late paleozoic glacial episodes in gondwanaland reflected in transgressive regressive depositional sequences in euramerica the late paleozoic glaciation of gondwanaland comprised two short episodes in the famennian i and visean ii confined to brazil and adjacent northwest africa and a long episode that started in the namurian iiia of eastern australia and bolivia argentina expanded to cover much of gondwanaland in the stephanian asselian iiib and collapsed in the early sakmarian iiic dropstones in eastern australia indicate that small ice centers lingered to the kazanian across the belt of low latitudes north of gondwanaland short ranging fossils in widespread shallow marine and paralic deposits indicate synchronous deposition of transgressive regressive sequences in different parts of euramerica these sequences correlate with glacial events in gondwanaland at three levels a four major regressions in euramerica in the famennian 1 visean 2 namurian 3 stephanian 4 and the tastubian transgression that preceded the sterlitamakian regression 5 also recorded in gondwanaland correlate with glacial episodes i ii and iiia iiib and iiic b the time interval of cyclothemic deposition in euramerica brigantian or latest visean to sterlitamakian correlates with that of glacial episode iii and c the dominant period of the euramerican cyclothems as estimated from the middle and late pennsylvanian deposits of the mid continent of north america and of the thickest known gondwanaland glacigenic sediment the earliest permian lyons group of western australia is 0 4 ma equivalent in turn to the long orbital eccentricity period of the quaternary ice age and the dominant period of fluctuation of the late miocene antarctic ice cap the three levels of correlations confirm wanless and shepard9s 1936 hypothesis that the late paleozoic cyclothems are controlled largely by sea level fluctuations related to the gondwanaland glaciation

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

sedimentary structures tentatively attributed to seismic events abstract fingerprints of earthquakes in the sedimentary record are as yet difficult to identify this is particularly true for failure phenomena dewatering slumping fault graded and turbidite structures that could have been triggered also by other kinds of energy input other promising candidates are strange biostratinomic features convex down stacking of shells current orientation in wave ripple accumulations as well as certain preservational features found in geosynclinal pelagic limestones but in every case verification of the seismic origin is still needed

mud volcano eruptions and earthquakes in the northern apennines and sicily italy abstract the relations between earthquakes and the eruption of mud volcanoes have been investigated at the pede apennine margin of the northern apennines and in sicily some of these volcanoes experienced eruptions or increased activity in connection with historical seismic events showing a good correlation with established thresholds of hydrological response liquefaction to earthquakes however the majority of eruptions have been documented to be independent of seismic activity being mud volcanoes often not activated even when the earthquakes were of suitable magnitude and the epicentre at the proper distance for the triggering this behaviour suggests that paroxysmal activity of mud volcanoes depends upon the reaching of a specific critical state dictated by internal fluid pressure and implies that the strain caused by the passage of seismic waves can activate only mud volcanoes in near critical conditions i e close to the eruption seismogenic faults such as the pede apennine thrust often structurally control the fluid reservoirs of mud volcanoes which are frequently located at the core of thrust related folds such an intimate link enables mud volcanoes to represent features potentially suitable for recording perturbations associated with the past and ongoing tectonic activity of the controlling fault system

late quaternary earthquake related soft sediment deformation along the belgian portion of the feldbiss fault lower rhine graben system abstract trench investigations along the bree fault scarp in belgium in the framework of a first paleoseismological experience in the area of the lower rhine graben system have not only demonstrated the existence of seismogenic faults almost extending to the present ground surface but also exposed several types of soft sediment deformation affecting sandy sediments and soils of inferred late weichselian to holocene age the observed features include asymmetric folding small scale normal faulting possible sand intrusions and small water escape or load structures establishing a seismic origin for the individual features is not always possible based on their sedimentary characteristics only particularly due to the potential confusion with periglacial phenomena but their abundance the close association of different deformational styles and their vicinity to a known active fault all seem to be compatible with an earthquake induced scenario the features are to some extent comparable to those generated during the recent ms 5 3 roermond earthquake at the opposite side of the roer valley graben stratigraphical and mutual geometrical relationships suggest the occurrence of at least three distinct deformational events since probably 30 000 years and one event before that time since nothing is yet known about their regional distribution however estimating the associated paleomagnitudes from these soft sediment deformations is premature

earthquake magnitude frequency epicentral distance and soft sediment deformation in sedimentary basins abstract empirical equations available for earthquake magnitude frequency and the maximum epicentral distance of liquefied sites versus magnitude are combined with the characteristic instantaneous sediment deposition rate at a station in a sedimentary basin to form a model for the local stratigraphic frequency of earthquake induced soft sediment deformation structures both the style of sedimentation and the characteristics of the earthquake source combine to determine the pattern of incidence of the structures in a basin the model is probably most directly applicable to the geodynamic interpretation of fluvial basins in which substantial volumes of readily liquefied sands accumulate at high local short term rates

abraded sand volcanoes as a tool for recognizing paleo earthquakes with examples from the cisuralian talchir formation near angul orissa eastern india abstract one of the bedding planes of a sandstone unit belonging to the cisuralian talchir formation is well exposed along the nandir jhor river in eastern india it shows a few dozens of circular structures commonly with diameters of a few decimetres a concentration is found in an area of some 50 m 2 where 12 well developed specimens occur the structures are interpreted as abraded sand volcanoes which interpretation is supported by the occurrence on the same bedding plane of a sand volcano with a diameter of over a meter the concentrated structures thus represent a sand volcano field a phenomenon that has not been recognized earlier in the pre holocene geological record but that in recent times seems always to be related to an earthquake the structures described here might therefore help to recognize earthquakes that occurred in the geological past

evidence from seismites for glacio isostatically induced crustal faulting in front of an advancing land ice mass rugen island sw baltic sea abstract it is hitherto commonly thought that earthquakes triggered by geologically rapid changes in the pressure caused by the fluctuating extent of thick land ice masses occur exclusively during ice retreat our study of deformed sediment layers within an undeformed glaciolacustrine and glaciofluvial succession exposed in a coastal cliff on rugen island south western baltic sea challenges this widespread idea based on their structural and deformational features the layers under investigation are interpreted as seismites which formed as a result of seismically induced liquefaction the stratigraphic context aided by optically stimulated luminescence osl dating indicate that the documented seismites must have formed shortly before the front of the pleistocene scandinavian ice sheet reached the study area during the last glacial maximum thus during a stage of ice advance this implies that the flexural isostatic response of the earth s crust as a consequence of the ice load during ice advance was accompanied by earthquakes probably due to local re activation of pre existing faults the crustal response to an increasing ice load was consequently less gradual than previous studies about glaciation related tectonics suggest

indicative value of non pollen palynomorphs npps and palynofacies for palaeoreconstructions holocene peat brazil abstract the results of the palynological study of the samples from the core performed in the aguas claras peatland rs brazil 50 45 00 w 30 00 15 s focus on detailed taxonomic analysis of non pollen palynomorphs npps and palynofacies from the holocene peat and underline the late pleistocene mud and sandy mud that were represented npps from the samples revealed taxonomic variety of fungal palynomorphs presented by brachysporium clastesporium dicellaesporites dicellaeporisporites gelasinospora glomus sordaria helicoon and others the habitats of above mentioned taxa are varied aquatic mycorrhizal parasitic organic matter decaying and dung coprophilous freshwater algal palynomorphs were composed of botryococcus closterium debarya mougeotia pseudoschizaea spirogyra and zygnema the percentage ratio between algal and fungal palynomorphs was changed from the different samples of the core reflecting climatic oscillations more humid dryer prevalence of fungal palynomorphs was connected with dryer climate and on the contrary freshwater algal palynomorph predominance was related with increasing humidity the six palynomorph zones that corresponded to the six principal phases of environmental and climatic changes were determined the zone from the uppermost part of peat was characterized by relatively frequent dung coprophilous and parasitic fungi as a result of agricultural and domestic activities palynofacies analysis combined to npps was used for palaeoenvironmental and paleoclimatic reconstructions palynofacies from the samples were characterized by evident changes in relationship between the different types of organic matter their quality and quantity and fluorescence index the obtained data contribute to the understanding of the peat deposition the combined use of npps and palynofacies analyses provided a valuable approach for the paleoenvironmental and paleoclimatic reconstructions

origin and hydrology of a large intact early cambrian paleocave system and its role in overlying fluidisation structures arctic canada abstract paleokarst is most commonly expressed as subtle stratigraphic surfaces rather than large void systems penetrating deeply into the paleo subsurface in contrast a regional precambrian cambrian unconformity on victoria island nwt canada is associated with exceptional exposure of large intact cambrian paleocaverns 100 m diameter tens of m high the paleocaves are distributed along a paleo horizontal plane and an associated gryke network is present in the 30 60 m of neoproterozoic dolostone between cave rooves and the base of overlying cambrian sandstone both are filled by cambrian sandstone the formation and preservation of such karst features require aggressive dissolution along a stable paleo water table shortly before transgression and deposition of shallow marine sand over the dolostone during the transgression the karst network acted as a conduit for flowing groundwater that was discharged through overlying unconsolidated cambrian shallow marine sand producing water escape structures sand volcanoes and their conduits the conduits are preserved as cylindrical remnants of the sand volcanoes feeder pipes sediment fluidisation was probably caused by variations in the hydraulic head gradient in a meteoric lens near the cambrian coastline under a tropical climate with abundant probably seasonally variable rainfall that caused pulses in subsurface fluid flow spatial distribution of the paleocaves and sand volcanoes suggests their formation on the southeast side of a recently faulted horst of proterozoic carbonate bedrock that formed a nearshore island during early cambrian sea level rise fluidisation structures such as those reported here have generally been difficult to interpret owing to a lack of data on the fluid hydraulics of the underlying aquifer this is the first report linking the hydraulics of a well characterised paleokarst to development of fluid escape structures such structures are widely known from sandstones overlying the sub cambrian unconformity around the circumference of laurentia

the influence of microbial mats on the formation of sand volcanoes and mounds in the red sea coastal plain south jeddah saudi arabia abstract extensive areas covered by microbial mats have been found in the upper intertidal flats and supratidal pools in the red sea coastal plain of south jeddah saudi arabia numerous microbially controlled sediment surface morphologies are evident such as flat cohesive mats that commonly pass into mats with wrinkles reticulates and tufts together with erosion pockets and mat chips these microbial mats form cohesive surface layers that lead to biostabilization of the sediment surface fluidization of the underlying sediments is due to tidal influences and pressurized gas escape from decay and photosynthesis of microbial mats and causes deformation and rupture of the cohesive surface mat layer via vertical and sub vertical pipes extrusion of fluidized sediments and water through these pipes leads to redeposition of sediment grains above the surface mat layer to form sand volcanoes and mounds most of the sand volcanoes present in the intertidal flats and supratidal pools show a symmetrical morphology whereas in tidal channels asymmetrical forms are more common extrusion of underlying sediments through several adjacent vents leads to coalescence of sand volcanoes to form sand mounds in this study sand volcanoes are also compared with other cone like features from the red sea such as gas domes and crab mounds this comparison should help in differentiating similar cone like features associated with microbial mats in the rock record

soft sediment deformation structures in cambrian siliciclastic and carbonate storm deposits shandong province china differential liquefaction and fluidization triggered by storm wave loading abstract this paper focuses on soft sediment deformation structures ssds in both siliciclastic and carbonate storm deposits of the cambrian mantou and chaomidian formations shandong province china in order to understand their deformation mechanisms and possible triggers siliciclastic ssds e g sand volcanoes and pillows and carbonate ssds e g sedimentary dykes grainstone matrix breccias deformed cross beddings and marlstone matrix breccias occur exclusively in hummocky cross stratified fine sandstone and peloidal grainstone respectively the siliciclastic ssds formed in porous and permeable surface sediment whereas the carbonate ssds formed under shallow burial conditions when early marine cementation prevailed the various deformation structures resulted mainly from differences between siliciclastic and carbonate sediment conditions and resulting deformation mechanisms sand volcanoes formed by upward extrusion of over pressured fluidized sandy sediment whereas sand pillows resulted from upward injection of lower density muddy sediment into overlying liquefied sandy sediment sedimentary dykes and grainstone matrix limestone breccias formed as a result of differential liquefaction and fluidization of heterogeneously cemented carbonate sediment whereas deformed cross beddings and marlstone matrix limestone breccias developed by the thixotropic liquidization and injection of clayey sediment and further disruption of thin peloidal layers sedimentary facies analysis and analysis of the physical processes indicate that the ssds were most likely caused by cyclic loading of storm waves

comparative study of cyclicity of lithofacies in lower gondwana formations of talchir basin orissa india a statistical analysis of subsurface logs abstract cyclic characters of karharbari barakar and barren measures formations of the talchir gondwana basin have been studied in the subsurface logs statistically using first order markov chain and entropy analyses results strongly suggest that the sediments of these formations were deposited by markovian mechanism and all the three formations represent cyclic sedimentation the complete cycles of all the three formations are identical and exhibit fining upward character each complete cycle starts with a thin conglomerate or pebbly to coarse grained sandstone at the base and successively followed by medium and fine grained sandstones interbedded sandstone shale shale and terminates with a coal seam at the top there are however minor variations of facies transition in different formations entropy analysis also corroborates these findings the upward sequence of facies states which is stationary at individual localities is non stationary over the entire area broad regional variations in the depositional environment that are not significant at the local scale may be the plausible explanation the karharbari barakar and barren measures sediments of the talchir gondwana basin fit suitably into the concept of fluvial cycles

an overview of geotechnical aspects of the cay eber turkey earthquake abstract the cay eber earthquake md 6 0 occurred in the afyon province in the western part of turkey on 3 february 2002 and resulted in the loss of 42 lives and damage to buildings in the settlements particularly close to the epicenter in this study characteristics of the main shock and its geotechnical aspects such as local site conditions and their effects liquefaction phenomena and natural slope failures are evaluated the causative fault is a normal fault with a slight left lateral component and produced very short surface ruptures due to the presence of top soft and thick alluvial sequence filled the earthquake affected basin horizontal acceleration time histories and collapse direction of various buildings show a good agreement and indicate directivity effect the earthquake caused soil liquefaction and limited rock falls the presence of fine grained and low permeability topsoil layers in the alluvial sequence prevented a widespread liquefaction and associated ground deformations based on the back analysis of liquefaction data and the results of cyclic triaxial testing values of peak horizontal ground acceleration to initiate liquefaction are inferred in addition for selected sites the assessments based on the soil amplification factors estimated from equivalent shear wave velocities and available microtremor data and acceleration response spectra revealed that the resonance phenomena was one of the contributing factors in the damage sustained by some buildings

classification and analysis of palynodebris from the palaeocene sediments of the forties field sedimentary organic matter behaves as sedimentary particles and this study attempts to interpret its occurrence in the palaeocene sands and mudstones of the forties field of the north sea new nomenclature and classification of this palynodebris are presented and are used to make quantitative counts of the palynodebris from nearly 600 samples of known sedimentary character the new categories are further refined by objective testing of the data by principal components analysis and cluster analysis it is argued that two types of sedimentary organic matter are of particular value because they are preferentially deposited in different environments palynowafers are most commonly deposited in the submarine fan lobes and channel complexes and amorphous matter occurs mostly in the lower energy basin plain sediments

extensive soft sediment deformation structures in the early darriwilian middle ordovician shallow marine siliciclastic sediments formed on the baltoscandian carbonate ramp northwestern estonia abstract the nearshore middle ordovician early darriwilian deposits of the baltoscandian basin formed on the flank of tectonically stable fennoscandian shield comprise numerous soft sediment deformation structures the areal extent of the deformed interval extends up to 9000 km 2 from nw estonia to se sweden the deformation structures occur within a meter scale sandstone horizon that includes load casts flame structures ball and pillow morphologies up to 2 m wide sedimentary dykes autoclastic breccias sand volcanoes and other related soft sediment deformation structures evidently these deformation structures formed during a single seismic event that caused liquefaction and fluidization of the water saturated unconsolidated shallow marine sediments within almost the entire sandstone unit pakri formation probably a unique catastrophic earthquake of magnitude 7 or higher occurred in this region penecontemporaneously with the deposition of these sediments the ultimate cause of seismic event of such magnitude in the tectonically stable baltoscandian basin is unclear however deposition and deformation of the pakri formation fall within the middle ordovician meteoritic bombardment period which resulted from the disruption of a large parent body in the asteroid belt approximately 470 ma ago this in turn suggests a potential impact origin for the single catastrophic earthquake in the tectonically stable study region although impact crater of suitable age is currently not known from the region then previous studies have documented some impact metamorphic shock lamellae i e pdfs and abundant extraterrestrial chromite grains from the deformed sediments

seismically induced deformation structures in oligocene shallow marine and aeolian coastal sands paris basin abstract soft sediment deformation structures have been identified in the oligocene coastal sand body in the southern part of the paris basin stampian sables de fontainebleau formation these coastal barrier sediments are characterized by pure fine grained sands the deformed beds are observed over some 60 110 km2 and are present either in foreshore sands or aeolian sand dunes convoluted laminations of an average amplitude around 0 70 m were identified in the foreshore or interdune sediments these are interpreted as the result of liquefaction conversely deformed sets of aeolian dune sand often involve large amounts of sediment these large scale contorted laminae several metres thick with minor internal faulting suggest deformation by slope failure under wet conditions such large scale soft sediment deformations may have been generated by storm surges and earthquakes which have similar liquefaction potentials we propose that the deformation structures were created by a single triggering event because of the absence of superposition of deformed layers over the study area the earthquake triggering hypothesis is supported by the large amount of sand involved in the slope failure features and the persistence of the contorted laminations over a wide area

soft sediment deformation structures in the earth s oldest seismites abstract the chaibasa formation in eastern india which was deposited between 2100 and 1600 million years ago shows deformations that must have formed when the sediments were not yet consolidated some of these deformation structures have never been described before here they are described depicted and their origin is analysed we show that they must be the result of shocks which can only be explained satisfactorily as triggered by earthquakes the layers containing these deformation structures are termed seismites they are among the earliest records of earthquakes known in the earth s history

devonian lake margin environments and processes se shetland scotland the devonian lake or lakes of se shetland were characterized by 4 environments 1 a marginal environment dominated by the high energies of the surf zone and just lakeward of the breaker zone 2 an additional marginal environment consisting of small shallow oxidizing lakes on a low gradient coastal flood plain over which waters from the main body of the lake fluctuated 3 an intermediate environment characterized by continuous to intermittent wave agitation in water depths of probably 5 10m the marginal environment was influenced by both wave and current processes a friction dominated outflow produced sedimentary structures that indicate a south easterly flow and depositional slope outflow competed with shoaling waves which advanced from e to w onto the lake shoreline where outflow was weakest wave processes dominated longshore drift was an additional component in the movement of the nearshore waters the devonian lake or lakes of se shetland possessed rather shallow shoaling margins

late pleistocene seismites from lake issyk kul the tien shan range kyrghyzstan abstract the aim of the study is to record the occurrence of sediment deformation structures in one of the tectonically most active areas on the globe the tien shan range in central asia and to examine the significance of the deformations as indicators of palaeoseismicity soft sediment deformation structures in form of balls and pseudo nodules are exposed in the issyk kul basin within interfingering beds of shallow lacustrine beach and fluviatile origin additional deformation structures that were encountered are a complex and chaotic folded structure giant balls and a pillar structure which has not been previously reported where marl intrudes down into coarse pebbley sand and forms pillar morphology liquefaction features and bedforms related to storm and breaking waves were not encountered neither was there evidence of turbidites seven field criteria for relating soft sediment deformation to palaeoseismic triggering provide strong evidence for a seismic origin of the deformation structures empirical relationships between magnitude and the maximum distance from an epicenter to liquefaction sites make the active epicentral zone north of lake issyk kul with its frequent high magnitude events the most favorable source for the deformation structures luminescence dating of the sediments gives a time window of 26 2 1 to 10 5 0 7 ka bp indicating latest pleistocene seismic activity

soft sediment deformation structures from an ice marginal storm tide interactive system permo carboniferous talchir formation talchir coalbasin india abstract permo carboniferous talchir formation talchir coalbasin india records sedimentation during a phase of climatic amelioration in an ice marginal storm affected shelf evidences of subtidal processes are preserved only under thick mud drapes deposited during waning storm phases various soft sediment deformation structures in some sandstone siltstone mudstone interbeds like syn sedimentary faults deformed laminations sand silt flows convolute laminations and various flame structures suggest liquefaction and fluidization of the beds due to passage of syn depositional seismic shocks in the late paleozoic ice marginal shelf such earthquake tremors could be generated by crustal movements in response to glacioisostatic adjustments of the basin floor

seismites in the fluviatile bima sandstones identification of paleoseisms and discussion of their magnitudes in a cretaceous synsedimentary strike slip basin upper benue nigeria abstract the upper benue basin northeastern nigeria is interpreted as a complex strike slip basin which consists of a set of sub basins controlled by synsedimentary n60 c e trending strike slip faults which were active during early cretaceous times the oblique planar cross beds made of the medium to fine grained sandstones of the upper member of the bima sandstone formation are affected by various soft sediment i e early diagenetic but soft sediment deformational structures these are present not only close to the synsedimentary faults but also on a larger regional scale three main types of structures undulated and recumbent folded cross bedded lamination dislocated convolutions and concordant microbreccias discordant fluidised intrusions are described these are related to processes of sediment deformation favored by sand hydroplasticity liquefaction and fluidization the local organization of these soft sediment intrastratal deformational structures their spatial distribution with respect to synsedimentary faults and their independance with respect to marginal paleoslopes suggest that they cannot be explained by slumping or current drag all the deformations are related to pore water expulsion and it is proposed that the required sand reorganization was triggered by seismic waves the spatial and chronologic distribution and intensity of the various types of deformation structures suggest that they were produced around different epicenters repeated by earthquakes of varying magnitudes associated with the synsedimentary strike slip tectonics

deglacial control on sedimentation and basin evolution of permo carboniferous talchir formation talchir gondwana basin orissa india abstract the permo carboniferous talchir formation in the southeastern part of the talchir basin is represented by about 260 m thick clastic succession resting on the precambrian basement rocks of the eastern ghats group the succession is tentatively subdivided into four lithostratigraphic units namely a i a ii b and c from base to top unit a i comprises mud matrixed very poorly sorted diamictites and interbedded thin sandstone and mudstone yielding dropstones they reveal deposition in a proglacial lake environment in which ice rafting and suspension sedimentation as well as meltwater underflow processes produced variety of facies the succession of unit a ii is dominated by pebble to boulder conglomerates and sandstones they were deposited mostly from various kinds of high energy sediment gravity flows both subaerial and subaqueous and formed steep faced fan delta on the margin of the basin unit b demonstrates turbidite sedimentation in lake margin slope and base of slope environments in which a sublacustrine channel fan system developed the lake margin slope was dissected by channels which were accompanied by overbank and levee deposits sediments delivered from the mouth of a channel were deposited at the base of slope forming a fan lobe which prograded onto the lake basin floor unit c dominantly consists of mudstone with intercalations of siltstone and sandstone and forms a large scale coarsening upward deltaic sequence eventually covered by the fluvial deposits of the karharbari formation following the glacially influenced sedimentation the talchir succession shows a vertical facies progression suggesting gradual deepening of the lake basin and eventual filling up of it due to rapid delta progradation such a succession represents deglacial control on basin evolution during the talchir time in the initial stage of glacial recession collapse of a glacier and failure of montane glacial lakes frequently occurred and gave rise to generation of a highly sediment laden debris flow and a catastrophic flood which brought abundant coarse clastics into the lake and built a fan delta on the basin margin the continued recession and disappearance of glacier resulted in abundant supply of ice melt water into the graben as well as eustatic sea level rise being the cause of the rise in lake level subsequent rapid delta progradation and eventual filling up of the lake basin suggest rapid lake level fall after deepening of lake basin it was possibly caused by the regional uplift due to post glacial isostatic rebound rapid draining of lake water through the graben gave rise to the establishment of an axial drainage system which rapidly filled the lake basin in form of an axially fed delta

debris flow and glacioisostatic induced soft sediment deformation structures in a pleistocene glaciolacustrine fan the southern baltic sea coast poland abstract middle pleistocene glaciolacustrine fan sediments are exposed along a cliff at the baltic sea coast where plastic and brittle soft sediment deformation structures ssds commonly occur 1 fold structures various types of folds and flexures 2 load structures load casts pseudonodules and flame structures 3 water escape structures wes and 4 brittle deformation structures such as faults medium and small scale reverse and normal and fragments of broken up laminae the origins of the ssds can be linked to gravitational processes promoted by shear stresses in subaqueous debris flows on the glaciolacustrine fan and by the weight of overlying sediments and or to the glacial rebound of earth s crust during deglaciation because in the pleistocene the baltic sea and surrounding areas were covered by ice sheets many times the question investigated here concerns recognition of the trigger mechanisms responsible for the development of ssds and the criteria needed to recognize those mechanisms based on the lithological and deformational features of the sediments involved some types of ssds can look similar regardless of trigger mechanisms but some occur more often as a result of a specific mechanism is it possible to distinguish ssds of seismic origin in a glaciolacustrine fan succession affected by multiple debris flows and of ssds that evolved as a consequence of slope processes we suggest criteria to recognize ssds triggered by the glacioisostatic rebound as well as those which can develop as a result of the rebound and slope processes

sub aqueous sand extrusion dynamics extruded sandstone mounds and sandstone sheets are increasingly recognized in the geological record and seismic data yet the underlying mechanisms that control these features and determine whether deposits form discrete accumulations or areally extensive sheets remain poorly understood here we address these issues through study of a well exposed ancient sand sheet in the shannon basin ireland sand volcanoes are shown to have erupted contemporaneously following liquefaction and fluidization of delta front mouth bar sands and silts the expelled sediment forming an extruded sheet of sand the sand sheet formed during a single prolonged eruption event with the interaction of radial gravity currents from the hundreds of vents exerting control on the internal architecture of the extrudite based on our observations here we develop a process based model that demonstrates that sand extrusions can form sheets only if 1 multiple vents are extruding coevally causing gravity currents to interact or 2 topographic forcing such as channelling redirects the otherwise radial gravity currents resulting in sheet like deposition of extruded material away from the vent site this study provides a new model of sand extrudite formation and examines the potential for identifying extrudites from core and bed scale studies and differentiating them from liquefied beds

assessment of liquefaction and lateral spreading on the shore of lake sapanca during the kocaeli turkey earthquake abstract the 1999 kocaeli earthquake of turkey m w 7 4 caused great destruction to buildings bridges and other facilities and a death tall of about 20 000 during this earthquake severe damages due to soil liquefaction and associated ground deformations also occurred widespread in the eastern marmara region of turkey soil liquefaction was commonly observed along the shorelines one of these typical sites is sapanca town founded on the shore of lake sapanca this study was undertaken as quantitative measurement of ground deformations induced by liquefaction along the southern shore of lake sapanca the permanent lateral ground deformation was measured through the aerial photogrammetry technique at several locations both along the shoreline and in the town in situ soil profiles and material properties at sapanca area were obtained based on the data from 55 borings and standard penetration tests spt and laboratory tests respectively the data and the empirical methods recommended by an nceer workshop were employed to evaluate the liquefaction resistance of the soils in addition simple shaking tests on a limited number of samples were also performed the permanent ground displacements were estimated from the existing empirical models sliding block method and residual visco elastic finite element methods then these estimations were compared with the observed ground displacements the assessments suggested that liquefaction at sapanca have occurred within quaternary alluvial fan deposits at depths 1 and 14 m and the major regions of liquefaction and associated ground deformations were located along the shore and creeks the evaluations also indicated that for sites with no sand boils but with ground displacement greater than 1 m thickness of the non liquefiable layer was large it is also noted that no liquefaction induced ground surface disruption is expected at the site when the thickness of the liquefiable and non liquefiable layers vary between 0 5 and 1 5 m and 3 5 and 5 5 m respectively except one model all the empirical models employed in the study over predicted the observed lateral ground displacements while sliding block method and residual visco elastic finite element methods yielded reasonably good results if the known properties of liquefied soils are used

earthquakes and deformational structures seismites in holocene sediments from the himalayan andaman arc india soft sediment deformational structures from the himalayan arc caused by episodic earthquake recurrences during the holocene recent are produced by the ongoing tectonic processes these small scale subtle structures occur along some major thrusts in the garhwal himalaya and vary from normal faults in the lower zone to compressional structures in the middle zone along the main central thrust in the tons valley the latter includes isoclinal angular kink and disharmonic folds with discrete displacements along their axial surfaces thrusts with decollement listric and overstep thrusts in duplex style and load slumping the upper zone is marked by very low angle thrusts with left lateral displacement and associated displacement shears d riedel shears r and thrust shears p as well as small scale sporadic kinks three zones reveal changing tectonic character from gravity tectonics in the lower zone to compression in both the middle and upper zones with the maximum principal stress 1 oriented n60 to n110 respectively along the tons thrust post depositional structures include drag along normal fault zone characterized by d r and p shears and conjugate fractures that provide localized orientation of stresses 1 at 75 n60 2 at 12 n280 and 3 at 12 n290 earthquake induced liquefaction and subtle variations in physiomechanical properties of soft sediments have primarily controlled the deformational pattern due to localized tectonic stresses ground and sediment deformations during two earthquakes in the himalayan andaman arc provide additional support for the seismogenic origin of such structures preserved in loose or consolidated sediments

western davis strait a volcanic transform margin with petroliferous features abstract we present a compilation of the western davis strait region offshore southeastern baffin island nunavut canada with new subsurface geological structural details and observations regarding past hydrocarbon occurrences from scientific and commercial exploration this consists of seismic mapping with archival data correlated with a filtered marine bouguer anomaly gravity compilation and magnetic data sets covering northern saglek basin the western part of the lady franklin basin and the ungava fault zone from south of baffin bay a regional seismic horizon for mapping basin architecture comes from the top of the paleogene volcanic syn magmatic zone where pervasive volcanic flows and intrusions are intermingled with the sedimentary section the seismic depth map to the top of the regional volcanic seismic horizon shows pre rift sedimentary basins having maximum depths of approximately 4 5 km flanking the shallower ungava fault zone correlation of bouguer anomaly gravity and magnetic data interpretations with the seismic mapping indicate that over some areas true crystalline basement is deeper than can be determined by reflection seismic as the base of the syn magmatic section is not resolvable for seismic mapping extensive paleogene mafic intrusives and extrusive basalts dominate the architecture of this volcanic rifted margin as seen by the dominant high amplitude magnetic anomalies associated with many deeper structures the over 250 km long davis strait fault is recognised as the key structural element of the ungava fault zone ufz and valley complex the adjoining davis strait high maps on seismic as a continuous structure running the length of davis strait plunging southwards to a bouguer gravity high feature that terminates the western end of the extinct eocene spreading zone south of davis strait this horn shaped structural feature establishes the presence of an accommodation zone with multiple faults and localised thrust faulting as required to fit the complex mechanics for strike slip motion that occurs along the south end of this transform fault system the revised marine bouguer anomaly gravity data set also defines two new near shore grabens east of cumberland sound the southern tariut basin and the northern imaqpik basin each extending over 100 km in length with sediment thicknesses of at least 4 km these pre rift basins most likely originate from the paleozoic based on seafloor dredge and nearby shallow drill cores from previous studies the hydrocarbon charge of a previously unexplained petroliferous shallow marine drill core that is adjacent the eastern edge of the tariut basin is attributed to paleozoic source rocks that have undergone enhanced thermal maturation from sill intrusion associated with rifting the imaqpik basin shows strong evidence of a hydrocarbon system from the proximity of clustered interpreted sea surface oil slicks mapped from satellite radar images and a local zone of anomalously high dissolved methane measured within the water column that originates from the seafloor immediately east of cape dyer at the northern limit of that basin the overlying cape dyer flood basalt field extends from limited onshore exposures into the offshore and maps with magnetic data over an area of approximately 13 000 km2 this extrusive feature and it s implicit underlying intrusive components are likely the unconventional heat source for the anomalous enhanced thermal maturation of paleozoic to paleogene source rocks in these pre rift basins that host this previously unrecognised petroleum system

soft sediment deformations from glaciodeltaic glaciolacustrine and fluviolacustrine sediments in the kleszczow graben central poland

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

earthquake induced soft sediment deformation structures in upper jurassic open marine microbialites neuquen basin argentina penecontemporaneous decimetre scale soft sediment deformation structures are reported from the basal part of the upper jurassic lower cretaceous vaca muerta formation in the malargue las lenas area of the back arc neuquen basin mendoza province central andes the deformed interval amarillas bed is only 0 3 to 0 9 m thick but occurs in a wide area larger than 1500 km2 its age determined by ammonite biostratigraphy is early tithonian the soft sediment deformation structures were generated in finely laminated partially consolidated organicrich carbonate microbialites that were deposited in open marine poorly oxygenated settings apparently devoid of any significant slope those structures include boudins of different sizes and complexity a variety of folds normal listric dm scale faults sub horizontal detachment surfaces and other features which are part of several larger scale complex slump structures deformation was dominantly plastic but near to the ductile brittle field transition on the basis of the observed soft deformation structures their geographic distribution their lateral homogeneity and the geodynamic framework of the basin in which it was generated the amarillas bed can be tentatively attributed to a large intermediate depth earthquake that occurred within the plate that subducted beneath the andean continental margin and the neuquen back arc basin

soft sediment deformation in a tectonically active area the plio pleistocene zarzal formation in the cauca valley western colombia abstract the plio pleistocene zarzal formation corresponds to fluvio lacustrine sediments deposited in an intramontane depression within the colombian andes associated with the cauca romeral fault system it crops out mainly in the cauca valley where numerous field sections have permitted the mapping of the vertical and lateral lithological variations lacustrine deposits of sands silts clays and diatomites are interbedded with fluvial sand and gravel beds and fluvio volcanic mass flows derived from the volcanic central cordillera numerous soft sediment deformation structures are encountered in this formation particularly in fine to medium grained sands silts and clays load structures load casts flame structures pseudonodules water escape structures water escape cusps dish and pillar and pocket and pillar structures soft sediment intrusions clastic sills and dykes disturbed laminites convolute laminations slumps and synsedimentary faulting deformation mechanisms and driving forces are related essentially to gravitational instabilities dewatering liquidization and brittle deformations field and regional geological data show that most of these deformations are related to seismicity and can be interpreted as seismites this area has a geological and recent seismic history and outcrops show both syn and post depositional faulting related to the transpressional regime of this part of the colombian andes which generates strike slip faults and associated local normal faults the drainage pattern within the zarzal formation shows the signature of neotectonics moreover the fine to coarse grained sands of the zarzal formation are lithologies prone to liquefaction when affected by seismic waves the intercalation of the deformed intervals within undisturbed strata confirms the catastrophic nature of the events finally the large areal extent of the deformations and the type of structures are compatible with seismites consequently the existence of seismites in the zarzal formation represents corroboration of tectonic activity in this area during the pleistocene earthquakes with a magnitude higher than 5 can be postulated based upon the proximity of active faults and the types of deformations

funnel shaped breccia filled clastic dykes in the late cambrian chaomidian formation shandong province china abstract some examples of a funnel shaped structure filled with both angular and rounded clasts occur in a peloidal grainstone bed of the chaomidian formation late cambrian in the jiulongshan area shandong province china the clasts consist of peloidal grainstone which is the same as that of the walls of the funnels the structures are interpreted as dykes formed by upward escape of pore water and or fluidized sediment through a narrow conduit which was gradually widened by the force of the intruding fluid sediment the erosional capacity of the pressurized fluid sediment mixture consequently diminished upwards which explains the gradual decrease in intensity of fragmentation from the adjoining walls in this direction

storm influenced deltas and ice scouring in a late pleistocene glacial lake this paper identifies the sedimentary record of storms and bottom scouring ice masses that is preserved in upper pleistocene glaciolacustrine delta sediments deltaic sedimentation occurred on the margin of an enlarged ice dammed ancestral lake ontario with a surface elevation at least 80 m above the modern level beds of amalgamated hummocky and swaley cross strata separated by fairweather muds represent delta front storm deposits and overlie laminated prodelta clays the central and thickest part of a 5 km long outcrop exposes variably cross stratified sand in multiple channels inset within tabular sheets of rippled sand this complex represents a broad distributary channel system about 1 6 km wide and 20 m deep cut into delta front storm sequences a large scour and related deformation structures are attributed to bottom dragging ice masses possibly pressure ridged lake ice the depositional setting outlined in this paper emphasizes the importance of storm waves in large continental glacial lakes and provides a contrast with better known low energy conditions in small glacial lake basins

combinations of processes responsible for martian impact crater layered ejecta structures emplacement 1 we utilized images and stereo derived topographic data acquired by the high resolution stereo camera hrsc and thermal emission imaging system themis images together with other data in order to study the geology of layered ejecta structures associated with relatively pristine martian impact craters the geomorphology and morphometric properties indicate their origin as complex combinations of a variety of impact processes the studied inner layered ejecta structures often exhibit ground hugging characteristics and many of them do not have topographic profiles expected from simple ballistic emplacement such profiles include ones that are plateau shaped or thickening outward we think that water rich fluidized flows driven by the momentum due to the impact and by gravity together with ballistic emplacement and vortex produced by the atmosphere ejecta curtain interaction were essential to the inner layered ejecta structure formation we hypothesize that the thinner outer layered ejecta structures were formed by various combinations of shockwave induced liquefaction of water rich near surface sediments ballistic emplacement of ejecta entraining water and strong winds expanding vapor vortex base surge related to the impact the contribution of each proposed layered ejecta structure formation mechanism should have been variable depending on the condition of the impact

seismically induced clastic dikes as a potential approach for the estimation of the lower bound magnitude intensity of paleoearthquakes abstract we compiled a database that includes 36 sites wherein the injection and neptunian dikes associated with 16 instrumental seismic events were studied some information in the database was obtained from our field work in the epicentral area of the 2003 ms 7 5 chuya and the 1950 ms 7 mondy earthquakes the bounding relationships between the surface wave magnitude ms and maximum width w cd visible maximum height h cd and intensity index of clastic dikes i cd and local macroseismic intensity i l and the same three parameters were established as was hypothesized larger metrics of clastic dikes can be expected from earthquakes with higher magnitudes and macroseismic intensities the analysis of the obtained relationships showed that when estimating the lowest potential magnitude or local macroseismic intensity it is better to use all three parameters of clastic dikes and take the maximum level for seismic hazard evaluation this reduces the underestimation of the earthquake potential thus clastic dikes can be applied as a potential approach for a lower bound magnitude intensity estimation of paleoearthquakes which is particularly important in the construction of critical facilities this work should stimulate geologists to record the metrics of seismically induced clastic dikes to improve the equations proposed in the present paper

synsedimentary deformation of pleistocene glaciolacustrine deposits in the albese con cassano area southern alps northern italy and possible implications for paleoseismicity abstract we describe and interpret the well exposed soft sediment deformations preserved in a mid pleistocene proglacial sequence outcropping at albese con cassano near como southern alps n italy the observed deformations affect six distinct stratigraphic intervals within the same depositional sequence the stratigraphy of this sequence the geomorphic setting and the careful geological mapping of the area clearly show that these deformations are not the result of glaciotectonics or cryoturbation but are due to six separate events of synsedimentary liquefaction in particular the 3 basal deformed units include sand and gravel volcanoes that formed at the bottom of a proglacial lake we examined several hypothesis of possible causative mechanism for the formation of these features taking into account all the information available on the local geology and sedimentary environment it is possible to assess that the liquefaction features at albese con cassano had a coseismic origin to our knowledge this would be the first report of similar evidence of paleoseismicity in the lombardia southern alps also there is no record of historical liquefaction triggered by seismic events in an area of ca 70 km of radius near albese con cassano including the town of como the large metropolitan area of milano and most of w lombardia that is one of the largest industrial districts in europe therefore the interpretation of the observed deformations can have critical impact for understanding the current seismicity level in the region and mitigating the associated risk in this paper we show that this interpretation is not a simple process liquefaction features must be treated with caution in order to derive suitable information for seismic hazard characterization even if their coseismic origin has been definitely proved it is necessary to understand the amount of seismic shaking for instance in terms of local macroseismic intensity that can have produced that specific feature at that specific site the location of the causative seismic event epicenter and focal depth and eventually its size in terms of epicentral intensity and or earthquake magnitude in the case of albese con cassano the implications in terms of seismic hazard of the observed possible earthquake paleoliquefactions can only be assessed through the definition of several scenarios taking into account a different thresholds of shaking for triggering the described synsedimentary structures and b different seismotectonic frameworks related to the mid pleistocene to holocene evolution of the s alps including seismicity induced by isostatic glacial rebound we conclude that it is worth checking these scenarios in the field with further paleoseismological research on other possible evidence of past earthquakes there are no unequivocal sedimentological indicators of paleoseismicity however when carefully interpreted within the proper local seismotectonic context and compared with other earthquake induced features soft sediment deformations can offer information of critical value for seismic hazard assessment

soil liquefaction during the arequipa mw 8 4 june 23 2001 earthquake southern coastal peru abstract the arequipa june 23 2001 earthquake with a moment magnitude of mw 8 4 struck southern peru northern chile and western bolivia this shallow 29 km deep interplate event occurring in the coupled zone of the nazca subduction next to the southeast of the subducting nazca ridge triggered very localized but widely outspread soil liquefaction although sand blows and lateral spreading of river banks and road bridge abutments were observed 390 km away from the epicenter in the southeast direction nearing the town of tacna close to the chile border liquefaction features were only observed in major river valleys and delta and coastal plains in the meizoseismal area this was strongly controlled by the aridity along the coastal strip of southern peru from the sand blow distribution along the coastal area a first relationship of isolated sand blow diameter versus epicentral distance for a single event is ever proposed the most significant outcome from this liquefaction field reconnaissance is that energy propagation during the main june 23 2001 event is further supported by the distribution and size of the isolated sand blows in the meizoseismal area the sand blows are larger to the southeast of the epicenter than its northwestern equivalents this can be stated in other words as well the area affected by liquefaction to the northwest is less spread out than to the southeast implications of these results in future paleoliquefaction investigations for earthquake magnitude and epicentral determinations are extremely important in cases of highly asymmetrical distribution of liquefaction features such as this one where rupture propagation tends to be mono directional it can be reliably determined an epicentral distance between earthquake and liquefaction evidence and an earthquake magnitude only if the largest sand blow is found therefore magnitude estimation using this uneven liquefaction occurrence will surely lead to underrating if only the shortest side of the meizoseismal area is unluckily studied which can eventually be the only part exhibiting liquefaction evidence depending on the earthquake location and the distribution of liquefaction prone environments

late middle to late ordovician seismites of kentucky southwest ohio and virginia sedimentary recorders of earthquakes in the appalachian basin synsedimentary ball and pillow beds breccias and faults in late middle to late ordovician foreland basin rocks of kentucky southwest ohio and virginia indicate broad zones of seismicity near the cincinnati arch and taconic orogenic front during deposition earthquake induced liquefaction formed seismites that include ball and pillow beds and rare sedimentary breccias that are correlative over large areas hundreds to thousands of square kilometers comparison of these features with liquefaction structures in holocene sediments indicates that the ordovician ball and pillow beds were probably generated by large earthquakes magnitudes 6 the ordovician seismites also provide information about epicenter location and the recurrence interval of large earthquakes in the ordovician foreland basin some were produced by faulting in the foreland and accretionary prism however horizons of resedimented lithoclastic breccias in the jeptha knob cryptoexplosive structure appear to correlate with several ball and pillow beds on jessamine dome along the cincinnati arch suggesting that some of the seismites may be genetically related to this enigmatic structure

lateral variability of ancient seismites related to differences in sedimentary facies the synrift escucha formation mid cretaceous eastern spain abstract lateral extent and continuity of deformation has been used as criterion for the recognition of a seismic origin of soft sediment deformations particular problems are posed by ancient seismites developed in deposits that show lateral variability of sedimentary facies in such a context the lateral continuity of deformation will depend on the lateral variability of physical properties of sediments that ultimately results in the lateral variability of seismites in a single deformation event a variety of decimetre scale soft sediment deformation structures occurs in the synrift escucha formation late aptian middle albian in teruel spain these structures which include pseudonodules ball and pillow structures slumps water escape structures multi phase deformed structures folds sagging like structures and synsedimentary faults were developed contemporaneous to the formation of dark grey silty mudstones and grey clayey siltstones in a shallow marine environment the soft sediment deformation is constrained to a 1 2 m thick horizon exposed in four outcrops consisting of quiet water mudstones and heterolithic storm deposits the deformed horizon can be sub divided into two parts each reflecting a deformation event that affected both cohesive and granular non cohesive sediments the deformed structures occur in the vicinity of the gargallo normal growth fault which is several kilometres long activity along this fault controlled the facies distribution of the unit bearing soft sediment deformations high energy facies were located in the fault tip while low energy facies developed in both the down tilted hanging wall and footwall blocks in addition fault induced shocks released enough kinetic energy to trigger soft sediment deformation the soft sediment deformation in the escucha formation represents different responses of deformation susceptible sediments to earthquakes which reflect the lateral variability of sedimentary facies

soft sediment deformation structures in nw germany caused by late pleistocene seismicity new data on seismically triggered soft sediment deformation structures in pleniglacial to late glacial alluvial fan and aeolian sand sheet deposits of the upper senne area link this soft sediment deformation directly to earthquakes generated along the osning thrust which is one of the major fault systems in central europe soft sediment deformation structures include a complex fault and fold pattern clastic dikes sand volcanoes sills irregular intrusive sedimentary bodies flame structures and ball and pillow structures the style of soft sediment deformation will be discussed with respect to brittle failure liquefaction and fluidization processes and was controlled by 1 the magnitude of the earthquake and 2 the permeability tensile strength and flexural resistance of the alluvial and aeolian sediments it is the first time in northern germany that fluidization and liquefaction features can be directly related to a fault the occurrence of seismicity in the late pleistocene and in the seventeenth century indicates ongoing crustal movements along the osning thrust and sheds new light on the seismic activity of northern germany the late pleistocene earthquake probably occurred between 15 9 1 6 and 13 1 1 5 ka the association of soft sediment deformation structures implies that it had a magnitude of at least 5 5

seismites an attempt at critical analysis and classification abstract the main types of seismites are reviewed following the proposed classification and are illustrated by our own case studies the large variety of seismites depends on the sedimentologic hydrodynamic and diagenetic characters of the deposits subject to seismic shocks on a given site generally different types of seismites cane be related to the same seismic event these peculiar but widespread sedimentary structures are not always univocal and may often be related to different causes therefore the structures discussed must necessarily be placed in a detailed geological context

seismites in a proterozoic tidal succession singhbhum bihar india abstract early proterozoic metasediments of the chaibasa formation galudih ghatsila dhalbhumgarh region singhbhum bihar india comprise a number of cyclic fining upward prograding successions of tidalites the tidalites show indications for earthquakes in the form of synsedimentary deformation features apart from the structures due to high energy wave action deformed cross bedding convolute laminations synsedimentary faults graben like structures sandstone dykes pseudonodules and slump folds record the seismic activity a gradual decline in the frequency of seismites and tsunami related depositional features in combination with an upward increase in thickness of the tidal cycles are attributed to gradual diminishing of tectonic activity within the basin

seismically induced soft sediment deformation structures seismites around sumdo in the lower spiti valley tethys himalaya abstract soft sediment deformation structures were observed in 120 m thick fluvio lacustrine sediments exposed in the sumdo area in the lower spiti valley tethys himalaya himachal pradesh india these structures vary in their morphology and pattern and occur at eight stratigraphic levels s1 s8 spaced at irregular intervals the deformation structures include over steepened stratification diapiric flame like intrusions of clayey material or complex type recumbent folding of flame like nature pseudonodules large scale soft sediment folding faulting small scale associated with folding and sand dykes these structures are restricted to single stratigraphic layers separated by undeformed beds and can be correlated over a large distance the deformation of the soft sediments is attributed to the combined effects of fluidization liquefaction and shear stress and can be related to past seismic activity in the area recently on 19 january 1975 a major earthquake kinnaur earthquake of magnitude 6 8 caused extensive damage including ground rupturing in the sumdo kaurik area this earthquake has been related to the activation of the kaurik chango fault the deformed layers seismites reported here lie adjacent to this fault zone and can be related with episodic seismicity along this fault it is evident from this study that the kaurik chango fault has been re activated a number of times and that the area suffered at least nine major earthquakes with a magnitude of more than 6 during late pleistocene holocene time including the 1975 kinnaur earthquake

recognition of trigger mechanisms for soft sediment deformation in the pleistocene lacustrine deposits of the santʻarcangelo basin southern italy seismic shock vs overloading abstract the lacustrine deposits of the san lorenzo cycle belong to the infill succession of the sant arcangelo basin a pliocene to pleistocene satellite basin developed close to the front of the south apennines thrust belt the lower to middle pleistocene lacustrine succession is made up of siltstone and claystone interbedded with sandstone carbonate and volcaniclastic beds arranged in fining upward sequences the upper to middle part about 50 m thick of the succession about 200 m thick has been investigated in detail in the depocentral sector of the lacustrine basin here soft sediment deformation structures occur in fine grained sandstone and claystone alternations and show a wide morphological variability deformed laminations slumps load structures large vertical water escape structures and neptunian dykes their formation occurred during and after sedimentation with different mechanisms of deformation some structures are related to liquefaction and fluidization processes viscous fluid behaviour while others occurred when sediment had already undergone lithification and its behaviour was plastic and or brittle facies analysis and detailed morphologic study of the soft sediment deformation structures indicate that the main trigger agents for deformation were seismic shocks and overloading induced by sudden deposition of coarser sediments on clays due to the arrival of density currents thus the soft sediment deformation structures provide a continuous record of the tectonic and sedimentary processes that acted in the lacustrine basin from sedimentation until diagenesis

palaeoproterozoic terrestrial sedimentation in the beasley river quartzite lower wyloo group western australia abstract pre 2 2 ga aeolianite deposits are relatively rare in the geological record due to reworking of aeolianites either by fluvial systems transgression or non recognition here we present high resolution sedimentary facies analysis of a section through the 2 2 ga beasley river quartzite lower wyloo group western australia the unambiguous presence of terrestrial fluvial aeolian deposition is documented in the form of fluvial architectural elements channel bar lateral accretion and overbank deposits and aeolian features dune pin stripe lamination wind streaks and adhesion features these observations contrast strongly with a previous interpretation of marine deposition which is discounted our data is consistent with the dominantly terrestrial depositional mode of the rest of the lower wyloo group including the basal three corners conglomerate member and the subaerial cheela springs basalt we conclude that the lower wyloo succession formed in a terrestrial regime during continental rifting

the origin of muddy sand sediments associated with mud volcanism in the horonobe area of northern hokkaido japan 1 the origin of muddy sand and gas in muddy sand sediments in the horonobe area of northern hokkaido japan was investigated by analyzing the mineralogical and chemical compositions of the sediments and the chemical isotopic compositions of the gas x ray fluorescence and x ray diffraction analyses indicate that chemically the muddy sand is derived from a mixing of components from the hakobuchi and overlying formations and that the characteristic mineral of the muddy sand is heulandite which in the study area has been detected only in the hakobuchi formation these results suggest that the sediments ascended from depths of at least 2200 2400 m the 13cch4 values and the methane ethane propane ratios of the gas indicate that the primary origin of the methane is by thermogenic decomposition of coal bearing beds in the haboro or hakobuchi formations or further deep sources this study provides new data on processes of onshore mud volcanism in japan and contributes to an understanding of processes of subsurface mass transport in regions of mud volcanic activity

wave modified turbidites combined flow shoreline and shelf deposits cambrian antarctica sandstone tempestite beds in the starshot formation cen tral transantarctic mountains were deposited in a range of shoreline to shelf environments detailed sedimentological analysis indicates that these beds were largely deposited by wave modified turbidity currents these currents are types of combined flows in which storm generated waves overprint flows driven by excess weight forces the interpreta tion of the tempestites of the starshot formation as wave dominated turbidites rests on multiple criteria first the beds are generally well graded and contain bouma like sequences like many turbidites the soles display abundant well developed flutes they also contain thick divisions of climbing ripple lamination the lamination however is dominated by convex up and sigmoidal foresets which are geometries identical to those produced experimentally in current dominated com bined flows in clear water finally paleocurrent data support a tur bidity current component of flow asymmetric folds in abundant con volute bedding reflect liquefaction and gravity driven movement and hence their orientations indicate the downslope direction at the time of deposition the vergence direction of these folds parallels paleocur rent readings of flute marks combined flow ripples and a number of other current generated features in the starshot event beds indicating that the flows were driven down slope by gravity the wave component of flow in these beds is indicated by the presence of small to large scale hummocky cross stratification and rare small two dimensional ripples wave modified turbidity currents differ from deep sea turbidity cur rents in that they may not be autosuspending and some proportion of the turbulence that maintains these flows comes from storm waves such currents are formed in modern shoreline environments by a com bination of storm waves and downwelling sediment laden currents they may also be formed as a result of oceanic floods events in which intense sediment laden fluvial discharge creates a hyperpycnal flow event beds in the starshot formation may have formed from such a mechanism oceanic floods are formed in rivers of small to medium size in areas of high relief commonly on active margins the starshot formation and the coeval douglas conglomerate are clastic units that formed in response to uplift associated with active tectonism sedi mentological and stratigraphic data suggest that coarse alluvial fans formed directly adjacent to a marine basin the geomorphic conditions were therefore likely conducive to rapid fluvial discharge events asso ciated with storms the abundance of current dominated combined flow ripples at the tops of many starshot beds indicates that excess weight forces were dominant throughout deposition of many of these beds

estimation of the paleoepicentral area from the spatial gradient of deformation in lacustrine seismites tierras blancas basin mexico abstract a new methodology is introduced to estimate the most probable epicentral area for a paleoearthquake interpreted from seismites within a quaternary basin seismites were described from various detailed stratigraphic logs within the tierras blancas basin tbb a pleistocene lacustrine area located in the central part of the trans mexican volcanic belt tmvb the lacustrine landscape evolution of tbb has been determined by the recent fault activity of the morelia acambay fault system mafs the tbb is bounded by active normal faults striking e w this fault activity has generated soft sediment deformation structures sand silt and gravel dikes pillows diapirs and decametric slumps disturbing the sedimentary infilling from these seismites and their stratigraphic spatial correlation five strong moderate paleoearthquakes e1 e5 have been established in the basin the spatial distribution of these seismites exhibits a gradient of perturbation defined by the intensity of deformation three different degrees of intensity deformation ddi are associated with the liquefacted grain size sediments i silt liquefaction ii silt and sand liquefaction and iii silt sand and gravel liquefaction this spatial gradient indicates an increase of the energy involved from the seismic activity related with the proximity of the source mapping the boundaries among these zones of deformation and interpolation of each ddi limit for paleoearthquake e4 was used to construct paleoseismic isolines of deformation as a potential indicator of the most probable paleoepicentral zone a 1 5 km 2 elongate zone oriented nnw sse is the potential paleoepicentral area associated with paleoearthquake e4 within the tbb

sedimentological evidence of pleistocene earthquakes in nw poland induced by glacio isostatic rebound abstract soft sediment deformation structures are abundantly present in two levels within warthanian eemian lacustrine sediments at siekierki near the polish german border the two event horizons show intense folding collapse sag and load structures indicative of liquidization and fluidization the structures must have been caused by sudden shocks most probably resulting from earthquakes that were induced by glacio isostatic rebound probably after the warthanian deglaciation such seismites have not been previously recognized in polish quaternary sediments they provide supporting evidence for glacio isostatic movements that were interpreted up till now based on drilling lithostratigraphic geophysical and geodetic data the recognition of seismites in nw poland may help recognize other deformed event horizons in pleistocene sediments as glacio isostatic or neotectonic seismites

kinematics of the gondwana basins of peninsular india abstract the gondwana successions 1 4 km thick of peninsular india accumulated in a number of discrete basins during permo triassic period the basins are typically bounded by faults that developed along precambrian lineaments during deposition as well as affected by intrabasinal faults indicating fault controlled synsedimentary subsidence the patterns of the intrabasinal faults and their relationships with the respective basin bounding faults represent both extensional and strike slip regimes field evidence suggests that preferential subsidence in locales of differently oriented discontinuities in the precambrian basement led to development of gondwana basins with varying but mutually compatible kinematics during a bulk motion grossly along the present day e w direction the kinematic disparity of the individual basins resulted due to different relative orientations of the basement discontinuities and is illustrated with the help of a simple sandbox model the regional e w motion was accommodated by strike slip motion on the transcontinental fault in the north

soft sediment deformation structures interpreted as seismites in lacustrine sediments of the prebetic zone se spain and their potential use as indicators of earthquake magnitudes during the late miocene lacustrine formations of late miocene age in the prebetic area se spain show several types of deformational structures that are interpreted as seismites they are present in both marginal and deep lacustrine facies seismites formed in marginal lake environments comprise sand dikes pillows and intruded and fractured gravels in deep lacustrine facies the seismites are represented by pseudonodules mushroom like silts protruding into laminites mixed layers disturbed varved lamination and loop bedding the measured orientations of these structures are consistent with the orientations of the main faults limiting the basins showing that their origin is clearly related to the tectonic stress field that prevailed in the region during the late miocene the magnitudes of the earthquakes that deformed the sediments have been estimated after published data from both ancient and recent lake deposits accumulated in tectonic active regions elsewhere a rank of earthquake magnitudes with two end members i e the lowest magnitudes recorded by loop bedding in laminites and the highest magnitudes represented by intruded and fractured gravels is proposed

hummocky cross stratification and post vortex ripples length scales and hydraulic analysis duke 1987 argues that the structure reported by greenwood sherman 1986 as hummocky cross stratification from a shallow lacustrine environment is instead bedding formed by simple post vortex oscillation ripples his primary concern is with the length scale of the structures identified in box cores however using measured flow data it is shown here that existing models of bedform generation based upon wave orbital velocity orbital diameter and grain diameter do not support a simple post vortex ripple interpretation in particular the relative steepness of the structure refutes such an origin the structural characteristics of the lacustrine cores most closely match those associated with classic hummocky cross stratification and were produced under a combined oscillatory quasi steady flow field

climate vegetation and ecology during harappan period excavations at kanjetar and kaj mid saurashtra coast gujarat a multi proxy study was carried out to address climate culture relationship from two trenches one each from kaj and kanjetar mid saurashtra coast deposited in a lacustrine setting since 1960 cal bc and 2230 cal bc respectively the salinity of aqueous soil solution 0 1 ppt and fresh water thecamoebians in both the sites indicate fresh water depositional environment but an increase in salinity 0 2 ppt in the top clayey sediment in kanjetar is attributed to water evaporation through upward capillary action from moisture deficit exposed land the fragments of ancient potteries and other artefacts recovered from the bottom sediment provide evidences of sorath harappan colonization in the vicinity which was not an urban site the abundant cyanobacterium remains low terrigenous organic matter aquatic pollen and low thecamoebians in bottom sediment indicates low precipitation and arid climatic conditions 2000 bc during this period the dominance of evergreen and moist deciduous arboreals from both the sites do not show equilibrium with the prevailing dry arid climate and therefore the pollen assemblage here represents the remnants of wetter middle holocene vegetation in the region phytoliths of drought tolerant summer season crops also reflects here changes made in the agricultural strategy by harappans in response to climate the increase in deciduous arboreal pollen since the last 2000 years represents equilibrium with the dry arid climate but enhanced limnic conditions recorded with the help of thecamoebians during this period is attributed to changes in wetland configuration induced by hydrostatic changes in the river mouth that was largely defined by the dynamics of sediment deposition through rain fed rivers streams in the region