seismites dans le jurassique superieur du bassin anglo parisien normandie oxfordien superieur calcaire greseux de hennequeville abstract synsedimentary deformation structures are observed on the armorican border of the anglo paris basin in the late oxfordian calcaire greseux de hennequeville formation these detrital sediments are well exposed on the normandy coast between trouville and honfleur outcropping both in the cliffs and on the beach they comprise silty limestone with abundant sponge spicules rhaxella deposited in a restricted subtidal depression mostly above the storm wave base and located in the northern flanks on the sables de glos delta the formation is subdivided into three members deformational structures observed at a centimetre to metre scale and associated with massive early diagenetic cherts are developed only in the middle member which is 1 5 m thick this depositional environment was the shallowest of the whole formation the soft deformation structures are various comprising 1 low amplitude structures observed at the lower and upper surfaces of the limestone beds 2 features with a wash basin form 3 boudinage structures and 4 large scale ball and pillow structures or blagues a tabac tobacco pouches showing vertical dimension of over 1 m and observed only in a few sections of the cliffs all deformational structures are overlain by undisturbed silty limestones and silty clays suggesting a synsedimentary deformation the soft deformations are interpreted to have been induced by the liquefaction of unconsolidated spiculitic silty muds during earthquakes liquefaction may have been induced by a number of processes which affect grain supported sediments a seismic origin is supported not only from particular palaeogeographic context by reference to the whole nw of europe in the late oxfordian but also by the great lateral extent of the deformational structures which occurs along more than 4 km of coastal outcrops there is only one deformed unit the morphology and size of the seismites are directly controlled by the stratonomy and thicknesses of the limestone most of the structures have a dominant vertical trend with an upward or a downward polarity earthquakes are always difficult to recognize in the sedimentary record they were recorded in the case of the calcaire greseux de hennequeville because of a set of exceptional conditions which led to their preservation these were seismic activity associated with recurrent faulting alternating beds of porous wet and well sorted fine sands with muds favourable to thixotropic processes and deposition in a relatively protected depositional environment

synsedimentary tectonic soft sediment deformation and volcanism in the rifted tethyan margin from the upper triassic middle jurassic deep water carbonates in central sicily abstract the pizzo lupo section sicanian mts central sicily is an upper triassic lower jurassic condensed deep water succession where the relationships among synsedimentary tectonic soft sediment deformations volcanism and lithological changes reflect the evolution of a rift basin the morphostructural setting of the studied basin appears as a gently dipping slope where a fault delimited area graben to halfgraben was developed the instability of the sea floor related to the seismic shocks was the cause of the gravity driven deformational sedimentary structures slumping breccia channelized bodies the partly stratified basaltic rocks with disorganized and chaotic stratification suggest the occurrence of a volcanic complex located in neighbouring areas a regional comparison with the tectono sedimentary evolution of the pelagic drowning platform succession i e trapanese domain auct outcropping in adjacent areas suggests that these different domains were close to each other during the studied period forming a stepped margin platform to basin system the environmental changes synsedimentary tectonic activity and gravity driven phenomena were the result of repeated events occurred during a long time interval spanning from late triassic to early jurassic

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

earthquake triggered soft sediment deformation structures seismites in travertine deposits abstract earthquakes related soft sediment deformations seismites are relevant structures to help reconstructing the palaeoseismicity in a region nevertheless although seismites have been described for a large variety of palaeo environments and stratigraphic settings they are rare and in some cases ambiguous structures in this paper we document for the first time impressive seismites affecting a latest quaternary travertine deposit located in southern tuscany serre di rapolano italy these structures are extremely relevant as seismites have been never described for this kind of terrestrial deposits the seismites developed within a 2 5 m thick stratigraphic succession made of alternating terrigenous and carbonate sediments embedded within the travertine deposits earthquake produced liquefaction and fluidization of some terrigenous levels and the injection of fluidized silty sediments dykes and sills into carbonate and terrigenous levels slumped levels and associated decollement surfaces produced highly non cylindrical folds overall induced by the loss of brittle shear strength along the basin slopes the occurrence of these soft sediment deformations implies an important seismic event that took place in a time spam encompassed between 84 8 and 48 92 5 08 ka in an area characterized by low seismicity and scarce knowledge of its seismotectonic setting their spectacular exposition and preservation in saw cuts of an abandoned quarry cava oliviera quarry highlights their relevance and importance

a new insight into probabilistic seismic hazard analysis for central india the son narmada tapti lineament and its surroundings of central india ci is the second most important tectonic regime following the converging margin along himalayas myanmar andaman of the indian sub continent which attracted several geoscientists to assess its seismic hazard potential our study area a part of ci is bounded between latitudes 18 26 n and longitudes 73 83 e representing a stable part of peninsular india past damaging moderate magnitude earthquakes as well as continuing microseismicity in the area provided enough data for seismological study our estimates based on regional gutenberg richter relationship showed lower b values i e between 0 68 and 0 76 from the average for the study area the probabilistic seismic hazard analysis carried out over the area with a radius of 300 km encircling bhopal yielded a conspicuous relationship between earthquake return period t and peak ground acceleration pga analyses of t and pga shows that pga value at bedrock varies from 0 08 to 0 15 g for 10 t 475 years and 2 t 2 475 years probabilities exceeding 50 years respectively we establish the empirical relationships text zpa t 475 0 1146 v text s 30 0 2924 and text zpa t 2475 0 2053 v text s 30 0 2426 between zero period acceleration zpa and shear wave velocity up to a depth of 30 m v s 30 for the two different return periods these demonstrate that the zpa values decrease with increasing shear wave velocity suggesting a diagnostic indicator for designing the structures at a specific site of interest the predictive designed response spectra generated at a site for periods up to 4 0 s at 10 and 2 probability of exceedance of ground motion for 50 years can be used for designing duration dependent structures of variable vertical dimension we infer that this concept of assimilating uniform hazard response spectra and predictive design at 10 and 2 probability of exceedance in 50 years at 5 damping at bedrocks of different categories may offer potential inputs for designing earthquake resistant structures of variable dimensions for the ci region under the national earthquake hazard reduction program for india

ancient wet aeolian environments on earth clues to presence of fossil live microorganisms on mars abstract ancient wet aeolian wet sabkha environments on earth represented in the entrada and navajo sandstones of utah contain pipe structures considered to be the product of gas water release under pressure the sediments originally had considerable porosity allowing the ingress of living plant structures microorganisms clay minerals and fine grained primary minerals of silt and sand size from the surface downward in the sedimentary column host rock material is of a similar size and porosity and presumably the downward migration of fine grained material would have been possible prior to lithogenesis and final cementation recent field emission scanning electron microscopy fesem and eds energy dispersive spectrometry examination of sands from fluidized pipes in the early jurassic navajo sandstone reveal the presence of fossil forms resembling fungal filaments some bearing hyphopodium like structures similar to those produced by modern tropical leaf parasites the tropical origin of the fungi is consistent with the paleogeography of the sandstone which was deposited in a tropical arid environment these fossil fungi are silicized with minor amounts of caco 3 and fe and in some cases a si al ratio similar to smectite they exist as pseudomorphs totally depleted in nitrogen adhering to the surfaces of fine grained sands principally quartz and orthoclase similar wet aeolian paleoenvironments are suspected for mars especially following catastrophic sediment charged floods of enormous magnitudes that are believed to have contributed to rapid formation of large water bodies in the northern plains ranging from lakes to oceans these events are suspected to have contributed to a high frequency of constructional landforms also known as pseudocraters related to trapped volatiles and water enriched sediment underneath a thick blanket of materials that were subsequently released to the martian surface forming piping structures at the near surface and constructional landforms at the surface this constructional process on mars may help unravel the complex history of some of the piping structures observed on earth on earth evidence for the constructional landforms has been all but erased and the near surface piping structures exposed through millions of years of differential erosion and topographic inversion now occur as high standing promontories if the features on both earth and mars formed by similar processes especially involving water and other volatiles and since the piping structures of earth provided suitable environments for life to thrive in the martian features in the northern plains should be considered as prime targets for physico mineral chemical microbiological analyses once the astrobiological exploration of the red planet begins in earnest

shock induced resuspension deposits from a pleistocene proglacial lake kleszczow graben central poland abstract several glaciolacustrine successions forming part of the quaternary fill of the kleszczow graben contain massive and widespread fine grained units that are abnormally thick and homogeneous field studies of such a unit indicate that it is the result of rapid settling of particles from a sediment cloud consisting of material that had once settled on the lake bottom but were resuspended the geological setting makes it likely that the trigger mechanism responsible for the sediment cloud in the lake water was a shock and that this shock most probably an earthquake was caused by tectonic activity in the graben

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

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

problems and progress in the research on soft sediment deformations abstract the study of soft sediment deformations has gradually evolved from describing them as remarkable features into a structural analysis that should contribute to the reconstruction of the sediments early diagenetic history it appears that most attention has been devoted to this field during a few phases of the development of sedimentology a third phase when interest was renewed started in the eighties but progress is still hampered by inefficient scientific communication due to the absence of an unambiguous terminology specific topics deserving of much more attention in the near future are the interrelationships between the various forces that may effect a sediment simultaneously the development of deformational structures during a number of subsequent stages the preservational potential of the structures and systematic experiments that deal with the influence of the physico chemical and physico mechanical properties of the sediment

sediment deformation in miocene and post miocene strata northeastern brazil evidence for paleoseismicity in a passive margin abstract stratigraphic intervals characterized by varied and complex styles of soft sediment deformation structures are well preserved in miocene and late pleistocene to holocene deposits of a sedimentary basin located in northeastern brazil the miocene strata represented by the barreiras formation record only brittle structures including numerous faults and fractures with straight and high angle dipping planes that are often filled with sands derived from overlying beds folds consisting of broad anticlines and synclines are also present in this unit the late pleistocene to holocene deposits named post barreiras sediments contain an indurated sandy package with a large variety of ductile and brittle deformation structures i e massive sandstones with isolated sand fragments and breccias undulatory strata sand dykes and diapirs sinks and bowls pebbly pockets plunged sediment mixtures fitted sand masses cone shaped cracks fault grading and sedimentary enclaves these features confined to sharp based stratigraphic horizons that progressively grade downward into undisturbed deposits are related to seismic shocks of high surface wave magnitude i e ms 5 or 6 amalgamated seismites suggest that previously formed seismites were affected by subsequent seismic wave propagation seismic waves caused by activity along one or most likely several tectonic structures would have propagated throughout the depositional environment producing laterally extensive seismites the close proximity to earthquake epicenters would have promoted pervasive re sedimentation due to pore overpressure resulting high volumes of massive sandstones and breccia the similarity between deposits with correlatable strata from many other areas along the brazilian coast allows raise the hypothesis that the seismic episodes might have affected sedimentation patterns in a large i e extension of several hundreds of kilometers geographic area thus the modern seismicity recorded along northeastern brazil was recurrent during the quaternary and perhaps also in the pliocene the estimated high magnitude of the seismic events and the great regional extent of the affected area demonstrate that the brazilian coast experienced tectonic stress through the last geological episodes of its evolution which would have favored sediment accumulation and penecontemporaneous re sedimentation this geological context is unexpected in a passive margin inducing to revisit the debate on how active is a passive margin

syneresis cracks subaqueous shrinkage in argillaceous sediments caused by earthquake induced dewatering abstract syneresis cracks often confused with subaerial desiccation phenomena are traditionally ascribed to subaqueous shrinkage whereby salinity changes caused deflocculation of clay this and other previously proposed mechanisms fail to account for their occurrence in low energy typically non evaporitic facies stratigraphically sporadic distribution intrastratal formation under shallow burial depths variation in morphology degree of contraction generation of sedimentary dikelets as crack fills and deformation of dikelets and enclosing layers instead it is suggested that ground motion from strong synsedimentary earthquakes caused argillaceous sediments to dewater interbedded sands and silts to be almost simultaneously liquefied and injected into the resulting fissures and then these dikelets to be distorted comparative rarity of syneresis cracks in phanerozoic versus precambrian marine strata is considered to be primarily an evolutionary consequence of theological changes caused by increased organic binding of clay flocs in the water column greater input of organic matter into the sediment and the diversification of sediment dwelling bacteria and meiofauna in phanerozoic deposits

long term seismic observations along myanmar sunda subduction margin insights for 2004 m w 9 0 earthquake the present study investigates the temporal variation of few seismic parameters between the myanmar zone i andaman nicobar northwest sumatra zone ii southeast sumatra west indonesia zone iii and east indonesia zone iv converging boundaries in reference to the generation of 26 december 2004 mw 9 0 off sumatra mega earthquake event the four segments are distinguished based on tectonics parameters distinct geological locations great earthquake occurrences and the wadati benioff zone characteristics two important seismic parameters such as seismic energy and b values are computed over a time window of 6 month period during the entire 1976 2013 period for these segments the b values show a constant decrease in zones ii iii and iv whereas the zone i does not show any such pattern prior to the 2004 mega event the release of seismic energy was also gradually decreasing in zones ii and iii till the 2004 event and little similar pattern was also noted in zone iv this distinct observation might be indicating that the stress accumulation was dominant near the sumatra java area located towards southeast of zone ii and northwest of zone iii the released strain energy during the 2004 event was subsequently migrated towards north rupturing 1300 km of the boundary between the northwest sumatra and the north andaman the occurrence of 2004 mega event was apparently concealed behind the long term seismic quiescence existing near the sumatra and nicobar margin a systematic study of the patterns of seismic energy release and b values and the long term observation of collective behaviour of the margin tectonics might have had given clues to the possibility of the 2004 mega event

pliocene burdur basin sw turkey tectonics seismicity and sedimentation the pliocene burdur formation of sw turkey was deposited in a ne sw trending half graben with a major basement fault along its se margin hangingwall sourced fans were confined proximally by basement topography distally they developed 9ideal9 fan geometries these fans became submerged by the lake that occupied the centre of the basin this transgression was caused by the migration with time of the hangingwall pivot away from the basin controlling fault footwall sourced fans exhibit three distinctly different geometries at the northern end of the basin a wide braidplain developed due to the rapid erosion of both penecontemporaneous volcaniclastic deposits to the east and the footwall crest of a newly formed fault within the basin along the footwall scarp in the central part of the basin a narrow bajada formed in the south a large alluvial fan had its source in the relay structure between two left stepping en echelon fault segments the small size of footwall sourced fans compared with those sourced on the hangingwall slope was due to rapid subsidence of the basin floor adjacent to the footwall scarp although this suggests high levels of seismicity the general paucity of wet sediment deformation within the burdur formation indicates that seismicity in the burdur region during the pliocene was more subdued than at present

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

paleo earthquakes in passive margin settings an example from the paleocene of the golfo san jorge basin argentina abstract paleocene sedimentary rocks in the golfo san jorge basin include the marine salamanca formation and the continental rio chico formation both units contain soft sediment deformation features and evidence of contemporary tectonics which include 1 sediment filled fissures hosted in muddy marine sediments of the salamanca formation fragmentosa section where the sandy infill of the fissures took place from above 2 synsedimentary normal faults in the uppermost levels of the salamanca formation with vertical throws rarely exceeding 1 m 3 fault graded beds in the banco negro inferior marine continental transition which show a deformed sequence with small scale normal faults at the bottom and intraformational breccias on top and 4 liquefaction and or fluidization pillars v or funnel shaped with vertical extension of up to 5 m and preserved into fluvial channels of the rio chico formation deformed strata are bounded by undisturbed horizons and some of these features can be correlated along 60 km of exposures the suite of soft sediment deformation structures is considered a secondary evidence of synsedimentary paleo earthquakes seismites in this portion of the south american passive margin this work shows new evidence of syndepositional tectonic activity in the lowermost paleogene of the golfo san jorge basin

syndepositional tectonics recorded by soft sediment deformation and liquefaction structures continental lower permian sediments southern alps northern italy stratigraphic significance abstract the lower permian succession of the central southern alps lombardy northern italy was deposited in fault controlled continental basins probably related to transtensional tectonics we focussed our study on the stratigraphic record of the lower permian orobic basin which consists of a 1000 m thick succession of prevailing continental clastics with intercalations of ignimbritic flows and tuffs pizzo del diavolo formation pdv resting on the underlying prevailing pyroclastic flows of the cabianca volcanite the pdv consists of a lower part composed of conglomerates passing laterally to sandstones and distally to silt and shales a middle part pelitic with carbonates and an upper part alternating sandstone silt and volcanic flows syndepositional tectonics during the deposition of the pdv is recorded by facies distribution thickness changes and by the presence of deformation and liquefaction structures interpreted as seismites deformation is recorded by both ductile structures ball and pillow plastic intrusion disturbed lamination convolute stratification and slumps and brittle structures sand dykes and autoclastic breccias both the sedimentological features and the geodynamic setting of the depositional basin confidently support the interpretation of the described deformation features as related to seismic shocks the most significant seismically induced deformation is represented by a slumped horizon about 4 m thick on average which can be followed laterally for more than 5 km the slumped bed consists of playa lake deposits alternating pelites and microbial carbonates associated with mud cracks and vertebrate tracks the lateral continuity and the evidence of deposition on a very low angle surface along with the deformation liquefaction of the sediments suggest that the slump was triggered by a high magnitude earthquake the stratigraphic distribution of the seismites allows us to identify time intervals of intense seismic activity which correspond to rapid and basin wide changes in the stratigraphical architecture of the depositional basin and or to the reprise of the volcanic activity the nature of the structures and their distribution suggest that the magnitude of the earthquakes responsible for the observed structures was likely higher than 5 in order to produce sediment liquefaction and probably reached intensity as high as 7 or more the basin architecture suggests that the foci of these earthquakes were located close to the fault controlled borders of the basin or within the basin itself

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

septarian concretions internal cracking caused by synsedimentary earthquakes septarian concretions are abundant in many phanerozoic marine and marginal marine shales and mudstones they range from a few centimetres to several metres in size and are spherical or ellipsoidal in morphology in general formation by localized calcite or siderite cementation in argillaceous sediments began under less than a few metres of burial septarian cracks vary widely in shape and configuration included are networks of wide vertically radially and sometimes concentrically oriented lenticular shrinkage cracks and narrower parallel sided straight to irregular tension cracks locally accompanied by brecciation and plumose and en echelon sigmoidal cracks indicative of shear stresses crack types are intergradational many concretions exhibit multiple cracking events enclosed macrofossils and isopachous fibrous calcite cement that lines earlier formed cracks are commonly broken and displaced in some cases cracks contain injected lime mud and silt these features taken together testify that cracking involved a spectrum of responses in concretion interiors from loss of shear strength dewatering and shrinkage to brittle failure demonstrating variations in and contrasts between the rheological properties of the matrix and enclosed objects localization to interiors and outward tapering of lenticular cracks make a case for fracture partitioning and indicate that interiors were softer than exteriors at the time of shrinkage parallel sided cracks point to greater stiffness and evolving crack shape in multiply cracked concretions shows that rigidity increased with time crack orientations indicate highly variable tensile and shear stress directions within individual concretions rupture brecciation displacement of fragments loss of shear strength liquefaction and injection of unconsolidated granular sediment suggest that deformation events were rapid if not virtually instantaneous previous explanations for the internal cracking such as gas generation spontaneous chemical dehydration or localized overpressuring due to compaction seem either untenable or fail to account for the spectrum of observed features however syndepositional earthquake induced shaking of cementing bodies of varying rigidity at shallow burial depths seems to be a plausible source for the requisite short lived variable to anisotropic high stress regime inside the concretions septarian concretions may thus preserve a signature of basin seismicity as it relates to their cementation history

seismic b values and its correlation with seismic moment and bouguer gravity anomaly over indo burma ranges of northeast india tectonic implications abstract b value is one of the most significant seismic parameters for describing the seismicity of a given region at a definite time window in this study high resolution map of the gutenberg richter b value seismic moment release bouguer gravity anomaly and fault plane solutions containing faulting styles are analyzed in the indo burma ranges of northeast india using the unified and homogeneous part of the seismicity record in the region january 1964 december 2016 the study region is subdivided into few square grids of geographical window size 1 1 and b values are calculated in each square grid our goal is to explore the spatial correlations and anomalous patterns between the b value and parameters like seismic moment release bouguer gravity anomaly and faulting styles that can help us to better understand the seismotectonics and the state of present day crustal stress within the indo burma region most of the areas show an inverse correlation between b value and seismic moment release as well as convergence rates while estimating the b value as a function of depth a sudden increase of b value at a depth of 50 60 km was found out and the receiver function modeling confirms that this depth corresponds to the crust mantle transition beneath the study region the region is also associated with negative bouguer gravity anomalies and an inverse relation is found between gravity anomaly and b value comparing b values with different faulting styles reveal that the areas containing low b values show thrust mechanism while the areas associated with intermediate b values show strike slip mechanism those areas where the events show thrust mechanism but containing a strike slip component has the highest b value

high density crustal intrusive bodies beneath shillong plateau and indo burmese range of northeast india revealed by gravity modeling and earthquake data abstract modeling and analysis of gravity and earthquake data of a critically dynamic northeastern region of india assumes a special significance for understanding the seismicity and geodynamics in this paper the relation between lateral heterogeneity of gravity interfaces with subsurface structures and seismic characteristics of northeast india are studied in detail to understand the seismicity and dynamics of the region using bouguer gravity earthquake and magnetotelluric data the modern scaled power spectral analysis of gravity data has brought out crustal lateral heterogeneity at a depth of 8 33 km 19 73 km and 37 14 km that correlate well with 10 km upper crust 20 km lower crust and a moho at 28 42 km revealed by 1d seismic crustal velocity and tomography studies the inferred crustal depths support thinner crust over uplifted shillong plateau and gradual increase of depths over subduction interface of indo burmese range 2d gravity modeling constrained by seismic velocity model and 3d euler deconvolution technique along two specific e w and three n s regional gravity transects delineated three significant high density anomalous heterogeneous intrusive bodies presumably due to underplating beneath shillong plateau mikir massif and indo burmese range based on the seismicity and stress pattern analysis through seismic b value variation we infer that the study region exhibits compressive stress concentrations in the form of brittle deformation at shallow depths and weakening of lower crust by high density intrusive mafic ultramafic bodies of ductile nature which may cause intense seismicity besides the ongoing collision of north drifting indian plate with eurasia to the north and the eastern subduction interface of indo burmese range we also infer that the ne to nw trending v shaped areas outlined north of shillong plateau south of mikir massif and ne sw trending thrust belt of schuppen exhibit aseismic nature and may be the future impounding seismic sources in this region

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

high resolution geological record of historic earthquakes in the dead sea basin a 2000 year paleoseismic record of the dead sea area was recovered from a lacustrine sedimentary section the section is being exposed at the ze elim terrace on the shores of the dead sea due to the fast retreat of the lake the section consists of laminated detrital and chemical mainly aragonite sediments that were deposited in the holocene paleo dead sea eight layers in the section show deformed sedimentary structures and are identified as seismites their chronology was determined by radiocarbon dating on organic remains the seismite ages are well correlated with the historically documented earthquakes of 64 and 31 b c and 33 363 1212 1293 1834 and 1927 a d the few historically documented earthquakes that have no correlatives in the ze elim seismite record occurred in times of sedimentary hiatuses at this site e g 749 a d based on modern analogues and the association of similar disturbed layers with syndepositional faults the ze elim terrace seismites indicate m 5 5 earthquakes the average recurrence interval is estimated as 100 300 years and represents slip events on different faults in the dead sea area the ze elim section provides a unique opportunity to correlate two independent and extensive data sets the historical and sedimentary records this study opens the way for better understanding of spatial and temporal distribution of earthquakes along the dead sea transform and elsewhere

3 d geometry and luminescence chronology of quaternary soft sediment deformation structures in gravels northeastern brazil abstract this paper reports and describes soft sediment deformation in gravels and gravelly sediments in quaternary alluvial deposits of the potiguar basin northeastern brazil deformation structures were measured in terms of geometry size and relationship with sedimentary bedding using geological mapping and ground penetrating radar tl and osl irsl methods following mar and sar protocols were used to date sediments and soft sediment deformation events our results indicate that soft sediment deformation structures are widely distributed in several stratigraphic intervals of alluvial channel deposits in a low lying topographic valley depending on their geometry and composition two types of soft sediment deformation structures occur pockets and dome like load structures these structures resulted from the shaking of sediments with a reverse density gradient system which caused collapse and realignment of pebbles these features are similar in morphology and size to modern examples of seismically induced soft sediment deformation in coarse sediments tl and osl ages indicate that sediment deposition and associated soft sediment deformation occurred at least six times from 352 ka to 9 ka

cause of the rupture and distribution of broken submarine carbonate chimneys in the gulf of cadiz southwestern spain abstract during the 2000 and 2001 r v cornide de saavedra cruises a vast field of hydrocarbon derived carbonate chimneys was discovered and sampled along the cadiz contourite channel and guadalquivir diapiric ridge photographs taken on board using an underwater camera revealed a spectacularly high density of pipe like chimneys lying on the sea floor though some of them were also found protruding from muddy sediment the major axes of the fallen chimneys which can be as long as 1 m exhibit a regular spatial distribution showing a conspicuous nw se trend furthermore their basal morphology shows a characteristic angular breakage associated to a flexo traction process both the uniform distribution of the major axis and the basal morphology of the chimneys imply that the cause of the rupture could be related either to strong bottom sea currents or to inertia forces associated with oscillatory ground motion due to seismic shaking the preferential orientation of the broken chimneys their mechanical properties the geological and topographical conditions of the area in relation to seismic ground motion amplification and the flow speed of the mediterranean outflow water mow along the cadiz contourite channel suggest that the most probable cause of the chimneys rupture was an earthquake the minimum magnitude of this seismic event is estimated to be more than 7 0 the causative fault being located directly under the chimney field or as far as 30 60 km away the chimneys rupture took place between ca 5 ka to present

pervasive near surface stratal disruption in an accretionary prism setting kaczawa complex sw poland the tectonized and metamorphosed mudrocks within the variscan accretionary prism of the kaczawa mountains in sw poland comprise sedimentary melanges together with more coherent stratigraphic units some represent large olistoliths deposited in a submarine trench we infer a trend of progressive near surface stratal disruption in mud dominated deposits due to dewatering that forms a continuum with subduction related tectonic structures imposed on unconsolidated sediment during deeper burial the assemblage of characters suggests that an accretionary prism environment can influence and leave characteristic traces of the total burial history of a trench succession

seismic behaviour of the dead sea fault along araba valley jordan the dead sea fault zone is a major left lateral strike slip fault south of the dead sea basin the wadi araba fault extends over 160 km to the gulf of aqaba the dead sea fault zone is known to have produced several relatively large historical earthquakes however the historical events are unequally distributed along the fault and only four events have been reported in the araba valley over the last few thousands of years magnitudes estimated from the historical record are probably slightly smaller than that of the m w 7 3 earthquake that struck the gulf of aqaba in 1995 the fault cuts straight across pleistocene to holocene alluvium and shows morphologic evidence for essentially pure strike slip motion regional seismic monitoring reveals little microseismicity along the fault except around the dead sea and gulf of aqaba where the fault splays into complex pull apart basin fault systems we have investigated the fault zone at several sites selected from spot images and the study of aerial photography at the site of the now destroyed tilah castle a well preserved wall dated to be about 1200 yr bp 14 c age on charcoal is cut by the fault and offset by 2 2 m comparison with offset gullies at a nearby site 3 km to the north and at three other sites respectively 25 50 and 65 km to the south reveals that this specific fault displacement is probably related to the last seismic event that ruptured that fault segment possibly in ad 1458 moreover the offset gullies suggest a characteristic slip behaviour with recurring slip of about 1 5 m on average given the 4 2 mm yr 1 slip rate derived for this fault segment we infer that the fault should produce m w 7 earthquakes along some segment in the araba valley about every 200 years the historical period with only four well documented large earthquakes in ad 1068 ad 1212 ad 1293 and ad 1458 thus appears to have been relatively quiescent with a 20 per cent deficit of m w 7 earthquakes however our data do not exclude the possibility of larger m w 7 6 earthquakes or time clustering of earthquakes over longer timespans an alternative seismic behaviour involves m w 7 6 earthquakes about every 6000 years and m w 7 earthquakes about every 250 years the historical catalogue would then appear to be complete for m w 7 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

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

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

extreme aridification since the beginning of the pliocene in the tarim basin western china abstract mid latitude central asia is characterized by an extreme arid landscape among the central asian deserts the taklimakan desert is the largest shifting sand desert which is located in the rain shadow of the tibetan plateau and of the other central asian high mountains the formation of this desert is important for placing widespread aridification into a regional tectonic context at the western end of the himalayan tibetan orogen however there still exists considerable controversy regarding the timing of desert formation thus impeding our understanding of the climatic effects of the tibetan uplift and regional environmental changes here we report new biostratigraphic age control and multiple high resolution climatic records from the center of the taklimakan desert our results reveal dramatic environmental changes at 5 ma suggesting that an extremely dry climate has prevailed since the beginning of the pliocene which is consistent with findings from a high resolution borehole record about 670 km to the east in the same basin the two records combined demonstrate that an extremely dry environment prevailed in the entire tarim basin from approximately 5 ma this was related to the reduced transport of water vapor by westerlies in response to the retreat of the paratethys ocean driven by global climatic cooling and the closed oceanic water vapor pathway between the pamir and the tian shan ranges driven by the ongoing india eurasia collision

late quaternary lacustrine paleo seismic archives in north western alps examples of earthquake origin assessment of sedimentary disturbances abstract the late quaternary sedimentary fills of several lakes of the north western alps are revealed to be possible paleo seismological archives in a moderately active seismo tectonic region the strongest historically reported events can be correlated with specific layers whose textures result from different processes i mass failures of sub aqueous slope deposits especially delta foresets evolving into hyperpycnal currents influenced by seiche effects and or multiple reflections on lake basin slopes ii in situ liquefaction and flowage and iii micro fracturing based on identification of the sedimentary signature of a well documented historical earthquake the paleoseismic interpretation can be extrapolated back to 16 000 yrs bp with a reconstruction of a time series and textural identification of slope failure related turbidites the most frequent earthquake signature the obtained time series are compatible with historical seismicity in terms of recurrence interval

the seismic b value and its correlation with bouguer gravity anomaly over the shillong plateau area tectonic implications abstract clues to the understanding of intra and inter plate variations in strength or stress state of the crust can be achieved through different lines of evidence and their mutual relationships among these parameters bouguer gravity anomalies and seismic b values have been widely accepted over several decades for evaluating the crustal character and stress regime the present study attempts a multivariate analysis for the shillong plateau using the bouguer gravity anomaly and the earthquake database and establishes a causal relationship between these parameters four seismic zones zones i iv with widely varying b values are delineated and an excellent correlation between the seismic b value and the bouguer gravity anomaly has been established for the plateau low b values characterize the southwestern part zone iv and a zone zone iii of intermediate b values separates the eastern and western parts of the plateau zones i and ii which have high b values positive bouguer anomaly values as high as 40 mgal a steep gradient in the bouguer anomaly map and low b values in the southwestern part of the plateau are interpreted as indicating a thinner crustal root uplifted moho and higher concentration of stress in comparison the negative bouguer anomaly values flat regional gradient in the bouguer anomaly map and intermediate to high b values in the northern part of the plateau are consistent with a comparatively thicker crustal root and lower concentration of stress with intermittent dissipation of energy through earthquake shocks further depth wise variation in the b value for different seismic zones delineated under this study allowed an appreciation of intra plateau variation in crustal thickness from 30 km in its southern part to 38 km in the northern part the high b values associated with the depth coinciding with lower crust indicate that the shillong plateau is supported by a strong lithosphere

holocene earthquakes inferred from a fan delta sequence in the dead sea graben abstract the holocene sequence of the fan delta of nahal darga in israel records deformation associated with earthquakes related to the dead sea transform in general and to the jericho fault in particular the fan delta sequence is well exposed and 20 radiocarbon ages help to date the earthquakes that are inferred from a displacement along faults b liquefaction features associated with 11 separate sandy and silty layers and c slumped allocthonous bodies of sediments located directly above one of the main splays of the jericho fault on average an earthquake larger than m 5 5 has occurred approximately every 600 years this estimate is based on the earthquake record of the complete stratigraphic sequence with erosional hiatuses omitted from the calculations the most recently deformed layer is related to the 1927 jericho m l 6 2 earthquake this layer provides a modern analog for the style of soft sediment deformation associated with earthquakes in the late pleistocene and holocene silty sand beds of the fan delta complexes of the dead sea and its predecessor lake lisan

seismogenic deformation structures in microbialites and mudstones silurian lockport dolomite northwestern ohio u s a syndepositional deformation structures are present at two different stratigraphic levels in the silurian lockport dolomite at a quarry in maumee ohio such structures are absent in this unit at twelve other quarries in northwestern ohio the structures at maumee present within stromatolites thrombolites and variably bedded mudstones include convolute layers homogenization of bedding and breccia clasts clasts of stromatolites boudinage structures normal reverse and thrust faults and discordant and concordant breccias the distribution of deformation structures within beds suggests substantial control from substrate rheology possibly resulting from differences in degrees of lithification and from variations in water content the extensive variety of syndepositional deformation structures juxtaposed evidence for nearly synchronous compression and dilation proximity 4 5 km of the structures to the largest fault in northwestern ohio the bowling green fault and the restricted geographic distribution of the deformation structures suggest seismic shaking as a probable mode of genesis similarities between features produced by seismogenic deformation of siliciclastic sediments and deformation features in the lockport dolomite provide additional evidence that the latter features are seismogenic it is postulated that two earthquakes one with a magnitude 5 caused the formation of the syndepositional deformation structures present in the youngest facies in the lockport dolomite at maumee quarry the bowling green fault 4 5 km west of maumee was a growth fault during formation of the lockport dolomite and is considered to have been the source of earthquakes that created the syndepositonal deformation structures in this unit at maumee quarry evidence from the lockport dolomite in northwestern ohio suggests that seismogenic deformation structures created by two earthquakes along the bowling green fault with magnitudes of 5 did not form in this unit over large areas i e all of northwestern ohio this evidence challenges the suggestion that syndepositional seismogenic deformation structures are always formed over a large area

synsedimentary brecciation in the eifelian middle devonian baltic basin sudden catastrophe or diagenetic collapse the eifelian sedimentary record in the epeiric baltic basin contains an extensive brecciated interval known as the narva breccia during recent decades the origin of this breccia has been attributed to 1 palaeoseismicity 2 extraterrestrial impact event or 3 diagenetic collapse our studies show the presence of two different breccia types that form 11 stratigraphic horizons and contain several laterally and stratigraphically unrelated breccias the occurrence of type 1 and type 2 breccias together with carbonate sabkha and carbonate inter to supratidal tidal flat deposits on the basin margins indicates synsedimentary brecciation formed in a sabkha environment type 2 breccia could also originate from wave cycling loading

early cretaceous slumps and turbidites with peculiar soft sediment deformation structures on lingshan island qingdao china indicating a tensional tectonic regime abstract some sections on lingshan island in the yellow sea close to the city of qingdao show the early cretaceous lingshandao formation the exposed succession consists mainly of turbidites some of which show uncommon soft sediment deformation structures and contains well developed large scale slumps that consist of sets of turbidites the sediments were deposited as part of lobes of turbidites and hyperpycnites deposits of flood generated sediment laden bottom currents derived from an estuary in a deep sea environment that formed part of an inter arc basin with a tensional tectonic regime some of the slumps have dimensions of the order of metres to tens of metres they consist of the turbidites that build most of the succession the soft sediment deformation structures in the turbidites represent a wide variety of types most of which are common in subaqueous environments with a high accumulation rate the most interesting are however structures that indicate active tectonic tension these structures are boudins which are present with two subtypes the most common are pinch and swell structures sometimes leading to isolated parts of the affected sandy layer enveloped by shales of the under and overlying shale layers the second type consists of domino boudins which have as far as we are aware of not earlier been described from sediments that were still unlithified during their formation the presence of the boudins and associated structures which indicate synsedimentary stretching related to an extensional tectonic setting form an additional argument in the long lasting debate about the question of whether a compressional or an extensional tectonic regime dominated in the area during the early cretaceous

seismites in continental sand sea deposits of the late cretaceous caiua desert bauru basin brazil abstract two large scale sediment deformation structures minor fold occurrences in cross bedded sand dune deposits and complex convolute folds are observed in red sandstones in a zone about 1 5 km long in floodway cuts at the sergio motta porto primavera dam sao paulo state brazil the most important structures are confined to planar zones up to 10 m thick in undeformed dune foreset strata were they can be traced laterally for about 50 60 m the sandstones are part of the rio parana formation caiua group which accumulated in a great sand sea of about 100 000 km2 the caiua desert developed during the late cretaceous in the southern part of the bauru basin an intracontinental subsiding area in the central southern part of the south american platform the basin was filled by a sandy sequence about 300 m thick the sand sea deposits correspond to the caiua group and comprise a deposits of dry sand sheets santo anastacio formation b deposits of medium sized dunes and humid interdunes of the sand sea peripheral zones goio ere formation and c deposits of large sized complex aeolian dunes and draas that correspond to the central part of the inland sand sea rio parana formation the deformations in the sediments are attributed to the effects of fluidization liquefaction and shear stress which are interpreted as being earthquake induced structures mainly because 1 the deformed horizons are confined between undeformed cross bedded strata 2 the complex convolute folds sometimes include nappe like structures that overlie foreset facies 3 during the bauru basin infilling there was tectonic activity associated with alkaline volcanism on the borders of the basin and related silicification in the central southern part the main silicification zones are aligned to regional lineaments that cross the area near the large scale sedimentary deformation structures

crustal heterogeneity highlighted by spatial b value map in the wellington region of new zealand summary we map the b value in the subduction zone of the wellington region new zealand using a high quality earthquake catalogue relocated with a 3 d seismic velocity model consisting of 50 314 events that occurred between 1990 and 2005 in order to investigate heterogeneity in the crust of the overlying plate and in the upper plane of the wadati benioff zone wbz we analyse a series of cross sections perpendicular to the strike of the subduction zone we calculate the b values selecting events with magnitude of completeness 2 4 and depth 65 km and projecting the seismicity within 20 km on each side of the cross sectional planes we observe areas of high b value 1 7 near the plate interface and regions of low b value anomalies are detected both in the wbz in the northwest region below 40 km depth and in the overlying plate in the northern south island at 10 km depth the anomalies are statistically significant based on utsu s p test and the bootstrap method and are not data processing method or parameter dependent we compare the b value distribution with previously determined 3 d distributions of vp vp vs and qp from seismic tomography this comparison suggests that material inhomogeneity caused by fluid filled cracks resulting from dehydration of the subducted slab and subducted sediments is the predominant cause of b value variation in the shallow part of this subduction zone our observations are consistent with a previously proposed conceptual model that fluid distribution in the shallow part of this subduction zone is controlled by the permeability of geological terranes in the overlying plate

a seismite in triassic gypsum deposits grabfeld formation ladinian southwestern germany an approximately 1 m thick gypsum bed and its underlying 45 cm dolomite bed with variable soft sediment deformation structures are described from the grundgips member of the grabfeld formation middle keuper ladinian in southwestern germany the deformation structures are mainly convolutions folds cusps domes and off shooting dykes and less common brecciation or faulting these deformation structures are interpreted to be caused by liquefaction and or fluidization of the semiconsolidated sediments by a seismic shock of approximately magnitude 6 7 palaeoseismicity is thought to be related with a nearby wrench fault system associated with a major suture zone of the variscan basement

lake mire deposition earthquakes and wildfires along a basin margin fault ronne graben middle jurassic denmark abstract regional uplift of structural highs took place in the greater north sea region in early middle jurassic times resulting in a change from marine shelf deposition in the early jurassic to widespread emergence erosion and localized deposition in grabens the middle jurassic baga formation exposed on the island of bornholm in the baltic sea was deposited in the ronne graben which forms a dog leg pull apart basin linking the northern and southern branches of the tornquist zone the studied succession is situated on the hanging wall immediately adjacent to the main eastern graben margin fault and the footwall consists of deeply weathered granite it is the only locality along the northern branch of the tornquist zone where active tectonic influence on middle jurassic deposition can be demonstrated in outcrop small alluvial fans composed of poorly sorted washout sands and muddy debris flows with weathered granite boulders fringed the footwall scarp syn depositional soft sediment deformation and chaotic bedding structures interpreted as seismites caused by earthquake shocks are characteristic at several levels on the hanging wall further away from the active fault the depositional environment was dominated by shallow freshwater lakes with deposition of clay lake deposition outpaced subsidence and open oxygen deficient freshwater mires were formed during periods of no or only incremental fault movement the mires were only occasionally isolated from clastic input due to doming and dense vegetation resulting in accumulation of pure peat beds the content of spores and pollen shows that the mires were covered by a vegetation of arborescent and herbaceous filicopsida ferns lycopsida club mosses cycadales bennettitales ginkgoales caytoniales taxodiaceae or cupressaceae and araucariaceae wildfires were common in the mires and also on the footwall probably followed by episodes of increased run off and erosion of the upland the presence of common washout sands debrites seismites and abundant lacustrine flooding surfaces indicating sudden drowning of the mires was caused by abrupt movements on the fault with associated earthquakes the succession thus provides an example of temporal changes in deposition in response to changes in tectonic conditions the study illustrates how regional uplift of structural highs caused a restriction of deposition to narrow grabens like the ronne graben facies patterns changed dramatically from laterally extensive uniform packages controlled by sea level changes in the early jurassic to strongly localized deposition with marked facies changes controlled by faulting and earthquakes in the middle jurassic the succession thus serves as an excellent example of tectonically controlled deposition under humid conditions in a continental graben

large scale mud diapirism as a record of late stage laramide tectonism within the eocene green river formation wyoming abstract the gruene and verde mud diapirs which range in size from 70 to 95 m in diameter are exposed within the wilkins peak member of the eocene green river formation near flaming gorge reservoir southwest wyoming these diapirs are sourced from the lower unit of the wilkins peak member lower middle and upper units can be defined based on dominant lithology and were emplaced into the upper unit of the wilkins peak member cross cutting hundreds of meters of strata the structures contain brecciated dolomicritic and lime mudstones with minor amounts of siliciclastic clays pervasive quartz veining is present throughout both diapirs though heavily disturbed original bedding can be seen in both localities either dipping radially outward towards the margins of the diapir as is dominant at the gruene diapir or tilted but near horizontal as is the dominant expression at the smaller verde diapir the gruene diapir can be seen in contact with several fluvial sandstone bodies within the upper wilkins peak strata in outcrop and these fluvial sandstones transition from regional near horizontal dips to steeply dipping beds and bedsets within 50 m of the diapir these sands show no signs of brittle deformation and dip ranges from 20 to 50 radially away from the center of the diapir to the north west and east where sands are observed these are interpreted here to have been deformed pre lithification at or near the surface by the rising mud diapir offering an important control on the timing of diapirism near the end of the early eocene deformation structures such as clastic dikes brecciation and convoluted bedding have been documented by others at or near this stratigraphic interval in utah wyoming and colorado and these smaller structures have been interpreted as seismites we suggest that these mud diapirs are a larger scale expression of this same seismic activity

storms versus tsunamis dynamic interplay of sedimentary diagenetic and tectonic processes in the cambrian of montana the upper cambrian deadwood formation of north central montana is composed mainly of fine grained calcareous sandstone and intercalated silty shale and contains scattered intraclastic flat pebble conglomerate these rocks typical of many mixed carbonate siliciclastic subtidal shelf successions of proterozoic through early ordovician age are distal storm deposits in which the conglomerates are conventionally thought to record occasional very high energy events that scoured incipiently cemented layers in the deadwood formation most sandstone beds have a linear to crudely reticulate pattern of vertical cracks filled with injected silt and clay the cracks exhibit a consistent northwest southeast trend and are very shallow burial deformation structures caused by the passage of seismic waves possibly originating from strong earthquakes in idaho most conglomerates are composed of angular to subangular sandstone intraclasts the polygonal plan view of which is similar in outline to the areas between cracks in the sandstones the deformation implied by the cracks sporadic distribution of conglomerates high degree of scouring indicated and angularity of the intraclasts argue that rather than storms the conglomerates were generated by occasional tsunamis the sweep of these tsunamis across the shallow intracratonic sea created extraordinarily strong oscillating bottom currents at the deeper reaches of storm wave base tsunamites are therefore identified with confidence virtually for the first time in shallow subtidal shelf deposits

percussion marks on bone surfaces as a new diagnostic of hominid behaviour since stone tool cut marks and carnivore tooth marks were first described systematically on plio pleistocene archaeological bone1 2 bone surface modification has played a prominent role in interpreting early archaeological site formation and hominid behaviour3 15 here we introduce a new class of bone surface modification which we call percussion marks percussion marks were produced during experimental breakage of marrow bones and occur as pits or grooves impressed on a bone s surface by natural protrusions on the granitic hammerstone and anvil used although percussion marks can superficially mimic carnivore tooth marks they nonetheless are closely associated with hammerstone impact notches and show consistent micromorphological features which distinguish them from tooth marks and other classes of bone surface modification given indications of prehistoric hammer stone breakage of marrow bones1 7 an awareness of percussion marks is critical for accurately identifying the biological agents of bone modification at archaeological sites and provides a new diagnostic of carcass processing by hominids

eocene paleoseismic record of the green river formation fossil basin wyoming u s a implications of synsedimentary deformation structures in lacustrine carbonate mudstones abstract laterally extensive intervals containing sedimentary deformation features are identified in outcrops of lacustrine deposits of the eocene 52 51 ma green river formation in fossil basin southwestern wyoming fossil basin is the smallest of the paleo lakes in the green river system and is located in the sevier fold and thrust belt which was tectonically active during deposition deformation structures include convolute lamination load structures hybrid brittle ductile features sedimentary dikes microfaults fluid escape features such as cusps and pipes oil shale breccias and mass transport deposits in most cases these structures are hosted by finely laminated variably organic rich carbonate mudstones that accumulated in a low energy profundal lacustrine environment deformed intervals range from a few centimeters to 5 m in thickness and are bound above and below by undeformed strata of the same facies which demonstrates the early post depositional timing of deformation the distribution of these features indicates a primary control exerted by sediment rheology resulting from variation in grain size clay and organic content and degree of lithification which in turn were governed by the depositional environment and early diagenesis based on their morphological attributes lateral extent and recurrence at different stratigraphic levels along with their sedimentary environment and the tectonic setting of the basin the deformation structures are interpreted to be seismites i e the result of stresses induced by syndepositional earthquakes and other potential trigger agents are rejected moreover stratigraphic relationships indicate that these small scale deformation features as well as the mass transport deposits formed on a virtually flat lake floor ruling out instability caused by the gravitational regime syndepositional deformation in fossil basin points to tectonic activity along the nearby absaroka and or hogsback thrusts and related fault systems seismites point to possible tectonic forcing as a mechanism for changes in bathymetry and sedimentation in the green river formation and consequently demonstrate their potential for elucidating the tectonic history of other lacustrine and marine basins

estimates of large magnitude late cambrian earthquakes from seismogenic soft sediment deformation structures central rocky mountains a variety of unusual early post depositional deformation structures exist in grainstone and flat pebble conglomerate beds of upper cambrian strata western colorado including slide scarps thrusted beds irregular blocks and internally deformed beds thrusted beds up to tens of centimetres thick record thrust movement of a part of a bed onto itself along a moderate to steeply inclined 15 to 40 ramp locally producing hanging wall lenses with fault bend geometries thrust plane orientations are widely distributed and in some cases nearly oppositely oriented in close proximity indicating that they did not form as failures acted upon by gravity forces irregular bedded to internally deformed blocks are isolated on generally flat upper bedding surfaces these features represent parts of beds that detached moved up onto and some distances across the laterally adjacent undisturbed bed surfaces deformation of thin intervals of mud on the ocean floor by moving blocks rules out the possibility of storm induced deformation because the mud was not eroded by high shear stresses that would accompany the extremely large forces required to produce and move the blocks finally internally deformed beds are characterized by large blocks fitted fabrics of highly irregular fragments and contorted lamination which represent heterogeneous deformation such as brecciation and liquefaction the deformation structures were produced by earthquakes linked to the reactivation of mesoproterozoic crustal scale shear zones in the central rockies during the late cambrian analysis of the deformation structures indicates very large body forces and calculated earthquake generated ground motion velocities of ca 1 6 m sec 1 these correspond to moment magnitudes of ca 7 0 or more and a mercalli intensity of x these are the only known magnitude estimates of phanerozoic other than quaternary large intensity earthquakes for the rocky mountain region and they are as large as or larger than previous estimates of proterozoic earthquakes along these major shear zones of the central rockies

long term earthquake clustering a 50 000 year paleoseismic record in the dead sea graben the temporal distribution of earthquakes in the dead sea graben is studied through a 50 000 year paleoseismic record recovered in laminated sediments of the late pleistocene lake lisan paleo dead sea the lisan represents more than 10 times the 4000 years of historical earthquake records it is the longest and most complete paleoseismic record along the dead sea transform and possibly the longest continuous record on earth it includes unique exposures of seismite beds earthquake induced structures associated with slip events on syndepositional faults the seismites are layers consisting of mixtures of fragmented and pulverized laminae the places where the seismites abut syndepositional faults are interpreted as evidence for their formation at the sediment water interface during slip events on these faults thicker sediment accumulation above the seismites in the downthrown blocks indicates that a seismite formed at the water sediment interface on both sides of the fault scarps modern analogs and the association with surface ruptures suggest that each seismite formed during a m l 5 5 earthquake the 230 th 234 u ages of a columnar section obtained by thermal ionization mass spectrometry give a mean recurrence time of 1600 years of m l 5 5 earthquakes in the dead sea graben the earthquakes cluster in 10 000 year periods separated by quiet periods of similar length this distribution implies that a long term behavior of the dead sea transform should be represented by a mean recurrence of at least 20 000 year record this observation has ramifications for seismic hazard assessment based on shorter records

pleistocene glaciolacustrine breccias of seismic origin in an active graben central poland varved layers in the partly consolidated glaciolacustrine early saalian deposits exposed in the belchatow mine central poland show specific types of deformations two types dominate half varve deformations constituting the uppermost clayey part of a single varve and multi varve deformations affecting a few varves the latter are found either as clast supported breccia beds with varve fragments in a quasi horizontal position within a clayey matrix or as deformed beds resulting from subsequent plastic deformation and folding the deformed beds are interpreted as seismites derived from earthquakes related to the deep graben structure the magnitudes of the earthquakes have determined the type of deformations the seismites are thought to have originated intraformationally

late quaternary co seismic sedimentation in the sea of marmara s deep basins the deep northern part of the sea of marmara northwestern turkey is composed of several aligned actively subsiding basins which are the direct structural and morphological expression of the north anatolian fault s northern branch the last 20 kyr of their sedimentary fill lacustrine before 12 kyr bp have been investigated through giant piston coring onboard r v marion dufresne marmacore cruise 2001 and chirp subbottom profiler onboard r v atalante during marmarascarps cruise 2002 especially during the lacustrine stage the infilling of the deep basins tekirda central kumburgaz and cinarcic basins up to 1250 m depth was dominated by turbidites with coarse mixed siliciclastic and bioclastic basal part intercalated in hemipelagic type finegrained calcareous and slightly siliceous clays often especially in the thickest ones the turbidites show strong segregation and a sharp boundary between coarse part and suspendedload part in the central basin 8 m of a unique sedimentary event include a 5 to 8m thick homogenite well imaged on seismic profiles the latter is interpreted as related to a major possibly triggered tsunami effect as described in the eastern mediterranean by kastens and cita 1981 in the marine holocene upper part of the sedimentary fill repeated to and from structures affecting silt or fine sand are evidencing seiche like effects and thus earthquake triggering detailed correlations between two deep coring sites 1250 and 1200 m indicate more than 100 overthickening in the deepest one this implies specific processes of distribution of terrigenous input by dense hyperpycnal currents high kinetic energy seiche effect complex reflections on steep slopes the peculiar sedimentary infilling of the sea of marmara s central basin and by extrapolation of the whole set is tentatively interpreted as a direct consequence of the strong seismic activity the imprint of the latter is more obvious prior to the base of the holocene as environmental conditions favoured marginal accumulation especially on the southern shelf of large amounts of erosion products available for mass wasting

quaternary tectonics in a passive margin marajo island northern brazil marajoisland is located in a passive continental margin that evolved from rifting associated with the opening of the equatorial south atlantic ocean in the late jurassic early cretaceous period this study based on remote sensing integrated with sedimentology as well as subsurface and seismographic data available from the literature allows discussion of the significance of tectonics during the quaternary history of marginal basins results show that eastern marajoisland contains channels with evidence of tectonic control mapping of straight channels defined four main groups of lineaments i e nne ssw ne sw nw se and e w that parallel main normal and strike slip fault zones recorded for the amazon region additionally sedimentological studies of late quaternary and holocene deposits indicate numerous ductile and brittle structures within strati graphic horizons bounded by undeformed strata related to seismogenic deformation during or shortly after sediment deposition this conclusion is consistent with subsurface bouguer mapping suggestive of eastern marajoisland being still part of the marajograben system where important fault reactivation is recorded up to the quaternary together with the recognition of several phases of fault reactivation these data suggest that faults developed in association with rift basins might remain active in passive margins imposing important control on development of depositional systems copyright 2007 john wiley sons ltd

pillow beds a new type of seismites an example from an oligocene turbidite fan complex alicante spain a new type of soft sediment deformed beds termed pillow beds originally a packet of calcarenitic turbidites show sand in sand loading with plane lower and upper surfaces the pillow beds have some resemblance to ball and pillow structures and they are considered to have formed as a result of dewatering the pillow beds are oligocene in age and are part of turbidite lobes in a submarine fan system which was fed through a canyon along the southern border of the ancient iberian continent three hypotheses may explain their occurrence overloading sliding or seismic shock a seismic origin is preferrred on the basis of the flat undeformed lower surface of the pillow beds excluding dewatering of and loading into the previously deposited beds furthermore the pillow bed structures are related to grain size and may show repetitions thus excluding sliding the scale and nature of the pillow beds suggest they could be the result of an earthquake with a magnitude of 6 7 on the richter scale

provenance and earthquake signature of the last deglacial xinmocun lacustrine sediments at diexi east tibet abstract well preserved lacustrine sediments are found in some areas in east tibet this region is characterized by a windy and semi arid climate alpine valleys and frequent earthquakes measurements of rare earth elements observations from a scanning electron microscope and a high resolution record of grain size measurements allowed us to compare fine sediments from the xinmocun section in the diexi lake with loess from the chinese loess plateau and south china results indicate that fine grains of the xinmocun lacustrine sediments were transported by wind and trapped in the lake whereas the 16 m fraction was likely from local sources the grain size changes within the section repeatedly show abrupt coarsening and upward fining probably due to palaeoearthquake events large earthquakes in the study area often caused rockfalls and landslides exposing fine sediments that had accumulated on mountains slopes the fine grains were then retransported by wind to the diexi lake optically stimulated luminescence dating of the xinmocun section indicates continuous deposition from 18 65 to 10 63 ka these results indicate that palaeoearthquakes in the study area had a mean recurrence interval of 0 32 ka therefore we propose that lacustrine sediments in a tectonically active region have the potential to record a continuous history of palaeoearthquakes palaeoearthquakes probably produced numerous rockfalls and landslides in alpine valleys and provided significant sources of regional eolian dust

soft sediment deformation structures from the marinoan glacial succession adelaide foldbelt implications for the palaeoaltitude of late neoproterozoic glaciation abstract a suite of soft sediment deformation structures occurs in tidal rhythmites of fine sand to silt grade in the late neoproterozoic 600 ma elatina formation which is part of the marinoan glaciogenic succession in the adelaide foldbelt south australia the structures include 1 sets of asymmetrical cuspate ridges 13 50 cm h 3 5 cm formed on bed surfaces and underlain by folds affecting as much as 60 cm thickness of strata 2 symmetrical and interference ripple forms 3 15 cm h 1 5 cm mostly confined to the troughs between the cuspate ridges and which are underlain by folds involving up to 20 cm thickness of strata that commonly parallel the undulations of the bed surface but in places have steepened limbs 3 rill marks on the flanks of cuspate ridges and some ripple forms the crests of the cuspate ridges and ripple forms commonly were draped and locally eroded and truncated during overall vertical accretion the cuspate structures are interpreted as gravity slide deposits that formed after transformation of surficial sediment to a hydroplastic state possibly by the cyclic stresses generated by storm waves and its sliding on tidal delta slopes the ripple forms resulted from continuing wave activity and were maintained by draping and vertical accretion from unidirectional currents and locally by deposition of supercritical cross lamination the further deformation of the cuspate folds as revealed by palaeomagnetic analyses of the structures implies additional sliding and or the differential loading of hydroplastic sediment in the troughs between the cuspate ridges this study confirms that positive palaeomagnetic fold tests on several cuspate folds indicate a primary origin for the shallow palaeomagnetic inclination 5 3 of the elatina formation and hence the equatorial palaeolatitude of late neoproterozoic glaciation in south australia

grain coatings diagenesis of jurassic sandstones in south central utah and implications for targeting fossil microbes on mars abstract clusters of large scale decameters to 100 m dia fluidization pipes have been identified at several locations in jurassic navajo and entrada sandstones in south central utah these typically cut the cross bedded aeolian sabhka host rock at right angles similar pipe like structures have been tentatively identified on mars and the question of the diagenesis of host rock has important implications for the genesis of pipe structures current thinking regarding the genesis of host rock structures is that the grains were derived from wet aeolian sabkha environments eds of all samples indicates a si al ratio of 2 1 suggesting smectite clay minerals are to be expected in a dry mid latitude climatic zone and unlike the pipe structures which contain hyphopodium like structures fungal filaments similar in morphology to modern tropical leaf parasites the host rock is relatively bereft of microbes entombed in grain coatings moreover microtextural data from host rock grains in these wet aeolian wet sabkha environments suggest a lack of volatility judging from infrequent observation of percussion crack evidence of grain collision presumably during the time of formation a microfeature commonly found within the pipe structures the diagenesis process can be reconstructed from the composition of the coatings on recovered grains of quartz feldspar mica and occasional calcite as imaged with the sem and studied by eds xrd of the coatings provides confirmation of the clay mineralogy and inaa is used to cross check the chemistry obtained by eds if similar microfeatures exist on grains from both earth and mars materials transported by similar aeolian processes one would not expect to find fossil evidence of life on grains in host rocks while martian pipe structures may be the optimum target for the astrobiological exploration of the red planet host rock might be relatively devoid of fossil microbes if diagenesis of sandstones on mars is anything like earth

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

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