transient seepage model for saturated unsaturated soil systems a geotechnical engineering approach a two dimensional finite element model is proposed to simulate transient seepage for complex groundwater flow systems the complete soil system is treated as a continuum encompassing flow in both saturated and unsaturated zones in the unsaturated zone the air phase is assumed to be continuous and open to atmospheric pressure the coefficient of permeability of the unsaturated soil is assumed to be a function of pore water pressure the governing differential equation is derived within a framework familiar to geotechnical engineers the stress state variables and the constitutive relationships for an unsaturated soil are used in the derivation the finite element solution to the governing differential equation is based on the galerkin weighted residual method the nonlinearity of the equation is solved by iterative procedures the finite element formulation is implemented into a computer model named trasee the model can be applied to a wide variety of problems involving complex boundary conditions and geo

a linear regression framework for predicting subsurface geometries and displacement rates in deep seated slow moving landslides abstract a new numerical integration linear regression tool is used to investigate kinematic behavior in deep seated sliding surface deeper than 3 m mass movements the technique is developed in the context of real inclinometer records and numerical integration using nine inclinometer case histories from four well documented large landslides carrot river montebestia karya village and pietrapertosa axial metric subsurface geometric deformation rates are predicted and compared for four different case studies from the literature a reactivated composite extremely slow earth slide earthflow a reactivated composite extremely slow debris slide rock fall an active composite very slow earth slide earth flow and a reactivated complex slow earth slide earth spread sensitivity analysis based on sliding surface depth to length d l ratios show that the mobility of these slow moving masses is closely dependent on the mode of sliding the results also show that short term and long term dynamics of slow moving landslides can be captured by geometrical patterns because the parameter determined is a geometric property the technique used in the investigation can be applied in new landslide problems independent of local conditions and triggering mechanisms within the confines of the stipulated boundary conditions hence with this framework also unrelated landslide problems can be analyzed and compared as demonstrated herein additionally this approach is useful for two dimensional reconstructions of subsurface displacement and velocity profiles and thus may act as a precursor to detailed field investigation programs warning systems and mitigation projects at minimal costs

criteria for stratigraphic correlation using aerial photographs examples from the south central pyrenees photostratigraphy a new method of aerial photo interpretation establishes local photostratigraphic correlation frameworks with relative chronostratigraphic significance this method is based on the analysis of strata geometry their relationships and the photographic aspect of the rocks for identification and hierarchic organization of photostratigraphic units the definition of these units does not presuppose any a priori genetic implications the units represent volumes of rocks bounded by surfaces with chronostratigraphic significance photostratigraphic units contain time transgressive photofacies and photofacies units which record lithologic and depositional characteristics of the strata the procedure for establishing photostratigraphic correlation frameworks is illustrated through examples from the south central pyrenees direct integration with field data allows the comparison of photostratigraphic frameworks with frameworks based on other stratigraphic criteria photostratigraphy is proposed as an independent and relatively rapid preliminary approach to the study of a basin

stability analysis of three dimensional slopes under water drawdown conditions the traditional approaches for evaluating the stability of slopes or earth dams subjected to water drawdown are performed under plane strain two dimensional 2d condition three dimensional 3d effect is neglected in assessment of the safety of a slope limited by rigid structures or a dam constrained by a narrow valley based on the kinematic approach of limit analysis a 3d rotational failure mechanism is adopted here to investigate the influence of water drawdown on stability of 3d slopes several stability charts are presented to conveniently estimate the safety factor of 3d slopes under four different types of drawdown processes an example is given to demonstrate the difference in the safety factors obtained from 2d and 3d analyses when a slope is constrained to a large width the ratio of the width to the height b h 10 0 the 3d effect can be neglected and the plane strain analysis is appropriate to assess its safety

stratigraphic sequences and their chronostratigraphic correlation abstract the exxon sequence models of posamentier and coworkers incorporate two concepts which i question they suggest that rivers grade to a bayline but evidence from modern major rivers indicates that they do not they also proposed that fluvial sedimentary accomodation space is generated by the seaward shift in equilibrium profiles during sea level fall but this is too simplistic a model based on the use of schematic continental margin configurations which do not incorporate real slope and relief data in most cases a fall in base level leads to deltaic progradation and upstream fluvial incision most coastal plain fluvial wedges result from two processes sea level rise with the drowning and filling of estuaries and active source area tectonism major tectonic events adjacent to foreland basins such as terrane collisions lead to the development of sequences of third order type duration approximately 1 15 m y changes in intraplate stress regimes resulting from changes in regional plate kinematics have a similar episodicity and can be shown to be responsible for some third order cycles on extensional continental margins examination of the chronostratigraphic basis of the mesozoic cenozoic cycle chart of haq and coworkers reveals internal inconsistencies and an unrealistic downplaying of the built in potential for error this chart is not an approved global standard and it should be used with extreme caution

the relationship between the geometry of normal faults and that of the sedimentary layers in their hanging walls abstract we derive an analytical expression that relates the shape of a fault in cross section to the shape of the bedding horizons in its hanging wall block the expression assumes that the hanging wall deforms by simple shear and that the footwall remains undeformed throughout although this paper concentrates on normal faults the expression is equally valid and applicable to thrust faults the direction of simple shear in the hanging wall block is arbitrary and has a dramatic effect on the predicted fault or bedding geometry there is no reason to believe that the simple shear occurs on vertical planes as is commonly assumed in graphical approaches to this problem and ignoring the presence of inclined simple shear is likely to lead to considerable underestimates of the amount of extension across normal faults and in the amount of shortening across thrusts similar though more complicated expressions can be obtained when compaction within the hanging wall block is taken into account for a planar normal fault such compaction may result in the development of a hanging wall syncline

glacial lake saskatchewan and lake agassiz deltas in east central saskatchewan with special emphasis on the nipawin delta the nipawin delta extends eastward from the town of nipawin in east central saskatchewan the prince albert and fort a la corne deltas formed in lake saskatchewan at the mouths of the south and north saskatchewan rivers whereas the nipawin and mossy vale deltas formed in lake agassiz at the mouth of the saskatchewan river these deltas became lower in elevation and younger eastward clays beneath the nipawin and mossyvale deltas can be traced beneath the prince albert and fort a la corne deltas with little change in thickness suggesting that most of the clays beneath the nipawin and mossyvale deltas were deposited during the formation of the prince albert and fort a la corne deltas the nipawin delta formed between 10 200 and 9500 bp the campbell strandline emerson phase was the shoreline of the nipawin delta the mossyvale delta formed about 9500 bp the surface of the mossyvale delta mccauleyville level is about 40 m below the surface of the nipawin delta campbell level

sea level changes an integrated approach sea level changes an integrated approach in october 1985 sepm sponsored a four day conference entitled sea level changes an integrated approach the purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues the conference was successful in bringing together scientists from industry academia and government representing all of the major geosciences disciplines presentations of many new papers plus significant releases of data that were previously held proprietary provided fertile ground for discussion this much cited volume represents the best of the material presented at the conference includes the early vail chart

climate of the supercontinent pangea numerous climate models predict that the geography of the supercontinent pangea was conducive to the establishment of a megamonsoonal circulation in general geologic evidence supports the hypothesis of a megamonsoon that reached maximum strength in the triassic pangea in the late carboniferous had widespread peat formation in what is now central and eastern north america and europe and relatively dry conditions on the colorado plateau the equatorial region of the continent became drier through the end of the carboniferous by the permian the equatorial region of pangea was dry and indicators of aridity and rainfall seasonality became more widespread wind directions from colorado plateau eolian sandstones are consistent with an increasing influence of monsoonal circulation at this time in the triassic climate in the colorado plateau region became relatively wet though still seasonal and the few eolian sandstones indicate a major shift in wind direction at that time in addition sedimentation

origin of rollover rollover is the folding of hanging wall fault blocks by bending or collapse in response to slip on nonplanar commonly listric normal faults the shapes of rollover folds are controlled by a number of variables including 1 the shape of the fault 2 the total fault slip after a bed is deposited 3 the direction of relative particle motion in hanging wall collapse 4 the history of sedimentation rate relative to fault slip rate and 5 compaction the importance and role of each of these variables is illustrated by a two dimensional balanced structural modeling technique that treats continuously curved faults as though composed of a large number of straight fault segments in this modeling an active axial surface oriented parallel to the direction of relative p rticle motion in hanging wall collapse emanates from each fault bend and is the instantaneous locus of folding the quantitative correctness of this theory of rollover is tested by modeling natural structures from the gulf of mexico for which both fault shape and fold shape are known from high quality seismic and well sections the direction of hanging wall collapse commonly is in the antithetic or synthetic normal fault or coulomb shear orientations although sliding along weak bedding planes also is an important collapse mechanism in some regions collapse is in the antithetic shear direction for concave fault bends and in the synthetic shear direction for convex bends these collapse directions can be observed directly in some high quality seismic images as axial surfaces emanating from fault bends the shapes of rollovers within growth strata depend strongly on the sedimentation rate relative to fault slip rate as well as the total slip after a bed is deposited the crests of classic gulf coast rollovers are growth axial surfaces along which are abrupt changes in sedimentation rate within the growth st atigraphic interval these changes are produced by deformation of the sediment water interface along active axial surfaces compaction can substantially modify the relationship between fault shape and rollover shape however under certain common conditions the history of compaction can be neglected if the folding is modeled in the compacted state

dip analysis as a tool for estimating regional kinematics in extensional terranes abstract in basin analyses that rely almost solely on seismic reflection data to configure the underlying structure it has become common practice to use extensional fault geometries to infer kinematic histories this procedure relies on the existence of fault geometries predicted by ideal orthogonal extension and assumes the structure is well constrained in areas where data are sparse or of equivocal quality this often leads to circular analysis that is ideal orthogonal extension is assumed to have been operative then under constrained fault geometries are mapped according to model predictions fault geometries so derived are subsequently used as evidence that orthogonal extension was operative and that the direction of extension is determinable we develop an alternative tool for inferring kinematics which is independent of fault geometries the method relies on the empirical evidence that the dip of the hangingwall s is systematic and predictable in extensional systems even when fault geometries are non ideal although not without significant limitations dip analysis can provide additional constraints for structural and kinematic interpretations especially where seismic reflection data are the main source of information and dip domains define discrete crustal blocks

stratigraphic effects of change from internal to external drainage in an extending basin southeastern nevada observations from southern white river valley southeastern nevada shed light on sediment dispersal and geomorphic development during and after extensional faulting that formed the valley fine grained lacustrine and alluvial sediments of the late neogene white river narrows formation were deposited in a subsiding half graben while coeval coarse grained deposits were confined to within 1 km of the active fault the syntectonic deposits are overlain along an erosional unconformity by post tectonic uniformly coarse grained alluvial plain and fluvial terrace deposits this sequence conforms to a recent proposal that fine grained intervals in extensional basins are deposited syntectonically whereas coarse grained intervals are deposited during post tectonic progradation of marginal clastic wedges the stratigraphy and geomorphology of the study area suggest that post tectonic progradation of coarse clastic sediment resulted from incorporation of the white river valley into the colorado river drainage system meadow valley wash also links previously closed young but presently quiescent extensional basins to the colorado river system by contrast most nearby basins that contain quaternary scarps remain internally drained maintenance of internal drainage by active subsidence therefore may have been important in ponding of coarse grained sediments next to the fault after tectonic subsidence ceased the basin drainage became southward this action resulted in post tectonic progradation of coarse grained clastic deposits as sediment dispersal systems responded to the new external base level regional comparisons however indicate that depending on local rates of tectonic subsidence and erosion a basin may become externally drained syntectonically which can cause syntectonic deposits to be coarse grained in addition a basin may remain closed long after tectonic activity ceases causing fine grained deposits to continue to accumulate in a quiescent basin we conclude that the interplay between internal and external drainage which depends not only on the rate of local fault activity but also regional tectonics climate and other factors is a significant factor in the stratigraphic evolution of continental extensional basins

a transient analysis of slope stability following drawdown after flooding of a highly plastic clay the stability of slopes at bridge abutments across the carrot river in east central saskatchewan was not influenced significantly by drawdown after flooding in the spring of 1995 traditional metho

comment on an alternative view on the origin of chemical and isotopic patterns in groundwater from the milk river aquifer canada by m j hendry and f w schwartz wrr 1988 24 10 1747 1763

movement triggers and mechanisms of two earth slides in the thompson river valley british columbia canada since the construction of the canadian pacific railway and canadian national railway main rail lines in western canada in 1885 and 1905 respectively both companies have had to contend with 11 large translational retrogressive earth slides in the thompson river valley south of ashcroft british columbia the initiation of these slides is associated with the down cutting by the thompson river through the quaternary sediments in its valley the slides move on two subhorizontal weak layers in a glaciolacustrine clay silt unit within this quaternary sediment sequence transient seepage and stability analyses were conducted for two sample slides and the results were in agreement with inclinometer and piezometric data it is concluded that the thompson river triggers the movements in a drawdown mechanism and or erosion mechanism the thompson river affects the stability of these slides in three ways i by changing the pore pressure on the rupture surface ii by changing the supporting force on the toe

first quantitative test of alluvial stratigraphic models southern rio grande rift new mexico since 1978 the results of computational architectural models have been widely used to aid interpretation of ancient alluvial successions here we present the first quantitative test of such models we parameterize variables from field and magnetostratigraphic data collected from the well exposed pliocene pleistocene camp rice and palomas formations of the rio grande rift in south central new mexico computational runs establish that the lab leeder allen and bridge model correctly predicts the gross architectural patterns of ancestral axial rio grande half grabens and full grabens convergence of tectonic subsidence rate and mean sedimentation rate over the studied interval suggests that the dynamic basis of the models is correct i e it is the tectonic drawdown of axially supplied sediment that controls the net preservation potential of alluvial successions

the geometry of listric normal faults and deformation in their hangingwalls abstract in cross sections containing listric extensional faults area balancing techniques for depth to decollement are usually based on either bed length conservation or displacement conservation listric fault geometry may be constructed from a hangingwall roll over profile using the chevron construction this construction based on conservation of heave necessitates a reduction in fault displacement with decreasing fault dip a modification of this construction utilizing conservation of fault displacement predicts a listric fault that detaches at a shallower depth a new construction based on slip lines uses fault perpendicular displacement segments to generate listric fault shape fault propagation strain may be responsible for anomalous hangingwall geometries and these can be predicted by forward modelling using either a modified chevron construction or a slip line construction

the hepburn landslide an interactive slope stability and seepage analysis mechanisms of active landslides are continuous processes involving the dynamics of slope failure interacting with the groundwater regime this process is simulated in phases by combining stability calculations interactively with a seepage analysis to determine the factor of safety for a dormant landslide near hepburn saskatchewan the landslide is a multiple retrogressive failure with two parallel slip surfaces at different elevations the slip surfaces are in originally overconsolidated cretaceous and tertiary clays softened by shear from glaciation an artesian aquifer is present at the base of the slip surface causing saline springs at the base of the valley slope a residual effective friction angle of 6 7 with zero cohesion was found to best characterize the shear strength of the clays in the failure zone potential nets and head profiles from the seepage analysis illustrate the strong influence of changing topography on the groundwater flow system the present day factor of safety for the dormant

balanced cross section construction from seismic sections in areas of extensional tectonics abstract the application of the technique of balanced section construction initially developed for areas of compressional folding and faulting is reviewed with reference to extensional tectonics a number of examples are discussed where these techniques have been successfully applied in the north sea the interpretation of geoseismic sections is considered to be greatly assisted by careful application of geometrical balance and a consideration of strain even in areas of low crustal extensions the nature of seismic sections however places limitations on the validity of balancing which must be borne in mind with such interpretations and wherever possible the balancing of a geoseismic section should be confirmed by complete depth conversion the rapid testing of the integrity of the geoseismic section by attempting to balance the section at the interpretational phase can eliminate many problems as well as allowing the fullest use to be made of the geophysical information

deformation of the deer creek bridge by an active landslide in clay shale two parallel concurrently active slip surfaces of a landslide in clay shale of the cretaceous lea park formation are causing deformation of a bridge structure across the north saskatchewan river n

onlap offlap and the origin of unconformity bounded depositional sequences christie blick n 1991 onlap ofttap and the origin of unconformity bounded depositional sequences mar geol 97 35 56 unconformity bounded depositional sequences represent the fundamental building blocks of sedimentary successions they are typically characterized by onlap at the base and by offlap at the top and they tend to be markedly asymmetrical with onlap accounting for a larger part of any cycle of sedimentation than offlap offlap cannot be attributed solely to erosional truncation but instead implies that sequence boundaries develop over a finite interval of time depositional sequences are commonly associated with a cyclic arrangement of facies but transgressive regressive cycles are out of phase with respect to sequence boundaries which in down dip locations are both overlain and underlain by progradational deposits and hence form during times of regression of the shoreline these observations are used to develop some ideas about the origin of unconformity bounded sequences with reference to the inter related roles of changes in depositional base level and sediment supply in particular it is shown than onlap and offlap are due to lateral migration of a line of critical bypassing defined so as to incorporate the effects of sediment loading and compaction as well as the rate of change of elevation with respect to sea level downward shifts in onlap may be achieved by either an increase in the rate of eustatic fall or a decrease in the rate of tectonic subsidence and it is premature to assume that eustatic and tectonic controls on sea level may be distinguished solely on the basis of the frequency of depositional cyclicity small shifts in the position of onlap can also be produced by changes in sediment supply and more attention needs to be paid to the influence of sediment supply in the development of minor boundaries unconformities related to eustatic fluctuations are thought to correspond approximately to times of relatively rapid sea level fall inflection points but questions remain about the existence of possible leads and lags of up to cycle and hence about the degree to which sequence boundaries of eustatic origin may vary in age both within a given basin and from one basin to another

the sequence stratigraphy of fluvial depositional systems the role of floodplain sediment storage abstract the currently used model for alluvial sequence stratigraphy has been criticised miall 1991 and an alternative model is offered here in this model alluviation mainly takes place during transgressive and not highstand phases when accommodation space allows sediment storage the high capacity for some river systems to store floodplain sediments is a critical consideration the effects of climatic and intrinsic geomorphic changes during fluvial deposition are likely to greatly complicate simple base level controlled sequence models and recognising higher order fourth and fifth order cycles will be particularly difficult

limitations of transient seepage analyses for calculating pore pressures during external water level changes abstractexternal water level variations such as rapid drawdown or flood loading change the internal pore pressures in an embankment as a result of changes in the boundary conditions three different effects result 1 changes in water pressure on the slope change the seepage boundary conditions 2 changes in the total stress applied by the weight of the water on the slope change the confining pressure on the soil and 3 changes in the stabilizing load from the reservoir cause changes in shear stress uncoupled transient seepage analyses which consider only the first effect are increasingly being advocated as an appropriate means to calculate pore pressures for effective stress stability analyses following water level changes this paper discusses the limitations of uncoupled transient seepage analyses for calculating pore pressures during drawdown explains the requirements for more appropriate analyses and gives examples that show the errors incumbent on the use of uncoupled analyses

an alternative view on the origin of chemical and isotopic patterns in groundwater from the milk river aquifer canada the milk river artesian aquifer underlies 15 000 km2 of southern alberta canada it consists of thin 30 75 m thick sandstone and is confined above by the pakowki shale typically 120 m thick and below by the colorado shale the aquifer subcrops in southern alberta and northern montana groundwater movement is to the north west and east from the outcrop area dominant recharge area cl and i concentrations increase in the direction of flow from less than 0 05 and 0 001 mmol l respectively near the recharge area to more than 140 and 0 15 mmol l at the northern edge of the aquifer similarly waters become more enriched in oxygen 18 and deuterium from less than 21 0 and 167 near the recharge area to values approaching 8 0 and 70 0 in the north isotope values in the recharge area plot on the global meteoric water line and indicate that the recharge waters are isotopically unaltered meteoric waters downgradient from the recharge area the data deviate from the meteoric water line slope of 6 3 instead of 8 0 three mechanisms have been advanced to explain the origin of the chemical and isotopic patterns the introduction of connate formation water through the colorado shale and subsequent mixing with infiltrating meteoric water a finite source of meteoric recharge mixing with more saline water in the aquifer and chemical and isotopic enrichment due to ion filtration hydraulic conductivity and hydraulic head data cl concentrations of drill cuttings and isotopic values from groundwater from the colorado shale provide arguments for reevaluating these ideas an alternative mechanism based on diffusion between saline isotopically enriched water in the colorado shale and fresher isotopically depleted water in the aquifer is tested using an analytical mass transport model although uncertainty exists in the model parameters results showed that the patterns in cl i 18o and 2h in the aquifer can be explained by aquitard diffusion further aquitard diffusion must be considered when using chlorine 36 dating methods in aquifer aquitard systems such as the milk river aquifer

tectonic systems tract and depositional architecture of the western border of the triassic iberian trough central spain abstract during the permian and triassic a sedimentary wedge developed overlying a listric normal fault on the western border of the iberian trough central spain an area was selected for study that provides optimal conditions for a detailed analysis to be made of relationships between geometric strata arrangements tectonic control and sedimentary responses the excellent quality of the outcrops allows the observed patterns of strata to be related to fault growth and developmental of the basin the recognition and mapping of local discontinuities throughout the study area were possible packages of similar strata with different angularity can be discerned between the two main discontinuities geometrical relationships can be established for depositional unit boundaries the architectural style and sediment dispersal patterns interpreted as the results of interactions between sedimentation and tectonics are integrated into a three dimensional tectono sedimentary facies model to explain the basin s infilling is interpreted to be tectonic the rift related three dimensionally linked depositional systems recognized might be defined as tectonic systems tract prosser s 1993 rift related linked depositional systems and their seismic expression in williams g d dobb a eds tectonics and seismic sequence stratigraphy geol soc london spec publ 71 35 66 five such tracts are recognized and related to specific phases of tectonic development

tectonic and hydrodynamic control of landslides in the northern area of the central rif morocco the northern edge of the central rif morocco is subject to numerous landslides where mechanisms do not correspond to the classical models used by geomechanics specialists it is necessary to adopt a multidisciplinary approach that combines geomorphology geology hydrogeology and geotechnics in order to understand how such slope failures are generated especially in a region with a heterogeneous structure characterised by significant lithological differences severe fracturing and thrust sheets where tectonic contacts play a major role in groundwater circulation this report shows that these failures are essentially controlled by the tectonic contact separating the tisirene and chouamat thrust sheets and by subsurface hydrodynamic conditions a model of spatial and temporal variations in the factor of safety is proposed

mixed siliciclastic carbonate marine and continental syn rift sedimentation upper jurassic lowermost cretaceous todos santos and san ricardo formations western chiapas mexico initial mesozoic sedimentation in western chiapas represented by the upper jurassic lowermost cretaceous todos santos and san ricardo formations occurred over a horst and graben terrane formed during rifting in the ancestral gulf of mexico basin the todos santos consists of fluviolacustrine sequences deposited over block faulted granodiorite the san ricardo overlies and interfingers with the todos santos and consists of siliciclastics carbonates and evaporites deposited in arid tidal flat beach restricted back barrier lagoon barrier shoreface and shelf environments san ricardo facies distribution outlines three transgressive and regressive or still stand sequences of oxfordian kimmeridgian and tithonian early hauterivian age the correspondence between the ages of these sequences and the age of eustatic cycles suggests that their development was primarily influenced by global sea level changes superimposed on this eustatic pattern are stratigraphic features attributed to variable tectonic subsidence of basement blocks including abrupt lateral thickening or thinning of facies the localization of ooid grainstone deposition on horsts and carbonate platform drowning locally consistent patterns of thickening or thinning of both continental and marine facies indicates rift related block faulting was active throughout todos santos and san ricardo deposition this style of rift basin sedimentation contrasts with the atlantic margin type by including normal salinity marine facies in addition to continental and restricted marine facies the identification of this style in the gulf of mexico is important for reconstructing and differentiating rift and postrift stages of basin development and for predicting the subsurface pattern of upper jurassic neocomian facies

development of tectonic cyclothems in rift pull apart and foreland basins sedimentary response to episodic tectonism the thickest part of asymmetric rift pull apart and foreland basin fills commonly consists of large scale hundreds to thousands of metres thick tectonically generated cyclothems of fine grained marine lacustrine or longitudinal fluvial deposits and coarse grained transverse braid plain or alluvial fan deposits the appearance of coarse clastics in these basin fills is typically noted as the time of tectonically rejuvenated source area uplift based on the conceptual tie between relief and coarse grain size and on the application of the davis theory of landform development we propose the opposite interpretation that the commencement of fine grained sedimentation above coarse grained deposits in a tectonic cyclothem is the best indicator of renewed tectonic activity this reinterpretation is more consistent with 1 modern examples 2 the consideration of source area and sedimentary basin geomorphology 3 the disparity between the reaction rates of the various environments to subsidence 4 the disparity between the rates of tectonic uplift and erosion and 5 the controls on elastic wedge progradation in our model extensive coarse grained clastic wedge progradation is an indicator of tectonically quiescent phases

early depositional history of a rift basin miocene in western sinai abstract the cenozoic stratigraphic record in the gulf of suez provides a model of six events for the early sedimentologic history of a rifted basin classic exposures on the east coast of the suez in the western sinai yield a composite section of the miocene succession 1 1 oligocene early miocene nukul formation terrigenous clastics in fluvial fandelta and littoral environments filled local valleys 2 2 during early miocene transgression lower rudies member nearshore and shelf sediments accumulated at a rate no less than 4 cm 1000 yrs rates of accumulation increased dramatically at the beginning of the middle miocene 3 3 during the early part of the middle miocene basinal muds and evaporites upper rudeis member kareem formation and part of belayim formation accumulated at a rate of 106 146 cm 1000 yrs 4 4 rates slowed during short term shoaling periods when shelf carbonates hammam faraun member were deposited 5 5 a fifth event is represented by more than 2 km of late miocene evaporites zeit south gharib formations which accumulated at a minimum rate of 32 cm 1000 yrs 6 6 the post evaporite event of alluvial and shallow deep marine sedimentation began in the pliocene and is continuing today local carbonate buildups developed upon fault blocks during the second and fourth stages evaporite deposition can be a very rapid process in the filling of rifted basins

time varying reliability analysis of huangtupo riverside no 2 landslide in the three gorges reservoir based on water soil coupling abstract the filling of the three gorges reservoir in china inevitably deteriorated the slope stability near the reservoir and triggered many landslides which have become a serious geo hazard the fluctuation of the water level and the changes in pore water pressure in the slope lead to stability changes of the reservoir slopes taking the huangtupo riverside no 2 landslide hr2l as a case study a comprehensive geotechnical investigation is performed first the soil water characteristics curve swcc and the long term strength of the slip zone soils and landslide soils are obtained based on the experiments second a numerical simulation is used to obtain the distribution characteristics of the saturation line finally the reliability of the landslide is evaluated the results show the following 1 at the same reservoir level the saturation line will change with different reservoir statuses 2 when considering the matric suction the safety factor of the landslide is larger by 3 than that without considering this component 3 as the reservoir water level rises the safety factor of the slope increases 4 the slip zone soils of the landslide show significant creep characteristics under the effect of creep the long term strength decreases gradually 5 considering the long term strength of the slip zone soils the variation of landslide reliability decreases gradually the slope stability gradually changes from a less stable state to a worse state