shallow marine carbonate sedimentation in a tectonically mobile basin the muschelkalk middle triassic of upper silesia southern poland abstract earthquakes and resulting tsunamis are important geological phenomena however their sedimentary paleorecord is difficult to identify because some fabrics can be generated by other processes and the criteria for discrimination of seismic and non seismic triggers are not fully established this paper presents several deformation and sedimentary structures in the middle triassic carbonates of upper silesia and discusses their seismogenic and tsunami origin and controls on the deformation type intensity preservation potential and geographic distribution the deformation type and intensity were controlled by the primary lithology whereas the lateral continuity of deformed horizons depended on the lateral extent of hosted facies the thickness and abundance of these structures increase towards the krakow lubliniec fault zone which bounded the area from the east and is considered as the main epicentrum of earthquakes and tsunami initiation the discussed fabrics have a universal significance and can potentially be found in other shallow marine carbonate successions

seismically generated hydroplastic deformation structures in the late miocene lacustrine deposits of the malatya basin eastern turkey abstract the late miocene succession of continental deposits in the malatya basin eastern anatolia comprises alluvial fan lacustrine and fluvial facies associations this fault bounded basin formed in a tectonically active region notorious for strong earthquakes still today the lacustrine deposits in the northern part of the basin show several isolated horizons of soft sediment deformation including such structures as slump folds load and flame features sand dikes and small scale synsedimentary reverse faults with associated folds there is no direct evidence supporting instabilities due to unequal loading or overloading wave induced cyclical and or impulsive stresses sudden changes in groundwater level or bioturbation capable of producing these deformation structures the soft sediment deformation structures described in the lacustrine deposits are interpreted as having developed as a result of seismic activity taking place along the malatya fault zone based on the tectonic setting of the basin the lateral extent of the soft sediment deformation structures over hundreds of metres their confinement by undeformed layers the presence of complex structures and similarities with structures interpreted as being seismically induced in other areas and those obtained experimentally

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

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

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

tectonic deformation of soft sediment convolute folds abstract the structures of the precambrian ghatsila galudih fold belt of eastern india have been studied in great detail but in the absence of suitable strain markers there is no estimate of strain for these rocks however tectonically deformed soft sediment convolute folds are plentiful in these rocks these spectacular structures morphologically resemble sheath folds but have been produced by tectonic deformation of lobes of soft sediment contortions an estimate of the magnitude of bulk tectonic strain 3 0 31 across the axial plane cleavage along with the assumption of no volume change during tectonic deformation gives us crucial information about the pretectonic shape of the convolutes that can be utilised to determine strain along the x and y axes 1 2 6 2 1 24 the shapes of inclusion trails in garnet porphyroblasts within the mica schists indicate that the axis of rotation is parallel to the y axis of bulk strain the bulk deformation involves a non coaxial general flattening with 1 2 1 3 with the vorticity vector approximately parallel to the 2 axis

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

determining the origin of soft sediment deformation structures a case study from upper carboniferous delta deposits in south west wales uk determining the cause of sediment mobilization is a major problem possible triggers include earthquakes sediment loading and wave action a detailed sedimentological and palaeoenvironmental analysis of soft sediment deformation in upper carboniferous deltaic deposits in sw wales uk shows that two styles of deformation occur type a syndepositional convolute stratification affects most sandstone beds and was generated by rapid sedimentation type b localized sandin sand pseudonodules incorporates beds that already contained type a deformation and developed when the substrate was liquefied by disturbance due to movement on a nearsurface gravity slide neither type of deformation was triggered by seismic events

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

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

the paleoclimatic significance of deformation structures in neoproterozoic successions abstract this paper reviews the different types of soft sediment deformation structures that can form in glacial and non glacial settings and explores the potential use of these structures in resolving long standing debates in paleoenvironmental reconstructions of neoproterozoic glacigenic successions soft sediment deformation structures are created when compressional gravitational or shear stress is applied to unlithified sediments during or shortly after deposition in subglacial or ice marginal glacial settings shear and compressional stress imparted by ice moving on top of a deformable substrate or advancing ice buldozing unlithified ice marginal sediments can result in a wide range of folding faulting and shear structures in glaciofluvial or stagnant ice marginal setting gravitational collapse and remobilization of sediments associated with the melting of buried ice can result in normal faulting and broad folding in glaciolacustrine or glaciomarine settings compressional shear and gravitational types of deformation structures can occur as a result of grounding ice or icebergs rapid sedimentation and reworking downslope associated with high sedimentation rates in non glacial settings similar deformation structures can form as a result of slope instability and reworking of sediments downslope rapid sedimentation seismic shaking wave induced shearing or loading in this context two case studies are presented to demonstrate the type of paleoenvironmental information that an analysis of deformation structures can provide in the first case study analysis of deformation in the port askaig formation scotland reveals a distinctive stratigraphic distribution of deformation structures the types of deformation observed together with their recurrence over several 100s of meters and their basinal context are used to infer a seismic origin for the deformation which in turn suggests a significant tectonic control on sedimentation atop a record of ice margin fluctuations in a glaciomarine setting in the second example analysis of deformation in the smalfjord formation northern norway provides strong evidence for deformation by active ice overriding glaciofluvial deposits the types of deformation in this example together with its complexity scale and associated facies provide the strongest case for ice marginal deformation in sum analysis of deformation structures together with analysis of structural geology stratigraphy facies and facies associations can provide additional constraints on paleoenvironmental conditions at the time of deposition which can help us refine or test paleoenvironmental models proposed for this critical time period in earth 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

vein reactivation and complex vein intersection geometries in the taconic slate belt abstract this paper describes some complex intersection geometries for veins in the taconic slate belt of western new england u s a the complexity is primarily a result of the preferential reactivation during slaty cleavage development of one set of veins within an orthogonal system of pre cleavage veins the relative age of the precleavage veins also influences the intersection geometry in that the non reactivated veins which form the younger set of pre cleavage veins act as barriers to the propagation of the syn cleavage veins these types of intersection geometries are easily misinterpreted without microscale observations of vein textures and may be more common than is currently appreciated

facies and evaporite genesis of the kuscular formation lower paleocene saline playa complex eastern turkey abstract the kuscular formation lower paleocene located in eastern turkey is an alluvial and playa foreland basin succession deposited in a semi arid climate the playa deposits of the kuscular formation composed of interbedded green sandstone siltstone mudrock gypsiferous sandstone red green gypsiferous mudrock and banded nodular secondary gypsum are found among the distal alluvial fan deposits interbedded green sandstone siltstone mudrock with desiccation cracks are interpreted as dry mudflat sandflat deposits the banded nodular secondary gypsum and gypsiferous mudrocks which contain desiccation cracks are interpreted as a saline playa and saline mudflat distal alluvial fan deposits are represented by stratified conglomerate and stratified pebbly sandstone the sulfur in the evaporites was very likely derived from the oxidation of sulfides in upper cretaceous magmatic rocks comprising the basement of the basin soft sediment deformation structures slump folds which indicate seismically active areas were formed within the playa and dry mudflad sandflat complex the facies aspects of playa deposits would suggest that the climate in turkey was semi arid during the early paleocene

overview of the meso to neoproterozoic evolution of the vindhyan basin central india abstract despite its origin in a stable intracratonic basin the vindhyan supergroup central india embodies tectonic driven depositional cycles of various orders a marked change in sedimentation pattern was coupled with a transient plate margin compression in the otherwise extensional regime an unconformity laterally correlatable with a conformity that divides the supergroup in two sequences arose in consequence maximum flooding surfaces mfs within the sequences can generally be correlated with intrabasinal volcanism that drastically diminished through the initial rift to later sag stage of basin evolution concomitantly with the change in tectonic milieu paleoseismic deformation structures and related deposits also became drastically reduced in scale nevertheless metre and decametre scale depositional cycles correlate well with the subtle record of paleoseismicity intermittent tilting of the depositional substratum is demonstrable in systematic bed dip changes in metre scale fining upward depositional cycles in the rift stage in the sag stage it is reflected merely in consistent deflection of paleocurrent directions at the top of the decametre scale parasequence sets towards the top of the supergroup progressive thickening and decreasing frequency of parasequences indicates a declining rate of basin subsidence progradation despite punctuation thus resulted in basin filling

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

molar tooth carbonates shallow subtidal facies of the mid to late proterozoic discussion from field work in northern canada and many other examples documented in the literature james et al 1998 highlighted the potential use of molar tooth structures i e a series of spar filled cracks as a stratigraphic indicator for the mesoproterozoic and neoproterozoic these authors also stated that all known occurrences where molar tooth structures are volumetrically significant are from shallow water carbonates although these are comprehensive statements considering that most molar tooth structures reported so far are from shallow water mesoproterozoic and neoproterozoic deposits i am concerned about such proposed temporal and environmental constrictions which are not supported by the field data summarized in the following detailed field work in the grajau basin northern brazil revealed that structures similar to the ones reported by james et al 1998 are volumetrically widespread in the codo formation this is a lacustrine lithostratigraphic succession formed during the early stages of the south atlantic rifting in the aptian e g petri and fulfaro 1983 the sedimentary features described here occur in lime mudstone to grainstone ostracodal grainstone and crystalline limestone interbedded with shales strongly affected by penecontemporaneous deformation as indicated by a variety of complex convolute folds small faults fissures and bed collapses the molar tooth structures occur throughout these beds although they substantially increase in volume downward where evidence for soft sediment deformation diminishes these

soft sediment deformation associated with the east patna fault south of the ganga river northern india influence of the himalayan tectonics on the southern ganga plain abstract the geomorphic tectonic and seismic aspects of the ganga plain have been studied by several workers in the recent decades however the northern part of this tectonically active plain has been the prime focus in most of the studies the region to the south of the ganga river requires necessary attention especially regarding the seismic activities the region lying immediately south of the outer himalayas i e the ganga plain responds to the stress regime of the himalayan frontal thrust zone by movement along the existing basement faults extending from the indian peninsula and creating new surface faults within the sediment cover as well as a result several earthquakes have been recorded along these basement faults such as the great earthquakes of 1934 and 1988 associated with the east patna fault large zones of ground failure and liquefaction in north bihar close to the himalayan front have been recorded associated with these earthquakes the present study reports the soft sediment deformation structures from the south bihar associated with the prehistoric earthquakes near the east patna fault for the first time the seismites have been observed in the riverine sand bed of the dardha river close to the east patna fault several types of liquefaction induced deformation structures such as pillar and pocket structure thixotropic wedge liquefaction cusps and other water escape structures have been identified the location of the observed seismites within the deformed zone of the east patna fault clearly indicates their formation due to activities along this fault however the distance of the liquefaction site from the recorded epicenters suggests its dissociation with the recorded earthquakes so far and hence possibly relates to any prehistoric seismic event the occurrence of the earthquakes of a magnitude capable of forming liquefaction structure in the southern ganga plain indicates the transfer of stress regime far from the himalayan front into the peninsular region through these basement faults northward extension of the east patna fault coincides with the region of the himalayan front which corresponds to a less slip potential therefore an association of frequent earthquakes in this region indicates strain release along the east patna fault

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

chronology of relict lake deposits around the suwalong paleolandslide in the upper jinsha river se tibetan plateau implications to holocene tectonic perturbations abstract the suwalong paleolandslide is located in the batang zhongza reach of the upper jinsha river at the southeast margin of the tibetan plateau where tectonic activity is very strong and has formed a great deal of large paleolandslides or their relicts the relict deposits that have been exposed around the suwalong paleolandslide provide an opportunity to understand the formation process and potential origin of a former landslide dammed lake in the active belt region two level platforms of ancient dammed lake deposits were found on both the upstream and downstream sides of the relict landslide dam the chronology of the landslide and its surrounding relict lake deposits were studied by using 14 c dating and osl dating the minimum age of the suwalong landslide blocking the jinsha river was shown to be about 1355 yr bp and those of its surrounding two platforms of lacustrine sediments were shown as 1 8 and 1 3 ka bp the recordings of the soft sediment deformations induced by seismic liquefaction were found in the dammed lake sediments thus providing substantial evidence for the existence of the paleoseismic events we can infer that the suwalong landslide may have been triggered by a paleoearthquake or combination of paleoearthquake and rainfall events the chronology of the landslide dammed lake deposits around the relict suwalong landslide dam reveals that the large scale landslides in the batang zhongza reach of the upper jinsha river were formed during numerous periods namely the large scale landslides may have been triggered by several paleoearthquake events occurring at around 1900 1355 and 1115 yr bp indicating that the jinsha river faults in the area may have been quite active since the late holocene

soft sediment deformation structures from the diexi paleo dammed lakes in the upper reaches of the minjiang river east tibet abstract the north south trending upper reaches of the minjiang river run along the longmen shan min shan fault zone a zone of abrupt topographic change along the eastern margin of the tibetan plateau multiple levels of well preserved soft sediment deformation structures seismites occur in sediments deposited in paleo dammed lakes in the upper part of the minjiang river valley these deformation structures include liquefied convolute deformation water escape structures flame structures pseudonodules ball and pillow structures sedimentary dykes mud lenses and large scale folds several kilometers from the barrier bar of the diexi paleo dammed lakes seven deformed structural layers were identified at different heights in late quaternary stratigraphic sequences near shawan village maoxian county analyses of the deformation structures landforms and the structural environment indicate that these deformation structures were caused by earthquakes slumps and landslides osl optical stimulated luminescence and 14c dating of soft sediment layers from the shawan site indicate that intense earthquakes occurred during the period 25 20 ka b p therefore accurate geological dating of deformed features in dammed lake deposits in high mountains and canyons enables the record of moderate to large magnitude earthquakes to be extended to the late pleistocene holocene upon the eastern tibetan plateau

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

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

an extensive erosion surface of a strongly deformed limestone bed in the gushan and chaomidian formations late middle cambrian to furongian shandong province china sequence stratigraphic implications abstract in order to understand sequence development and sea level fluctuations during the late middle cambrian to early furongian on the north china epeiric platform the present study focuses on a unique subtle erosion surface of an extensive approx 100 km strongly deformed limestone bed in the uppermost part of the gushan formation shandong province china the gushan formation and the overlying chaomidian formation consist mainly of shales and a variety of carbonates that were deposited in subtidal environments e g deep subtidal shallow subtidal shoreface shoal subtidal microbial flat and restricted platform interior three third order depositional sequences s1 3 are identified each of which comprises a thin transgressive systems tract tst and a relatively thick highstand systems tract hst each sequence is bounded by a drowning unconformity sb1 a subaerial unconformity sb2 or a surface of submarine erosion sb3 the upper sequence boundary sb2 of sequence 1 s1 is represented by a subtle erosion surface of an extensive deformed limestone bed with a wide variety of soft sediment deformation structures e g lime mudstone breccias chaotic wacke packstone laminae and fragments homogenized oolites and clastic dykes and is overlain by small sporadic microbial buildups and an extensive bioclastic grainstone bed the deformed limestone was formed during early diagenesis by differential deformation processes brecciation liquefaction fluidization and injection which were most likely induced by pore water overpressure during the period of rapid sea level fall despite the lack of subaerial exposure features e g paleokarst paleosol etc the characteristics of the erosion surface cutting well lithified sediment below the missing of a significant geological record the prochuangia biozone and the worldwide correlatable positive carbon isotope excursion collectively indicate that the erosion surface developed under conditions of subaerial exposure after contemporaneous marine cementation of the deformed sediment the missing of the prochuangia biozone is most likely due to non deposition at a subaerial hiatal surface the erosion surface was submerged as a result of subsequent rise in sea level where sporadic microbial buildups formed under suitable conditions freshly deposited winnowed shell dominated transgressive lag deposits containing chuangia trilobite fragments brachiopod shells and abundant glauconite grains formed with continued rise in sea level which became in turn overlain by shale dominated facies the unique combination of the subtle erosion surface sensu stricto a subaerial unconformity and the underlying deformed limestone bed provides an important criterion for recognizing the subtle changes in relative sea level on shallow epeiric platforms

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

neoproterozoic environmental change recorded in the port askaig formation scotland climatic vs tectonic controls abstract the snowball earth hypothesis suggests that the neoproterozoic was characterized by several prolonged and severe global glaciations followed by very rapid climate change to hot house conditions the neoproterozoic port askaig formation of scotland consists of a thick succession of diamictite sandstone conglomerate and mudstone sedimentological and stratigraphic analysis of port askaig deposits exposed on the garvellach islands was carried out to establish the nature of neoproterozoic palaeoenvironmental change preserved in this thick succession particular emphasis was placed on identifying and distinguishing between climatic and tectonic controls on sedimentation port askaig formation diamictite units are attributed to deposition by sediment gravity flow processes or rainout of fine grained sediment and ice rafted debris in a glacially influenced marine setting associated facies record various depositional processes ranging from sediment gravity flows conglomerate massive sandstone and laminated mudstone to deposition under other unidirectional currents cross bedded and horizontally laminated sandstone the port askaig formation is also characterized by abundant soft sediment deformation features that occur at discrete intervals and are interpreted to record episodic seismic activity stratigraphic analysis of the port askaig formation on the garvellach islands reveals three phases of deposition phase i was dominated by sediment gravity flow processes and sedimentation was primarily tectonically controlled phase ii was a transitional phase characterized by continued tectonic instability an increased supply of sand to the basin and the preservation of current generated facies in the third and final phase of deposition the interbedded units of sandstone and diamictite are interpreted to reflect development of large sandy bedforms and ice margin fluctuations in a tectonically stable marine setting sedimentological and stratigraphic analysis of the port askaig formation demonstrates that tectonic activity had a significant influence on development of the lowermost parts of the succession climatic influences on sedimentation are difficult to identify during such phases of tectonic activity but are more easily discerned during episodes of tectonic quiescence e g phase iii of the port askaig formation the thick succession of diamictite interbedded with current deposited sandstone preserved within the port askaig formation is not consistent with deep freeze conditions proposed by the snowball earth hypothesis

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

soft sediment deformation structures and their implications for late quaternary seismicity on the south tibetan detachment system central himalaya uttarakhand india abstract the south tibetan detachment system stds defines the lithological and tectonic boundary between the higher himalayan crystallines and the tethyan sedimentaries earlier studies have suggested that the stds has been dormant since its inception during the miocene along with the main central thrust mct however recent studies indicate that the stds was active during the pleistocene holocene period we provide additional support for this more recent activity based on the occurrence of seismically induced soft sediment deformation structures ssds preserved in relict lake sediments in the dhauli ganga gori ganga and kali ganga river basins of the central himalaya the relict lakes are located on the hanging wall of the stds an optical chronology of the lake sediments brackets the seismically induced ssds between 20 ka and 11 ka with a major seismic event of magnitude 6 5 occurring between 17 ka and 13 5 ka since mct and stds are considered to be the coupled structures our observation supports the hypothesis that the stds is providing accommodation space to the strain gradient arising due to the north south compression in the himalaya during the late quaternary

tsunami backwash deposits with chicxulub impact ejecta and dinosaur remains from the cretaceous palaeogene boundary in the la popa basin mexico the la popa basin in north eastern mexico features outstanding continuous three dimensional exposures of the cretaceous palaeogene boundary event deposit in shallow shelf environments pierced by salt stocks in the area to the south east of the el papalote diapir the cretaceous palaeogene deposit consists of two superimposed sedimentary units and erosively overlies upper maastrichtian sand siltstones with soft sediment deformation and liquefaction structures the basal unit 1 is an up to 8 m thick chaotic carbonate rich bed that discontinuously fills incised gutters and channels besides abundant silicic and carbonate ejecta spherules from the chicxulub impact unit 1 includes large sandstone boulders and abundant shallow water debris for example mud clasts algae bivalve shells gastropod shells and vertebrate remains unit 1 is conformably overlain by unit 2 distal to the diapir unit 2 consists of a centimetre to decimetre thick conglomeratic coarse bioclast and spherule bearing sandstone bed closer to the diapir unit 2 becomes a metre thick series of four to eight conglomeratic to fine grained graded sandstone beds rich in shell debris and ejecta spherules unit 2 is conformably overlain by structureless to parallel laminated sandstone beds that may mark the return to the pre event depositional regime the sedimentary characteristics of the cretaceous palaeogene deposit including its erosive base its sheet like geometry the presence of multiple graded beds evidence for upper flow regime conditions and the absence of bioturbation support an origin by a short term multiphase depositional event the occurrence of soft sediment deformation structures for example liquefaction below the cretaceous palaeogene deposit suggests that earthquakes were the first to occur at la popa then shelf collapse and strong backflow from the first tsunami waves may have triggered erosion and deposition by violent ejecta rich hyperconcentrated density flows unit 1 subsequently a series of concentrated density flows resulting from tsunami backwash surges may have deposited the multiple graded bedding structures of unit 2 the specific depositional sequence and the fe mg rich as well as si k rich composition of the ejecta spherules both provide a critical link to the well known deep marine cretaceous palaeogene boundary sites in the adjacent burgos basin in north eastern mexico moreover the pulse like input of chicxulub ejecta material at the base of the event deposit allows for correlation with other cretaceous palaeogene boundary sites in the gulf of mexico and the atlantic as well as in central and northern america the presence of diverse dinosaur and mosasur bones and teeth in the event deposit is the first observation of such remains together with chicxulub ejecta material these findings indicate that dinosaurs lived in the area during the latest maastrichtian and suggest that the tsunami waves not only eroded deltas and estuaries but the coastal plain as well

paleoseismic inferences from a high resolution marine sedimentary record in northern chile 23 s abstract the active margin of northern chile is characterized by strong seismic events which induce gravity instability for sedimentary sequences located along the outer forearc of the andean range even though the narrow continental platform of this area limits the accumulation of marine sediments a detailed paleoceanographic reconstruction using high resolution sedimentological and geochronological techniques of a holocene sedimentary sequence in mejillones bay 23 s provides important tools to infer the occurrence of past great subduction earthquakes and or associated tsunamis from the analyses of short cores retrieved in this shallow marine basin we infer the occurrence of two strong seismic events during historical times the first one dated between the years 1409 and 1449 ad produced an angular unconformity and associated lenticular coarse grained deposits generated after local reworking of shallower material the second one dated between the years 1754 and 1789 ad caused slumping erosive processes and local reworking of material the analysis of seismic profile data acquired in this bay allowed the recognition of a major slump deposit within the upper sedimentary sequence tentatively dated as of middle holocene age this event might record the greatest earthquake and tsunami affecting the basin within the last few thousand years we interpret that destabilization of sediments occurs most probably in response to local reactivation of faults within the mejillones peninsula during strong earthquakes especially the mejillones fault

deposition and deformation of fluvial lacustrine sediments of the upper triassic lower jurassic whitmore point member moenave formation northern arizona abstract the stratigraphic section of the upper triassic lower jurassic whitmore point member of the moenave formation at potter canyon arizona comprises c 26 m of gray to black shales and red mudstones interbedded with mainly sheet like siltstones and sandstones these strata represent deposition from suspension and sheetflow processes in shallow perennial meromictic to ephemeral lakes and on dry mudflats of the terminal floodout of the northward flowing moenave stream system the lakes were small as indicated by the lack of shoreline features and limited evidence for deltas changes in base level likely forced by climate change drove the variations between mudflat and perennial lacustrine conditions lenticular sandstones that occur across the outcrop face in the same stratigraphic interval in the lower part of the sequence represent the bedload fill of channels incised into a coarsening upward lacustrine sequence following a fall in base level these sandstones are distinctive for the common presence of over steepened bedding dewatering structures and less commonly folding deformation of these sandstones is interpreted as aseismic due to the lack of features typically associated with seismicity such as fault graded bedding diapirs brecciated fabrics and clastic dikes rapid deposition of the sands on a fluid rich substrate produced a reverse density gradient that destabilized and potentially fluidized the underlying finer grained sediments this destabilization allowed synsedimentary subsidence of most of the channel sands accompanied by longitudinal rotation and or ductile deformation of the sand bodies

genesis and implication of soft sediment deformation structures in high energy fluvial deposits of the alaknanda valley garhwal himalaya india abstract valley fill terraces and fluvio lacustrine sediment successions were investigated for the nature and type of soft sediment deformation structures ssds in the alaknanda valley of the garhwal himalaya based on their morphologies sediment characteristics and comparison with existing data on ssds these features are classified into seismic and aseismic categories the study indicates that despite the terrain being in the seismically active domain of the central himalaya the majority of the deformation structures seem to have been generated aseismically we attribute their genesis to uneven loading slope failure and most importantly turbulent flow and sudden loading by flash floods the study suggests that a cautious approach is needed before assigning a seismic origin to deformation structures in sediments deposited in high energy fluvial systems

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

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

alluvial and lacustrine facies in an extensional basin the miocene of malatya basin eastern turkey abstract during the neogene both strike slip and extensional regimes coexisted giving rise to a number of fault bounded basins in eastern turkey one of these basins the malatya basin contains a thick sequence up to 2000 m of alluvial and lacustrine deposits this paper focuses on the miocene alluvial and lacustrine deposits in the northern part of the basin alluvial and lacustrine deposits in the study area having a thickness over 1200 m are divided into three units on the basis of their vertical sequential changes and lithologic characteristics these are the lower alluvial unit lacustrine unit and upper alluvial unit the lower alluvial unit is composed of stratified conglomerate gm planar cross stratified conglomerate gp trough cross stratified sandstone st planar cross stratified sandstone sp horizontally stratified sandstone sh ripple cross laminated sandstone sr red mudstone fm carbonaceous claystone fl1 and rarely limestone pf facies gm gp and sh characterize alluvial fan to sheetflood deposits facies st sp sh and sr are interpreted as braided stream to sheetflood deposits facies fm fl1 and siltstone are interpreted as deposits in an alluvial plain system with an ephemeral setting carbonaceous claystone fl1 and limestone pf are interpreted as a shallow lake situated as a distal environment in alluvial plain the middle unit interpreted as channel crevasse splay swamp and lacustrine deposits is composed of interbedded sandstone siltstone grey claystone sf low angle cross stratified sandstone sl planar cross stratified sandstone sp limestone pf carbonaceous claystone fl1 marl fl2 and coal c the upper alluvial unit is composed of gm gp st sp sh sr and fm characterizing a low sinuosity river most of the alluvial input into the basin was from the north northeast and east soft sediment deformation structures slump folds which indicate seismically active areas were formed within the lacustrine facies the sediment supply lake level fluctuation and facies architecture were mainly controlled by synsedimentary tectonism

the development and seismic expression of synsedimentary features within the chalk of southern england seismic reflection data acquired onshore to the north of bournemouth southern england image clearly a series of prominent concave up troughs or depressions and concave down mounded structures within the white chalk subgroup the chalk lithostratigraphy in the area of study is established from borehole geophysical log correlations these correlations then provide calibration of the seismic reflection data indicating that the structures are concentrated at levels between the lewes nodular chalk formation and tarrant chalk member and towards the base of the portsdown chalk formation onlap downlap and truncation of reflectors are observed with the most dramatic features forming a stacked series directly overlying faulting of jurassic strata similar stratal geometries have been described from comparable levels in the chalk of the north sea and in outcrop in britain and france to many they represent channels formed by submarine erosion and redeposition of the chalk during relative sea level falls linked to tectonics we also interpret a number of apparently incisive structures and slumped infill sequences described here as being of primary syndepositional origin the slumping and the close association of these features with underlying faults and proximity to nearby major crustal faults may be indicative of submarine erosion of the chalk caused by sea level changes linked to syndepositional fault movements however evidence of toplap downlap pairs is also suggestive of more aggradational mounding or laterally migrating surfaces or facies belts the presence of any such structures implies rapid lateral variations in the chalk that would have implications not only for aquifer management and future storage schemes but also during the processing of seismic reflection data and general studies and correlations of the chalk across southern britain

soft sediment deformation structures in late albian to cenomanian deposits sao luis basin northern brazil evidence for palaeoseismicity soft sediment deformation structures from the alc ntara formation late albian to cenomanian sao luis basin northern brazil consist of 1 contorted structures which include convolute folds ball and pillow structures concave up paths with consolidation lamination recumbently folded cross stratification and irregular convolute stratification that grades into massive beds 2 intruded structures which include pillars dykes cusps and subsidence lobes and 3 brittle structures represented by fractures and faults displaying planes with a delicate ragged morphology and sharp peaks these structures result from a complex combination of processes mostly including reverse density gradients fluidization and liquefaction reverse density gradients promoted by differential liquefaction associated with different degrees of sediment compaction led to the genesis of convolute folds more intense deformation promoted the development of ball and pillow structures subsidence lobes and sand rolls which are attributed to denser and thus more compacted less liquefied portions that sank down into less dense more liquefied sediments irregular convolute stratification that grades into massive beds would have formed at periods of maximum deformation the subsidence of beds was accompanied by lateral current drag and fluid escape from water saturated sands in addition the fractures and faults record brittle deformation penecontemporaneous with sediment deposition all these mechanisms were triggered by a seismic agent as suggested by a combination of criteria including 1 the position of the study area at the edge of a major strike slip fault zone that was reactivated several times from the albian to the holocene 2 a relative increase in the degree of deformation in sites located closer to the fault zone 3 continuity of the deformed beds over large distances several kilometres 4 restriction of soft sediment deformation structures to single stratigraphic intervals bounded by entirely undeformed strata 5 recurrence through time and 6 similarities to many other earthquake induced deformational structures

a hypersaline ichnoassemblage from the middle triassic carbonate ramp of the tatricum domain in the tatra mountains southern poland abstract the middle triassic of the tethyan domain contains heavily bioturbated carbonates known as vermicular limestones in the tatricum domain in the tatra mountains western carpathians these were deposited on a restricted carbonate ramp below the fair weather wave base sedimentological and geochemical evidence points to a hypersaline depositional environment the vermicular limestones contain an impoverished ichnoassemblage of the cruziana ichnofacies dominated by planolites small size thalassinoides is less common balanoglossites and rhizocorallium are rare and helminthopsis phycosiphon and taenidium are very rare the ichnoassemblage points to environmental stress related foremost to hypersaline conditions and less so to lowered oxygenation trace fossil diversity and abundance diminishes from totally bioturbated limestones to dolomitic limestone and dolostones and disappears in the dolostones probably due to an increase in salinity to values in which burrowing fauna is eliminated the repetitive occurrence of the vermicular limestones and associated facies reflects partly fluctuations of salinity which were probably climatically controlled

evolution of early triassic outer platform paleoenvironments in the nanpanjiang basin south china and their significance for the biotic recovery detailed microfacies and paleoenvironmental analyses were conducted through the early triassic interval of the outer platform ammonoid rich series of the nanpanjiang basin luolou formation guangxi province south china extensive investigations on outcrops and on thin sections reveal that the widely reported well diversified latest permian fauna dominated by abundant corals calcareous algae calcareous sponges crinoids brachiopods gastropods ostracods and foraminifera is abruptly replaced by decimated early triassic communities essentially composed of low diversity bivalves microgastropods ostracods and rare foraminifera along with this drastic change in faunal assemblages the recolonization of devastated habitats by calcimicrobial frameworks is observed in the aftermath of the end permian mass extinction calcimicrobialites of griesbachian age are followed by mixed ammonoid and conodont rich carbonate siliciclastic series consisting of dark suboxic laminated mudstones intercalated with organic rich shales of dienerian to late smithian age the carbonate siliciclastic series are interrupted by a brief carbonate episode during the early middle smithian massive carbonate production resumes only from the early spathian onward and persists throughout the spathian the initial deposition of both carbonate episodes is coeval with i re establishment of well oxygenated conditions ii a marked early smithian to extreme early spathian ammonoid conodont diversification iii a significant increase in the skeletal grain diversity and abundance and iv peak carbon isotope values a short interval of black organic rich shales precedes the onset of these two distinct carbonate events which are both marked by a positive carbonate carbon isotope excursion known from other tethyan marine localities the comparison between the early triassic stratigraphic evolution of tethyan outer platform paleoenvironments and platform basin margin settings of the nanpanjiang basin suggests a causal connection between large fluctuations of the global carbon cycle climate shifts sea level changes oxygen availability in the oceans and the biological rediversification in the wake of the end permian biotic crisis

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

large earthquakes in the katun fault zone gorny altai paleoseismological and archaeoseismological evidence abstract paleoseismological and archaeoseismological research in the katun fault zone in gorny altai reveals soft sediment deformation structures ssds in late quaternary sediments that fill the yaloman graben ssds seismites were produced by large paleoearthquakes m 5 5 5 along the katun fault that occurred about 150 and 90 ka in the 38 19 and 19 12 5 ka intervals and after 12 5 ka the event after 12 5 ka within the graben had a magnitude of ms 7 2 7 6 traces of another event shaking intensity i v esi 2007 intensity scale timed in the range from the 3rd century bc to the 1st century ad were discovered during studies of a scythian necropolis at the chultukov log 1 site located within the manzherok graben in the northern end of the katun fault burial mounds near a mountain slope at the site are damaged by colluvium rocks of the same colluvium are scattered over 25 m off the slope and deform burial structures cairns and stone rings and inner stone walls of grave chambers as well as the primary anatomical position of buried bodies including those in burials not damaged by colluvium from outside thus the katun fault was an active structure generating large earthquakes from the middle pleistocene through the holocene

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