 300 m apart and petrographic analysis the reconstructed section shows the facies transition from relative proximal to distal carbonate ramp settings carbonate facies associations are grouped according to the dominant carbonate types buildup dominated systems and coated grain dominated systems detailed mapping of facies and bounding surfaces documents distinct ramp depositional units with downdip facies changes occurring within the 1 3 km length of the outcrop the arroyo cerezo outcrop indicates that the ramp facies continuity when based on a 5 10 km distance well log correlation is mostly apparent use of detailed spatial and temporal analysis of high quality outcrop analogs promotes more realistic models for understanding the interwell meter scale heterogeneity and the scale of these depositional heterogeneities although being below resolution of subsurface tools governs in fact along with diagenetic modifications the fluid flows within a reservoir the scale of these stratigraphic heterogeneities needs to be considered in order to optimize and enhance hydrocarbon production and last recovery

predicting the terrestrial flux of sediment to the global ocean a planetary perspective a new model for predicting the long term flux of sediment from river basins to the coastal ocean is applied to a global data set of 340 river basins the model is based on relief basin area or averaged discharge and basin averaged temperature basinaveraged temperature is determined from basin location latitude longitude and the lapse rate across the basin relief hypsometric approximation the sediment flux model incorporates climate through basin temperature and hydrologic runoff solutions are provided for each of the major hemispheric climate regions polar temperate and tropic the model successfully predicts the pre anthropogenic flux of sediment to within the uncertainties associated with the global observations within a factor of two for 75 of rivers that range across five orders of magnitude in basin area and discharge most of the problem rivers are associated with low observational loads often smaller rivers where anthropogenic impacts are often magnified and temporal variability is high model predictions provide a baseline for researchers 1 to question the quality of observational data where available and disagreement is greatest 2 to examine a river basin for unusually large anthropogenic influences i e causes of erosion or causes of hinterland sediment retention and 3 to uncover secondary factors not addressed by our model lithology lakes the model provides a powerful tool to address the impact of paleo climate fluctuations warmer colder wetter drier on the impact of sediment flux to the coastal ocean d 2003 elsevier b v all rights reserved

multi scale stratigraphic forward modelling of the surat basin for geological storage of co2 underground geological storage of co2 gsc requires a high level of subsurface understanding that is often hindered by a lack of data this study demonstrates the use of stratigraphic forward modelling sfm in generating and characterising a static reservoir model using limited well data with multiple potential applications within the gsc workflow sedsim sfm software was used to create a static model of the surat basin including a high resolution nested model of the epq 7 gsc tenement within the basin deposition and burial of the jurassic precipice sandstone evergreen formation and hutton sandstone were simulated modelling results show a close match with gamma ray well logs in the tenement area and the model can be considered a credible model of the subsurface the sedsim predicted formation thicknesses and porosity and permeability distributions meet criteria set for gsc suggesting that the epq 7 tenement may be a prospective gsc location

facies characteristics morphology and depositional models of clay slide deposits in terraced fjord valleys norway abstract many bedrock confined fjord valleys along the norwegian coast contain thick accumulations of fine grained sediments that were deposited during and after the last deglaciation the deposits gradually emerged above sea level due to glacioisostatic uplift and fjord marine sedimentation was gradually followed by shallow marine and fluvial processes during emergence terraces and river cut slopes were formed in the valleys subsequent leaching of salt ions from the pore water in the marine deposits by groundwater has led to the development of quick clay the deposits are subject to river erosion and destructive landslides involving quick clay most slides are of prehistoric age others are known from modern observations as well as from historic records landforms such as distinct slide scars or the hummocky terrain of slide deposits may be strongly modified by secondary processes in addition deposits from the most liquid part of quick clay slides may have planar surfaces clay slide deposits on a fluvial or deltaic terrace therefore are not always easily recognized from morphology and only exposures may reveal their internal structures and allow them to be distinguished from overbank flood sediments detailed sedimentological work shows that slide deposits in such setting consist of distinct facies containing reworked marine sediments we propose three facies successions of clay slide deposits that form a continuum the dominant components of these succession types are slightly deformed blocks of laminated clay and silt a highly deformed clay and silt with gravel clasts b and massive to stratified clay and silt with scattered clasts c we suggest that in many cases a basal muddy diamicton is a characteristic and possibly diagnostic feature processes and depositional models are interpreted from the different succession types the results may be relevant for identifying clay slide deposits elsewhere and may be useful during general mapping of fjord marine deposits and characterization of slide prone areas as well as during identification of prehistoric slides

sequence stratigraphic modelling and reservoir architecture of the shallow marine successions of baram field west baram delta offshore sarawak east malaysia abstract the baram delta province is located in the northern part of sarawak west baram delta and extends north eastward into brunei and further into the south western part of sabah east baram delta the delta is a neogene basin which developed over an accretionary wedge implying cretaceous to eocene sediments during the late eocene to late miocene times tongkul 1991 hutchison et al 2000 morley et al 2003 sapin et al 2011 facies and well log analyses were carried out on core and well data for the late miocene successions of baram field a medium sized oilfield located in the north eastern flank of the baram delta oil province offshore sarawak a numerical model of sea level fluctuations and progradational basin fill was generated using the clastic modeling program hardy and waltham 1992a and 1992b waltham 1992 software to evaluate the possible controls of sea level changes in the development of the siliciclastic successions and their bounding surfaces this model was based on four lines of evidence namely core data fieldwide wireline logs correlation seismic sections and average thickness variations across the field cored intervals of the upper cycle v late miocene display reservoir successions dominated by thick swaley cross stratified scs sandstones thin hummocky cross stratified sandstones and other shallow marine wave and storm dominated facies interbedded with laminated shelfal mudstones the vertical facies organisation suggests deposition during shoreface progradation associated with a fall of relative sea level analysis and correlation of well logs reveal stacking patterns comprising three scales of depositional cyclicity the parasequences 10 30 m thick the parasequence sets 45 130 m thick and the major cycles 600 800 m thick field wide dip oriented seismic sections show very well developed horizontal to slightly upward convex layers traceable over great distances which suggests a ramp type margin in which the basin floor dipped gradually seaward and lacked a distinct shelf slope margin the evidences gathered demonstrate that the deposition and build up stratigraphy of the late miocene sedimentary successions could have been strongly controlled by superimposed short term medium term and long term sea level changes the simulated sea level and sedimentary basin fill model generated by the clastic modelling program match to the well log correlation this model illustrates that high frequency sea level fluctuations enable sands to be distributed over large areas within a shallow low gradient shelf our study shows that integrated studies incorporating cores well logs seismic sections and simulated models can be employed as important tools for correlation and reservoir modelling

non uniform subsidence and its control on the temporal spatial evolution of the black shale of the early silurian longmaxi formation in the western yangtze block south china abstract the ordovician silurian transition was a significant period when an obvious variation occurred worldwide in terms of tectonics climate oceans paleontology and sedimentology here we use stratigraphic forward modeling constrained by paleobiota paleobathymetry sedimentology and geochemistry to study the tectonic subsidence history of the early silurian in the western yangtze block south china numerical modeling suggests that the tectonic subsidence was not uniform during the deposition of the early silurian black shale of the longmaxi formation with acceleration of tectonic subsidence during the later regression period furthermore the subsidence rate at this time was at least three times that during the early transgression period this acceleration resulted from the collision between the yangtze block and the southeastern cathaysia block which affected the tectonic subsidence and the heterogeneity of the black shale the results may provide quantitative implications for the reconstruction of the paleoenvironment the evolution of paleobiota the temporal spatial distribution of the black shale and the mechanism of block assemblage in south china

simulation of the interactions between gravity processes and contour currents on the algarve margin south portugal using the stratigraphic forward model sedsim abstract the margin of the gulf of cadiz is swept by an intermediate current the mediterranean outflow water mow flowing from the mediterranean to the atlantic on the northern margin of the gulf algarve margin south portugal the mow intensity is low and fine grained contourite drifts are built up with an alongslope alignment recent sedimentological studies emphasize the presence of complex process interactions resulting in the formation of a unique depositional architecture alongslope processes related to contour currents generate contourite drift while downslope processes form canyons and channels aligned on deep faults this paper uses a combined oceanographic and geological dataset to simulate the different types of interactions between gravity processes and contour currents which were evidenced on this margin an extrapolation of the contour current intensity has been used based on the present day velocity field and sea level fluctuations over the simulated geological time scale according to our model results the construction of the contourite drift is closely linked to contour current velocities and directions the types of sediments transported and the existing topography using modern sedimentological understanding of the area we have correlated gravity flow s strongest activity to sea level lowstand periods mainly due to a closer connection between canyon s mouth and river or deltaic systems the simulated gravity flows are initialized at different locations and times on the margin depending on the preserved lobes retrieved from seismic analysis their resulting morphological features are identified as perched lobes with volumes and forms close to the ones observed on portimao and lagos drifts this study provides a process based understanding of the construction of contourite system and a physical evaluation of the interactions between gravity flows perpendicular to the slope and alongslope processes in addition it shows the influence of autocyclic factors in the construction of contourite sedimentation which is important to consider in future sedimentary paleo reconstruction interpretations

persistent drainage migration in a numerical landscape evolution model 1 numerical landscape evolution models driven by uniform vertical uplift often develop a static drainage network and a precise balance between uplift and erosion small scale physical models of uplifting drainage basins however continually reorganize by ridge migration and do not reach an ideal steady state here i show that the presence or absence of persistent drainage migration in a bedrock numerical landform evolution model depends on the flow routing algorithm used to determine upstream contributing area the model version that uses steepest descent routing achieves an ideal steady state while the model version that uses bifurcation routing results in continually evolving drainage basins even under conditions of uniform vertical uplift bedrock erodibility precipitation and landsliding threshold this result suggests that persistent drainage migration can occur by erosional processes alone this result has important implications for numerical modeling methodology our understanding of the natural variability of landform evolution and the interpretation of thermochronological data

clues for a relation between rotational effects induced by the 2009 mw 6 3 l aquila central italy earthquake and site and source effects abstract the 2009 m w 6 3 l aquila earthquake produced an impressive number of rotational effects on vertically organized objects such as chimneys pillars capitals and gravestones we present a dataset of such effects that consists of 105 observations at 37 different sites and represents a compendium of earthquake induced instances of rotational effects that is unprecedented in recent times we find that the absolute majority of the reported effects were observed in the epicentral zone and that most of the observations are located where the mercalli cancani sieberg intensity is between 7 and 8 9 the evident asymmetry in the distribution of the rotational effects resembles the southeastward directivity of the macroseismic effects and highlights a significant convergence between rotations and damage finally we perform some qualitative analyses to recognize and evaluate which geological and seismological parameters can be significant contributors to local rotations we find that surface geology and amplification of the seismic motion at each reported location strongly influence the occurrence and the nature of the earthquake induced rotational effects conversely the contribution of the pattern of slip distribution on the fault plane plays only a secondary role in enhancing the rotational motion at each site

rupture history of the 2009 l aquila italy earthquake from non linear joint inversion of strong motion and gps data 1 we image the rupture history of the 2009 l aquila central italy earthquake using a nonlinear joint inversion of strong motion and gps data this earthquake ruptured a normal fault striking along the apennines axis and dipping to the sw the inferred slip distribution is heterogeneous and characterized by a small shallow slip patch located up dip from the hypocenter 9 5 km depth and a large deeper patch located southeastward the rupture velocity is larger in the up dip than in the along strike direction this difference can be partially accounted by the crustal structure which is characterized by a high velocity layer above the hypocenter and a lower velocity below the latter velocity seems to have affected the along strike propagation since the largest slip patch is located at depths between 9 and 14 km the imaged slip distribution correlates well with the on fault aftershock pattern as well as with mapped surface breakages

coseismic and initial post seismic slip of the 2009 mw 6 3 l aquila earthquake italy from gps measurements summary here we report the preliminary results of gps data inversions for coseismic and initial afterslip distributions of the mw 6 3 2009 april 6 l aquila earthquake coseismic displacements of continuous and survey style gps sites show that the earthquake ruptured a planar sw dipping normal fault with 0 6 m average slip and an estimated moment of 3 9 1018 nm geodetic data agree with the seismological and geological information pointing out the paganica fault as the causative structure of the main shock the position of the hypocentre relative to the coseismic slip distribution supports the seismological evidence of southeastward rupture directivity these results also point out that the main coseismic asperity probably ended downdip of the paganica village at a depth of few kilometres in agreement with the small 1 10 cm observed surface breaks time dependent post seismic displacements have been modelled with an exponential function the average value of the estimated characteristic times for near field sites in the hanging wall of the fault is 23 9 5 4 d the comparison between coseismic slip and post seismic displacements for the first 60 d after the main shock shows that afterslip occurred at the edges of the main coseismic asperity with a maximum estimated slip of 25 cm and an equivalent seismic moment of 6 5 1017 nm the activation of the paganica fault spatially intermediate between the previously recognized main active fault systems suggests that strain accumulation in the central apennines may be simultaneously active on distinct parallel fault systems

a three dimensional high resolution reservoir model of the eocene shahejie formation in bohai bay basin integrating stratigraphic forward modeling and geostatistics abstract reservoir characterization based on geostatistics method requires well constraints e g seismic data with high quality to predict inter well reservoir quality that is conformed to geological laws nevertheless the resolution of seismic data in multiple basins or reservoirs is not high enough to recognize the distribution of different types of sand bodies in this paper we propose a new method to improve the precision of reservoir characterization reservoir modeling with the constrains of sedimentary process model and sedimentary microfacies we employed stratigraphic forward modeling a process based method to constrain the reservoir modeling in one oil bearing interval of the third member of eocene shahejie formation in j oilfield of liaoxi sag bohai bay basin we divide reservoir modeling into two orders using different types of constrains in the first order we use the simulated shale model from stratigraphic forward model that is corrected by wells data as a 3d trend volume to constrain the reservoir sand shale modeling in the second order different types of sedimentary microfacies in the sandy part of the model are further recognized and simulated within the constrains of sedimentary microfacies maps consequently the porosity permeability and oil saturation are modeled under the control of precise sedimentary microfacies model the high resolution reservoir model shows that the porosity permeability and oil saturation of distributary channel is generally above 20 10md and 50 respectively which are much higher than that of other types of sedimentary microfacies it can be concluded that comparing to other types of sedimentary facies distributary channel has better physical properties and more oil accumulation in the fan delta front and therefore is the most favorable zones for petroleum development in the research area

3d geostatistical inversion of induced polarization data and its application to coal seam fires we applied the principal component geostatistical approach pcga to the inversion of time domain induced polarization data in terms of resistivity and chargeability distributions the pcga presents two major advantages over standard methods 1 it avoids the storage of the usually large covariance matrix which contains the geostatistical information by factorizing it in a product of low rank matrices 2 it does not assemble the jaco bian matrix per se we determine the robustness of this approach with three examples we first reconstruct the electrical conductivity and chargeability fields of two synthetic models generated using the geostatistical software stanford geostatistical modeling software the pcga approach performs better than the tikho nov based regularization approach when the true fields are very heterogeneous and the amount of data is limited the third example is devoted to a field study over the former lewis coal mine in colorado usa we perform a 3d localization of the burning front of this coal seam fire by applying our geostatistical inverse methodology to a time domain induced polarization data set in this case the horizontal components of the semivariogram are determined from a self potential map and the correlation length scale for the vertical component is determined from the known thickness of the coal bed the tomogram presents a high normalized chargeability associated with the burning front we evaluate the high normalized chargeability of the burning front in terms of the physical mechanism associated with the cation exchange capacity of the coal and the effect of temperature this demonstrates the potential of the geostatistical inversion and its suitabil ity for inverting geophysical data especially when the data density is sparse in the case of coal seam fires we determine the suitability of the induced polarization method to localize the burning front and the effect of temperature on the normalized chargeability

what can be learned from rotational motions excited by earthquakes summary one answer to the question posed in the title is that we will have more accurate data for arrival times of sh waves because the rotational component around the vertical axis is sensitive to sh waves although not to p sv waves importantly there is another answer related to seismic sources which will be discussed in this paper generally not only dislocations commonly used in earthquake models but also other kind of defects could contribute to producing seismic waves in particular rotational strains at earthquake sources directly generate rotational components in seismic waves employing the geometrical theory of defects we obtain a general expression for the rotational motion of seismic waves as a function of the parameters of source defects using this expression together with one for translational motion we can estimate the rotational strain tensor and the spatial variation of slip velocity in the source area of earthquakes these quantities will be large at the edges of a fault plane due to spatially rapid changes of slip on the fault and or a formation of tensile fractures

the first world catalog of earthquake rotated objects eros part ii statistical analyses and related interpretations the article presents the results of the quantitative statistical analyses of the first world catalog of earthquake rotated objects eros presented in part i of the study cucci et al 2016 we searched for possible relations between the epicentral distance of eros occurrence and a number of customary seismological observables such as magnitude intensity focal mechanism etc the reliability of results is quantitatively checked by means of some suitable statistical tests we found strong evidence of a clear log linear dependence of the epicentral distance to which an ero can be observed on the magnitude m w of the source event we note that the probability of observing eros near the epicentral area d 10 km inversely decreases with the earthquake magnitude and that for large earthquakes m w 8 this probability remains significant around 30 beyond 100 km from the epicenter unexpectedly we did not find significant relations between eros occurrence and epicentral intensity possibly because of high dispersion of intensity values the data analyzed in the present study identifies intensity 6 as the lowest intensity for rotation occurrence this is different from the main macroseismic scales which indicate the eros as a diagnostic of larger intensity degrees this outcome could suggest the need for revision and for updating the diagnostics indicated in the intensity scales as for the focal mechanisms of the seismic events we found higher probabilities of observing rotations beyond 10 km distance from the epicenter of a thrust faulting earthquake than for a normal faulting earthquake this probability reverses beyond 50 km distance especially for high magnitude seismic events our results indicate interesting insights to potential end users of the eros catalog in the fields of historical seismology and earthquake engineering

perspectives on the sequence stratigraphy of continental strata this report is the result of a working group on continental sequence stratigraphy that was set up at the 1991 nuna conference in banff canada to date sequence stratigraphic concepts have been applied mainly to the marine realm but unconformity bounded units have long been recognized in nonmarine strata successful application of sequence stratigraphic concepts to continental strata requires careful consideration of controls on base level and sediment supply as with shallow marine environments relative sea level can be considered as the stratigraphic as well as the geomorphic base level for coastal nonmarine settings farther inland stratigraphic base level which determines accommodation space is more complex and takes various forms such as the graded profile for fluvial strata groundwater tables for some eolian strata and lake level for some intermontane sediments sediment supply is also generally a more complex variable for nonmarine environments than in the marine realm because of the proximity to the source area the influence of climate and tectonism on sediment supply can clearly be seen in many continental sediments the fact that the major controls of climate tectonism and eustasy are somewhat interdependent and that a change in one parameter will most likely be reflected in others is also more readily apparent in continental strata although in its infancy sequence stratigraphic concepts have been applied to a wide variety of continental settings in attempts to explain variations in facies architecture of particular interest are studies that have linked fluvial architecture on coastal plains to variations in relative sea level as indicated by coeval marine strata and studies of lacustrine environments that show marked variation in facies between highstand and lowstand deposits the application of sequence stratigraphy to continental strata will likely result in the development of better correlation techniques and models that better predict the location and nature of fluvial and eolian reservoirs

sedimentary fills and sensitivity analysis of deep lacustrine facies in multi segment rift basins insights from 3d forward modeling abstract this article presents a series of stratigraphic forward simulations of deep lacustrine sedimentary fills of continental multi segment rift basins these models integrate basin filling with the evolution of the extrabasinal catchment area and relate tectonism and precipitation fluctuations to changes in lake level and sediment supply the models reproduce the physical processes acting on the whole depositional environment from the site of erosion in the catchment area to deposition deep in the basin and capture the complexity and variability of lacustrine rift basins results from these simulations show 1 both extremely arid and extremely high precipitation conditions are not favorable for the development of a large proportional volume of deep lacustrine facies in rift basins 2 an increase of basin subsidence rate or a decrease of erosion rate in the source area increases both the proportional volumes of deep lacustrine sediment contained within the total rift fill and sand rich sediment contained within deep lacustrine facies 3 the development of deep lacustrine facies is more sensitive to basin subsidence and source erosion under very high precipitation conditions and 4 under various scenarios of basin subsidence and source area erosion the proportion and style of deep water sand accumulation is shown to be insensitive to climate conditions our simulations shed light on deep lacustrine fills in lacustrine rift basins and deepen the understanding of the influences of different conditions of evaporation precipitation from arid to humid subsidence rates e g reflecting end member processes of continental extension and erosion rates e g reflecting varying bedrock terranes within the catchment which help predict favorable conditions for the development of lacustrine source rocks and deep water hydrocarbon reservoirs

analyzing geophysical signature of a hydrocarbon contaminated soil using geoelectrical surveys in february 1994 a major oil blow out occurred as a consequence of an accident at an exploration drill hole at trecate north west italy more than 15 years after the incident a series of geophysical and hydrogeological surveys were conducted for investigating the hydrocarbon contaminated soil the hydrocarbon is still spatially distributed as residual phase in the unsaturated zone a free phase exists between the transition zone and the vadose zone in what is defined as a smear zone geoelectrical methods have shown their potential in contaminant detection and are increasingly used for contaminated sites characterization we carried out geoelectrical surveys over the most contaminated area of the site in order to analyze the changes in geophysical signature due to the presence of contaminants and furthermore to understand the role of biomass activity in degrading the hydrocarbon and altering petrophysical properties of the soil acquisition of time and frequency domain resistivity data allowed us to approach the same features with different methods providing a better understanding of the problem we further analyzed the role of soil properties on electrical resistivity porosity pore water specific resistivity and the influence of cation exchange capacity on the bulk resistivity at the site the electrical resistivity observed at the site shows a clear relationship with water saturation porosity and soil texture as well as with resistive hydrocarbon species we also monitored soil polarizability in the same frequency range of electrical resistivity measures allowing better delineation of the degrading processes underway in the contaminant which constitutes an additional substrate for the proliferation of anaerobic degraders

effect of time dependence on probabilistic seismic hazard maps and deaggregation for the central apennines italy abstract we produce probabilistic seismic hazard assessments for the central apennines italy using time dependent models that are characterized using a brownian passage time recurrence model using aperiodicity parameters of 0 3 0 5 and 0 7 we examine the sensitivity of the probabilistic ground motion and its deaggregation to these parameters for the seismic source model we incorporate both smoothed historical seismicity over the area and geological information on faults we use the maximum magnitude model for the fault sources together with a uniform probability of rupture along the fault floating fault model to model fictitious faults to account for earthquakes that cannot be correlated with known geologic structural segmentation we show maps for peak ground acceleration pga and 1 0 hz spectral acceleration sa 1 on rock having 10 probability of exceedence in 50 yr we produce maps to compare the separate contributions of smoothed seismicity and fault components in addition we construct maps that show sensitivity of the hazard for different parameters and the poisson model for the poisson model the addition of fault sources to the smoothed seismicity raises the hazard by 50 at locations where the smoothed seismicity contributes the highest hazard and up to 100 at locations where the hazard from smoothed seismicity is low for the strongest aperiodicity parameter smallest the hazard may further increase 60 80 or more or may decrease by as much as 20 depending on the recency of the last event on the fault that dominates the hazard at a given site in order to present the most likely earthquake magnitude and or the most likely source site distance for scenario studies we deaggregate the seismic hazard for sa 1 and pga for two important cities rome and l aquila for pga both locations show the predominance of local sources having magnitudes of about 5 3 and 6 5 respectively for sa 1 at a site in rome there is significant contribution from local smoothed seismicity and an additional contribution from the more distant apennine faults having magnitude around 6 8 for l aquila the predominant sources remain local in order to show the variety of impact of different values we also obtained deaggregations for another three sites in general as decreases periodicity increases the deaggregation indicates that the hazard is highest near faults with the highest earthquakes rates this effect is strongest for the long period 1 sec ground motions

the 2009 l aquila earthquake central italy a source mechanism and implications for seismic hazard an edited version of this paper was published by agu copyright 2009 american geophysical union

inversion of induced polarization data we present an algorithm for inverting induced polarization ip data acquired in a 3 d environment the algorithm is based upon the linearized equation for the ip response and the inverse problem is solved by minimizing an objective function of the chargeability model subject to data and bound constraints the minimization is carried out using an interior point method in which the bounds are incorporated by using a logarithmic barrier and the solution of the linear equations is accelerated using wavelet transforms inversion of ip data requires knowledge of the background conductivity we study the effect of different approximations to the background conductivity by comparing ip inversions performed using different conductivity models including a uniform half space and conductivities recovered from one pass 3 d inversions composite 2 d inversions limited aim updates and full 3 d nonlinear inversions of the dc resistivity data we demonstrate that when the background conductivity is simple reasonable ip results are obtainable without using the best conductivity estimate derived from full 3 d inversion of the dc resistivity data as a final area of investigation we study the joint use of surface and borehole data to improve the resolution of the recovered chargeability models we demonstrate that the joint inversion of surface and crosshole data produces chargeability models superior to those obtained from inversions of individual data sets

resonance of subsurface sediments an unforeseen complication for designers of roman columns abstract most of ancient rome was settled on the tiber river holocene flood plain monuments of imperial age i to v century show evidence of significant damage mainly produced by earthquakes generated in the seismogenic areas of the central apennines 70 to 130 km away from rome the different level of damage suffered by the two most important honorary columns in rome those of trajan and marcus aurelius located 700 m apart suggests the occurrence of strong variations of ground motion across a narrow zone due to changes in the local geology in order to check this hypothesis we investigate the details of surface and subsurface geology of the area we construct a 2d geological profile which includes topographic variations and heterogeneities of the elastic and anelastic parameters a finite difference technique is used to compute the sh wave response along the profile numerical modeling of seismic response at the site of marcus aurelius9 column shows a significant spectral amplification in a narrow frequency band corresponding to the natural vibrational mode of the column the amplification attains much lower values at the trajan9s column site

architecture of a forced regressive systems tract in the turonian ferron notom delta southern utah u s a abstract the large scale stratigraphic architecture of forced regressive deposits has been documented in many previous studies bed scale facies architectural analyses of these deposits however are still very limited the cretaceous ferron notom delta in southern utah u s a contains a 20 km dip oriented exposure of a stepped forced regressive systems tract the main focus of this paper is to reconstruct the paleogeography and depositional history of the systems tract based on detailed stratigraphic and facies architectural analysis using 23 geological sections photomosaics and walking out of beds internally the systems tract consists of 6 parasequences 11f to 11a from the oldest to the youngest during the progradation of parasequences 11f to 11b the paleoshorelines were wave dominated as indicated by the abundance of hcs and or scs beds wave ripple cross laminated beds and the occurrence of diverse and robust ichnological suites attributable to the skolithos and cruziana ichnofacies progradation of the wave dominated shorelines resulted in more homogeneous and laterally continuous sand bodies from 11b to 11a however there is a distinct change in paleoshoreline regime from wave dominated to tide influenced as indicated by the common occurrence of tidal facies in 11a including 1 lenticular wavy and flaser bedding and bidirectional dipping cross strata 2 reactivation surfaces double mud drapes and ripple cross lamination with opposing dips at the toe of large dune scale cross sets 3 inclined heterolithic strata ihs and sigmoidal bedding with tidal rhythmites and 4 cyclic vertical variation in facies and bed thickness and the common occurrence of sand mud couplets these tide influenced facies show overall lower bioturbation intensity bi 0 3 progradation of the tide influenced shoreline results in more heterolithic delta front facies tidal and or tidal fluvial channels further dissect delta front sandstones forming more isolated sand bodies data from this study as well as previous work show that width and thickness of the forced regressive parasequences are small typically less than 5 km and 20 m respectively in subsurface studies identifying and correlating such small scale parasequences using sparse data involve significant uncertainties a combination of the diagnostic features indicating forced regression and different data sets is essential to better constrain the geometry and architecture these small scale bodies