late miocene early pliocene reactivation of the main boundary thrust evidence from the seismites in southeastern kumaun himalaya india abstract tectonic history of the himalaya is punctuated by successive development of the faults that run along the boundaries between different lithotectonic terrains the main boundary fault defining the southern limit of the lesser himalayan terrain is tectonically most active a review of published literature reveals that the nature and age of reactivation events on the main boundary fault is one of the poorly understood aspects of the himalayan orogen by systematic outcrop mapping of the seismites this study identifies a late miocene early pliocene reactivation on the main boundary thrust in southeast kumaun himalaya relatively friable and cohesionless neogene sedimentary sequences host abundant soft sediment deformation structures in the vicinity of the main boundary thrust among a large variety of structures deformed cross beds liquefaction pockets slump folds convolute laminations sand dykes mushroom structures fluid escape structures flame and load structures and synsedimentary faults are common the morphological attributes the structural association and the distribution pattern of the soft sediment deformation structures with respect to the main boundary fault strongly suggest their development by seismically triggered liquefaction and fluidization available magnetostratigraphic age data imply that the seismites were developed during a late miocene early pliocene slip on the main boundary thrust the hypocenter of the main seismic event may lie on the main boundary thrust or to the north of the study area on an unknown fault or the basal detachment thrust

core evidence of paleoseismic events in paleogene deposits of the shulu sag in the bohai bay basin east china and their petroleum geologic significance abstract the shulu sag located in the southwestern corner of the jizhong depression bohai bay basin of east china is a ne sw trending elongate cenozoic half graben basin the lowermost part of the third member of the shahejie formation in this basin is characterized by continental rudstone and calcilutite to calcisiltite facies based on core observation and regional geologic analysis seismites are recognized in these lacustrine deposits which include soft sediment deformation structures sedimentary dikes hydraulic shattering diapir structures convolute lamination load flame structures ball and pillow structures loop bedding and subsidence structures synsedimentary faults and seismoturbidites in addition mixed source rudstones consisting of the paleozoic carbonate clasts and in situ calcilutite clasts in the lowermost submember of shahejie 3 appear in the seismites suggesting an earthquake origin a complete representative vertical sequence in the lowermost part of the third member found in well st1h located in the central part of the shulu sag shows from the base to the top underlying undeformed layers synsedimentary faults liquefied carbonate rocks allogenetic seismoturbidites and overlying undeformed layers seismites are widely distributed around this well and there are multiple sets of stacked seismites separated by undeformed sediment the nearby nw trending taijiazhuang fault whose fault growth index is from 1 1 to 1 8 and the nne trending xinhe fault with a fault growth index of 1 3 1 9 may be the source of the instability to create the seismites these deformed sedimentary layers are favorable for the accumulation of oil and gas for example sedimentary dikes can cut through many layers and serve as conduits for fluid migration sedimentary faults and fractures induced by earthquakes can act as oil and gas migration channels or store petroleum products as well seismoturbidites and mixed source rudstones are excellent reservoirs due to their abundant primary or dissolved pores

events of sediment deformation and mass failure in upper cretaceous estuarine deposits cameta basin northern brazil as evidence for seismic activity abstract event beds recording late cretaceous synsedimentary seismicity occur in the cameta subbasin northern brazil the deposits consist of nearly 40 m of kaolinized fluvio estuarine deposits the lower fluvial tidal influenced complex which carries a high quality commercial kaolin includes genetically related channel fill floodplain crevasse splay and mud plug deposits the upper estuarine deposits contain trace fossils indicating marine influenced settings thalassinoides ophiomorpha teichichnus diplocraterion skolithos cylindrichnus rhizocorallium and planolites and include heterolithic sandy and bioturbated units interpreted as tidal flat storm overwash and low energy estuarine bay deposits respectively in the upper portion of the estuarine lithosomes four successive events events 1 4 of synsedimentary brittle and ductile deformation and large scale sediment failure anomalous in estuarine settings were recognized and attributed to earthquakes event 1 is recorded by heterolithic and bioturbated deposits with vertical to subvertical fractures that disappear into underlying undeformed deposits event 2 is recorded by thin sharply bounded sections composed of heterolithic mudstone and very fine grained sandstone that shows convolute folds and pillow like structures event 3 is documented by intraformational conglomerate and breccia and minor mudstones and sandstones with abundant trace fossils skolithos and thalassinoides event 4 is characterized by vertical to subvertical fractures and faults with homogenized sandstone intrusions along their planes mostly developed in the upper parts of the deposits corresponding to event 3 a detailed analysis of facies relationships combined with consistent orientations of brittle deformation structures and the regional tectonics of the cameta subbasin suggests earthquakes as the triggering mechanism for sediment deformation and large scale mass failure

subrainband structure and dynamic characteristics in the principal rainband of typhoon hagupit 2008 abstractthe principal rainband in tropical cyclones is currently depicted as a solitary and continuous precipitation region however the airborne radar observations of the principal rainband in typhoon hagupit 2008 reveal multiple subrainband structures these subbands possess many characteristics of the squall lines with trailing stratiform in the midlatitudes and are different from those documented in previous principal rainband studies the updraft and reflectivity cores are upright and elevated the updraft is fed by a low level radial outflow from the inner side the tangential wind speed shows a clear midlevel jet on the inner side of the reflectivity core except for the structural similarities the dynamics of the subbands is also similar to the squall lines the local environment near the subbands shows little convective inhibition modest instability and vertical wind shear the temperature retrieval shows a cold pool structure in the stratiform precipitation region the estimated vertical w

clastic intrusions in deep sea fan deposits of the rosroe formation lower ordovician western ireland abstract the rosroe formation contains discordant elastic intrusions and essentially stratiform clastic intrusions up to 40 cm thick that display little evidence of injection features of the elastic intrusions such as upper surface irregularities and tapered lateral margins also occur in wedged clastic layers up to 30 cm thick in the rosroe formation and suggest they may be injected sheets a few of the mostly granule grade injected sheets in the rosroe formation contain banding that is remarkably similar to the banding in the formation s stratified pebbly sandstone together with the existence of essentially stratiform injected sheets the banding suggests that some elastic sills in deep sea fan deposits may be indistinguishable from normally deposited beds contactual features sharp upper contacts upper surface irregularities truncation of superjacent strata upper surface inclusions nesting and blunt steep and tapered lateral margins and internal characters lenticular breccia and trains of aligned laminite clasts of the elastic intrusions in the rosroe formation provide tentative criteria for the identification of clastic sills that simulate normally dep sited beds in deep sea fan deposits

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

the governing dynamics of the secondary eyewall formation of typhoon sinlaku 2008 abstractthrough successful convection permitting simulations of typhoon sinlaku 2008 using a high resolution nonhydrostatic model this study examines the role of peripheral convection in the storm s secondary eyewall formation sef and its eyewall replacement cycle erc the study demonstrates that before sef the simulated storm intensifies via an expansion of the tangential winds and an increase in the boundary layer inflow which are accompanied by peripheral convective cells outside the primary eyewall these convective cells which initially formed in the outer rainbands under favorable environmental conditions and move in an inward spiral play a crucial role in the formation of the secondary eyewall it is hypothesized that sef and erc ultimately arise from the convective heating released from the inward moving rainbands the balanced response in the transverse circulation and the unbalanced dynamics in the atmospheric boundary layer along with the positive feedback between these processes

rapid filamentation zones in intense tropical cyclones intense tropical cyclones often possess relatively little convection around their cores in radar composites this surrounding region is usually echo free or contains light stratiform precipitation while subsidence is typically quite pronounced in this region it is not the only mechanism suppressing convection another possible mechanism leading to weak echo moats is presented in this paper the basic idea is that the strain dominated flow surrounding an intense vortex core creates an unfavorable environment for sustained deep moist convection strain dominated regions of a tropical cyclone can be distinguished from rotationdominated regions by the sign of s 2 s 2 2 where s1 ux y and s2 x uy are the rates of strain and x uy is the relative vorticity within the radius of maximum tangential wind the flow tends to be rotation dominated 2 s 2 s 2 so that coherent structures such as mesovortices can survive for long periods of time outside the radius of maximum tangential wind the flow tends to be strain dominated s 2 s 2 2 resulting in filaments of anomalous vorticity in the regions of strain dominated flow the filamentation time is defined as fil 2 s 2 s 2 2 1 2 in a tropical cyclone an approximately 30 kmwide annular region can exist just outside the radius of maximum tangential wind where fil is less than 30 min and even as small as 5 min this region is defined as the rapid filamentation zone since the time scale for deep moist convective overturning is approximately 30 min deep convection can be significantly distorted and even suppressed in the rapid filamentation zone a nondivergent barotropic model illustrates the effects of rapid filamentation zones in category 1 5 hurricanes and demonstrates the evolution of such zones during binary vortex interaction and mesovortex formation from a thin annular ring of enhanced vorticity

the influence of convective thermal forcing on the three dimensional circulation around squall lines abstract midlatitude squall lines are typically trailed by a large region of stratiform cloudiness and precipitation with significant mesoscale flow features including an ascending front to rear flow a descending rear inflow jet line end vortices and at later times mesoscale convective vortices the present study suggests that the mesoscale circulation in the trailing stratiform region is primarily determined by the time mean pattern of heating and cooling in the leading convective line analysis of the line normal circulation shows that it develops as thermally generated gravity waves spread away from the leading line midlevel line end vortices are the result of diabatically driven tilting of horizontal vorticity generated by the time mean thermal forcing in the presence of the coriolis force a symmetric thermal forcing generates an asymmetric stratiform circulation and a pattern of vertical displacement that resembles the comma shaped stratiform anvil observed in real systems this suggests tha

objective convective updraft identification and tracking part 1 structure and thermodynamics of convection in the rainband regions of two hurricane simulations to better understand the life cycles of convective elements in numerical model simulations a convective updraft tracking algorithm dubbed the statistical and programmable objective updraft tracker spout is developed spout identifies updraft cores in horizontal slices through a given model data set links these cores in three dimensions to form vertically coherent updrafts and then tracks updrafts in time via estimates of the mean local advection spout is evaluated in idealized hurricane simulations from both the regional atmospheric modeling system rams and weather research and forecasting wrf in both simulations spout indicates most updrafts live less than 60 min but some can persist for over 2 h updrafts are typically manifested as shallow cumulus cumulus congestus and deep cumulonimbus overall there is reasonable agreement between the vigor of convection and the amount of localized conditional convective instability also the majority of updrafts attain a tilted structure that is in accordance with the localized vertical wind shear nonetheless there are striking differences between models with the higher resolution wrf simulation producing around twice as many updrafts as rams moreover the wrf updrafts are significantly weaker this paper highlights the utility of spout for studying convective life cycles in high resolution numerical simulations and provides some basic features of convection in two hurricane simulations

soft sediment deformation structures induced by cyclic stress of storm waves in tempestites miocene guadalquivir basin spain the identification of triggering agents for soft sedimentation structures is an enigmatic geological problem mainly seismic induced soft sediment structures have been recognized in ancient sediments rather than those resulting from storm waves we analyse soft sediment deformation structures in upper miocene calcarenitic tempestites of the guadalquivir basin southern spain the most common structures are load casts which vary in height and width from 10 centimetres to several metres the structures are always restricted to a small part of the stratigraphic sections in exclusive association with tempestites the analysed soft deformation structures are interpreted to be the result of liquidization processes chiefly from their inferred depositional environment and subordinately from the deformation style we have devised basic criteria to identify the trigger mechanism in these soft sediment deformation structures the liquefaction was triggered by pore pressure changes induced by cyclic and residual stress of storm waves

slump sheets as a record of regional tectonics and paleogeographic changes in south china abstract slumps of various scales are recognized in the late katian late ordovician mixed carbonate and siliciclastic slope successions in the changshan area western zhejiang province south china in order to understand their deformational processes triggering mechanisms paleo slope orientation and geological implications a detailed sedimentological study was carried out on four outcrop sections in the southern changshan the putangkou zhoutang and shikeng sections we recognized three slumping episodes ca 3 5 m 11 m and 73 m in thickness in stratigraphically ascending order and co occurred debris flows at the sanqushan section 11 5 km north of changshan thirteen slump units each being tens of cm to 6 m in thickness are recognized facies analyses and diagenetic characteristics of these slumps and their internal deformation structures suggest that they formed as a result of plastic and brittle deformation and liquefaction and fluidization during slumping the rip up blocks cracks and ruptured beds in the slumps of southern changshan indicate extensional features whereas recumbent and disharmonic folds in the slumps of northern changshan represent compressional features these spatially different features suggest that the slumps may have been generated on a paleo slope dipping generally to the north the case study of slumps and debris flows from the putangkou section indicates a significant mass flow transition from a slumped mass into debris flow deposits autogenic triggering mechanisms of these slumps e g rapid deposition storm wave loading and tidal shear are ruled out by the results of facies analysis instead the slumps might have been triggered by relative sea level changes or tectonically induced progressively steepening of the slope which is likely related to the contemporaneous kwangsian orogeny

secondary eyewall formation in an idealized tropical cyclone simulation balanced and unbalanced dynamics abstractthe secondary eyewall formation sef in an idealized simulation of a tropical cyclone tc is examined from the perspective of both the balanced and unbalanced dynamics and through the tangential wind vt budget analysis it is found that the expansion of the azimuthal mean vt above the boundary layer occurs prior to the development of radial moisture convergence in the boundary layer the vt expansion results primarily from the inward angular momentum transport by the mid to lower tropospheric inflow induced by both convective and stratiform heating in the spiral rainbands in response to the vt broadening is the development of radial inflow convergence and the supergradient flow near the top of the inflow boundary layer results from the vt budget analysis show that the combined effect of the mean advection and the surface friction is to spin down vt in the boundary layer while the eddy processes eddy radial and vertical advection contribute positively to the spinup of vt in the sef region

hummocky cross stratification tropical hurricanes and intense winter storms most previous workers have inferred a storm origin for hummocky cross stratification which typically occurs in shallow marine deposits on the modern earth the only storms capable of profoundly affecting shallow marine depositional environments are severe tropical cyclones hurricanes and mid latitude winter wave cyclones intense winter storms this paper examines the palaeogeographic distribution including palaeolatitude and palaeogeographic setting of 107 occurrences of hummocky cross stratification ranging in age from the proterozoic to recent in each of these stratigraphic units both palaeolatitude and palaeogeography are consistent with a direct storm influence associated with the passage of hurricanes or winter storms directly over the site of deposition this palaeogeographic evidence lends support to the inferred storm origin for hummocky cross stratification further the distribution of the structure suggests that most occurrences 73 were generated by tropical hurricanes the remaining 27 being generated by intense mid latitude winter storms the preferential generation of hummocky cross stratification by hurricanes is consistent with 1 the known differences in the nature of the bottom flows generated by the two major storm types and 2 the inferred nature of the flows which form hummocky cross stratification hurricanes couple less effectively with the water column than do intense winter storms due to this ineffective coupling hurricane generated bottom flows tend to be oscillatory or multidirectional dominant with only minor unidirectional components of motion in contrast intense winter storms generally do couple effectively with the water column generating bottom flows which possess a dominant or significant unidirectional component most previous workers have suggested that hummocky cross stratification forms under oscillatory or multidirectional dominant flow thus it is conceptually reasonable that the vast majority of ancient occurrences of hummocky cross stratification were probably hurricane generated as suggested by the aforementioned palaeogeographic distribution the proterozoic palaeozoic neogene and quaternary were times when global climate was similar to that of today the distribution of hummocky cross stratification deposited during these times suggests that both hurricanes and intense winter storms occupied latitudinal belts during these times which were essentially identical to those occupied by their modern counterparts the mesozoic and palaeogene were non glacial times when global climate was much warmer than that of today the distribution of hummocky cross stratification deposited during this interval suggests that hurricanes occurred more frequently at higher latitudes during non glacial times than they do at present the possibility of a broadened hurricane belt during the mesozoic and palaeogene is consistent with climatic considerations a limited number of mesozoic and palaeogene rock units containing hummocky cross stratification were deposited in palaeogeographic settings that preclude a direct hurricane influence these examples were deposited in the middle latitudes suggesting that intense winter storms continued to form hummocky cross stratification in the middle latitudes during these much warmer times some previous workers have suggested that tsunamis may be capable of generating hummocky cross stratification the palaeogeographic distribution of the structure does not support an origin due to tsunamis lacustrine examples of hummocky cross stratification reported herein are the first known non marine occurrences they suggest that storm effects strongly influence the sedimentary record of some lakes

seismically induced soft sediment deformation structures in an active seismogenic setting the plio pleistocene karewa deposits kashmir basin nw himalaya abstract recent uplift in the nw himalaya has exposed more than 1000 m of the plio pleistocene so called karewa deposits in kashmir these deposits mostly consist of horizontal stratified sand silt clay conglomerates and lignite beds the sedimentary succession belongs to the kashmir basin that is located in a seismically active zone the area was previously affected by large earthquakes the observed soft sediment deformation structures ssds are predominantly developed in the sand silt and clay beds and include load and water escape structures intrusive sedimentary bodies convolute bedding disturbed laminites and slump structures deformation mechanism and driving forces of the ssds were seismic shock waves sediment loading and storm events as driver for the ssds are less likely and the proximity of the ssds to faults underlines the seismic origin of these structures syn and post depositional faults and deformation bands developed in the karewa deposits support the interpretation of neotectonic activity and point to an earthquake of magnitude 5 5 that struck the kashmir basin in the plio pleistocene

gravity induced soft sediment deformation in glaciomarine sequences of the upper proterozoic port askaig formation scotland large numbers of post depositional deformation structures in the form of downward penetrating sandstone bodies are identified on well exposed diamictite surfaces of the glaciogenic upper proterozoic port askaig formation scotland on the garvellach islands downfolds irregular dykes and a polygonal network of wedges are composed predominantly of massive fine to medium grained sandstone these structures occur towards the top of crude coarsening upward glaciomarine sequences of massive diamictite stratified diamictite variably cross stratified sandstone and conglomeratic lags massive diamictites record the dominance of pelagic sedimentation and ice rafting succeeding lithofacies indicate the increasing importance of marine traction currents these sequences are repeated in the port askaig formation and by comparison with late cenozoic glaciomarine sequences may have formed in response to changing water depths during basin subsidence downfolds dykes and a polygonal wedge network appear to be genetically related expressions of subaqueous gravitational loading and intrusion of sand into low strength diamict acting in response to reverse density gradients created by coarsening upward glaciomarine sedimentation analogues are provided by published laboratory investigations analysis of the regional tectonic setting of the formation suggests the importance of seismic shock as a triggering agent the subaqueous deformation model presented in this paper is of considerable significance for reconstruction of late proterozoic palaeoenvironments because the downward penetrating sandstone structures of the port askaig formation are widely reported to be indicative of the former presence of subaerial permafrost this paper stresses the importance of identifying the lithofacies sequence in which structures occur as a guide to deformational environment

a convective cell in a hurricane rainband abstract on 10 october 1983 the two noaa wp 3d aircraft completed a mission designed to provide airborne doppler radar data for a convective cell embedded in a weak rainband on the trailing side of hurricane raymond comparisons of the wind field produced from the pseudo dual doppler radar technique with in situ wind measurements suggest that the larger convective scale feature may be resolved if the sampling time is kept to a minimum the convective cell was found to move downband faster than any environmental winds but slightly slower than the winds found in the reflectivity core that delineates the cell in the core of the cell the tangential wind is increased and the radial inflow turns to outflow with respect to the circulation center the flow field demonstrates that the downband stratiform portion of a rainband is not from cells currently active since the updraft detrains upwind relative to the cell but rather it is due to the fallout from ice particles placed into the upper troposphere by clouds t

small scale spiral bands observed in hurricanes andrew hugo and erin abstract analysis of radar data taken from the three intense hurricanes that passed close to wsr 57 and wsr 88d radar sites at their point of landfall illustrate small scale spiral bands that are frequently observed within 100 km or so of the hurricane center faintly visible in the radar reflectivity images these bands have scales of 10 km across the band and can extend for 100 km as they spiral outward in a clockwise fashion they appear to move around the hurricane with speeds close to the tangential wind at the level of the bands and are characterized by enhanced updrafts with higher equivalent potential temperature in the regions of elevated reflectivity they induce wind speed variations of at least 8 m s 1 across the bands the authors suggest that these small scale hurricane spiral bands are similar to boundary layer rolls although they extend through depths of 5 6 km which is more than would be expected for rolls in the boundary layer near the sea the data presented here are not sufficient to

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

dynamics of the stratiform sector of a tropical cyclone rainband abstractairborne doppler radar documented the stratiform sector of a rainband within the stationary rainband complex of hurricane rita the stratiform rainband sector is a mesoscale feature consisting of nearly uniform precipitation and weak vertical velocities from collapsing convective cells upward transport and associated latent heating occur within the stratiform cloud layer in the form of rising radial outflow beneath downward transport is organized into descending radial inflow in response to two regions of latent cooling in the outer upper regions of the rainband sublimational cooling introduces horizontal buoyancy gradients which produce horizontal vorticity and descending inflow similar to that of the trailing stratiform region of a mesoscale convective system within the zone of heavier stratiform precipitation melting cooling along the outer rainband edge creates a midlevel horizontal buoyancy gradient across the rainband that drives air farther inward beneath the brightband the organi

rapid filamentation zone in a numerically simulated tropical cyclone abstract in a recent study rozoff et al proposed a possible mechanism to explain the formation and maintenance of the weak echo annulus or moat outside of the primary eyewall of a tropical cyclone observed in radar images by this mechanism the moat is determined to be a region of the strain dominated flow outside of the radius of maximum wind in which essentially all fields are filamented and deep convection is hypothesized to be highly distorted and even suppressed this strain dominated region is defined as the rapid filamentation zone wherein the filamentation time is shorter than the overturning time of deep convection an attempt has been made in this study to test the hypothesis in a full physics tropical cyclone model under idealized conditions and to extend the concept to the study of the inner core dynamics of tropical cyclones the foci of this paper are the evolution of the rapid filamentation zone during the storm intensification the potential roles of rapid filamentation in the organiz

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

mechanisms for the generation of mesoscale vorticity features in tropical cyclone rainbands a high resolution tropical cyclone model with explicit cloud microphysics has been used to investigate the dynamics and energetics of tropical cyclone rainbands analysis of the vorticity interactions that occur within the simulated rainbands demonstrates that couplets of cyclonic anticyclonic mesovortices can be produced in outer bands the primary source of this vorticity is the upward tilting of system generated horizontal vorticity by diabatic heating gradients the vertical heating gradient in the stratiform cloud also creates a potential vorticity pv dipole that accelerates the tangential flow and develops a midlevel jet the strength of the jet is enhanced by the vortex pair that is oriented radially across the rainband the fourier decomposition of the absolute vorticity field shows two counterpropagating vortex rossby waves associated with the rainband the wave located on the inner side of the band transports energy toward the vortex center the outer wave is made up of high wavenumbers and uses the vorticity gradients generated by the rainband the results support the hypothesis that the heating profile in the stratiform regions of rainbands generates cyclonic pv across the freezing level which develops a midlevel jet this mechanism creates a vorticity gradient that enables the propagation of vortex rossby waves that could allow the rainbands to interact with the mean flow and potentially influence the evolution of the storm by contributing to the symmetric component of vorticity and the development of secondary eyewalls

towards a general model of quick clay development abstract within the clear definition of a quick clay as being a soil which has a sensitivity greater than 30 and a remoulded strength less than 0 5 kpa a general model for quick clay development is presented based on the influences of various material properties and natural processes on the sensitivity and remoulded strength the influences are separated according to depositional requirements and post depositional factors and according to whether the influence is to increase the undisturbed strength or to decrease the remoulded strength depositional factors are the requirements for a flocculated structure and the dominance of low activity minerals post depositional factors are cementation and slow load increase which increase the undisturbed strength and little consolidation leaching and dispersants which decrease the remoulded strength the application of the model to marine brackish water and freshwater sediments is discussed

tsunami induced conglomerates in miocene upper bathyal deposits chita peninsula central japan abstract the tsubutegaura conglomeratic tsunamiites occur in the middle section of the miocene storm related sand silt alternation system in the chita peninsula central japan deposition of the system in the upper bathyal environment in a bay and synsedimentary seismic activity has been elucidated by palaeontological palaeogeographical and sedimentological studies two coupled units each built up by a conglomerate layer with an overlying sandstone layer and the alignment of lenticular sedimentary bodies are exceptional in this sequence some typical lenticular bodies confined within sedimentary troughs consist of a boulder bearing conglomerate layer and calcareous sandstone layer of the lower couple and another conglomerate layer of the upper couple the tuffaceous sandstone layer of the upper couple is distributed more widely than the other lithologies the framework gravels in the coupled conglomerates form a clast supported fabric and are quite notably monomictic the clasts are angular and imbricated partly forming peculiar gravel clusters due to traction current transportation conspicuous laminations develop in the coupled sandstone layers antidunes with chute and pool structure in the upper couple sandstone layer indicate deposition from an upper flow regime current on the other hand the calcareous composition of the lower couple sandstone layer reveals shallow water provenance thixotropic deformations and diastasis cracks in the siltstone bed immediately beneath the layers of the couples show that a severe earthquake tremor and a rapid change of water pressure occurred just before the deposition of the tsunamiites submarine debris flows due to collapse of a fault scarp in a shallow bank and the ensuing wash by two pulses of the tsunami induced ebb current comprise the scenario for the formation of the tsubutegaura conglomeratic tsunamiites

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

mesoscale and convective scale characteristics of mature hurricanes part i general observations by research aircraft abstract the analysis of instrumented aircraft data from four recent mature hurricanes reveals common mesoscale and convective scale features the structure and organization of the convection precipitation and wind flow are studied by combining the airborne observations using basic instrumentation with quantitative radar measurements three predominant precipitation features seen are 1 the eyewall 2 a stratiform rain region adjacent to and outside the eyewall and 3 rainbands that contain both convective and stratiform regions the eyewall is so named because it surrounds the rain free eye but several additional features distinguish it from other convective bands in the hurricane in particular the updraft tangential wind maximum and highest rainfall have preferred locations relative to each other with the updraft being radially inward from the rain and wind maxima the 10 dbz radar reflectivity contour indicative of the inner edge slopes substantially outward with height and there is evide

shallow marine massive sandstone sheets as indicators of palaeoseismic liquefaction an example from the ordovician shelf of central bolivia abstract the middle to upper ordovician siliciclastic succession in central bolivia provides excellent exposures of up to 1 m thick massive sandstone beds produced by liquefaction induced sediment remobilisation these fine grained massive sandstones occur in shallow marine nearshore facies that were deposited above storm wave base vertical to steeply inclined clastic dykes which penetrate up to 1 5 m of the overlying sediment pile feed into the basal parts of massive sandstone sheets these dykes are interpreted as pathways used by liquefied sediment during upward directed escape from a subsurface horizon the relatively short lateral spacing of 5 to 25 m between the individual dykes initiated lateral coalescence of ejected individual sediment bodies as a result massive sandstone sheets formed and can be traced laterally over several kilometres while undeformed sandy deposits contain between 5 to 10 dispersed clay the average clay content in massive sandstone sheets is 15 the elongated sometimes s shaped form of the sandy laminated fragments reflects squeezing during movement showing that they have been deformed under shear stress during flow the axis of maximum elongation of the fragments indicates local flow direction as the massive sandstone sheets are likely the products of seismic shocks they provide the first evidence of tectonic activity in this part of the basin during the middle to late ordovician

formation and deformation of subglacial intrusive clastic sheets in the dwyka formation of northern natal south africa abstract an arenaceous diamictite rests on fissile silty mudstone and argillaceous diamictite and is overlain by a laminated muddy siltstone east of helpmekaar in the dundee district of northern natal the argillaceous deposits originated either in the subglacial or proglacial zone of a partly grounded marine ice sheet where sediment was supplied by debris laden floating ice meltwater plumes and turbidity currents the arenaceous diamictite is the product of melt out debris released close to the grounding line of the ice sheet where it was subjected to overriding by the ice and slumping and redeposition by sediment gravity flow the laminated siltstone represents sediment that was deposited in a low energy setting by turbidity currents and suspension settling downslope from a retreating g ounding line dispersed ice rafted clasts occur in these fine grained deposits the upper surface of the arenaceous diamictite displays regularly spaced linear undulations that are parallel to the former iceflow direction as are corrugations in discrete subhorizontal slip planes in its upper part dike like bodies of this diamictite are found in the underlying mudstone and argillaceous diamictite these dikes or wedge shaped sheets of sandy diamictite are nearly vertical in their upper parts but at depth curl to the southeast to form sill like bodies these intrusive diamictites record a novel and previously undescribed form of subglacial bed shear by repeated hydraulic injections which shuffled the upper layers of the substrate to the south southeast bed compaction and shear beneath the grounded ice is recorded by folds in steepened portions of the clastic intrusive sheets and by pinch and swell and folded pinch and swell of the clastic sills displacement of steep folded sheet elements along subhorizontal slicken sided slip planes indicate that bed shear continued along spaced planes of slip during the process of compaction the corrugated and planar slip surfaces and the formation of the listric or spoon shaped intrusions are all shown to be different expressions of bed shear induced by traction from the overriding ice flowing to the southeast when it was temporarily grounded the base of an ice sheet flowing from land into the sea undergoes flow acceleration and forms a ramp where it decouples from the high friction substrate the arenaceous diamictite mound most likely to have developed beneath this ramp is inferred to have a structural core of sediments that have been squeezed and sheared and have slipped from beneath the ice in the tidal grounding zone

convective structure of hurricanes as revealed by lightning locations cloud to ground lightning flash locations were examined for nine atlantic basin hurricanes using data from the national lightning detection network a common radial distribution in ground flash density was evident a weak maximum in the eyewall region a clear minimum 80 100 km outside the eyewall and a strong maximum in the vicinity of outer rainbands 210 290 km radius these results are consistent with the authors previous study of hurricane andrew none of the storms showed this characteristic radial structure during prehurricane stages the results support the division of precipitation in the hurricane into three distinct regimes the eyewall is a unique phenomenon but shares some attributes with deep weakly electrified oceanic monsoonal convection the region outside the eyewall and under the central dense overcast has characteristics of the trailing stratiform region of mesoscale convective systems including a relatively high fraction of positive polarity flashes the outer bands with mean maximum flash density at the 250 km radius contain the vast majority of ground flashes in the storms eyewall lightning defined as that within 40 km of the center was examined for four moderate to strong hurricanes such lightning occurred episodically during hurricane stage with 93 of hourly intervals containing no detected flashes eyewall lightning outbreaks over water always occurred at the beginning of or during times of intensification but often were indicative of the imminent end of deepening it is proposed that the existence of such inner core lightning might reveal the presence of an eyewall cycle for the one storm with available aircraft reconnaissance data eyewall cycles were reliably identified by the occurrence of inner core lightning and inner core lightning appeared only during such cycles suggestions are made as to how eyewall flashes in existing hurricanes might be used to help predict hurricane intensity change

concretion morphology classification and genesis abstract a discussion of the most relevant morphological features of concretionary bodies and the different classifications and the criteria involved in these classifications is presented together with suggestions for improvements to the various classification schemes the meaning of syngenetic diagenetic and epigenetic related to the relative timing and environment of growth of concretionary bodies is also reviewed and discussed the replacement of mixed morphogenetic classifications which lead to conflicting results by classification categories based on textural features is proposed because the identification of the genetic environment of a concretionary body tells little about its history i recommend defining growth patterns in which the successive steps associated with changes in composition and or texture and the development of new structures are recorded a new path is presented that accounts for the contradiction between textural and isotope features which suggests respectively syngenetic and diagenetic or even epigenetic signatures this new path is characterized by the preservation of large porosities over very long time spans and down to depths that are somewhat greater than expected due to the inhibition of normal compaction caused by early overpressuring this overpressuring is the result of the development of hydraulic seals since approximately the syngenetic phase times the concepts of force of crystallization and displacive growth are also reviewed it is being suggested to discard some controversial interpretations of their actual importance for true concretionary displacive growth under epigenetic conditions in accordance with other authors the conclusion is reached that displacive growth is only possible if the shear strength of the host is very low and the stress field within the host is almost hydrostatic a new model the symcompactional concretionary growth model is proposed which explains how a concretionary body generally a nodule can grow while its host thins down by compaction this overpressured undercompacted model will be useful for the interpretation of an assemblage of features such as injection dikes hydraulic breccias cone in cone structures among others that are thought to be representative of the former presence of overpressured horizons these overpressured horizons could serve as detachment planes in paleotectonically active basins seals that could have controlled the movement of brines and hydrocarbons during the diagenetic evolution of the basin can also be assessed this is relevant for the identification of maturation conditions the potential development of secondary fracture permeability due to hydraulic fracturing in buried areas of the basin can also be evaluated based on the identification of formerly overpressured horizons in outcrops the origin of concretions is generally a geological puzzle clifton 1957

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

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

boundary layer structure and dynamics in outer hurricane rainbands part i mesoscale rainfall and kinematic structure abstract results of hurricane boundary layer experiments conducted in outer rainbands of hurricanes josephine 1984 and earl 1986 are presented comparisons of precipitation and kinematic structures in these storms and in hurricane floyd 1981 indicate that principal rainbands have common characteristic mesoscale and convective scale features in the boundary layer the two dimensional mesoscale structure suggests that these rainbands are made up of a linear aggregate of cellular reflectivity elements on the inner upshear side of the band and stratiform rain on the outer downshear side the bands are oriented perpendicular to the shear above the boundary layer and cells move downband at about 85 of the density weighted mean wind speed of the 0 2 6 km layer the boundary layer wind field is strongly influenced by the rainband with alongband and crossband wind maxima located on the outer side of the band axis and minima 4 8 km to the inner side maximum crossband convergence and cyclonic shear vor

a wide rainband in a developing tropical cyclone abstract on 18 january 1987 the three aircraft from the equatorial mesoscale experiment emex completed a mission designed to identify the mesoscale reflectivity kinematic and thermodynamic structure of a convectively active rainband on the leading edge of developing tropical cyclone irma the reflectivity structure determined from land based and aircraft radars reveals that the band consisted of an unusually wide 80 km region of convective clouds that did not maintain a linear organization high e air entered from both sides in the subcloud and lower cloud layer thermodynamically the rainband was benign in the sense that it did not produce cold downdrafts or large regions of low e air that would limit the energy of the low level inflow to the developing eyewall region kinematically the band was a preferred location for the enhancement of the wind component parallel to the band the low level flow was along rather than across the major axis of the band above 4 5 km flow was from the inner to

field and laboratory tests for recognition of ediacaran paleosols abstract not a single paleosol had been described from rocks of ediacaran age until 2011 but 354 ediacaran paleosols have been described by 20 different authors since then some of these newly recognized paleosols have proven controversial so this paper reviews 20 distinct tests to determine whether a particular ediacaran bed could be a paleosol or not one problem has been that ediacaran paleosols are not precisely like modern soils because they lack root traces a diagnostic feature of silurian and geologically younger paleosols the principal problem for recognition of some ediacaran paleosols is the occurrence in them of megafossils assumed to have been marine although most of these fossils remain problematic for both biological and ecological affinities not all the tests discussed here are diagnostic of paleosols some are ranked permissive or persuasive permissive conditions for paleosols include ripple marks hummocky bedding pyritic limestones acritarchs or thalloid fossils low strontium isotopic ratios high 26 mg ratios and red color persuasive tests include loessites tsunamites desert playa minerals low boron content high 10 b isotopic ratios high carbon sulfur ratios and very low total reactive iron ratios diagnostic tests include matrix supported lapilli or crystal tuff parent materials ice wedges and other cryoturbation sepic birefringence fabrics evaporitic sand crystals and negative geochemical strain and mass transfer and highly correlated 13 c and 18 o like other geological periods the ediacaran is known from a variety of marine and non marine paleoenvironments

new chronological data esr and esr u series for the earliest acheulian sites of north western europe increasing evidence suggests that bifacial technology acheulian mode 2 arrived in europe during the early middle pleistocene i e significantly earlier than previously proposed in northern france and britain much of the age attribution for these assemblages has been based on biostratigraphy and lithostratigraphy rather than absolute dates this study presents a systematic application of electron spin resonance esr dating of sedimentary quartz and esr u series dating of fossil tooth enamel to key acheulian sites of this area although the age estimates have large associated uncertainties most of the derived dates are consistent with existing age estimates the new chronologies and the problems associated with dating material of early middle pleistocene age are discussed in britain the earliest archaeology cores and flakes mode 1 is older than marine isotope stage mis 15 whereas localities containing acheulian technologies span late mis 15 mis 13 through to mis 9 a similar pattern is seen in northern france although age estimates from sites such as la noira suggest the possible appearance of the acheulian in central france as early as mis 17 the dates presented here support the suggestion that the earliest acheulian appeared in nw europe during the early middle pleistocene significantly after its appearance in the southern parts of the continent

mechanisms and controls on the formation of sand intrusions sandstone intrusions are found in all sedimentary environments but have been reported most commonly from deep water settings they also appear to be more frequently developed in tectonically active settings where applied tectonic stresses facilitate development of high fluid pressures within the sediments a variety of mechanisms have been cited as triggers for clastic intrusions these include seismicity induced liquefaction application of tectonic stresses excess pore fluid pressures generated by deposition related processes and the influx of an overpressured fluid from deeper within the basin into a shallow sand body the formation of sandstone dykes and sills is investigated here by considering them as natural hydraulic fractures when the seal on an unconsolidated overpressured sand body fails the resulting steep hydraulic gradient may cause the sand to fluidize the fluidized slurry can then inject along pre existing or new fractures to form clastic intrusions the scale and the geometry of an intrusive complex is governed by the stress state depth and pre existing joints or faults within the sedimentary succession as well as the nature of the host sediments for the simplest tectonic setting where the maximum stress in a basin is vertical gravitational loading small irregular intrusions commonly result in the formation of sills at shallow depths within a few metres of the surface whereas at greater depth dykes and sills forming clastic intrusion networks are more typical a simple relationship is derived to calculate the maximum burial depth at which a dyke sill complex forms as a function of the source bed to sill height the bulk density of the surrounding sediments and the ratio of the vertical to horizontal effective stresses k 0 when applied to three examples of large scale dyke sill complexes developed within paleocene and eocene deep water reservoir sand bodies of the north sea maximum burial depths in a range of 375 to c 500 m 450 700 m and 550 850 m are estimated for intrusion of each of the three complexes

mesoscale and convective structure of a hurricane rainband abstract the mesoscale thermodynamic kinematic and radar structure of a hurricane floyd rainband observed on 7 september 1981 is presented data are from 26 aircraft passes through the rainband from 150 to 6400 m a composite technique which presents rainband structure as a function of distance from the storm circulation center reveals inflow from the outer edge of the band and a partial barrier to this flow below 3 km in the direction parallel to rainband orientation radar reveals cellular reflectivity structure on the upwind and central portions of the rainband the frequency of cellular precipitation decreases in favor of stratiform precipitation further downwind as the band spirals gradually towards the eyewall in the radial direction a decrease of 12 k in e is observed across the rainband in the subcloud layer convective scale up and downdrafts that are associated with cellular reflectivity structure are hypothesized to be responsible for the thermodynamic modification of the cloud and subc

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

kinematic structure of convective scale elements in the rainbands of hurricanes katrina and rita 2005 1 airborne doppler radar data collected during the hurricane rainband and intensity change experiment rainex show the convective scale air motions embedded in the principal rainbands of hurricanes katrina and rita these embedded convective cells have overturning updrafts and low level downdrafts originating at 2 4 km that enter the rainband on its radially outward side and cross over each other within the rainband as well as a strong downdraft emanating from upper levels 6 km on the radially inward side these vertical motion structures repeat from one convective cell to another along each rainband the resulting net vertical mass transport is upward in the upwind portion of the band and greatest in the middle sector of the principal rainband where the updraft motions contribute generally to an increase of potential vorticity below the 3 4 km level because the convective cells in the middle sector are systematically located radially just inside the secondary horizontal wind maximum shwm the local increase in vorticity implied by the convective mass transport is manifest locally as an increase in the strength of the shwm at midlevels 4 km the overturning updrafts of the convective cells tilt stretch and vertically transport vorticity such that the convergence of the vertical flux of vorticity strengthens the vorticity anomaly associated with the shwm this process could strengthen the shwm by several meters per second per hour and may explain how high wave number convective scale features can influence a low wave number feature such as the principal rainband and subsequently influence the primary vortex

reexamining the near core radial structure of the tropical cyclone primary circulation implications for vortex resiliency abstract recent theoretical studies based on vortex rossby wave vrw dynamics have established the importance of the radial structure of the primary circulation in the response of tropical cyclone tc like vortices to ambient vertical wind shear linear vrw theory suggests in particular that the degree of broadness of the primary circulation in the near core region beyond the radius of maximum wind strongly influences whether a tilted tc vortex will realign and resist vertical shear or tilt over and shear apart fully nonlinear numerical simulations have verified that the vortex resiliency is indeed sensitive to the initial radial structure of the idealized vortex this raises the question of how well the true nature of a tc s primary circulation is represented by idealized vortices that are commonly used in some theoretical studies in this paper the swirling wind structure of tcs is reexamined by utilizing flight level observations collected from atlantic and eastern pacific storms during 1977 2

oriented clastic dike swarms as indicators of paleoslope an example from the upper cretaceous nanaimo group canada abstract an impressive oriented clastic dike swarm 165 dikes occurs within 3 25 m of strata of a submarine fan turbidite succession of the upper cretaceous nanaimo group british columbia the dikes are remarkably parallel in orientation are consistently subvertical and strike southwest slump fold vergence paleocurrent indicators and other evidence indicate that local paleoslope strike was northwest with a downslope direction to the southwest thus the clastic dikes strike downslope indicating that extension occurred perpendicular to the regional downslope direction not parallel as generally expected two possible models are proposed 1 rapid downslope compression caused by sudden loading perhaps due to slumping events or deposition of thick turbidity current beds this downslope compression caused minor extension perpendicular to the downslope direction resulting in small extensional joints that accommodated clastic injection from buried overpressured sands 2 chaotic sedimentary breccias laterally adjacent to the dike swarm formed as part of a large slumping event which created a local slump channel minor slumping into the main channel from the sides caused extension parallel to the channel margin slope and formation of the clastic dikes parallel to the channel margin but perpendicular to the regional slope oriented clastic dike swarms may represent a new type of paleoslope indicator but they may be created by a number of processes and should therefore be used only in conjunction with supporting evidence

reexamining the vertical structure of tangential winds in tropical cyclones observations and theory a few commonly held beliefs regarding the vertical structure of tropical cyclones drawn from prior studies bothobservationalandtheoretical areexaminedinthisstudy oneofthesebeliefsisthattheoutwardslopeof the radius of maximumwinds rmw is a function of the size of the rmw another belief is that the outward slope of the rmw is also a function of the intensity of the storm specifically shea and gray found that the rmw becomes increasingly vertical with increasing intensity and decreasing radius the third belief evaluated here is that the rmw is a surface of constant absolute angular momentum m these three conventional wisdoms of vertical structure are revisited with a dataset of three dimensional doppler wind analyses comprising seven hurricanes on 17 different days azimuthal mean tangential winds are calculated for each storm andtheslopesofthermwandmsurfacesareobjectivelydetermined theoutwardslopeofthermw is shown to increase with radius which supports prior studies in contrast to prior results no relationship is found between the slope of the rmw and intensity it is shown that the rmw is indeed closely approximated by an m surface for the majority of storms however there is a small but systematic tendency for m to decrease upward along the rmw utilizing emanuel s analytical hurricane model a new equation is derived for the slope of the rmw in radius pressure space this predicts a linear increase of slope with radius and essentiallyno dependence of slope on intensity an exactly analogous equationcan be derivedin log pressure height coordinates and a numerical solution yields the same conclusions in geometric height coordinates these conclusions are further supported by the results of simulations utilizing emanuel s simple timedependent axisymmetric hurricane model as both the model and the analytical theory are governed by the dual constraints of thermal wind balance and slantwise moist neutrality it is demonstrated that it is these two assumptionsthat requirethe slope of the rmw to be a functionof its size but not of the intensityof the storm finally it is shown that within the context of emanuel s theory the rmw must very closely approximate an m surface through most of the depth of the vortex

storm generated sedimentary structures in subtidal marine facies with examples from the middle and upper ordovician of southwestern virginia abstract the role of storms is of major importance in forming stratification in open shelf facies though storm processes on modern shelves are not fully understood enough is known to see how sediments are influenced storms transport sand away from coastal areas and suspend and transport sand and mud on the open shelf when wave base is lowered storms generate winnowed lag deposits of shells or gravel but coarser sediment and shells of megafauna are little transported except in very near shore environments the martinsburg formation middle and upper ordovician of southwestern virginia was deposited on a storm influenced open marine platform in contrast to the classic turbidite flysch basin of the martinsburg in the great valley of virginia to the northeast deposition of most martinsburg sediments was due to storms sediments deposited during single storm events occur in characteristic fining upward sequences 1 to 80 cm thick in both carbonate and terrigenous clastic dominated areas of the platform individual storm deposits consist of a sharp erosional base overlain by a couplet of whole fossil packstone and laminated calcarenite siltite or quartzose siltstone to very fine sandstone which is gradational to shale packstones are typically intraclastic have shells aligned parallel o bedding and convex up often with adhering or contained mud and have abundant infiltration textures such as cement filled shelter voids packstones grade abruptly to a laminated bed with horizontal plane lamination large and small scale in phase undulatory lamination and wave ripple cross lamination commonly occurring in ordered vertical sequences laminated beds contain escape burrows are weekly graded and have irregularly mounded upper bed surfaces laminated beds grade upward to shale containing horizontal branching burrows and marine fossils the faunal content of the fining upward sequences matches that of the interbedded shale storm generated beds vary greatly in thickness laterally and frequently pinch out completely fining upward sequences formed by scouring winnowing and suspension of the sand and mud during the height of the storm to form the erosional base and autochthonous lag of whole fossils storms preferentially preserve whole fossils rather than fragmenting them infiltration of finer sediment into the lag deposit and deposition of the laminated bed occurred as the storm waned laminated beds are molded into a distinctive suite of sedimentary structures by wave generated currents the shale represents deposition of finest storm suspended material and continued hemipelagic sedimentation similar sequences are widely distributed in the geologic record variability of storm generated sequences can be related to changing water depth thus storm deposits may be useful in basin analysis to estimate relative water depths and trace transgressive and regressive events

airflow and precipitation properties within the stratiform region of tropical storm gabrielle during landfall abstract kinematic and microphysical characteristics of a stratiform rainband within tropical storm gabrielle during landfall on 14 september 2001 were investigated using data from a collocated 915 mhz wind profiler and scanning doppler radar the curved 60 km wide rainband was relatively intense with mesoscale updrafts and downdrafts exceeding 1 m s 1 the bright band is classified as strong as indicated by reflectivity factors in excess of 50 dbz and rainfall rates below the bright band peaking at 10 20 mm h 1 the melting layer microphysical processes were examined to understand the relation between brightband processes and precipitation intensity and kinematics mesoscale downdraft in particular below the melting layer the profiler and doppler radar analyses designed to maximize vertical resolution of flows within the melting layer disclose a striking convergence divergence couplet through the melting layer that implies a prominent cooling induced finescale circulation melting driven cooling in

the influence of convectively generated thermal forcing on the mesoscale circulation around squall lines abstract the dynamical processes that determine the kinematic and thermodynamic structure of the mesoscale region around 2d squall lines are examined using a series of numerical simulations the features that develop in a realistic reference simulation of a squall line with trailing stratiform precipitation are compared to the features generated by a steady thermal forcing in a dry simulation with no microphysical parameterization the thermal forcing in the dry simulation is a scaled and smoothed time average of the latent heat released and absorbed in and near the leading convective line in the reference simulation the mesoscale circulation in the dry simulation resembles the mesoscale circulation in the reference simulation and around real squall lines it includes an ascending front to rear flow a midlevel rear inflow a mesoscale up and downdraft an upper level rear to front flow ahead of the thermal forcing and an upper level cold anomaly to the rear of the thermal forcing it is also shown t

middle eocene paleohydrology of the dongying depression in eastern china from sedimentological and geochemical signatures of lacustrine mudstone previous understanding that stratigraphic variability in lacustrine sequences is primarily caused by depositional processes governed by regional tectonics and climatic change remains to be tested on microscopic scale here we study the upper fourth member es4u of the eocene shahejie formation the major source rock of the dongying depression eastern china in order to understand stratigraphic heterogeneity and tectonic and climate controls on depositional processes in lacustrine mudstone our study integrates core descriptions microscopic observations and studies of mineralogy toc and chemical weathering proxies of cia and ln al2o3 na2o from two full bore cores and correlation of gamma ray logs from six wells across the depression we identified four major lithofacies including the interbedded evaporite and mudstone deposited in a shallow salt lake the silt bearing clay rich mudstone deposited in a pro delta environment within a shallow open lake the laminated calcareous mudstone deposited in a deep stratified meromictic lake with frequent earthquake activities and the massive calcareous mudstone deposited in a shallow and oxygenated lake the es4u member changed from the interbedded evaporite and mudstone dominated lithofacies association to silt bearing clay rich mudstone dominated lithofacies association and then laminated calcareous mudstone dominated lithofacies association suggesting basin wide changes in depositional processes lake level lake water chemistry and paleohydrology we suggest that these changes reflect balance between sediment and water supply and potential accommodation of the lake basin which were governed by paleoclimate in the lake drainage and extensional tectonics we infer that during the deposition of the es4u member the lake basin evolved from an underfilled lake basin with salty lake water under arid climate to a shallow balanced fill lake basin when climate became humid then to a deep balanced fill basin with stratified bottom lake water when climate became more humid and the basin was deepened by tectonic activity this study demonstrates that climate and tectonics both control paleolimnological changes and depositional processes of lacustrine mudstone

half graben lacustrine sedimentary rocks of the lower carboniferous strathlorne formation horton group cape breton island nova scotia canada the strathlorne formation is the middle formation of a three part horton group stratigraphy present throughout the post acadian orogeny maritimes basin in atlantic canada it is up to 600 m in thickness and is of tournaisian age the formation was deposited in a complex lacustrine system during the period of maximum fault bounded extensional subsidence within two asymmetric half graben sub basin segments of a large rift this rift was located at a palaeolatitude of 10 15 s four facies assemblages are identified and interpreted 1 dark grey mudstone open lacustrine 2 grey very fine to fine grained sandstone nearshore shoreline 3 grey medium grained sandstone to conglomerate fan delta and 4 red siltstone to fine grained sandstone interdeltaic mudflat interpreted structural asymmetry of the fault bounded sub basins is evidenced by asymmetry of sediment input facies distribution and palaeoflow in the lacustrine sedimentary fill these indicators suggest that the sub basins which were linked end to end had opposed polarity of structural asymmetry during deposition of the strathlorne formation open lacustrine sediments are typified by stacked shallowing upward sequences each representing deepening due to sub basin wide subsidence events followed by gradual infilling to shallow water depths sub basin asymmetry is also reflected in the contrast of thick sequences and grouped thinner sequences at marginal and axial positions respectively the lakes which occupied the sub basins were large up to 100 50 km tens to hundreds of metres deep and periodically stratified presence of an anoxic hypolimnion at least near sub basin axes

spiral rainbands in a numerical simulation of hurricane bill 2009 part i structures and comparisons to observations abstractthis study examines spiral rainbands in a numerical simulation of hurricane bill 2009 this paper the first part of the study evaluates the structures of spiral rainbands and compares them to previous observations four types of spiral rainbands are identified principal secondary distant and inner rainbands principal rainbands tend to be stationary relative to the storm center while secondary rainbands are more transient and move around the storm center both principal and secondary rainbands are tilted radially outward with height and have many of the commonly observed kinematic features such as overturning secondary circulation and enhanced tangential velocity on their radially outward sides principal rainbands are bounded by very dry air on their radially outward sides distant rainbands are radially inward tilting convective features that have dense cold pools near the surface inner rainbands are made of shallow convection that appears to have originated from near the eyewall dif

gradient balance in tropical cyclones abstract analysis of a large inventory of in situ observations from research aircraft shows that the gradient wind approximates the axisymmetric swirling flow in the free atmosphere within 150 km of the centers of atlantic hurricanes and tropical storms in the middle and lower troposphere the rms difference between the azimuthal cream swirling and gradient winds is typically lt 1 5 m s 1 with zero bias this balance prevails only for the azimuthal mean not locally nor is balance to be expected in either the surface friction layer or the upper tropospheric outflow layer where the radial flow is comparable with the swirling flow it is theoretically possible that axisymmetric supergradient flow may occur in response to rapid radial acceleration where the radial flow slows in the friction layer beneath the eyewall or where it converges into intense diabatically forced updrafts nevertheless the observations in the free lower and midtroposphere show that systematic departures of the azimuthal mean vorte

origin and maintenance of the long lasting outer mesoscale convective system in typhoon fengshen 2008 abstractouter mesoscale convective systems omcss are long lasting heavy rainfall events separate from the inner core rainfall that have previously been shown to occur in 22 of western north pacific tropical cyclones tcs environmental conditions accompanying the development of 62 omcss are contrasted with the conditions in tcs that do not include an omcs the development kinematic structure and maintenance mechanisms of an omcs that occurred to the southwest of typhoon fengshen 2008 are studied with weather research and forecasting model simulations quick scatterometer quikscat observations and the simulations indicate the low level tc circulation was deflected around the luzon terrain and caused an elongated north south moisture band to be displaced to the west such that the omcs develops in the outer region of fengshen rather than spiraling into the center strong northeasterly vertical wind shear contributed to frictional convergence in the boundary layer and then the large moisture flux

convective scale variations in the inner core rainbands of a tropical cyclone airborne doppler radar documented a variety of convective scale structures within the inner core rainbands of hurricane rita 2005 as predicted by past studies wind shear determined azimuthal variations in the convection all convective scale circulations had radial inflow at low levels upward motion and outflow in the midtroposphere convective cells at smaller radii contained a low level tangential jet determined largely by tangential acceleration due to angular momentum conservation uy r term while cells at larger radii contained a low level and or midlevel jet determined jointly by the uy r and vertical advection terms the outflow was at a higher lower altitude for the outer inner cells radial variations in the convective cells are attributable to differencesin buoyancy and vertical shear of the radial wind u z more buoyant updrafts at larger radii enhance vertical advection of y creating local tangential jets at midlevels at smaller radii the stronger low level radial inflow contributes to a greater u z confining convectively generated jets to low levels the low level tangential jet and convectively generated pressure gradients produce outward pointing supergradient acceleration that decelerates the boundary layer inflow consequently this supergradient flow will enhance convergence and convection at the radius of inner rainbandcells increasing the likelihoodof secondary eyewall formation it is hypothesized that a critical zone for secondary eyewall formation exists where sufficiently high u z consistently constrains the altitudes of convectively generated supergradient flow so that convection in this radial zone leads to a newly developed eyewall once an incipient secondary eyewall forms at a certain radius subsidence occurring along its inner edge separates it from the primary eyewall

shallow water gravity flow deposits chapel island formation southeast newfoundland canada a remarkable suite of shallow water gravity flow deposits are found within very thinly bedded siltstones and storm generated sandstones of member 2 of the chapel island formation in southeast newfoundland medium to thick siltstone beds termed unifites range from non graded and structureless type 1 to slightly graded with poorly developed lamination type 2 to well graded with lamination similar to that described for fine grained turbidites type 3 unifite beds record deposition from a continuum of flow types from liquefied flows type 1 to turbidity currents type 3 calculations of time for pore fluid pressure dissipation support the feasibility of such transitions raft bearing beds consist of siltstone with large blocks or rafts of thinly bedded strata derived from the underlying and adjacent substrate characteristics suggest deposition from debris flows of variable strength estimates of debris strength and depositional slope are calculated for a pebbly mudstone bed using measurable and assumed parameters an assumed density of 2 0 g cm 1 and a compaction estimate of 50 gives a strength estimate of 79 7 dyn cm 2 and a depositional slope estimate of 0 77 the lithologies and sedimentary structures in member 2 indicate an overall grain size distribution susceptible to liquefaction inferred high sediment accumulation rates created underconsolidated sediments metastable packing types of sediment failure included in situ liquefaction disturbed bedding sliding and slumping raft bearing debrites resulted from sliding and incorporation of water locally hummocky cross stratified sandstone directly overlies slide deposits and raft bearing beds linking sediment failure to the cyclical wave loading associated with large storms the gravity flows of the chapel island formation closely resemble those described from the surfaces of modern mud rich marine deltas details of deltaic gravity flow deposition from this and other outcrop studies further our understanding of modern deposits by adding a third dimension to studies primarily carried out with side scan sonar

the organization of convection in the rainbands of tropical cyclone laurence abstract a slow moving weak tropical cyclone passed near darwin australia in december 1990 rainbands were observed by a doppler weather radar and a 50 mhz wind profiler for over 24 h the principal bands were seen to be organized on two distinct scales bands of stratiform precipitation formed at a radius of about 100 km from the center of the storm and moved outward at about 6 m s 1 these decayed after they moved past darwin over land a distinct midlevel jet extended along the bands within the bands convective lines formed at regular intervals propagated against and outward with respect to the mean flow and acted as a partial barrier to the radial inflow deep active convection was confined to these lines the vertical motion in the convection showed a distinct acceleration above the freezing level with measured updrafts of up to 10 m s 1 the convection elevated the tropopause height over the rainband it is hypothesized that an inertia gravity wave propagating from near the storm eye was resp

sedimentary records of paleoseismic events in the late pleistocene sediments of the southern yangtze river deltaic plain east china and their implications for differential subsidence of the taihu block abstract drilling cores from the hangjiahu coastal plain in the southwestern corner of the southern yangtze river deltaic plain east china contain a variety of soft sediment deformation structures in the late pleistocene lacustrine and tidal sediments they include load flame structures ball and pillow structures diapir structures liquefied sand veins liquefied breccias syn sedimentary fault seismo cracks and brittle breccias sedimentary facies assessment of host deposits and development features rule out an exogenic origin of the soft sediment deformation structures such as gravity flow storm activity wave action or flood these soft sediment deformation structures in the study area are interpreted as seismites their spatial distribution suggest that the earthquakes were sourced from the intersection of the majin wuzhen fault and the huzhou jiashan fault seismites recognized in cores indicate three episodes of short and sudden seismicity magnitude 5 which are interpreted as a response to syn depositional tectonic activity and differential subsidence of the taihu block during the late pleistocene period systematic study of spatial and temporal distribution of these seismites improves the understanding of the tectonic context and evolutionary history of sedimentary basement

outer rainbands driven secondary eyewall formation of tropical cyclones abstractsecondary eyewall formation sef could be considered as the aggregation of a convective ring coupling with a tangential wind maximum outside the primary eyewall of a tropical cyclone tc

secondary eyewall formation and concentric eyewall replacement in association with increased low level inner core diabatic cooling abstractthe role of increased diabatic cooling in secondary eyewall formation sef and eyewall replacement cycle erc is examined using idealized numerical simulation the experiment with the low

evolution of ptygmatic folds in migmatites from the type area s finland abstract it is proposed that ptygmatic folds in migmatites form during leucosome melanosome differentiation volume loss by depletion of quartz and feldspar takes place in the interlimb domains of folds leaving a residual melanosome buckling leucosomes increase in volume due to this process and are protected from substantial thinning concurrent with tectonic segregation albeit at a lower rate the leucosome expands by replacing the melanosome this process is induced by fluid activity at the leucosome boundary as suggested by the occurrence of secondary offshoot veinlets segregation and growth causes the most typical aspect of ptygmatic folds preservation of an overall buckle shape during the stage when the folds become isoclinal and devoid of interlimb matrix

secondary wind maxima in hurricanes airflow and relationship to rainbands abstract aircraft flight level data from 787 radial legs in 20 hurricanes are analyzed to identify the composite kinematic structure in the hurricane eyewall and especially with secondary horizontal wind maxima shwm that occur outside the eyewall similar to previous studies analysis of the flight level wind data in the eyewall reveals radial convergence near the radius of maximum wind rmw and the highest frequency of updraft and the largest upward mass transport radially inward of the rmw more than 20 of the flight legs contain substantial secondary horizontal wind maxima of specified strength and length the kinematic structure associated with shwm is similar to that of the hurricane eyewall with radial convergence near the radius of maximum wind and a preferred location for maximum upward motions and upward mass transport just inside the rmw statistical analysis confirms the similarity in characteristics between radial and vertical velocities of the eyewall and near the shwm in addition for

the dynamic response of the hurricane wind field to spiral rainband heating abstract the response of the hurricane wind field to spiral rainband heating is examined by using a three dimensional nonhydrostatic linear model of the vortex anelastic equations diabatic heat sources which are designed in accordance with previous observations of spiral rainbands are made to rotate with the flow around the hurricane like wind field of a balanced axisymmetric vortex common kinematic features are recovered such as the overturning secondary circulation descending midlevel radial inflow and cyclonically accelerated tangential flow on the radially outward side of spiral rainbands comparison of the responses to the purely convective and stratiform rainbands indicates that the overturning secondary circulation is mostly due to the convective part of the rainband and is stronger in the upwind region while midlevel radial inflow descending to the surface is due to the stratiform characteristics of the rainband and is stronger in the downwind region the secondary horizontal wind maxim

parametric representation of the primary hurricane vortex part ii a new family of sectionally continuous profiles abstract for applications such as windstorm underwriting or storm surge forecasting hurricane wind profiles are often approximated by continuous functions that are zero at the vortex center increase to a maximum in the eyewall and then decrease asymptotically to zero far from the center comparisons between the most commonly used functions and aircraft observations reveal systematic errors although winds near the peak are too strong they decrease too rapidly with distance away from the peak pressure wind relations for these profiles typically overestimate maximum winds a promising alternative is a family of sectionally continuous profiles in which the wind increases as a power of radius inside the eye and decays exponentially outside the eye after a smooth polynomial transition across the eyewall based upon a sample of 493 observed profiles the mean exponent for the power law is 0 79 and the mean decay length is 243 km the database actually contains 606 aircraft sorties but 113 of these failed

a spatial filter approach to evaluating the role of convection on the evolution of a mesoscale vortex abstracta new spatial filter is proposed that exploits a spectral gap in power between the convective scale and the system vortex scale during tropical cyclone tc genesis simulations using this spatial separation this study analyzes idealized three dimensional numerical simulations of deep moist convection in the presence of a symmetric midlevel vortex to quantify and understand the energy cascade between the objectively defined convective scale and system scale during the early stages of tropical cyclogenesis the simulations neglect surface momentum heat and moisture fluxes to focus on generation and enhancement of vorticity within the interior to more completely close off the energy budget and to be consistent for comparison with prior benchmark studies of modeled tc genesis the primary contribution to system scale intensification comes from the convergence of convective scale vorticity that is supplied by vortical hot towers vhts they contribute more than the convergence of system scale v

soft sediment deformation structures related to tectonomagmatic activity a case study from the borate bearing lacustrine deposits of early miocene bigadic basin nw turkey abstract this study documents soft sediment deformation structures in the lacustrine bigadic basin one of the early miocene terrestrial basins in the extensional tectonomagmatic province of northwestern anatolia the focus is on the upper borate unit of the basin fill succession which consists of sedimentary facies including massive conglomerates stratified sandstones siltstones organic rich claystones laminated limestones organic rich limestones marlstones borates and volcaniclastics their deposition including borates occurred in a deep lacustrine environment possible phases of lake shallowing are represented by stratified sandstones facies soft sediment deformation features include small scale folds formed by convolution with occasional basal decollement minor slumps load casts and related flame structures fragmented and mixed beds brecciated by pore water explusion shallow and deep rooted synsedimentary extensional faults with related neptunian dykes and large slump sheets of thick bed packages with recumbent folds these deformation features are interpreted to be of seismo tectonic and seismo volcanic origin related to syndepositional strike slip faulting and volcanic eruptions seismic tremors combined with the basin floor updoming by magma intrusions caused deep rooted normal faults and intra basinal slumps tens of metres thick the study may serve as a guide to similar deformation structures in the underlying part of the bigadic lake fill succession and in the other neogene basins of northwestern anatolia which shared the region s seismo tectonic magmatic palaeogeographic and sedimentation history

a sequence of soft sediment deformation dewatering structures in late quaternary subaqueous outwash near ottawa canada abstract a sequence of soft sediment deformation structures occurs in late quaternary sediments near ottawa canada the sediments are attributed to deposition on subaqueous outwash fans in the champlain sea at the submerged front of the retreating wisconsin glacier in upward sequence the deformed units comprise convolute stratification ball and pillow structures and dish structures deformation is attributed to slumping on the subaqueous fans and or to the melt out of ice blocks which had been buried by fan sediments the sequence of structures is interpreted in terms of a series of events as follows 1 1 local fluidization of low permeability sediments formed convolute stratification disrupted anticlines acted as vertical diapirs through which fluidized sediment ascended 2 2 the diapirs penetrated overlying more cohesive sediments forming ball and pillow structures 3 3 dish structures formed in silty fine sand which had passed upward through the diapirs and between the ball and pillow structures in some cases the silty sand moved downslope as a liquefied sediment flow and dish structures were deformed to give oval plan forms with long axes normal to the local paleoslope

observations of the eyewall structure of typhoon sinlaku 2008 during the transformation stage of extratropical transition abstracta unique dataset observing the life cycle of typhoon sinlaku was collected during the observing system research and predictability experiment thorpex pacific asian regional campaign t parc in 2008 in this study observations of the transformation stage of the extratropical transition of sinlaku are analyzed research flights with the naval research laboratory p 3 and the u s air force wc 130 aircraft were conducted in the core region of sinlaku data from the electra doppler radar eldora dropsondes aircraft flight level and satellite atmospheric motion vectors were analyzed with the recently developed spline analysis at mesoscale utilizing radar and aircraft instrumentation samurai software with a 1 km horizontal and 0 5 km vertical node spacing the samurai analysis shows marked asymmetries in the structure of the core region in the radar reflectivity and three dimensional wind field the highest radar reflectivities were found in the left of shear semicircle and maximum ascent was

reflectivity ice scattering and lightning characteristics of hurricane eyewalls and rainbands part i quantitative description abstract covering december 1997 through december 1998 261 overpasses of 45 hurricanes by the tropical rainfall measuring mission trmm satellite are used to document the observed radar reflectivity values passive microwave ice scattering magnitudes and total lightning cloud to ground plus in cloud these parameters are interpreted as describing convective vigor or intensity with greater reflectivities particularly aloft greater ice scattering lower 85 and 37 ghz brightness temperatures and increased lightning frequency indicating more intense convection for each parameter the full distribution of values observed during the trmm satellite s first year is presented for specific regions properties of three regions of the hurricane eyewall inner rainband and outer rainband are treated separately and compared to other tropical oceanic and tropical continental precipitation systems reflectivity profiles and ice scattering signatures are found to be fairly similar for both hurricane and non

quadrant dependent evolution of low level tangential wind of a tropical cyclone in the shear flow abstractthis study investigates the quadrant by quadrant evolution of the low level tangential wind near the eyewall of an idealized simulated mature tropical cyclone embedded in a unidirectional shear flow it is found that the quadrant averaged tangential wind in the right of shear quadrants weakens continuously while that in the left of shear quadrants experiences a two stage evolution a quasi steady stage followed by a weakening stage after the imposing of vertical wind shear this leads to a larger weakening rate in the right of shear and a stronger jet in the left of shear quadrants the budget analysis shows that the quadrant dependent evolution of tangential wind is controlled through the balance between the generalized coriolis force gcf i e the radial advection of absolute angular momentum and the advection terms the steady decreasing of the gcf is primarily responsible for the continuous weakening of jet strength in the right of shear quadrants for the left of shear quadrants the quas

bypass zone tempestite facies model and proximality trends for an ancient muddy shoreline and shelf member 2 of the late precambrian to lower cambrian chapel island formation of southeast newfoundland was primarily deposited in storm influenced nearshore and shelf environments along a fine grained coastline deposition took place within or adjacent to a deltaic system that supplied abundant silts and clays thin bedded graded sandstone beds hummocky cross stratified beds and a variety of very thin conglomerate units contain evidence for deposition by storm currents sedimentological and stratigraphic evidence is used to reconstruct the relative paleobathymetric position of the three major facies in member 2 the gutter cast facies is a shallow subtidal deposit characterized by very thin sandstone laminae and abundant pot and gutter casts the siltstone dominated facies contains more laterally extensive thin bedded sandstones and fewer erosional features and was deposited in the inner shelf the sandstone dominated facies consists of thin to medium graded and hummocky cross stratified sandstone beds deposited in a more distal shelf setting but above storm wave base the facies model and set of proximality trends developed for member 2 deposits may be applicable to other storm influenced fine grained shorelines in this model the shallow subtidal is a zone of throughput with high velocity sediment laden flows eroding deep narrow scours gutter casts and depositing very little sand outside of these scours as the storm generated flows move into deeper water they decelerate resulting in less erosion of the sea floor and depositing thicker and more continuous sand beds siltstone dominated facies further from shore bed thickness reaches a maximum sandstone dominated facies and hummocky crossstratification is abundant even more distally bed thickness decreases again represented by thinly laminated siltstones of the overlying member 3 analysis of sedimentary structures and paleocurrent data suggests deposition by storm currents that transported sediment nearly perpendicular to shore

surface cold pools in the outer rainbands of tropical storm hanna 2008 near landfall surface mesonet observations were used to document the structure of prominent cold pools associated with twoconvectiveouterrainbandsoftropicalstormhannaon5september2008 thedevelopingrainbandswere located 400 kmnorth ofthestormcenterastheycrossedthecarolinacoastlineandpassedover themesonet the combination of moderate cape moderate low level cross band vertical shear and dry midlevel air provided an environment supportive of surface cold pool formation and long lived quasi linear convection both rainbands exhibited multiple outward tilting convective cells and discrete line segments centered within a narrow zone of nearly continuous stratiform precipitation the mesonet observations provided a unique along and cross band perspective of discrete cold pools situated beneath andbehind the convection portions of each rainband prominentcold pools extended 40 80 km behind the rainband s leading edge and exhibited maximum potential temperature mixing ratio and equivalentpotentialtemperaturedeficitsof2 4 k 1 2 g kg 21 and4 10 k respectively inthecross banddirection convergence of storm relative inflow along the cold pool leading edge was coincident with a modest high pressure anomaly while inflow divergence prevailed through the cold pool and rainfall maxima several cold pools expanded along band while being advected downband by the prevailing cyclonic flow cold pool wakes were observed more than 50 km behind the rainband leading edge and up to 20 km downband from intense convection variations in cold pool intensitywerenotwell correlated with convectiveintensity rainfallrate or the degree of midlevel dryness implications of prominent cold pools on tropical cyclone convection size and intensity are discussed

sand injectites from source to emplacement an example from the miocene age frimmersdorf seam garzweiler open cast mine lower rhine embayment

soft sediment deformation structures as a tool to recognize synsedimentary tectonic activity in the middle member of the bakken formation williston basin north dakota abstract the bakken formation uppermost devonian lower carboniferous in north dakota consists of black shales with a middle member composed of mixed siliciclastics and carbonates millimeter to decimeter scale soft sediment deformation structures ssds are common in the upper third to quarter of the middle member having been observed in sixty three out of ninety cores studied the nine categories identified herein reflect brittle and ductile deformation and loss of sediment shear in compressional and extensional settings they are interpreted to form due to seismically induced folding liquefaction and fluidization of unconsolidated sediment as well as microfaulting and brecciation of consolidated sediment and reflect synsedimentary tectonic movements e g along faults that were active during deposition the distribution of ssds follows the orientation of the major structural elements rooted in the basement of the williston basin the stratigraphic and spatial distribution of ssds suggests variable tectonic activity cores near the most active fault systems have the highest net thickness of units with ssds whereas those farther from the most active faults exhibit only a few deformed units the predominance of ssds in the upper portion of the middle member suggests there was a change from relative tectonic quiescence to a more active regime which in turn led to modifications of basin geometry and new accommodation patterns synsedimentary deformation might have had a positive effect on reservoir quality in deformed units by increasing porosity and permeability as a result of cohesion loss and rearrangement of grains additionally multiple injection structures and complexes of small scale normal and reverse faults could contribute to better connectivity of reservoir units

the axisymmetric and asymmetric aspects of the secondary eyewall formation in a numerically simulated tropical cyclone under idealized conditions on an f plane abstractthe axisymmetric and asymmetric aspects of the secondary eyewall formation sef in a numerically simulated tropical cyclone tc under idealized conditions were analyzed consistent with p

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

evolution of the inflow boundary layer of hurricane gilbert 1988 abstract on 12 september 1988 the two noaa wp 3d aircraft conducted an experiment in and around an intense outer rainband located 175 km southeast of the center of hurricane gilbert radial height cross sections along a constant azimuth reveal a rapid and an exceptionally large increase of the equivalent potential temperature e of the inflow but in a region radially outward from the rainband kinematic analyses that incorporate both in situ and pseudo dual doppler data illustrate that the inflow is only 2 km deep and strongly divergent prior to reaching the convective core of the band the doppler derived wind fields which compare favorably with the in situ wind fields demonstrate that there is a radially outward or return flow directly above the inflow soundings show that this return flow is unusually moist despite being dominated by mesoscale descent which contrasts the dry conditions found under the anvil of virtually all tropical mesoscale convective systems a one dimensional general structure

hurricane spiral bands abstract the spiral bands that occur in tropical cyclones can be conveniently divided into two classes outer bands and inner bands evidence is presented here that the outer bands form as the result of nonlinear effects during the breakdown of the intertropical convergence zone itcz through barotropic instability in this process a zonal strip of high potential vorticity the itcz shear zone or monsoon trough begins to distort in a varicose fashion with the potential vorticity pv becoming pooled in local regions that are connected by filaments of high pv as the pooled regions become more axisymmetric the filaments become thinner and begin to wrap around the pv centers it is argued that inner bands form in a different manner as a tropical cyclone intensifies due to latent heat release the pv field becomes nearly circular with the highest values of pv in the cyclone center the radial gradient of pv provides a state on which pv waves the generalization of rossby waves can propagate the nonline