ichnofabric logs for the characterization of the organic content in carbonates abstract this study proposes an approach to visualize ichnological data from cores that allows direct comparison with downhole logs it provides preliminary but accurate environmental information especially on the oxygenation and or the organic matter content at the sea floor the method comprises three steps step 1 ichnological analysis of the sediments including quantification of bioturbation intensity identification of the main ichnotaxa and sizes of the burrows depth of burrowing or tiering and documentation of cross cutting relationships step 2 ichnofabric definition following a series of criteria including the bioturbation index the ichnoassemblage and the sediment type and step 3 the organization of the ichnofabrics from low bioturbation indices and deep tiers to completely bioturbated the resulting ichnofabrics are plotted against depth and can directly be compared to spectral natural gamma ray logs which in the discussed example are dominated by variations of the uranium content reflecting the organic matter content in the sediment the ichnofabric analysis of carbonate sediment cores of the maldives recovered during iodp expedition 359 demonstrates a good correlation between synthetic ichnofabric logs and downhole gamma radiation logs the combined study of these logs provides information on the main changes in the organic matter content of the sediment the graphical representation of ichnofabrics together with gamma ray logs presented here is a very useful implement for sedimentologists working on cores

measurement and characterization of infrasound from a tornado producing storm a hail producing supercell on 11 may 2017 produced a small tornado near perkins oklahoma 35 97 97 04 at 2013 utc two infrasound microphones with a 59 m separation and a regional doppler radar station were located 18 7 and 70 km from the tornado respectively elevated infrasound levels were observed starting 7 min before the verified tornado infrasound data below 5 hz was contaminated with wind noise but in the 5 50 hz band the infrasound was independent of wind speed with a bearing angle that was consistent with the movement of the storm core that produced the tornado during the tornado a 75 db peak formed at 8 3 hz which was 18 db above pre tornado levels this fundamental frequency had overtones 18 29 36 and 44 hz that were linearly related to mode number analysis of a larger period of time associated with two infrasound bursts the tornado occurred during the first event shows that the spectral peaks from the tornado were present from 4 min before to 40 min after tornadogenesis this suggests that the same geophysical process es was active during this entire window

conditions and timescales for welding block and ash flow deposits welding of pyroclastic deposits to reform a coherent rock mass is a common phenomenon especially for pumiceous pyroclastic density current deposits i e ignimbrites however and despite the pervasive abundance of block and ash flow baf deposits in the geological and modern record instances of strongly welded baf deposits are few here we present a series of high temperature 800 900 c compaction experiments designed to map the conditions deposit thickness stress and temperature viscosity and timescales that permit or inhibit the welding of baf deposits our experiments were performed on unconsolidated aggregates containing an ash and lapilli component derived from crushed and sieved lava blocks containing 25 crystals taken from the well documented welded baf deposit at mount meager volcano british columbia canada the experiments demonstrate that welding efficiency increases with increasing time and temperature progressive welding is expressed by increasing axial strain porosity loss and bulk density the rate of change of each of these physical properties reduces as welding progresses microstructural analysis of the experimental products shows that the loss of interclast porosity during welding results from the progressive sintering and amalgamation of vitric fragments and that the pore shape changes from sub equant pores to stretched lenses sandwiched between vitric and crystal fragments the coincidence between the microstructure and rock physical properties of the natural and experimental samples highlight that we have successfully reproduced welded baf in the laboratory furthermore our permeability measurements highlight a hysteresis in the return journey of the there and back again volcanic permeability cycle expressed by an increase in permeability due to vesiculation and fragmentation followed by a decrease due to welding this hysteresis cannot be described by a single porosity permeability power law relationship and reflects the change in pore shape and connectivity during welding finally we show that a simple model for welding can accurately forecast the welding timescales of the baf deposit at mount meager as reconstructed from the collapse of the lillooet river valley dam using our experimental data we use this validation as a platform to provide a universal window for the welding of baf deposits also applicable for comparable welded deposits e g welded autobreccias in block lavas and lava domes for a broad range of deposit thickness or stress and effective viscosity

neogene palaeoenvironmental evolution in the atlantic side of the rifian corridor morocco abstract outcrops of upper miocene to upper pliocene deposits in the atlantic side of the rifian corridor northwest morocco provide data that allow an assessment of the palaeoenvironmental evolution of the main seaway that connected the mediterranean to the atlantic ocean until its final closure at the end of the miocene a reconstruction of the sedimentary regimes and palaeobathymetries in the gharb and saiss basins has been carried out from the physical and microfaunal benthic foraminifera characteristics of sediments and three sedimentary sequences are distinguished from the oldest rocks deposited at the opening of the corridor more than 8 ma to the upper pliocene sediments younger than 4 ma that ended the marine sedimentation the maximum palaeodepth recognised about 500 m occurs in marly sediments of the coastal area bou regreg composite section between 8 and 5 9 ma this is followed by a tectonically controlled shallowing phase leading to the establishment of neritic conditions and corresponding to a relative sea level lowering of about 300 m that we suggest relates to closure of the passageway and consequent onset of the mediterranean evaporite deposition the persistence in the saiss basin of middle neritic palaeodepths since the upper tortonian about 7 8 ma suggests for this internal basin a sill physiography evidence from the present and previously documented palaeobathymetric reconstructions indicates that the tectonic activity in the atlantic corridor started from the eastern side and moved to the west

infrasound emitted by tornado like vortices basic theory and a numerical comparison to the acoustic radiation of a single cell thunderstorm this paper addresses the physics and numerical simulation of the adiabatic generation of infrasound by tornadoes classical analytical results regarding the production of infrasound by vortex rossby waves and by corotating suction vortices are reviewed conditions are derived for which critical layers damp vortex rossby waves that would otherwise grow and continually produce acoustic radiation these conditions are similar to those that theoretically suppress gravity wave radiation from larger mesoscale cyclones such as hurricanes to gain perspective the regional atmospheric modeling system rams is used to simulate the infrasound that radiates from a single cell thunderstorm in a shear free environment in this simulation the dominant infrasound in the 0 1 10 hz frequency band appears to radiate from the vicinity of the melting level where diabatic processes involving hail are active it is shown that the 3d rossby waves of a tornado like vortex simulated with rams can generate stronger infrasound if the maximum wind speed of the vortex exceeds a modest threshold technical issues regarding the numerical simulation of tornado infrasound are also addressed most importantly it is shown that simulating tornado infrasound likely requires a spatial resolution that is an order of magnitude finer than the current practical limit 10 m grid spacing for modeling thunderstorms

impact of restriction of the atlantic mediterranean gateway on the mediterranean outflow water and eastern atlantic circulation during the messinian 1 messinian foraminiferal stable oxygen and carbon isotopes of the montemayor 1 core guadalquivir basin sw spain have been investigated this record is exceptional to study the mediterranean outflow water mow impact on the atlantic meridional overturning circulation amoc and global climate during the messinian because the core is near the guadalhorce corridor the last betic gateway to be closed during the early messinian our results allow dating accurately its closure at 6 18 ma constant benthic 18o values high difference between benthic and planktonic 18o and low sedimentation rates before 6 18 ma indicate the presence of a two layer water column with bottom winnowing due to an enhanced mediterranean outflow current the enhanced contribution of dense mow to the north atlantic ocean likely fostered the formation of north atlantic deep water nadw after 6 18 ma benthic 18o values parallel that of the global glacioeustatic curve the difference between benthic and planktonic 18o is low and sedimentation rates considerably increased this indicates a good vertical mixing of the water column interruption of the mow and a dominant glacioeustatic control on the isotopic signatures according to the role of mow in the modern atlantic thermohaline circulation the reduction of the mow after the closure of the guadalhorce corridor might have resulted in a decreased nadw formation rate between 6 0 and 5 5 ma weakening the amoc and promoting northern hemisphere cooling after the gibraltar strait opening the restoration of the mow and related salt export from the mediterranean could have promoted an enhanced nadw formation

large burrow systems in marine miocene deposits of the betic cordillera southeast spain abstract large burrow systems occur in the miocene marine deposits of the almeria nijar basin betic cordillera southeast spain they consist of galleries of dense burrow segments locally forming irregular networks cylindrical branched y shaped structures with diameters ranging from 8 to 22 cm and minimum lengths of 30 60 cm are abundant in addition galleries longer than 70 80 cm are common and burrow segments larger than 200 cm are locally present burrows have smooth walls without pellet reinforcements but locally possible scratch marks are present burrow fill is structureless and has a similar composition to the host rock these structures are assigned to the ichnogenus thalassinoides ehrenberg displaying similarities with t suevicus identification of the possible tracemaker is not straightforward but decapod crustaceans probably shrimp or shrimp like organisms are the most likely candidates

voluminous lava like precursor to a major ash flow tuff low column pyroclastic eruption of the pagosa peak dacite san juan volcanic field colorado abstract the pagosa peak dacite is an unusual pyroclastic deposit that immediately predated eruption of the enormous fish canyon tuff 5000 km3 from the la garita caldera at 28 ma the pagosa peak dacite is thick to 1 km voluminous 200 km3 and has a high aspect ratio 1 50 similar to those of silicic lava flows it contains a high proportion 40 60 of juvenile clasts to 3 4 m emplaced as viscous magma that was less vesiculated than typical pumice accidental lithic fragments are absent above the basal 5 10 of the unit thick densely welded proximal deposits flowed rheomorphically due to gravitational spreading despite the very high viscosity of the crystal rich magma resulting in a macroscopic appearance similar to flow layered silicic lava although it is a separate depositional unit the pagosa peak dacite is indistinguishable from the overlying fish canyon tuff in bulk rock chemistry phenocryst compositions and 40ar 39ar age the unusual characteristics of this deposit are interpreted as consequences of eruption by low column pyroclastic fountaining and lateral transport as dense poorly inflated pyroclastic flows the inferred eruptive style may be in part related to synchronous disruption of the southern margin of the fish canyon magma chamber by block faulting the pagosa peak eruptive sources are apparently buried in the southern la garita caldera where northerly extensions of observed syneruptive faults served as fissure vents cumulative vent cross sections were large leading to relatively low emission velocities for a given discharge rate many successive pyroclastic flows accumulated sufficiently rapidly to weld densely as a cooling unit up to 1000 m thick and to retain heat adequately to permit rheomorphic flow explosive potential of the magma may have been reduced by degassing during ascent through fissure conduits leading to fracture dominated magma fragmentation at low vesicularity subsequent collapse of the 75 35 km 2 la garita caldera and eruption of the fish canyon tuff were probably triggered by destabilization of the chamber roof as magma was withdrawn during the pagosa peak eruption

high resolution sequence stratigraphy of clastic shelves iii applications to reservoir geology abstract high frequency clastic shelf sequences contain porous deposits consisting of coastal to shallow water sandstones and conglomerates which may represent very good reservoirs and therefore critical targets for exploration and production as well as for fluid hydrocarbon water or co2 storage the study of these reservoirs following a sequence stratigraphic approach is essential to predict their features and distribution within systems tracts forming high frequency sequences which in turn compose higher rank systems tracts and sequences a critical aspect to improve the exploitability of the reservoirs is their heterogeneity which directly affects the volume of the reservoirs and determine internal compartmentalization the heterogeneity can be primary related to depositional processes influencing grain size and facies distribution and secondary related to diagenesis in particular the primary heterogeneity is referred to the facies variability from distal to proximal settings to the accumulation of condensed shell beds and to facies characteristics of bedsets whereas the secondary heterogeneity derives from diagenetic processes at sequence stratigraphic surfaces and facies contacts and within sandbodies both the distribution of reservoirs and their heterogeneity can be predicted following a high resolution sequence stratigraphic approach ultimately the integration of subsurface data with the analysis of outcrop analogs is essential to better understand the features of clastic shelf reservoirs and to develop 3d models of fluid migration

messinian paleoenvironmental evolution in the lower guadalquivir basin sw spain based on benthic foraminifera abstract benthic foraminiferal assemblages of a drill core from the lower guadalquivir basin northern gulf of cadiz sw spain have been analyzed in order to reconstruct the paleoenvironmental evolution in the vicinity of the betic seaways during the messinian the core consists of marine sediments ranging from the latest tortonian to the early pliocene changes in the abundance of certain marker species planktonic benthic ratio p b ratio paleodepth estimated with a transfer function content of sand grains and presence of glauconitic layers indicate a complete transgressive regressive sea level cycle from the bottom to the top of the section an abrupt sea level rise from inner middle shelf to middle slope is recorded at the lowermost part of the core latest tortonian earliest messinian followed by a relatively rapid shallowing from middle slope to outer shelf magnetobiostratigraphic data show that this sea level fall postdates the onset of the messinian salinity crisis msc in the mediterranean finally the early pliocene deposits are interpreted as inner middle shelf changes in the benthic foraminiferal assemblages through the core are mainly controlled by the trophic conditions specifically by the quantity and quality of the organic matter reaching the sea floor the upper slope and part of the outer shelf assemblages are highly diverse and dominated by shallow infaunal species indicating a generally mesotrophic environment with moderate oxygenation these environments have likely been affected by repeated upwelling events documented by increased abundance of uvigerina peregrina s l an opportunistic species thriving in environments with enhanced labile organic matter supply the assemblages of the transitional interval between upper slope to outer shelf and of the outer shelf are generally characterized by a relatively low diversity and epifaunal shallow infaunal taxa indicating oligotrophic and well oxygenated conditions the inner middle shelf assemblages are characterized by very low diversity and dominance of intermediate to deep infaunal taxa suggesting an eutrophic environment with low oxygen content these assemblages are dominated by nonion fabum and bulimina elongata two taxa that are able to feed from continental low quality organic matter most likely derived from river run off the paleoenviromental evolution on the atlantic side of betic and rifian seaways is similar during the messinian with a messinian continuous sea level lowering driven by regional tectonic uplift and upwelling related waters reaching the upper slope this study will further contribute to understand the role of tectonics on the sea level changes as well as on the closure of the atlantic mediterranean gateways that led to the msc and on the paleoceanography on the atlantic sides of these corridors

vegetation sea level and climate changes during the messinian salinity crisis the messinian salinity crisis late miocene is one of the most fascinating paleoceanographic events in the recent geological history of the mediterranean sea defining a time when it partly or nearly completely dried out however the relative roles of tectonic processes and sea level changes as triggers for restriction and isolation of the mediterranean sea from the open ocean are still under debate in this study we present a detailed pollen dinoflagellate cyst dinocyst and magnetic susceptibility analysis of a sequence of late neogene between ca 7 3 and 5 2 ma marine sediments from the montemayor 1 core lower guadalquivir basin southwestern spain which provides a continuous record of paleoenvironmental variations in the atlantic side of the betic corridors during the late miocene our results show that significant paired vegetation and sea level changes occurred during the messinian likely triggered by orbital scale climate change important cooling events and corresponding glacio eustatic sea level drops are observed in this study at ca 5 95 and 5 75 ma coinciding with the timing and duration of oxygen isotopic events tg32 and tg22 20 recorded in marine sediments worldwide it is generally accepted that the onset of the messinian salinity crisis began at ca 5 96 0 02 ma therefore this study suggests that the restriction of the mediterranean could have been triggered at least in part by a strong glacio eustatic sea level drop linked to a climate cooling event occurring at the time of initiation of the messinian salinity crisis

chronology and tectono sedimentary evolution of the upper pliocene to quaternary deposits of the lower guadalquivir foreland basin sw spain this paper presents new litho chrono and magnetostratigraphic data from cores of 23 exploratory boreholes drilled in the abalario and marshlands areas of the lower guadalquivir basin the western sector of the guadalquivir foreland basin sw of spain the lithologic logs of these boreholes identify four main sedimentary formations namely almonte sand and gravel lebrija clay and gravel marismas clay and abalario sand respectively interpreted as proximal alluvial distal alluvial alluvial estuarine and aeolian from radiocarbon and magnetostratigraphic data these formations were dated as upper pliocene to holocene in the marshlands area three main sedimentary sequences are present an upper pliocene to lower pleistocene sequence of the almonte and lebrija lower unit formations a pleistocene sequence of the lebrija upper unit and the lower marismas formations and a latest pleistocene to present day sequence of the upper marismas formation the three sequences began as a rapid alluvial progradation on a previously eroded surface and a subsequent alluvial retrogradation in the third sequence estuarine and marsh sediments accumulated on top of the alluvial sediments the aeolian sands of the abalario topographic high developed coeval to alluvial and estuarine sedimentation after the first alluvial progradation and continuously until the present correlation with the surrounding areas show that the sequences are the result of the forebulge uplift of the northern margin of the basin sierra morena and the adjacent neogene oldest sediments of their northern fringe both form the main source area of the study formations this uplift occurred simultaneous to the flexural subsidence sse tilting of the southern part of the basin where sedimentary aggradation dominated

low frequency atmospheric acoustic energy associated with vortices produced by thunderstorms an infrasonic observatory collocated with the colorado state university chill radar during the summer of 1995 permitted unique comparisons between severe storm kinematics and detected acoustic energy at subaudible frequencies near 1 hz radar observations of a velocity couplet aloft evolving into a tornado showed a circulation maximum descending for about 30 min while moving to the east the detected infrasound followed the trend of these observations a model of sound radiated from vortex systems predicts frequencies in the range observed these data are interpreted in the context of past infrasonic observations an ongoing study comparing regional tornado and funnel sightings with archived infrasonic data has identified over 100 cases to date where the infrasonic signals occurred at the time of and from the direction of the vortices for some of these cases the distances were greater than 100 km the author and his associates continue to collect datasets to permit further evaluation of infrasonic detection methods

history and evolution of the north betic strait prebetic zone betic cordillera a narrow early tortonian tidal dominated atlantic mediterranean marine passage abstract the north betic strait located in the prebetic zone outermost part of the betic cordillera was a narrow seaway connecting the atlantic ocean and the mediterranean sea through the betic cordillera during the early late miocene strait facies consist of heterozoan bioclastic carbonates and mixed siliciclastics carbonates local fan delta deposits conglomerates also occur the north betic strait deposits exhibit huge trough cross bedded structures single troughs are up to 5 m high and point to the east in easternmost outcrops in central outcrops they reach up to 15 m in height and some tens of metres in length and point both to the east and to the west the westernmost outcrops show the largest cross bedded structures up to 20 m in height and some hundred of metres in length all pointing to the west the large scale cross bedding was generated by the migration of very large dunes moved by tides the largest structures are inferred to have formed at depths of 90 m depth estimations indicate that the north betic strait shallowed to the east and deepened to the west the miocene evolution towards the formation of the north betic strait can be divided into a series of steps the palaeogeography evolved from a south facing platform marginal to a northeastern relief to a wide open marine passage limited by a southern platform and finally to a tidal dominated strait the closing of the north betic strait is recorded by the presence of lagoonal silty sediments covered by a stromatolite layer and crowned by a red soil in the westernmost outcrops

the 1984 nuee ardente deposits of merapi volcano central java indonesia stratigraphy textural characteristics and transport mechanisms for many centuries merapi volcano has generated hot avalanches of blocks lapilli and ashes derived from the destruction of partially solidified viscous lava domes merapi type nuees ardentes on 15 june 1984 at least four nuees ardentes came down the southwest slope of the merapi the first and the last being responsible for more than 99 of the deposits which are now exposed the first nuee ardente a merapi type nuee ardente was produced by the destruction of the dome travelled 7 km from the crater leaving a measured deposit 2 7 m thick 4 km from the crater near its upper depositional limit regularly increasing to a maximum measured thickness of 12 m at the front of the deposit the lower contact is sharp non erosive with pines still rooted in the underlying paleosol the deposit consists of 50 ash 33 lapilli and 17 blocks with two subpopulations one rosin and one normal and is finespoor with less than 4 of fine ash d finer than 4 the deposit displays reverse population grading of both vesiculated and massive clasts and of the maximum grain size the maximum size significantly increases regularly down current over most of the exposed length of unit 1 and bed thickness increases for the entire length of the deposit the deposit of the second nuee ardente is only 6 21 cm thick and of very limited lateral extent it is a normally graded coarse to fine ash with a finespoor base the third unit consists of fines poor normally graded coarse ash exposed in low amplitude 20 40 cm 12 m wavelength dunes the deposit of the fourth nuee ardente rests in sharp erosive contact on the underlying unit increasing in thickness down flow it consists of transitional coarse and fine grained strata 6 130 c cm thick dipping 5 10 down flow the deposit made up of two subpopulations one rosin and one normal is normally graded over the entire bed but coarsegrained strata are reversely graded the relative content of vesiculated clasts increases up bed in both strata types from 12 at the base to 40 at the top the characteristics of unit 1 suggest that it accumulated from a concentrated suspension of cohesionless solids exhibiting non newtonian behavior where dispersive pressure played an important role in the suspension of the clasts units 2 and 3 were probably deposited from dilute turbulent suspensions whereas the upper unit 4 is a classic example of deposition from a high density turbulent suspension leading to the formation of multiple traction carpets driven by the overlying lower density surge the horizontal distance travelled by a hot rock avalanche may be influenced by its transport mechanism debris flows are mobile on very low slopes as low as 1 whereas grain flows even density modified grain flows require relatively high slopes more than 6 at merapi to maintain their mobility if the present merapi dome were to collapse and produce a debris flow its present volume coupled with the minimal 1 5 km vertical drop could travel a distance ranging between 15 and 30 km however if transport were by grain flow mechanisms the mass could come to rest as it reaches a 5 10 slope

compaction and gas loss in welded pyroclastic deposits as revealed by porosity permeability and electrical conductivity measurements of the shevlin park tuff pyroclastic flows produced by large volcanic eruptions commonly densify after emplacement processes of gas escape compaction and welding in pyroclastic flow deposits are controlled by the physical and thermal properties of constituent material through measurements of matrix porosity permeability and electrical conductivity we provide a framework for understanding the evolution of pore structure during these processes using data from the shevlin park tuff in central oregon united states and from the literature we find that over a porosity range of 0 70 matrix permeability varies by almost 10 orders of magnitude from 10 20 to 10 11 m 2 with over three orders of magnitude variation at any given porosity part of the variation at a given porosity is due to permeability anisotropy where oriented core samples indicate higher permeabilities parallel to foliation horizontally than perpendicular to foliation vertically this suggests that pore space is flattened during compaction creating anisotropic crack like networks a geometry that is supported by electrical conductivity measurements we find that the power law equation k 1 1 3 10 21 5 2 provides the best approximation of dominant horizontal gas loss where k 1 permeability and porosity application of kozeny carman fluid flow approximations suggests that permeability in the shevlin park tuff is controlled by crack or disk like pore apertures with minimum widths of 0 3 and 7 5 m we find that matrix permeability limits compaction over short times but deformation is then controlled by competition among cooling compaction water resorption and permeable gas escape these competing processes control the potential for development of overpressure and secondary explosions and the degree of welding in the deposit processes that are applicable to viscous densification of volcanic deposits in general further the general relationships among porosity permeability and pore geometry are relevant for flow of any fluid through an ignimbritic host

geochemical compositional mapping of lower jurassic trace fossils palaeoenvironmental significance and methodological implications abstract analyses of x ray microfluorescence xrf elemental maps of the ichnofossil assemblages from the upper pliensbachian lower toarcian marl limestone rhythmite of the south iberian palaeomargin betic cordillera se spain show that the compositions of burrow infills are geochemically and mineralogically different with respect to the surrounding sediment xrf elemental maps and back scattered electron images show pyrite framboids within the burrows and enrichment in fe and s relative to the host sediment this is congruent with the position of burrows beneath the redox boundary at the time of their active or passive sedimentary infilling organic matter that accumulated at the seafloor was not preserved due to oxidation and consumption by benthic organisms however burrows located beneath the redox boundary served as traps for organic matter preservation the composition of burrow fills reflects the original signal of the redox conditions of pore waters below the sediment water interface which was not preserved in the surrounding sediment the xrf elemental maps also show that some trace fossils from limestone and marly limestone intervals contain high concentrations of si al k zn cr and ti with respect to the surrounding sediment this may reflect enrichment of clay minerals in the burrow fills derived from overlying marly layers this work proposes the use of elemental imaging of trace fossils prior bulk rock geochemical analyses in order to evaluate the potential for biogenic heterogeneity and elemental partitioning before sampling geochemical analysis of trace fossils represents an additional tool that may be of use in hydrocarbon exploration

cruziana and rusophycus like traces of recent sparidae fish in the estuary of the piedras river lepe huelva sw spain abstract modern fish are able to produce a plethora of different traces both bioturbation and bioerosion structures according to several behaviours yet only five ichnotaxa have been interpreted as produced by the activity of fish in the fossil record many taphonomic factors may favour the non fossilization of many of these traces and even fossilized they could have been misinterpreted in this contribution shallow and bilobed traces produced by the feeding activity of the perciform fish diplodus vulgaris sparidae in the estuary of the piedras river lepe huelva sw spain are described neoichnological study and comparison of these bioturbation structures with the fossil record allow associating them as cruziana and rusophycus like traces i e traces with features very similar to those of such ichnogenera since these ichnotaxa have been commonly interpreted as the result of the locomotion and resting of different kinds of invertebrates in order to get a better understanding of the marine and continental fossil record we also propose taking into account fish as potential producers of this kind of traces in future paleoichnological studies

modeling the evolution of the guadalquivir foreland basin southern spain 1 previous quantitative studies dealing with the origin of foreland basins have focused primarily either on the rheological basis of the lithosphere mechanical response or on the relationship between orogenic loading and sediment geometry to link the evolution of the guadalquivir foreland basin south iberia with the thermomechanical stratification of the iberian lithosphere we combine quantitative approaches to deep and shallow processes thrust loading lithospheric flexure thickness changes of the crust and the lithospheric mantle and surface mass transport a planform flexural analysis of the present day load distribution shows that basement subsidence is related not only to upper crustal thrusting but also to a deep seated additional load on the basis of the observed gravity and geoid fields we propose this additional load to be related to a lithospheric mantle thickening larger than the coeval crustal thickening further modeling of the evolution of a basin cross section reveals that the architecture of the sedimentary basin is additionally related to the lithosphere rheological response the quantitative study of the evolution of basement faulting and the forebulge uplift of sierra morena leads us to conclude that viscous stress relaxation and or plastic yielding within the lithosphere are key processes to explain the flexural evolution of the basin

stratigraphic variation in ichnofabrics at the shackleton site iodp site u1385 on the iberian margin paleoenvironmental implications abstract ichnofabric analysis was conducted on cores from site u1385 iodp expedition 339 to interpret paleoenvironmental conditions at the southwest margin of the iberian peninsula during the pleistocene site u1385 provides an important record for the study of orbital and suborbital scale climate variability changes related to ocean atmosphere dynamics and affected environmental parameters a detailed study of the ichnofabric characterization is presented focusing on the types of ichnofabrics relative abundance amount of bioturbation grouping ichnofabric succession transitions and vertical distribution seven ichnofabrics were differentiated green mottled ichnofabric planolites ichnofabric taenidium planolites ichnofabric thalassinoides like palaeophycus ichnofabric planolites thalassinoides thalassinoides like ichnofabric zoophycos ichnofabric and chondrites ichnofabric they exhibit significant differences in terms of ichnofabric features as well as in their stratigraphic distribution the most abundant ichnofabrics are planolites thalassinoides thalassinoides like ichnofabric and green mottled ichnofabrics with a dominance of the middle tier ichnofabrics the degree of bioturbation is moderate with a mean bi around 3 but showing a clear bimodal distribution one group of intervals is characterized by high bioturbation bi 6 while another displays low moderate bi values bi 1 2 in general ichnofabric features confirm generally good environmental conditions oxic environment and high food availability for the macrobenthic tracemaker community especially favorable in the uppermost part of the sediment a complete ichnofabric succession from deep to shallow tier ichnofabrics is commonly registered i e zoophycos ichnofabric or chondrites ichnofabric to planolites thalassinoides thalassinoides like ichnofabric and then either to green mottled ichnofabric or to planolites ichnofabric and then green mottled ichnofabric however there are some intervals where an incomplete succession between deep and shallow ichnofabrics is observed i e chondrites ichnofabric to green mottled ichnofabric or zoophycos ichnofabric to green mottled ichnofabric indicating relevant modifications of environmental parameters such as oxygen or food supply types of ichnofabrics and the bioturbation index show significant short term changes through the studied core such variations are probably correlated to millennial scale climatic perturbations such as glacial terminations and related phenomena heinrich events ice rafting events etc or long term cyclic patterns related to orbital climate variability the patterns could be tied to a significant change in the climate system such as the one associated with the middle pleistocene transition

ichnological analysis in high resolution sequence stratigraphy the glossifungites ichnofacies in triassic successions from the betic cordillera southern spain this study integrates ichnological and sedimentological data in order to refine sequence stratigraphy and interpretations of sea level dynamics for the ladinian middle triassic muschelkalk succession siles formation in the betic cordillera southern spain facies analysis was integrated with a detailed ichnological study focused on the middle part of the lower member of the muschelkalk succession transgressive systems tract which is characterized by an abundant and conspicuous trace fossil assemblage seven lithofacies were recognized recording sediment accumulation in tidal flat and inner to outer marine carbonate ramp depositional environments thin bedded marly limestones with bioclastic shelly beds facies e middle ramp with storm influence are characterized by diplocraterion and rhizocorallium diplocraterion is protrusive usually eroded on top and mainly recorded in the marly limestone intervals rhizocorallium preserves well defined scratch marks and is commonly emplaced in bioclastic shelly beds the assemblage represents the glossifungites ichnofacies sedimentological and ichnological data are interpreted to record a complex transgressive context associated with high frequency sea level dynamics that allowed formation of transgressive surfaces of erosion tse i e ravinement surfaces of different orders major tse associated with continuous bioclastic shelly beds delimit parasequences the absence of the glossifungites suite reveals that there was little time between erosion and deposition intermediate tse associated with discontinuous shell beds are related to comparatively less significant sea level rises and occur within parasequences the glossifungites suite reveals colonization of firmgrounds during relatively prolonged times between erosion and deposition related to intermediate tse minor order tse recorded between the intermediate tse are related to punctuated highest frequency sea level changes phases of colonization by the diplocraterion tracemaker and protrusive capped structures reveal more or less stillstand phases tse stillstand phases and minor order erosional phases

the record of oligocene middle miocene paleoenvironmental changes in a carbonate platform iodp exp 359 maldives indian ocean abstract the carbonate edifice of the maldives has an exceptional record of the global climate and ocean current reconfigurations during the neogene that set the path for the establishment of the present day global climate system the study of seismic profiles sedimentary facies microfacies and ichnofabrics of the oligocene miocene platform slopes allows reconstructing the different stages of basin evolution the focus is on the characterization of paleoenvironmental conditions along the slope at iodp expedition 359 drill sites as well as subtle changes of the slope depositional regime controlled by variations in the frequency and intensity of the platform shedding and the basin oxygenation natural gamma radiation and ichnofabric logs are used as a proxy for sea floor ventilation in the inner sea area which is today surrounded by atolls from the oligocene 25 5 ma to the end of the middle miocene climate optimum 15 ma the maldives carbonate platform slopes were poorly oxygenated the opening of the eastern passages through the maldives carbonate platform at 17 5 ma led to an improvement of the sea floor oxygenation sea level fluctuations controlled the sediment input from the platform onto the slope that resulted in changes of the fossil and trace fossil assemblages after the evolution from a ramp to a flat topped platform with well defined bank edges the platform developed hanging shoulder and more sigmoidal clinoforms this correlates to the global decline of coral reefs during the middle miocene climate transition 15 ma and a general sea level lowering the associated slope deposits show abundant channels and cyclic steps are rich in reworked bioclasts and have ichnofabrics pointing towards a good oxygenation of the sea floor the example of the maldives carbonate platform therefore shows how integrating seismic geometries and compositional changes i e microfacies and ichnofabrics allow identifying changes in sea level and in the current pattern as the main controlling factors on carbonate platform evolution

lepeichnus giberti igen nov isp nov from the upper miocene of lepe huelva sw spain evidence for its origin and development with proposal of a new concept ichnogeny abstract a new ichnotaxon lepeichnus giberti igen nov isp nov is described from sandy silts and sands of the upper miocene tortonian messinian of the guadalquivir basin lepe huelva sw spain it is a complex bioturbation structure consisting of two vertical shafts interconnected by a horizontal c shaped gallery which in turn exhibits a hook shaped branch l giberti is interpreted as probably produced by a crustacean that could have combined dwelling deposit feeding and farming strategies in a shallow marine environment its architectural similarities with modern upogebiid burrows suggest the record of a new burrowing behavior not yet known today for this group of mud shrimps the large number of studied specimens and their exceptional degree of preservation allow proposing the new concept of ichnogeny as a tool to describe the origin and development of a modern or fossil boring or burrowing trace

acoustic detection tracking and characterization of three tornadoes acoustic data recorded at 1000 samples per second by two sensor arrays located at ranges of 1 113 km from three tornadoes that occurred on 24 may 2011 in oklahoma are analyzed accurate bearings to the tornadoes have been obtained using beamforming methods applied to the data at infrasonic frequencies beamforming was not viable at audio frequencies but the data demonstrate the ability to detect significant changes in the shape of the estimated power spectral density in the band encompassing 10 hz to approximately 100 hz at distances of practical value from the sensors this suggests that arrays of more closely spaced sensors might provide better bearing accuracy at practically useful distances from a tornado additionally a mathematical model based on established relationships of aeroacoustic turbulence is demonstrated to provide good agreement to the estimated power spectra produced by the tornadoes at different times and distances from the sensors the results of this analysis indicate that qualit

outcrop and core integrative ichnofabric analysis of miocene sediments from lepe huelva sw spain improving depositional and paleoenvironmental interpretations abstract ichnofabric analysis was conducted in miocene sediments from lepe huelva sw spain based on integrative outcrop and core research to improve interpretations of depositional and paleoenvironmental conditions with special attention to sequence stratigraphy seven intervals were differentiated in outcrops based on stratigraphic and ichnological features consisting of two ichnofabrics ophiomorpha thalassinoides spongeliomorpha ichnofabric characterizes intervals 1 2 6 7 and 8 while palaeophycus planolites phycosiphon ichnofabric characterizes intervals 3 4 and 5 fourteen ichnofabrics were differentiated in the core mainly in view of lithological features including ferruginous material grain size mottled background ichnotaxa and bioturbation index a comparison between outcrop and core ichnofabrics through the upper 13 5 m corresponding to the uppermost tortonian lowermost messinian interval revealed certain similarities as well as some differences a continuous and relatively slow siliciclastic deposition with punctual variations in the sedimentation rate can be interpreted that associated with favorable paleoenvironmental parameters such as aerobic conditions and nutrient availability evidence that a well developed and diverse macroinvertebrate trace maker community existed at that time softgrounds are dominant but occasionally loosegrounds and even firmgrounds could develop the ichnofabric distribution shows long range patterns in outcrop and core and short range patterns exclusively in core long range patterns reflect the last phases of a transgressive system tract with a maximum flooding zone at the end and then a highstand normal regression high frequency short range repetitive patterns in ichnofabrics from core mainly between ichnofabrics 6 8 to 9 from lower to upper part of the pattern can be linked to local flooding surfaces subdividing the maximum flooding zone into parasequences our results reveals the usefulness of the integrative ichnofabric analysis including outcrop and core materials in sedimentary basin analysis assessing paleoenvironmental conditions and improving sequence stratigraphy characterization

infrasound pulses from lightning and electrostatic field changes observation and discussion 1 narrow 1 2 s infrasound pulses that followed with 11 to 50 s delays rapid changes of electrostatic field were observed by a microbarometer array in the czech republic during thunderstorm activity a positive pressure fluctuation compression phase always preceded decompression the compression was usually higher than the decompression the angles of arrival azimuth and elevation were analyzed for selected distinct events comparisons of distances and azimuths of infrasound sources from the center of microbarometer array with lightning locations determined by the european cooperation for lighting detection lightning detection network show that most of the selected events can be very likely associated with intracloud ic discharges the preceding rapid changes of electrostatic field their potential association with ic discharges and high elevation angles of arrival for near infrasound sources indicate that an electrostatic mechanism is probably responsible for their generation it is discussed that distinguishing the relative role of thermal and electrostatic mechanism is difficult and that none of the published models of electrostatic production of infrasound thunder can explain the presented observations precisely a modification of the current models based on consideration of at least two charged layers is suggested further theoretical and experimental investigations are however needed to get a better description of the generation mechanism

microboring and taphonomy in middle oxfordian to lowermost kimmeridgian upper jurassic from the prebetic zone southern iberia abstract microboring was investigated through thin section analysis of oxfordian rocks from the prebetic zone betic cordillera southern spain microboring description and distribution were analysed as was their correlation with traits such as the type and size of bioclasts and microtaphonomic features encrustation and fragmentation single and branching microboring are the two major morphological groups differentiated microborers were not identified but by their patterns of distribution in the bioclasts and in the environmental setting are assumed to be phototrophic microboring only affected bioclasts with higher values of microboring index mbi registered in thicker ammonoid shells and serpulids and lower ones in ostracods foraminifera and small bivalves gastropods and echinoderms a very close direct relationship exists between bioclast size and microboring abundance as well as between the microboring mbi and encrustation indexes ei used in contrast a clear relationship between mbi and the fragmentation index fi has not been proved microboring activity has been interpreted to be related to both bioclast size and time exposure of bioclasts on the seafloor the latter resulting directly proportional to the rate of sedimentation in low energy environments the studied features mbi fi ei and bioclast mean size were analysed taking into account the stratigraphic intervals investigated i transversarium zone to lower bifurcatus zone ii upper bifurcatus zone iii bimammatum zone and iv planula zone p p and the trends registered were interpreted as a final consequence of relative sea level fluctuations stratigraphic intervals i and iv characterised by higher values in mbi and ei were related to lower sedimentary rates during increasing distality in a context of relative sea level rise which is consistent with the development of transgressive system tract tst conditions stratigraphic intervals ii and iii showing lower values in mbi and ei are related to higher sedimentation rates and decreasing distance from shore during relative sea level falls which are in accordance with developing highstand system tract hst and shelf margin wedge smw conditions data obtained and interpretations agree with the general ecostratigraphic context in the studied area previously proposed by the authors