soft sediment deformation in the shallow submarine slope off nice france as a result of a variably charged pliocene aquifer and mass wasting processes abstract along the ligurian slope near nice southeastern france a combination of natural and man made factors govern slope stability and contributed to a devastating tsunamigenic landslide near nice airport in 1979 based on a total of 72 gravity and kullenberg cores we characterise the architecture and facies of the subbottom sediment a total of six sedimentary facies types were observed three of which represent the pliocene holocene background sediment in the wider nice area while another three are associated with the 1979 landslide and tsunami the three primary facies types are soft silty clay clayey silt somewhat indurated silt sand interbeds and pliocene conglomerates underlying the former the three other facies are poorly sorted mass wasting deposits up to pebble size silt representing the finer fraction of the mobilised mass and a tsunami related bed into which plant debris and artefacts got amalgamated accompanying geotechnical results attest that significant strength variations exist when comparing measurements from the narrow shelf shelf break and shallow slope as well as the 1979 slide scar factors such as groundwater charging in the more permeable horizons further lower the effective stress and in places approach lithostatic above such permeable silt sand beds deformation of soft clay is observed suggesting that leaching of ions from the clay mineral surfaces and frayed edges also facilitates weakening and creep micro slumping and folding elevated water supply as well as hydraulic fracturing of the clayey sediment is further attested by pipes of cm diameter and several decimeters length which entrained very soupy mud in the shallowmost deposits in and landward of the slide scar we also observe remnants from the catastrophic deposition associated with the 2 3 m high tsunami wave triggered in 1979 as attested by amalgamated sea grass and artefacts based on our observations and measurements on core scale and earlier models based on in situ cptu we suggest that a significant part of the quaternary delta and slope apron deposits are prone to being mobilised without a large external trigger so that all in all a high risk for a landslide event of considerable size off nice international airport is identified

an integrated model of extrusive sand injectites in cohesionless sediments clastic injection and surface expression of subsurface sediment remobilization is a phenomenon which is becoming increasingly recognized however understanding of the physical mechanisms that control these features remains limited dominated by inference from outcrop and seismic studies here this limitation is addressed through a set of experiments focused on the development and evolution of fluidization features in non cohesive bedded sequences fluidization and the onset of piping are shown to occur progressively through a sequence of discrete phases with initial void formation development of infiltration horizons rupture and finally pipe formation critically the style of piping the stability of piping and the temporal evolution of venting are shown to exhibit considerable variability in particular pipes may either be stable or very mobile migrating laterally over large distances these produce deposits that are typically interpreted in outcrop as being the product of en masse liquefaction rather than localized dynamic fluidization these differing elements are synthesized to produce a model of sand extrudites in addition the implications of this model are explored

soft sediment deformation structures induced by strong earthquakes in southern siberia and their paleoseismic significance abstract liquefaction induced soft sediment deformation structures ssds formed by earthquakes in southern siberia that were historically mentioned or monitored by instruments are described and analyzed clastic dikes are the most common among all ssds in the epicentral areas of the investigated seismic events they are also the most reliable paleoseismic indicators in regions where cryogenic processes are intense we suggest seven criteria that may be useful to distinguish the seismogenic clastic dikes from non seismogenic ssds in a single outcrop 1 pushed up sedimentary blocks within the dike body 2 regular distorted contacts of a dike with host sediments reflecting cyclic loading during propagation of seismic waves 3 turned up layers of host deposits on contacts with a dike 4 displacement along dike contacts usually in the form of a normal fault caused by subsidence that compensates for the removed sediment 5 a dike structure similar to a diapir 6 filling of a clasic dike with coarser materials than the host sediments and 7 a sediment layer extruded on the surface or between strata similar in composition to the dike in the extruded sandy gravel pebble layer rock fragments show normal grading from large to small clasts in addition to these indicators fractures may indirectly indicate the seismogenic genesis of liquefaction induced ssds due to the close spatial relationship of dikes with the fault structures of the investigated areas they can be used to identify seismogenic fault and the characteristics of dikes lateral gradual changes in the frequency size and type of the deformations can help to determine the epicenter magnitude and the local intensity of the associated earthquakes

modelling seismites with a digital shaking table abstract soft sediment deformation structures induced by seismically triggered liquefaction and or fluidization seismites have been reproduced with a digital shaking table we have used natural sediments with variable granulometric ranges clay silt and sand and an earthquake simulator that is able to reproduce real tridimensional seismograms acceleration and pore pressure recording allowed us to follow liquefaction and or fluidization processes in unconsolidated sediments during earthquakes different types of seismites were produced by variations in the tested sedimentary column

experimental studies of the fluidization of layered sediments and the formation of fluid escape structures experiments demonstrate that fluid escape structures can be produced as a result of unstable fluidization behaviour where a lower base layer of granular material is inhibited from fluidizing by the presence of an overlying non fluidizing top layer before the base layer can fluidize the weight of the overlying material must be balanced and this is accomplished by base layer material pressing against the bottom surface of the confining top layer forming a static layer this static layer allows the top layer to lift away from the base layer which is then free to fluidize a water filled crack forms below the static layer and as this grows instability causes the static layer and top layer to bend and conical voids to form below the antiformal sections rupture occurs at the apex of the water void allowing the underlying water and fluidizing material to burst out through the top layer the fluidized base layer material then flows through the rupture until all of this material except that in the static layer is deposited above the previously overlying layer and a stable fluidization system results the top layer material is bent upwards around the rupture and the resulting pillar type escape structure is preserved if flow then ceases the vigour of the burst out is greatest when the base layer material has a grain size 15 of the top layer material if the base layer grain size is less than 8 of the top layer then base layer material will pass through the top layer pore spaces without forming an escape structure if cohesive material is present escape structures form when a layer of fine grained cohesive material overlies a layer of cohesionless material at low flow rates small pipes with scattered angular bends pierce the top layer and base layer material passes through them the base layer material is ejected on to the top layer and builds up around the mouth of each pipe to form constructional structures sand volcanoes this is in contrast to the cohesionless experiments where the weight of material being deposited on the top layer caused an ejecta filled depression to form around the rupture if flow then ceases both the pipes and the sand volcanoes are preserved at high flow rates where the base layer fluidizes the top cohesive layer becomes fragmented small fragments circulate within the fluidizing base layer and are preserved as floating clasts large fragments sink to the bottom of the fluidizing base layer erosion of the bottom surface of these larger fragments causes this surface to become convex downward the experimentally derived structures are similar to pillar type structures observed in the field and the processes described can be used to investigate the development of these structures fluidization experiments also demonstrate the genesis of dish structures and the cohesive behaviour can be applied to the deformation of these structures after initial formation

experimental studies of gas escape and water escape structures mechanisms and morphologies abstract water escape and gas escape structures were generated in the laboratory to assess variations in deformational structures generated during these events particulate fluidization was observed to be the method by which grains were redistributed during water escape resulting structures of particulate fluidization comprised disrupted and downward deflected primary laminations and a massive appearing column of sand above the point source gas experiments with a low flow rate 6 167 10 6 m3 s allowed gas to disperse through fractures and only subtle deformation was achieved aggregative fluidization i e fluid movement through sediment as bubbles was the mechanism for grain displacement during gas escape with increased flow rate 7 67 10 5 m3 s aggregative fluidization occurred and particles were carried upward in the wake of the passing gas bubble aggregative fluidization resulted in broken upwards warping laminations and convoluted bedding experiments illustrate a significant morphological difference between water escape and gas escape water escape structures were bounded by downwards warping laminations consistent with water escape structures encountered in the rock record gas escape structures displayed upwards warping laminations and could represent a formation mechanism for convolute bedding

tectonic triggering of slump sheets in the upper cretaceous carbonate succession of the porto selvaggio area salento peninsula southern italy synsedimentary tectonics in the apulian carbonate platform abstract soft sediment deformation structures crop out in the upper cretaceous carbonate succession in porto selvaggio cove in the western salento peninsula apulian foreland southern italy the deformed interval is about 13 m thick and occurs between shallow water limestones and dolostones formed in peritidal and shallow subtidal environments it comprises well bedded grey mudstones interlayered with dark grey laminated microbioclastic wackestones characterized by couplets of closely spaced dark and bright laminae marked by the parallel orientation of calcareous microbioclasts and thin shelled bivalves the low biological diversity scarcity of burrowing biota and presence of a well preserved fish fauna provide evidence of anoxic conditions occurring in morphological depressions within the platform and a stagnant stratified water body affected by weak bottom currents indicating the sudden development of a localised and short lived intraplatform basin two soft sediment deformation horizons slump sheets separated by undeformed limestones with similar facies occur in this part of the succession the lower thicker slump sheet 1 0 1 3 m thick contains asymmetric and box folds well developed decollement surfaces locally containing thick brecciated zones cut the folds forming small scale thrust sheets and indicating mixed plastic to brittle behaviour the upper thinner slump sheet 0 25 0 35 m thick contains only asymmetric folds indicating plastic behaviour only the differences in deformation style are attributed to differences in facies measurements of fold axis orientations in the slump sheets show that they moved in similar directions recording the development of a local gently dipping palaeoslope autogenic internal trigger mechanisms are ruled out by a detailed consideration of facies the slump sheets were triggered by allogenic tectonic effects either the weakening of sediment by seismic activity or the tectonically induced steepening of slopes or a combination of both tectonically induced steepening is consistent with localised and sudden vertical facies changes related to the creation of an intraplatform basin the occurrence of slump sheets in carbonate platform successions is unusual since carbonate platforms are normally associated with shelves or low angle ramps

convolute laminations and load structures in turbidites as indicators of flow reflections and decelerations against bounding slopes examples from the marnoso arenacea formation northern italy and annot sandstones south eastern france abstract this work discusses the significance of particular types of soft sediment deformations very common within turbidite deposits namely convolute laminations and load structures detailed facies analyses of the foredeep turbidites in the marnoso arenacea formation northern italy and annot sandstones south eastern france show that these deformational structures tend to increase near morphological obstacles concomitantly with contained reflected beds the lateral and vertical distribution of convolute laminae and load structures as well as their geometry has a well defined depositional logic related to flow decelerations and reflections against bounding slopes this evidence suggests an interaction between fine grained sediment and the presence of morphologic relief and impulsive and cyclic wave loadings which are produced by flow impacts or reflected bores and internal waves related to impinging bipartite turbidity currents

seismites from a well core of palustrine deposits as a tool for reconstructing the palaeoseismic history of a fault abstract the concud fault is located at the junction between the jiloca and teruel grabens central eastern iberian chain spain the late pleistocene activity of this fault has been well logged from structural and palaeoseismological trench studies but only scattered data of the late pliocene seismic activity exist the late pliocene early pleistocene syn tectonic infill consists of an endorheic continental succession in which a 75 m long continuous well was drilled near the concud fault along the entire well core several types of soft sediment deformation structures with variable morphology size and frequency have occurred including clastic dykes load structures and slumps the rigorous analysis of the deformation structures their relationships with the involved sedimentary facies and the discrimination of possible deformation mechanisms and trigger processes allow us to interpret part of them as seismically induced structures the recognition of 21 deformed beds seismites allow the late pliocene early pleistocene seismic history of the concud fault to be reconstructed therefore 21 seismic events with m 5 and an apparent recurrence period of about 45 ka have been inferred

deformed cross stratified deposits in the early pleistocene tidally dominated catanzaro strait fill succession calabrian arc southern italy triggering mechanisms and environmental significance abstract the early pleistocene catanzaro strait fill succession consists of large scale tidal sets accumulated in a tectonically confined basin during a phase of rapid relative sea level rise it crops out mainly in the present day catanzaro trough where numerous field sections supported the characterization of the vertical and lateral facies variations and the documentation of a variety of soft sediment deformation structures exposed throughout their vertical and lateral extents the soft sediment deformation structures ssds are the result of liquefaction and fluidization processes that deformed cross laminations and other primary structures into folds fluid escape structures and structureless expanses three different groups of ssds have been documented in the cross stratified deposits of the catanzaro strait the detailed description of these soft sediment deformation structures in a depositional context established by facies analysis enables interpretation in terms of possible trigger mechanisms consistent relationships between the occurrence of distinctive ssds and specific tidally dominated facies have been established indicating a probable autogenic origin for the soft sediment deformations liquefaction and fluidization features are interpreted as the result of increases in water pore pressure induced by overloading in particular two types of overloading agents are hypothesized which affect the lee and stoss sides of the migrating dunes in distinct events and inducing the deformation of foreset laminae or sets of cross strata respectively

seismically induced liquefaction structures in la magdalena archaeological site the 4th century ad roman complutum madrid spain abstract the ancient roman city of complutum alcala de henares madrid founded in the 1st century ad was one of the most important cities of hispania the old roman city was destroyed abruptly abandoned relocated close by and rebuilt during the late 4th century ad destruction of the city and its relocation has not yet been explained by archaeologists in this paper with our multidisciplinary approach we identify and characterize earthquake archaeological effects eaes affecting the archaeological site the la magdalena an agricultural holding 4 km from the core of complutum the most important eaes in the site are liquefactions sand dikes and explosive sand gravel craters affecting roman structures such as water tanks cisterns houses and graves ground liquefaction generated significant ground cracks explosive craters and folds in foundations of buildings several other roman sites throughout the valley were also abandoned abruptly during the 4th century ad in some cases with eaes of similar origin this suggests the occurrence of a 5 0 6 6 mw seismic event in the zone in accordance with the minimum empirical limit of seismically induced liquefaction and the maximum surface rupture length of the henares fault

sedimentary record of seismic events in the eocene green river formation and its implications for regional tectonics on lake evolution bridger basin wyoming abstract outcrops and cores from the top of the lacustrine tipton member and the base of the wilkins peak member 51 5 ma of the eocene green river formation bridger basin in southwestern wyoming yield a wide variety of sedimentary deformation features many of which are laterally extensive for more than 50 km they include various types of folds load structures pinch and swell structures microfaults breccias and sedimentary dikes in most cases deformation is represented by hybrid brittle ductile structures exhibiting lateral variation in deformation style these occur in low energy profundal organic rich carbonate mudstones oil shales trona beds tuffs and profundal to sublittoral silty carbonate deposited in paleolake gosiute the deformation is not specific to the depositional environment because sedimentary units stratigraphically higher with similar facies show no deformation the studied interval lacks any evidence for possible trigger mechanisms intrinsic to the depositional environment such as strong wave action rapid sediment loading evaporite dissolution and collapse or desiccation so endogenic causes are ruled out thus the deformation features are interpreted as seismites and change in deformation style and inferred increase in intensity towards the south suggest that the earthquakes were sourced from the nearby uinta fault system the 22 levels exhibiting seismites recognized in cores indicate earthquakes with minimum magnitudes between 6 and 7 minimum epicentral intensity mcs of 9 and varying recurrence intervals in the seismic history of the uinta fault system with a mean apparent recurrence period of 8 1 k y using average sedimentation rates and dated tuffs in detail however there are two noticeably active periods followed by relative quiescence the stratigraphic position of these deformed intervals also marks the transition between two distinct stages in lake evolution from the balanced filled tipton member to the overlying underfilled wilkins peak member thus these seismites are evidence for regional scale changes in lacustrine sedimentation of eocene lake gosiute in response to syndepositional tectonic activity analysis of synsedimentary deformation features is therefore a promising yet under utilized tool to trace the tectonic evolution of lacustrine deposits of the green river formation and other tectonically active marine and non marine basins

geometry and lithofacies of coarse grained injectites and extrudites in a late pliocene trench slope basin on the southern boso peninsula japan abstract this study investigates the geometry and internal structures of coarse to very coarse grained volcanic sandstones and volcanic breccias with many siltstone clasts interpreted to be sill like injectites and extrudites occurring in an upper pliocene trench slope basin succession on the southern boso peninsula japan the injectites occur in the uppermost shiramazu formation and pinch out laterally into siltstone dominated deposits of the mera formation their thicknesses vary from a few centimeters to 2 m the basal and upper contacts of the injectites with host muddy deposits are sharp and or erosional and are locally discordant with the bedding of the host deposits siltstone clasts which were ripped up or ripped down from the host muddy deposits are commonly incorporated into the injectites although some siltstone clasts have geological ages older than those of the host deposits seven lithofacies have been identified in the injectites based on the internal structures the combinations of internal structures are different from those of high density turbidity current deposits and debrites and suggest that injection was promoted by a combination of turbulent and laminar flow conditions the extrudites show an overall convex up geometry and possess lithological features similar to those of the injectites they have been identified in the rendaiji conglomerate member which is encased in the mera formation and which rests on the uppermost shiramazu formation the extrudites are characterized by gently undulating waveforms that show upstream migration and climbing stacking patterns similar to the cross sectional geometry of cyclic steps or upstream migrating antidunes the active eruption of solid liquid mixtures onto the seafloor and sedimentary piles may have subsequently collapsed to produce supercritical high density gravity currents down the flanks of a neptunian volcano the injectites and extrudites locally contain calyptogena shells and shell fragments as well as fragments of carbonate concretions that exhibit low carbon isotopic ratios suggesting that fluidization of the source sediments was triggered by a combination of seepage of cold methane bearing water into the source sediments and seismic shaking volcaniclastic deposits older than the host muddy deposits are present in the trench slope basin deposits and these are the likely source of the injectites and extrudites

sedimentary and structural controls on seismogenic slumping within mass transport deposits from the dead sea basin abstract comparatively little work has been undertaken on how sedimentary environments and facies changes can influence detailed structural development in slump sheets associated with mass transport deposits mtds the nature of downslope deformation at the leading edge of mtds is currently debated in terms of frontally emergent frontally confined and open toed models an opportunity to study and address these issues occurs within the dead sea basin where six individual slump sheets s1 s6 form mtds in the late pleistocene lisan formation all six slumps which are separated from one another by undeformed beds are traced towards the ne for up to 1 km and each shows a change in sedimentary facies from detrital rich in the sw to more aragonite rich in the ne the detrital rich facies is sourced predominantly from the rift margin 1 5 km further sw while the aragonite rich facies represents evaporitic precipitation in the hyper saline lake lisan the stacked system of mtds translates downslope towards the ne and follows a pre determined sequence controlled by the sedimentary facies each individual slump roots downwards into underlying detrital rich layers and displays a greater detrital content towards the sw which is marked by increasing folding while increasing aragonite content towards the ne is associated with more discrete thrusts the mtds thin downslope towards the ne until they pass laterally into undeformed beds at the toe the amount of contraction also reduces downslope from a maximum of 50 to

controls on space time distribution of soft sediment deformation structures applying palaeomagnetic dating to approach the apparent recurrence period of paleoseisms at the concud fault eastern spain abstract this work describes soft sediment deformation structures clastic dykes load structures diapirs slumps nodulizations or mudcracks identified in three sections concud ramblillas and masada cociero in the iberian range spain these sections were logged from boreholes and outcrops in upper pliocene lower pleistocene deposits of the teruel concud residual basin close to de concud normal fault timing of the succession and hence of seismic and non seismic ssdss covering a time span between 3 6 and 1 9 ma has been constrained from previous biostratigraphic and magnetostratigraphic information then substantially refined from a new magnetostratigraphic study at masada cociero profile non seismic ssdss are relatively well correlated between sections while seismic ones are poorly correlated except for several clusters of structures between 29 and 35 seismic deformed levels have been computed for the overall stratigraphic succession factors controlling the lateral and vertical distribution of ssdss are their seismic or non seismic origin the distance to the seismogenic source concud fault the sedimentary facies involved in deformation and the observation conditions borehole core vs natural outcrop in the overall stratigraphic section seismites show an apparent recurrence period of 56 to 108 ka clustering of seismic ssdss levels within a 91 ka long interval records a period of high paleoseismic activity with an apparent recurrence time of 4 8 to 6 1 ka associated with increasing sedimentation rate and fault activity such activity pattern of the concud fault for the late pliocene early pliocene with alternating periods of faster and slower slip is similar to that for the most recent quaternary last ca 74 ka bp concerning the research methods time occurrence patterns recognized for peaks of paleoseismic activity from ssdss in boreholes are similar to those inferred from primary evidence in trenches consequently apparent recurrence periods calculated from ssds inventories collected in borehole logs close to seismogenic faults are comparable to actual recurrence times of large paleoearthquakes

facies control on seismites in an alluvial aeolian system the pliocene dunefield of the teruel half graben basin eastern spain abstract the recognition of seismically induced soft sediment deformation structures ssds in sedimentary successions characterized by different facies and hence by different rheology is challenging this is the case for high porosity and high permeability aeolian facies interbedded with muddy wet interdune deposits and alluvial conglomerates and sandstones several types of ssds have been studied in two exposures of the upper pliocene 2 9 2 6 ma sediments of a fault bounded intracontinental aeolian dune field in the teruel basin iberian chain eastern spain among ssds load and fluid escape structures apart from several animal tracks have been recognized those structures show an irregular distribution through the studied stratigraphic sections being scarce in homogenous aeolian sands and frequent in water related facies a detailed study of the distribution and geometry of ssds and their relationships with respect to the stratigraphic architecture and facies has allowed a critical discrimination of trigger mechanisms i e biological or physical overloading vs earthquakes the seismically induced structures are concentrated into seven deformed beds showing an uneven lateral distribution and geometry closely controlled by the hosting sedimentary facies and their rheology these seismites resulted from liquefaction during moderate earthquakes estimated magnitude from 5 0 to 6 8 the most probable seismogenic source was the sierra del pobo normal fault zone located 2 km to the east results show how an appropriate recognition of sedimentary facies is crucial to understand the lateral variability of seismites in sedimentary environments characterized by sharp facies changes

clastic dykes of the devono carboniferous horton bluff formation nova scotia storm related structures in shallow lakes abstract clastic dykes are common in the late devonian to early carboniferous horton bluff formation of nova scotia where they occur in wave dominated shoreline deposits of lacustrine shoaling upward cycles the dykes typically less than 25 cm wide and 40 cm in vertical extent project downward into clayshale from broad loads at the base of elongate isolated lenses of hummocky cross stratified siltstone ptygmatic folding of the dykes reflects a shale siltstone compaction ratio of 2 3 times and maximum depth of dyke penetration prior to compaction was 1 m dyke orientation parallels the orientation of wave ripple crests and the elongation direction of the siltstone lenses dyke formation was penecontemporaneous with sedimentation dyke and load formation was probably initiated in shallow water during storms which promoted sediment failure through cyclic wave loading microseisms and rapid deposition of hcs bearing siltstone lenses reversed density gradient and uneven sediment loading from silt lenses probably promoted downward emplacement loads reflect ductile failure of surficial water rich mud whereas dykes reflect downward injection of silt following brittle failure of underlying more compacted mud the depositional slope provided a tensional stress that controlled the fracture direction orthogonal to the slope of the failed sediment

soft sediment deformation produced by tides in a meizoseismic area turnagain arm alaska turnagain arm is a semidiurnal hypertidal estuary in southeastern alaska with a recorded tidal range of 9 m contorted bedding and flow rolls preserved in tidal sediments within the estuary have previously been interpreted as resulting from the mw 9 2 great alaskan earthquake of 1964 horizons of flow rolls between undeformed beds in sediments and rock strata have been used to infer ancient earthquakes in other areas although many types of soft sediment deformation structures can be formed by earthquakes observations of sedimentation on tidal flats in the inner parts of turnagain arm in the summers of 2003 and 2004 show that a wide range of soft sediment deformation structures similar to those inferred to have been formed by earthquakes can form in macrotidal estuaries in the absence of seismic shock during sedimentation rate measurements in 2004 soft sediment deformation structures were recorded that formed during one day s tide either in response to overpressurization of tidal flats during rapid tidal drawdown or by shear stress exerted on the bed by the passage of a 1 8 m tidal bore structures consisted of flow rolls dish structures flames and small dewatering pipes in a bed 17 cm thick in the future if the flow rolls in turnagain arm were found in isolated outcrops across an area 11 km in length in an estuary known to have been influenced by large magnitude earthquakes would they be interpreted as seismites these examples show that caution is needed when using horizons of flow rolls to infer paleoseismicity in estuarine deposits because many of the mechanisms tidal flux tidal bores slumping flooding that can cause deformation in rapidly deposited unconsolidated silts and sands are orders of magnitude more common than great earthquakes

towards establishing criteria for identifying trigger mechanisms for soft sediment deformation a case study of late pleistocene lacustrine sands and clays onikobe and nakayamadaira basins northeastern japan five main deformation units discrete sheets of deformed sediments that lie between a significant thickness of undeformed sediment were selected for study within late pleistocene lacustrine sands and clays in the onikobe and nakayamadaira basins northeastern japan the deformed units show evidence of deformation by a variety of mechanisms including fluidization liquefaction brittle failure and cohesive flow driving forces are thought to be primarily reverse density gradient systems but also include gravitational body force shear stress and unequal loading the main trigger mechanisms are firstly earthquakes secondly overloading from volcanic sands and thirdly to a lesser extent subaqueous currents consideration is given to criteria that allow the trigger mechanism to be identified this study shows that the following criteria can be used to identify a seismic triggering agent i setting ii the extent of the deformation units iii absence of evidence relating to other potential trigger mechanisms and iv evidence relating to other potential trigger mechanisms is present but can be seen elsewhere in the stratigraphic section associated with undeformed sediment conversely the following criteria while they are important in interpreting the driving force and deformation mechanism have no relevance to the trigger mechanism i sediment composition ii deformation structures being restricted to a single stratigraphic interval 1 m thick not necessarily correlatable over large areas and iii similarity to structures in the literature

soft sediment deformation structures in the lixian lacustrine sediments eastern tibetan plateau and implications for postglacial seismic activity abstract the eastern margin of the tibetan plateau is characterized by frequent earthquakes which are closely associated with tectonic activity to assess tectonic activity during the late pleistocene we studied a well exposed 23 m thick lacustrine sequence on the eastern margin of the plateau and found a variety of soft sediment deformation ssd structures distributed in 24 stratigraphic levels they comprise clastic dykes ball and pillow structures flame structures clastic gravels micro faults and slump folds most of the ssd structures indicate deformation mechanisms related to liquefaction and or fluidization processes most probably triggered by paleoseismic events given at least 4 historical earthquakes of m 7 in the study area most ssd structures in the lixian lacustrine sequence indicate seismic events with m 6 while simple flame structures point to some lower magnitude earthquakes osl dating indicates that the sequence accumulated between 15 8 and 6 0 ka giving a mean recurrence interval of 480 years for the 24 events and demonstrating that lacustrine sediments in eastern tibet have the potential to record a continuous seismic history on the centennial scale

terrestrial sensitivity to abrupt cooling recorded by aeolian activity in northwest ohio usa article i nfo article history received 7 may 2010 available online 21 february 2011 optically stimulated luminescence dated sand dunes and pleistocene beach ridges in northwest ohio are used to reconstruct landscape modification more than 5000 yr after deglaciation four of the osl ages 13 3 11 1 ka cluster around the younger dryas cold event five ages 10 8 8 2 ka cluster around the preboreal one young age 0 9 0 7 ka records more recent aeolian activity and one age of 15 1 13 1 ka dates a barrier spit in lake warren in northwest ohio both landscape instability recorded by aeolian activity and a vegetation response recorded by pollen are coeval with the younger dryas however the climate conditions during the preboreal resulting in aeolian activity are not recorded in the available pollen records from this we conclude that aeolian dunes and surfaces susceptible to deflation are sensitive to cooler drier episodes of climate and can complement pollen data younger dryas and preboreal aged aeolian activity in northwestern ohio coincides with aeolian records elsewhere in the great lakes region east of the prairie forest ecotone

soft sediment deformation structures in the mio pliocene misaki formation within alternating deep sea clays and volcanic ashes miura peninsula japan abstract the mio pliocene misaki formation of the miura group miura peninsula japan shows an extremely wide variety of soft sediment deformation structures the most common deformation structures are load casts and associated flame structures dish and pillar structures synsedimentary faults multilobated convolutions chaotic deformation structures sedimentary veins and dykes and large scale slides and slump scars the formation which accumulated in a deep sea environment 2000 3000 m is well exposed in and around jogashima it consists of relative thin commonly dm scale alternations of deep marine fine grained sediments and volcanic ejecta that are as a rule coarse grained since the formation represents fore arc deposits of the izu bonin and the honsu arc collision zone it might be expected that tectonic activity also played a role as a trigger of the soft sediment deformation structures that abound in these sediments this is indicated indeed by the abundance of soft sediment deformations over large lateral distances that occur in numerous beds that are sandwiched between undeformed beds on the basis of their characteristics and the geological context these layers can be explained satisfactorily only by assuming deformation triggered by seismicity which must be related to the izu bonin and honsu arc collision the layers thus form deep marine seismites

experimental soft sediment deformation structures formed by the liquefaction of unconsolidated sands and some ancient examples the effects of liquefaction in saturated sand bodies under a variety of driving forces are described from shaking table experiments and structures from the geological record are presented which are analogous to the experimental structures the collapse of sloping heaps of cross bedded sand under a gravitational body force generates low angle essentially uncontorted stratification a basal zone of shearing may be present with steepened and folded foresets stretching of foresets may be accommodated on normal faults and bottomsets may be contorted into inclined folds in natural systems the substrate may also liquefy causing deformation driven by an unevenly distributed confining load stratification in the surface bedform is flattened and stratification in the substratum contorted experiments failed to produce relative displacement at the interface between stacked sand bodies liquefaction of gravitationally unstable systems in sands generates load structures comparable to those from sand mud systems recumbent folded deformed cross bedding is formed by current shear over a liquefied bed as has been inferred from field and theoretical analyses shear of nonliquefied sand forms angular folds other deformation mechanisms such as fluidization or seepage may generate structures similar to all of these local water escape structures driven by fluidization occur in the upper parts of some liquefied sand bodies they include cusps sand volcanoes and clastic dykes transient cavities formed in some experiments and seemed to be preserved as breached cusps although the experiments tried to isolate individual driving forces driving forces may operate together and there may be a continuum between deformation driven by water escape and deformation driven by loading different structures from those described here may form where liquefaction develops in a buried layer as opposed to at the sediment surface

sediment creep on slopes in pelagic limestones upper jurassic of northern calcareous alps austria abstract slump structures in upper jurassic pelagic limestones of the northern calcareous alps were studied using methods of ductile structural geology the early deformation observed cannot be explained by conventional models for slumping commonly describing slump complexes with an extending upper and contracting lower part instead the structures suggest distributed bedding parallel surficial stretching and folding localized by roll over normal faulting the initially isoclinal and recumbent folds are pervasively overprinted by stretching causing reorientation of fold axes into the downslope direction transport of folds separates antiformal and synformal hinges and the resulting isolated hinges resemble intrafolial folds in metamorphic terranes only folds formed late in the process of lithification allow insight in the early stages of fold evolution we suggest that this type of early deformation represents sediment creep that may be characteristic for slump structures in pelagic carbonates

paleohydrologic controls on soft sediment deformation in the navajo sandstone abstract many workers have noted the presence of contorted cross strata in the navajo sandstone and other ancient eolianites and have recognized their significance as indicators of sediment saturation during the accumulation history horowitz 1982 proposed a general model for the production of such features in ancient ergs by episodic seismically induced liquefaction of accumulated sand a key feature of that popular model is the prevalence of a flat water table characteristic of a hyper arid climatic regime during deformation under arid climatic conditions the water table is established by regional flow and liquefaction is limited to the saturated regions below the level of interdune troughs however various paleohydrological indicators from navajo sandstone outcrops point toward a broader range of water table configurations during the deformation history of that eolianite some outcrops reveal extensive deformation complexes that do not appear to have extended to the contemporary depositional surface these km scale zones of deformation affecting multiple sets of cross strata and grading upward into undeformed crossbeds may represent deep water table conditions coupled with high intensity triggers which produced exclusively intrastratal deformation such occurrences contrast with smaller scale complexes formed within the zone of interaction between the products of soft sediment deformation and surface processes of deposition and erosion the horowitz model targets the smaller scale deformation morphologies produced in this near surface environment this study examines the implications of a wet climatic regime for the horowitz deformation model it demonstrates how a contoured water table characteristic of humid climates may have facilitated deformation within active bedforms as well as in the accumulation intra dune deformation would enable deflation of deformation features during the normal course of dune migration more parsimoniously accounting for the frequent occurrence of erosionally truncated deformation structures in the navajo sandstone the production of such erosional truncations during bedform climb and aggradation of the accumulation and the dramatic fluctuations in the water table required to deposit dry eolian sand deform those deposits under saturated conditions and then dry the deformed sand to enable deflation

new sedimentary structures in seismites from sw tanzania evaluating gas vs water escape mechanisms of soft sediment deformation seismite horizons are abundant in cretaceous sandstones of the rukwa rift basin southwestern tanzania diverse morphologies of soft sediment deformation are preserved including two new unusual sedimentary structures herein referred to as 1 balloon shaped inflation structures and 2 surface fractures with linked sandstone splays this original description of new sedimentary structures contributes to the growing catalogue of seismically induced deformation features their unusual morphologies bring to the forefront an important though seldom touched upon question of how to differentiate between gas and water escape in soft sediment deformation features the recognition of the spectrum of soft sediment deformation structures contained in strata and their deformational mechanisms is important because it permits the differentiation between triggering mechanisms particularly seismic activity and can constrain such events spatially and temporally we interpret the surface fractures and linked sandstone splays to reflect a high gas effusion rate formed by the release of high pressure gas followed by a limited expulsion of water the balloon shaped inflation structures reflect lower gas effusion rates due to expulsion of lower pressure gas that did not breach the cretaceous surface seal when these gas pulses did breach the paleosurface they formed gas discharge pits these seismogenic structures are consistent with deposition of cretaceous strata in the rukwa rift during periods of active carbonatite volcanism seismicity and possibly hot spring activity this documentation serves as an important data point for the re examination of the classification scheme of soft sediment deformation structures as primarily water escape structures to accommodate for the genesis of some secondary sedimentary features by gas escape

seismically induced soft sediment deformation structures associated with the magallanes fagnano fault system isla grande de tierra del fuego argentina abstract in this paper evidence of paleoearthquake induced soft sediment deformation structures associated with the magallanes fagnano fault system in the isla grande de tierra del fuego southern argentina has been identified well preserved soft sediment deformation structures were found in a holocene sequence of the udaeta pond these structures were analyzed in terms of their geometrical characteristics deformation mechanism driving force system and possible trigger agent they were also grouped in different morphological types sand dykes convolute lamination load structures and faulted soft sediment deformation features udaeta a small pond in argentina tierra del fuego is considered a quaternary pull apart basin related to the magallanes fagnano fault system the recognition of these seismically induced features is an essential tool for paleoseismic studies since the three main urban centers in the tierra del fuego province of argentina ushuaia rio grande and tolhuin have undergone an explosive growth in recent years the results of this study will hopefully contribute to future analyses of the seismic risk of the region

the relationships between soft sediment deformation structures and synsedimentary extensional tectonics in upper triassic deep water carbonate succession southern tethyan rifted continental margin central sicily abstract we describe soft sediment deformation structures into the upper triassic cherty limestone outcropping in the pizzo lupo section central sicily italy pertaining to the deep water palaeodomain of the southern tethyan margin in the study section mainly consisting of thin bedded mudstone marl alternations with bedded chert intercalations some lithofacies have been separated on the basis of the abundance of the calcium carbonate clay content and the overall textural features the deformational structures displaying different deformational styles as folded and faulted beds disturbed layers clastic dikes and slumps occur mainly in the deformed horizons that involve marl dominated lithofacies small scale water escape structures involve beds with nodular fabric synsedimentary faults affect the mud limestone dominated lithofacies which are characterized by fault rotating blocks producing lateral thinning these bodies appear to have moved coherently along an overall planar surface we relate these soft sediment deformations to slump sheets associated with down slope sliding of sedimentary masses the deformation mechanism and driving force for these soft sediment deformations are due essentially to gravitational instability and dewatering detailing rotational slump and translational glide slides and water escape are the main processes causing the distinguished deformational styles the synsedimentary extensional tectonics that affected the upper triassic pelagic deposits was the triggering process responsible for the instability of the seafloor inducing loss of coherence of the unconsolidated sediments on the sea bottom developing a large number of gravity driven slides the analysis of both of these ssdss and their relationships with the structural scenario allow us to hypothesise that they are seismically induced

earthquake induced soft sediment deformation structures in late pleistocene lacustrine deposits of issyk kul lake kyrgyzstan abstract this paper discusses the composition and distribution of soft sediment deformation structures induced by liquefaction in late pleistocene lacustrine terrace deposits on the southern shore of issyk kul lake in the northern tien shan mountains of kyrgyzstan the section contains seven deformed beds grouped in two intervals five deformed beds in the upper interval contain load structures load casts and flame structures convolute lamination ball and pillow structures folds and slumps deformation patterns indicate that a seismic trigger generated a multiple slump on a gentle slope the dating of overlying subaerial deposits suggests correlation between the deformation features and strong earthquakes in the late pleistocene

soft sediment deformation induced by sinkhole activity in shallow marine environments a fossil example in the apulian foreland southern italy abstract soft sediment deformation structures are exposed in sea cliffs in the lower part of the calcarenite di gravina formation late pliocene early pleistocene in the cala corvino area n of monopoli adriatic sector of the apulian foreland southern italy deformation affects a thickness of about 5 m involving a lower calcareous terrigenous sand and gravel unit and an upper heavily bioturbated grainstone and packstone unit deformation is absent from the overlying part of the succession large scale soft sediment deformation structures are collapse features comprising irregularly elongated conical zones of sinking in vertical section narrow drop zones occur in the lower sandy gravelly facies and large gentle folds in the upper grainstone packstone beds the degree of deformation decreases upwards small scale soft sediment deformation structures adjacent to the large scale conical collapse structures are narrow vertically elongated load structures about 2 m high and 30 50 cm wide that involve only the basal terrigenous facies the distribution of small and large scale soft sediment deformation structures corresponds closely to zones of fracturing in the underlying cretaceous limestones and the elongation directions of soft sediment deformation structures correspond to the orientation of major fractures in the limestones the soft sediment deformation occurred due to collapse associated with karstic sinkhole formation along fractures in the bedrock geometrical relationships between deformed and undeformed sedimentary units show that deformation occurred in a shallow marine environment the structures at cala corvino provide a rare outcrop scale record of sinkhole induced soft sediment deformation occurring in a shallow marine environment