rocket triggered lightning propagation paths relative to preceding natural lightning activity and inferred cloud charge lightning mapping array lma data are used to compare the propagation paths of seven rocket triggered lightning flashes to the inferred charge structure of the thunderstorms in which they were triggered this is the first lma study of florida thunderstorm charge structure three sequentially within 16 min triggered lightning flashes whose initial stages were the subject of hill et al 2013 are reexamined by comparing the complete flashes to the preceding natural lightning to demonstrate that the three rocket triggered flashes propagated through an inferred negative charge region that decreased from about 6 8 to about 4 4 km altitude as the thunderstorm dissipated two other flashes were also sequentially triggered within 9 min in a thunderstorm that contained a convectively intense region ahead of a stratiform region with similar observed results finally two unique cases of triggered lightning flashes are presented in the first case the in cloud portion of the triggered lightning flash after ascending to and turning horizontal at 5 3 km altitude just above the 0 c level was observed to very clearly resemble the geometry of the in cloud portion of the preceding natural lightning discharges in the second case a flash was triggered relatively early in the storm s lifecycle that did not turn horizontal near the 0 c level as is usually the case for triggered lightning in dissipating storms but ascended to nearly 7 5 km altitude before exhibiting extensive horizontal branching

the modern carbonate ramp slope of central west florida abstract a holistic investigation of the modern carbonate ramp slope of central west florida has been completed via analysis of approximately 1 500 km of air gun seismic reflection profiles tied to two drillcores and bottom samples recovered at 92 stations our primary goal has been to characterize modern depositional processes and products to compare and contrast results with modern rimmed platform slopes and to develop a model for application to the rock record the modern depositional environment of the west florida ramp slope was initiated 12 15 ma when depositional style changed from seaward prograding clinoforms to a pelagic slope front fill system bound along the shelf margin by contour parallel flow of the loop current a seaward thickening wedge 0 250 m of late miocene to recent pelagic carbonate ooze has been deposited across antecedent mid miocene topography in general the sea floor dips 1 2 seaward from water depths of about 200 2 000 m and slopes are relatively smooth however contemporary submarine geomorphology is controlled in part by earlier slope failures the primary control of modern sedimentation along the west florida slope is loop current flow which acts as a dynamic oceanographic boundary between outer shelf and upper slope winnows bottom sediments catalyzes early submarine cementation and stimulates pelagic production of calcium carbonate the axis of loop current circulation has also migrated laterally in response to climatically controlled sea level fluctuations which has resulted in a relatively wide 25 km band of winnowed sands and hardgrounds along the shelf margin climatic oscillations have also resulted in cyclic deposition of pelagically derived aragonite pteropods on the ramp slope that is out of phase with bank derived aragonite cycles of rimmed platform slope there are three major facies belts that parallel modern isobaths 1 a hardground facies of intraclastic grainstones and rhodolith rudstones as well as algal ridges along the outer shelf at water depths of approximately 200 400 m 2 a winnowed sand facies of planktonic forams intraclasts glauconite and reworked phosphorite grains as well as deep water coral mounds along the shelf margin at depths of approximately 400 600 m and 3 a bioturbated pelagic ooze facies along the ramp slope at depths of approximately 600 2 000 m these facies patterns geometries and grain types along with a general paucity of sediment gravity flow deposits readily distinguish this carbonate ramp slope from better known rimmed platform slopes of the bahamas

on abandoning the thunderstorm tripole charge paradigm we reexamine the original half century old in situ measurements of simpson and colleagues used to justify the tripole model of charge structure of a thunderstorm that became the paradigm for the charge structure of mature thunderstorms we find that the original measurements violate the criteria of the tripole model in 49 of the cases we also reexamine our soundings of electric field in thunderstorms and mesoscale convective systems in the same way as the original soundings were our soundings do not fit the tripole model in at least 86 of the storms even when we consider only the major features in the electric field profiles our data show noncompliance with the tripole model in 45 of the cases we conclude that we must abandon the paradigm of the tripole charge structure of thunderstorms

electrical structure in thunderstorm convective regions 1 mesoscale convective systems electric field e soundings through convective regions of mesoscale convective systems mcss are examined in this paper ten e soundings through updrafts in mcs convective regions and five soundings in mcs convective regions outside updrafts are used to show that a typical electrical structure exists in this region these 15 e soundings plus one other previously published sounding which is included in this analysis comprise all known soundings in the convective region of mcss the basic charge structure identified in mcs updrafts consists of four charge regions alternating in polarity with the lowest region positive and the highest region negative the basic charge structure outside updrafts in mcs convective regions has six charge regions alternating in polarity with a positive charge region lowest maximum e magnitudes of both polarities are larger and are located at lower heights in soundings outside updrafts compared to those within updrafts excepting the upper positive charge inferred charge regions are shallower and have larger charge densities outside updrafts the center of the main negative charge is lower and warmer outside updrafts 5 5 km 6 2 c than within updrafts 6 9 km 15 7 c these features inside and outside updrafts are incorporated in a new conceptual model of mcs convective region charge structure also an expanded conceptual model is developed using previously published data from other parts of mcss this more complete conceptual model shows the typical electrical charge airflow and reflectivity features in the stratiform region the transition zone and the convective region of midlatitude mesoscale convective systems

accuracy of the lightning mapping array 1 the location accuracy of the new mexico tech lightning mapping array lma has been investigated experimentally using sounding balloon measurements airplane tracks and observations of distant storms we have also developed simple geometric models for estimating the location uncertainty of sources both over and outside the network the model results are found to be a good estimator of the observed errors and also agree with covariance estimates of the location uncertainties obtained from the least squares solution technique sources over the network are located with an uncertainty of 6 12 m rms in the horizontal and 20 30 m rms in the vertical this corresponds well with the uncertainties of the arrival time measurements determined from the distribution of chi square values to be 40 50 ns rms outside the network the location uncertainties increase with distance the geometric model shows that the range and altitude errors increase as the range squared r2 while the azimuthal error increases linearly with r for the 13 station 70 km diameter network deployed during steps the range and height errors of distant sources were comparable to each other while the azimuthal errors were much smaller the difference in the range and azimuth errors causes distant storms to be elongated radially in plan views of the observations the overall results are shown to agree well with hyperbolic formulations of time of arrival measurements e g proctor 1971 two appendices describe 1 the basic operation of the lma and the detailed manner in which its measurements are processed and 2 the effect of systematic errors on lightning observations the latter provides an alternative explanation for the systematic height errors found by boccippio et al 2001 in distant storm data from the lightning detection and ranging system at kennedy space center

dynamics of tethyan carbonate platforms tethyan carbonate platforms are relatively short lived depositional systems which were born developed died and sometime resurrected in a tectonically active area in contrast with pericratonic platforms which are generally huge in size hundreds of kilometers across and show wide facies belts very gentle slopes ramps and transitional boundaries tethyan carbonate platforms are smaller tens of kilometers and have steep slopes generally faulted boundaries and abrupt facies changes it appears clear that the overall control on these two contrasting systems is the geodynamic milieu relatively stable in the first case where eustatic oscillations and long term subsidence are probably the main dictators quite dynamic and aggressive in the second one where carbonate platforms developed through the entire geodynamic spectrum rifting transtension transpression and collision of the wilson cycle primary controls on tethyan carbonate platforms appear to be tectonics most important and eustatic sea level oscillations which determine their emplacement growth and decay their overall shape and architecture are a function of these factors secondary factors affecting tethyan carbonate platform evolution are physiography oceanographic conditions and biology as a function of geologic time especially across the mesozoic tertiary boundary facies and facies distribution and to a lesser extent their shape are controlled by thesemore variables less

rhodolith assemblages from the lower tortonian carbonate ramp of menorca spain environmental and paleoclimatic implications abstract lower tortonian distally steepened carbonate ramp of menorca mostly consists of foramol and rhodalgal facies deposited in inner middle ramp ramp slope and outer ramp settings red algae are abundant from the middle ramp to the lower part of the slope and their taxonomic assemblages are clearly related to the bathymetric position melobesioids percentage increases basinward passing from 55 8 in the middle ramp to 97 in the toe of slope mastophoroids are more abundant in the middle ramp 43 1 and decrease toward deeper paleoenvironments 1 2 lithophylloids and sporolithaceans appear as accessory components from the middle ramp to slope settings the percentage of melobesioids and mastophoroids observed in the middle ramp suggest that growth of the rhodoliths started in a water depth below 10 20 m the deepest occurrence of the rhodoliths is in the ramp slope environment where the dominance of melobesioids and the low percentage of shallower water subfamily suggests a water depth range of 70 to 100 m shape and structure of rhodoliths are indicative of high energy conditions in all ramp settings and they do not reflect a decrease in hydrodynamic energy related to water depth increase these conditions are related to the presence of unidirectional currents that produced cross bedded grainstones existing in the middle ramp ramp slope and at the toe of the ramp slope settings the high percentage of mastophoroids in the shallowest environments and the presence of lithoporella and sporolithon in the coralline assemblages suggests that carbonate production took place in tropical waters

effects of charge and electrostatic potential on lightning propagation 1 three dimensional lightning mapping observations are compared to cloud charge structures and electric potential profiles inferred from balloon soundings of electric field in new mexico mountain thunderstorms for six individual intracloud and cloud to ground flashes and for a sequence of 36 flashes in one storm the comparisons consistently show good agreement between the altitudes of horizontal lightning channels and the altitudes of electric potential extrema or wells lightning flashes appear to deposit charge of opposite polarity in relatively localized volumes within the preexisting lower positive midlevel negative and upper positive charge regions associated with the potential wells the net effect of recurring lightning charge deposition at the approximate levels of potential extrema is to increase the complexity in the observed storm charge structure the midlevel breakdown of both normal intracloud flashes and negative cloud to ground flashes is observed to be segregated by flash type into the upper and lower parts of the deep potential well associated with the midlevel negative charge the segregation is consistent with perturbations observed in the bottom of the negative potential well due to embedded positive charge that was probably deposited by earlier flashes it is also consistent with an expected tendency for vertical breakdown to begin branching horizontally before reaching the local potential minimum the joint observations reconcile the apparent dichotomy between the complex charge structures often inferred from balloon soundings through storms and the simpler structures often inferred from lightning measurements

evolution of the total lightning structure in a leading line trailing stratiform mesoscale convective system over houston texas 1 line normal vertical cross sections of houston lightning detection and ranging ldar vhf radiation sources and radar reflectivity provide new insights into the three dimensional total lightning structure and evolution of a leading line trailing stratiform llts mesoscale convective system mcs over houston texas on 31 october 2005 previous research examining only the mature stage of an mcs showed that the overwhelming majority of vhf lightning sources occurred in the convective region with a lightning pathway extending rearward and descending in altitude into the stratiform region this descending pathway was most likely associated with small charged ice particles advected from the convective line unlike previous research the lightning pathway observed during the evolution of the mcs on 31 october 2005 initially extended rearward 40 km at a nearly constant height of 9 10 km in less than an hour the lightning pathway evolved into a sloped pathway similar to that found by previous research with a horizontal extent between 50 to 60 km and downward descent of 4 to 5 km during the lightning pathway evolution radar analysis showed an increase of reflectivity in the midlevels of the stratiform region consistent with increased depositional and aggregational growth above the melting layer broadening increased range of values of radar reflectivity above the melting layer was most likely an indication of a strengthening mesoscale updraft in the stratiform region this strengthening updraft may have contributed to an increase in the growth of the small charge carrying ice crystals giving them a greater fall speed in addition the mesoscale updraft may have promoted an environment conducive to local stratiform region charge generation in the mixed phase region just above the melting layer

a gps based three dimensional lightning mapping system initial observations in central new mexico a gps based system has been developed that accurately locates the sources of vhf radiation from lightning discharges in three spatial dimensions and time the observations are found to reflect the basic charge structure of electrified storms observations have also been obtained of a distinct type of energetic discharge referred to as positive bipolar breakdown recently identified as the source of trans ionospheric pulse pairs tipps observed by satellites from space the bipolar breakdown has been confirmed to occur between the main negative and upper positive charge regions of a storm and found to be the initial event of otherwise normal intracloud discharges the latter is contrary to previous findings that the breakdown appeared to be temporally isolated from other lightning in a storm peak vhf radiation from the energetic discharges is observed to be typically 30 db stronger than that from other lightning processes and to correspond to source power in excess of 100 kw over a 6 mhz bandwidth centered at 63 mhz

nearshore temperate carbonate depositional systems lower tortonian agua amarga basin southern spain implications for carbonate sequence stratigraphy abstract the bryozoan rich lower tortonian carbonates of the agua amarga basin in southern spain province of almeria provide an example of sediments formed in a nearshore non tropical depositional setting based on data derived from logging of sections and from field mapping these lower tortonian carbonates form a depositional sequence which is subdivided into several depositional systems a lowstand systems tract which consists of volcaniclastic fan deltas and washover deposits formed on the leeward side of a basement shoal which delimited the basin towards the south a transgressive systems tract which is characterised by a landward encroachment of deposits is represented by submarine bars and dune deposits a highstand systems tract consists of progradational beach deposits owing to strong reworking and re distribution of the particles by currents and waves microfacies differentiation of the deposits in poor these tortonian non tropical carbonates display a style of deposition similar to siliciclastics suggesting that sequence stratigraphic concepts derived from tropical carbonates do not apply to non tropical carbonates

paleobiogeography of scleractinian reef corals changing patterns during the oligocene miocene climatic transition in the mediterranean abstract during the oligocene miocene greenhouse to icehouse climatic transition the biogeography of reef corals or zooxanthellate like scleractinian corals was gradually changing from a pan tropical tethyan province in the eocene to three reef coral provinces of the western atlantic caribbean indo pacific and mediterranean our reefcoral database encompasses updated and homogenized data on paleoenvironmental and systematics of scleractinian corals occurring in the oligocene and miocene outcrops from circum mediterranean regions provided by most of relatively recently published data in the literature and by the study of published and unpublished collections of coral specimens from the same area including the important collections housed at the mnhn paris and our own collections as there is no validated direct criterion for the identification of the coral zooxanthellate symbiosis in the fossil record and considering the difficulty to use the biogeochemical approaches in the context of this study the subjectivity of the morphological criteria and the relative recent age of the fossil corals we are dealing with a uniformitarian approach has been used for inferring the symbiotic status of scleractinian genera in reefcoral among the 158 genera included in our database 93 can be considered as zooxanthellate and 10 have a doubtful zooxanthellate status this relatively exhaustive database was used to reconstruct the temporal and spatial distribution of scleractinian corals in the mediterranean during the oligocene miocene time in order to discuss the interplaying effects of the global cooling at that time the re organization of the tethyan realm resulting from the african arabian and eurasian plate collision and the emergence of the alpine chains driving the gradual northward movement of the whole region outside the tropical subtropical belt it is shown that the structure of the mediterranean z coral oligocene miocene paleobiodiversity was characterized by many geographically restricted genera with a moderate to short stratigraphical range and a few long ranging widespread genera a major consequence of this structure is that the extinction pattern has proceeded through the preferential extinction of rare occurrence genera through time the potential rapid long distance dispersal of most coral larvae compared to the size of the oligocene miocene mediterranean explains why no biogeographical subprovinces can be distinguished for the z coral fauna on a local scale ecological processes tend to sort coral taxa by limiting z coral development to geographically restricted and discontinuous areas this accounts for the large amount of geographically restricted taxa forming the mediterranean coral fauna the interaction of plate tectonics alpine orogenesis and climate at local to subregional scales exerts strong controls over the spatio temporal distribution of z coral assemblages within the circum mediterranean realm in particular we suggest that the richness and composition of the eastern atlantic coral fauna are indirectly related to the opening and closure of the eastern seaway connection with the indian ocean which controlled the e w circulation of surface waters and hence the westwards dispersal of pelagic larvae at the scale of the whole region the gradual regional climatic change produced by the northwards migration of the entire area superimposed on the global cooling appears in large part responsible for the extinction pattern of z corals through time in the mediterranean biogeographical province

electrical evolution during the decay stage of new mexico thunderstorms 1 the electric field e at the ground beneath a thunderstorm often exhibits an end of storm oscillation eoso during the storm s decay phase in which e typically undergoes three polarity changes over a period of 30 75 min to determine why the surface e oscillates the timing of the eoso polarity changes of a multicellular storm in new mexico has been compared to a series of balloon radar and lightning data three in situ balloon soundings provide vertical profiles of e and inferred charge regions just before and during the eoso these data have been compared to the evolving precipitation structure determined from orthogonal range height scans of two radars and to several other parameters including lightning mapping array data before the eoso began the storm had the typical electrical structure of the late mature stage estimates of the total charge magnitudes in each of the principal regions before and during the eoso ranged from 7 to 33 c the comparisons indicate that surface e polarity changes during the eoso were 1 primarily owing to the successive fallout of three of the four principal charge regions in the storm s mature stage charge structure modified by 2 the growth or decay of the charge regions as they descended and 3 changes in the screening charges at the upper and lower cloud boundaries more limited data from two other decaying storms indicate that similar in cloud evolution was probably occurring during their eosos

late miocene breccia of menorca balearic islands a basis for the interpretation of a neogene ramp deposit abstract neogene tortonian ramp facies associations crop out in the southern sector of menorca balearic island these are made mainly by sigmoidal and oblique clinoform units comprising rhodoliths bryozoans molluscs and foraminifera these units are interpreted as outer ramp deposits a breccia deposit infilling an erosional surface is found at the top of the carbonate ramp sequence the breccia components mainly rhodoliths and oolite clasts may represent erosion of the underlying ramp deposits and inner ramp counterparts which do not crop out on the island the study of components in the breccia deposits confirms the indigenous character of the outer ramp facies associations which suggests that the ramp was steepened distally the breccia deposits correspond laterally to a discontinuity surface locally showing karstic features transgressive sediments including a phosphatic crust are found above the discontinuity surface all together these features and the dolomitisation of the uppermost ramp sediments and breccia deposits suggest that the breccia originated from erosion of the ramp after a major relative sea level fall the breccia and discontinuity surface separate the ramp sequence from an overlying prograding sequence a correlation of this sequence boundary to other areas in the western mediterranean is proposed

inversion of the hz ratio of microseisms for s wave velocity in the crust summary s wave velocity in the shallow crust is an important controlling parameter for ground motion amplification it is a key parameter for prediction of ground motion and thus for earthquake hazard mitigation in general shallow s wave velocity structure has often been obtained from phase velocity of microtremors and microseisms we present a new approach which directly inverts the ratio of horizontal to vertical amplitudes of microseisms which is referred to as the hz ratio in this paper our approach consists of i isolation of rayleigh wave dominant portions in seismograms by using the 90 degree phase shift between horizontal and vertical component ii measurement of the hz ratios as a function of frequency and iii iterative inversion for s wave velocity structure in the crust depth sensitivity kernels of the hz ratios for density p wave velocity and s wave velocity are derived by a numerical method examples of the application of this method to data in southern california show that the hz ratio data require modification of the standard seismic velocity model in this region southern california earthquake center community velocity model 3 0 or scec cvm in the upper 10 15 km the derived models show amplification of incident sh waves by factors of 2 8 relative to the prediction by the scec cvm the proposed approach has promise for applications to other regions in the world because microseisms are observed everywhere in the world the method may become even more powerful if it is combined with phase velocity data

sea level changes an integrated approach sea level changes an integrated approach in october 1985 sepm sponsored a four day conference entitled sea level changes an integrated approach the purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues the conference was successful in bringing together scientists from industry academia and government representing all of the major geosciences disciplines presentations of many new papers plus significant releases of data that were previously held proprietary provided fertile ground for discussion this much cited volume represents the best of the material presented at the conference includes the early vail chart

relationships between lightning location and polarimetric radar signatures in a small mesoscale convective system abstract on 19 june 2004 the thunderstorm electrification and lightning experiment observed electrical microphysical and kinematic properties of a small mesoscale convective system mcs the primary observing systems were the oklahoma lightning mapping array the koun s band polarimetric radar two mobile c band doppler radars and balloonborne electric field meters during its mature phase this mcs had a normal tripolar charge structure lightning involved a midlevel negative charge between an upper and a lower positive charge and flash rates fluctuated between 80 and 100 flashes per minute most lightning was initiated within one of two altitude ranges 3 6 or 7 10 km msl and within the 35 dbz contours of convective cells embedded within the convective line the properties of two such cells were investigated in detail with the first lasting approximately 40 min and producing only 12 flashes and the second lasting over an hour and producing 105 flashes in both lightning was initiated in or nea

the 2010 eruption of eyjafjallajokull lightning and plume charge structure six lightning mapping array lma stations were deployed in april 2010 around eyjafjallajokull volcano in southern iceland single station lma observations were made during the first explosive period 14 18 april and three dimensional lma observations were made during the second explosive period 5 22 may the single station observations revealed that continuous rf electrical activity caused by high rates of small vent discharges occurred during the first explosive period but not the second indicating that the strength of vent charging varied between the first and second explosive periods during the second explosive period very little lightning was detected between 5 and 10 may while moderate rates of lightning were detected between 11 and 21 may signaling that another change occurred on 11 may that affected plume electrification the data do not make clear if it was changing eruptive activity or changing meteorological activity that resulted in the sudden onset of lightning the plume charge structure during the second explosive period was inferred from the three dimensional lightning data showing that the dominant charge structure varied between a positive monopole and a negative over positive dipole the predominance of a low altitude region of positive charge and the observation that electrical activity was concentrated near the vent indicate that net positive vent charging was dominating the electrification

radar and lightning observations of normal and inverted polarity multicellular storms from steps abstract this study discusses radar and lightning observations of two multicellular storms observed during the severe thunderstorm electrification and precipitation study the lightning mapping array data indicated that the charge structure of the 19 june 2000 storm was consistent with a normal polarity tripole while the 22 june 2000 storm exhibited an overall inverted tripolar charge structure the 19 june storm consisted of weaker convection and produced little to no hail and moderate total flash rates peaking between 80 and 120 min 1 the cells in the 22 june 2000 storm were much more vigorous exhibited strong broad updrafts and produced large quantities of hail as well as extraordinary total flash rates as high as 500 min 1 the national lightning detection network nldn indicated that the 19 june storm produced mostly negative cloud to ground cg lightning while the 22 june storm produced predominantly positive cg lightning peaking at 10 min 1 just after two cells merged however the los al

evolution of a lower paleozoic continental margin carbonate platform northern canadian appalachians the western margin of the northern appalachian orogene and adjacent craton is composed of a lower paleozoic low latitude carbonate platform which originally lay along the northern margin of iapetus ocean parts of the platform interior are now exposed in quebec much lies beneath the gulf of st lawrence and the outer shelf and deep water deposits crop out in western newfoundland the shelf break and upper slope are nowhere exposed but their nature has been determined from numerous clasts in sediment gravity flows redeposited on the lower slope and now stacked in allochthonous thrust complexes four separate phases recording platform growth and demise can be differentiated reflecting the interplay between tectonics eustasy and the evolving lower paleozoic biota phase 1 preplatform shelf reflects initial siliciclastic deposition on rifted crystalline basement followed by a short phase of carbonate sedimentation dominated by archeocyathan buildups and ooid shoals that was terminated by offlap of thick quartzarenites phase 2 narrow high energy platform is characterized by mixed siliciclastic carbonate peritidal sedimentation throughout manifest as three grand cycles contemporaneous deep water sediments comprise basal welded conglomerates overlain by quartzose carbonate turbidites phase 3 wide low energy platform is an onlap package of muddy fossiliferous subtidal and peritidal carbonates arranged inmore the form of two unconformity bounded megacycles the adjacent deep water slope was a narrow belt of debris flows and wide carbonate shale apron deposited in the lower part of an oxygen minimum zone phase 4 foundered platform documents the initial uplift faulting subsidence and fragmentation of the platform in a sequence of peritidal to subtidal to deep water carbonates reflecting the initial stages of the taconic orogeny less

sub wavebase cross bedded grainstones on a distally steepened carbonate ramp upper miocene menorca spain cross bedded grainstones on carbonate ramps and shelves are commonly related to the locus of major wave energy absorption such as shorelines shoals or shelf breaks in contrast on the early tortonian carbonate platform of menorca balearic islands coarse grained cross bedded grainstones are found at a distance from the palaeoshoreline where they were deposited below the wavebase excellent exposures along continuous outcrops on the sea cliffs of menorca reveal the depositional profile and three dimensional distribution of the different facies belts of the tortonian ramp depositional system basinward from the palaeoshoreline fan deltas and beach deposits pass into 5 km wide gently dipping bioturbated dolopackstone inner and middle ramp then into 12 20 dipping dolograinstone rudstone clinobeds ramp slope and finally into subhorizontal fine grained basinal dolowackestone to dolopackstone outer ramp in this miocene example coarse grained grainstones exist in five different settings other than beach deposits 1 on the middle ramp where cross bedded grainstones were deposited by currents roughly parallel to the shoreline at 40 70 m estimated water depth and are interbedded with gently dipping bioturbated dolomitized packstones 2 on the upper slope where clinobeds are composed mostly of in situ rhodoliths and red algae fragments 3 on the lower slope as small scale bedforms small three dimensional subaqueous dunes migrating parallel to the slope 4 at the transition between the lower slope and the outer ramp where mollusc rich and rhodolithic rudstones and grainstones interbedded in dolomitized laminated wackestones containing abundant planktonic foraminifera infill slide slump scars as upslope backstepping bodies backsets 5 at the toe of the slope where coarse skeletal grainstones indicate bedform migration parallel to the platform margin induced by currents at more than 150 m estimated water depth this late miocene example also illustrates how changes in intrabasinal environmental conditions nutrients and or temperature may produce changes in stratal patterns and facies architecture if they affect the biological system two depositional sequences compose the miocene platform on menorca where a reef rimmed platform prograded onto an earlier distally steepened ramp the transition from the ramp to the reef rimmed platform was effected by an increase in accommodation space caused by ecological changes promoting a shift from a grain to a framework producing biota

estimating mediterranean oligocene miocene sea surface temperatures an approach based on coral taxonomic richness abstract during the oligocene and miocene shallow water carbonates of the mediterranean region were rich in scleractinian corals thriving within various depositional settings including different reef types their diversity patterns although related to a complex interplay between a suite of environmental factors and palaeobiogeography are considered to be strongly controlled by climate variability and changes in sea surface water temperature by using the quantitative relationship between present day coral taxonomic richness and prevailing sea water temperature underlined by the so called energy hypothesis we test zooxanthellate coral generic richness values from a selection of 102 oligocene miocene localities of the mediterranean region as a proxy for relative palaeotemperatures for each oligocene miocene stage generic richness values per z coral site are firstly examined together with variations of the mediterranean z coral generic pool for better testing the method and assessing its potential application patterns of generic richness and inferred palaeotemperatures are then compared with global palaeoclimatic curves based on marine oxygen stable isotopes data or other climate proxies such as palaeoclimatic records from european continental floras and from fossil coral linear extension rate results clearly show that fluctuations of coral richness derived palaeotemperatures correspond relatively well with global changes of sea water temperature especially for the entire oligocene the chattian aquitanian boundary and the late miocene the well known mid miocene climatic optimum however is not recorded suggesting that regional factors acting together with important palaeogeographical changes exerted a strong control on the generic richness of mediterranean z coral communities a remarkable decline of taxonomic richness is recorded after the burdigalian together with a gradual decrease of palaeotemperatures in the region from the middle miocene onwards to the messinian however an increase in the temperature range of z coral localities is clearly visible indicating that z coral communities were able to thrive and adapt to a wider temperature range as the mediterranean was gradually migrating northwards outside the tropical belt the energy hypothesis if used at global or regional scale can be considered a promising and reliable method for estimating cenozoic palaeotemperatures from coral or other suitable fossil assemblages of shallow water carbonates

reef geometries erosion surfaces and high frequency sea level changes upper miocene reef complex mallorca spain the upper miocene reef complex of mallorca is a 20 km prograding unit which crops out in sea cliffs along the southern side of the island these vertical and exceptionally clean outcrops permit i identification of different facies lagoon reef front reef slope and open platform and their geometries and boundaries at different scales ranging from metre to kilometre and ii construction of a 6 km long high resolution cross section in the direction of reef progradation this cross section shows vertical shifts of the reefal facies and erosion surfaces linked to a general progradational pattern that defines the accretional units four hierarchical orders of magnitude 1 m to 4 m of accretional units are identified by consideration of the vertical facies shifts and by which erosion surfaces are truncated by other erosion surfaces all these orders show similar patterns horizontal beds of lagoonal facies in the upper part landward reefal and slope facies with sigmoidal bedding in the central part and open platform facies with subhorizontal bedding in the lower part basinwards the boundaries are erosion surfaces horizontal over the lagoon facies dipping basinwards over the reef front facies and connecting basinwards with their correlative conformities over the reef slope and open platform facies the four orders of accretional units are interpreted in terms of four 1 m to 4 m hierarchies of sea level cycles because i there is a close relation between the coral growth and the sea surface ii there are vertical shifts in the reefal facies and their relation to the erosion surfaces and iii there was very little tectonic subsidence in the study area during the late miocene additionally all these units can be described in terms of their position relative to the sea level cycle i the reefs prograde on the open platform sediments during low stands of sea level ii aggradation of the lagoon reef and open platform facies dominates during sea level rises and the lagoonal beds onlap landwards upon the previous erosion surface iii reefal progradation occurs during high stands of sea level and iv the 2 m sea level fall produces an off lapping reef and there is progradation with downward shifts of the reefal facies and erosion landward on the emerged older reefal units a erosion surfaces the 3 m and 4 m sea level falls produce only erosion b and c erosion surfaces although precise age data do not exist at present some speculations upon the frequency of these miocene relative sea level cycles can be made by comparisons with pleistocene cyclicity there is a good correlation between the miocene 2 m cycles and the 100 ka pleistocene cycles consequently the 1 m cycles can be assigned to a fourth order in relation to previously proposed global cycles and the 2 m to fifth order cycles all these accretional units could be defined as sequences according to the definition as commonly used in sequence stratigraphy however they represent higher than third order sea level cycles but are not parasequences the term subsequence therefore is suggested to define a part of a sequence bounded by erosion surfaces mostly subaerial and their correlative conformities basinwards a hierarchy of subsequences can be established

depositional sequences and correlation of middle to late miocene carbonate complexes las negras and nijar areas southeastern spain during serravallian through messinian time marine carbonates flanked topographic highs that rimmed neogene basins in the western mediterranean middle to upper miocene carbonate strata in the las negras and nijar areas southeastern spain are 50 150 m thick and display 50 200 m of shelf to basin relief over 1 2 km detailed studies in those areas document the effects of relative sea level change on sedimentation biotic composition and reef development we identify three previously unrecognized regionally correlatable depositional sequences ds1 ds2 ds3 that occur between the underlying basement and the overlying terminal carbonate complex the lower depositional sequences ds1 ds2 are mostly normal marine shelf ramp carbonates deposited on the flanks of basement highs the basal part of ds2 locally contains some megabreccia reef blocks composed of tarbellastraea and porites these blocks are the first evidence of reef growth in the area and represent a previously unrecognized period of reef development prior to the fringing reef development the reef blocks probably formed as upslope patch reefs that were eroded and transported to distal slope locations the upper sequence ds3 is characterized by clinoform strata of a porites dominated fringing reef complex that prograded basinward in a downstepping style with successively younger reefs forming in a topographically lower and more basinward position as a result of a net sea level drop regional correlation of miocene shallow marine strata between basins in spain and elsewhere in the western mediterranean is complicated because basins were semi isolated from adjacent basins making physical correlation impossible in addition age definitive biostratigraphic markers are poorly preserved in most of the miocene shallow water strata basinal sediments that are more easily dated by microfossils do not typically interfinger with the shallow marine strata in outcrop even where datable microfossils are found resolution of dating is poor our studies in the las negras and nijar areas illustrate the usefulness of integrating sedimentological geometric and biotic data with locally derived relative sea level accommodation space curves for correlation the relative sea level curves for each area show remarkable similarities in shape and magnitude of sea level changes these curves indicate several relative sea level fluctuations during miocene carbonate deposition prior to the major sea level drop at the end of ds3 deposition that culminated in the exposure of the basin margin deposits and the deposition of evaporites in basinal areas during the messinian the depositional sequences in the las negras and nijar areas may correlate with depositional sequences of similar age throughout the southern cabo de gata area in mallorca some 600 km to the northeast and possibly in other mediterranean locations the widespread occurrence and possible correlation of the depositional sequences suggest regional processes such as eustacy or tectonism for their formation the integration of sedimentological palaeontological and sequence stratigraphic studies and the construction of relative sea level accommodation space curves may help in the interpretation of depositional histories of shallow marine carbonate complexes and correlation of these strata between isolated areas other dating methods in addition to microfossil dating may allow for better age determination of the sequences and aid in identifying the importance of eustacy and tectonism in sequence development

coordinated lightning balloon borne electric field and radar observations of triggered lightning flashes in north florida this study examines coordinated storm and triggered lightning observations made in july august 2013 at the international center for lightning research and testing to determine why triggered flashes in florida typically transition from an upward vertical channel entering the cloud to horizontal structure near the storm s melting level data from a balloon borne electric field meter a mobile 5 cm wavelength radar and a small baseline vhf lightning mapping array acquired during a period in which three flashes were triggered on 1 august confirmed the hypothesis that the transition to horizontal lightning structure just above the melting level occurred in a layer of negative charge this experiment was the first to provide vertical profiles of the electric field in florida storms from which their vertical charge distribution could be inferred three dissipating storms observed on different days all had negative charge near the melting level but a growing mature storm had positive charge there

vhf lightning mapping observations of a triggered lightning flash 1 on 3 august 2010 an extensive lightning flash was triggered over langmuir laboratory in new mexico the upward positive leader propagated into the storm s midlevel negative charge region extending over a horizontal area of 13 13 km and 7 5 km altitude the storm had a normal polarity tripolar charge structure with upper positive charge over midlevel negative charge lightning mapping array lma observations were used to estimate positive leader velocities along various branches which were in the range of 1 3 104 m s 1 slower than in other studies the upward positive leader initiated at 3 4 km altitude but was mapped only above 4 0 km altitude after the onset of retrograde negative breakdown indicating a change in leader propagation and vhf emissions the observations suggest that both positive and negative breakdown produce vhf emissions that can be located by time of arrival systems and that not all vhf emissions occurring along positive leader channels are associated with retrograde negative breakdown

formation of charge structures in a supercell abstract lightning mapping electric field and radar data from the 26 may 2004 supercell in central oklahoma are used to examine the storm s charge structure an initial arc shaped maximum in lightning activity on the right flank of the storm s bounded weak echo region was composed of an elevated normal polarity tripole in the region of precipitation lofted above the storm s weak echo region later in the storm two charge structures were associated with precipitation that reached the ground to the left of the weak echo region six charge regions were inferred with positive charge carried on hail at the bottom of the stack farther forward in the storm s precipitation region four charge regions were inferred with negative charge at the bottom of the stack there were different charge structures in adjacent regions of the storm at the same time and regions of opposite polarity charge were horizontally adjacent at the same altitude flashes occasionally lowered positive charge to ground from the forwa

carbonate mineral cycles generated by foraminiferal and pteropod response to pleistocene climate west florida ramp slope carbonate ramps are gently sloping depositional surfaces where shallow water coarse grained facies pass basinward into fine grained deep water sediments with no abrupt change in slope the objectives of this study are i to integrate the depositional processes recorded in the pleistocene stratigraphy of the west florida outer ramp into a palaeoclimatic and palaeoceanographic framework for the eastern gulf of mexico and ii to examine the origin of mineralogical and sedimentary cycles in the light of pteropod and planktonic foraminiferal populations corresponding to climatic oscillations aragonitic pteropod rich sediments with large amounts of insoluble residue occur in sediments deposited during glacial intervals sandy calcitic sediments with abundant planktonic foraminifera accumulate during interglacials these cycles reflect variations in biological productivity of pelagic pteropods and planktonic foraminifera rather than preferential dissolution of either aragonitic or calcitic fractions species assemblages suggest that the productivity cycles are linked to changes in upwelling intensity at the margins of the loop current and variations in water mass salinities as well as terrigenous dilution from the mississippi delta these cycles are the response to pleistocene glacial interglacial oscillations controlled by milankovitch orbital parameters although the organisms contributing to deep water carbonate environments have changed through geological time facies patterns as well as sedimentary textures and structures identified in the west florida sediments provide criteria for recognition of ancient ramps an understanding of the processes on a modern ramp slope such as west florida may prove valuable in palaeoclimatic and palaeoenvironmental analysis of epicontinental carbonate sequences and ramps in the rock record

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

carbonate platform facies models various types of carbonate platforms are characterized by distinctive profiles facies and evolutionary sequences ramps may be homoclinal or distally steepened and may have fringing or barrier shoal water complexes of ooid pellet sands or skeletal banks homoclinal ramps pass seaward into deeper water without major break in slope and lack deep water breccias distally steepened ramps may be low energy and characterized by widespread shallow subwave base mud blankets or high energy with coastal beach dune complexes and widespread skeletal sand blankets slope facies may contain abundant breccias of slope derived clasts rimmed shelves have relatively flat tops and marked break in slopes at the high energy shallow shelf edge where they pass into deep water such shelves may be aggraded with peritidal facies extending over much of the shelf or incipiently drowned depending on magnitude of sea level fluctuations they may be accretionary or bypass types that include gullied slope escarpment and high relief erosional forms intrashelf basins occur on some shelves controlling distribution of reservoir and source beds isolated platforms are surrounded by deeper water and may be located on rifted continental margins or on submarine volcanoes most have high relief rimmed margins platforms that have been subjected to rapid sea level rise may be incipiently drowned and characterized by raised rims elevated patch or pinnacle reefs and widespread subwave base carbonate or fine clastic blankets completely drowned shelves develop where the shelf is submerged to subphotic depths terminating shallow water deposition and commonly resulting in blanketing of the shelf by deeper water facies some margins show extensive down to basin faulting that is contemporaneous with carbonate deposition or associated with thick prograding clastic sequences the various types of platforms change in response to variations in sedimentation subsidence or sea level rise and may form distinctive evolutionary sequences the relatively few models presented appear to accommodate most geological examples some of which contain major reservoir facies

the south pyrenean eocene carbonate megabreccias revisited new interpretation based on evidence from the pamplona basin abstract the south pyrenean foreland basin contains numerous units of eocene carbonate megabreccias intercalated with siliciclastic turbidites and derived by resedimentation of shallow marine carbonate platforms previous studies were limited mainly to the foreland eastern part known as the jaca basin the present study from the pamplona basin a western part of the foreland trough sheds new light on the origin and regional significance of these south pyrenean eocene carbonate megabreccias specms the number of the specm units in the foreland basin is higher than previously recognized and their age is somewhat older than originally assumed the specm units appear to occur as time stratigraphic clusters which can be correlated with the relative sea level lowstands and linked with phases of tectonic activity the megabreccias were derived from a carbonate platform system hosted by the foreland basin s southern passive margin the episodic instability and mass wasting were triggered by phases of structural steepening forebulge uplift accompanied by high magnitude earthquakes with the former causing platform emergence increased load stresses and excess pore water pressure in the carbonate ramp the specm deposits were emplaced by cohesive debris flows evolving into high density turbidite currents an ideal specm unit consists of 1 an immature homogeneous debrite in the proximal part 2 a differentiated bipartite debrite and turbidite in the medial part and 3 an incomplete base missing debrite overlain by turbidite or a turbidite alone in the distal part the debrite component volumetrically predominates in the specm units and the original terms megaturbidite and seismoturbidite thus seem to be inappropriate for these deposits

ecological control of sedimentary accommodation evolution from a carbonate ramp to rimmed shelf upper miocene balearic islands abstract stratal patterns and facies architecture develop in response to sediment flux and the available space for sediment accumulation accommodation in siliciclastic systems these two parameters are independent in carbonates however they are highly interdependent 1 sediment input production highly depends on biological systems and consequently on intrabasinal conditions nutrients temperature salinity etc 2 sediment dispersal depends on the production loci and on the interaction between the amount and type of sediment being produced and the hydraulic energy additionally biological processes binding baffling framework construction and even cementation frequently modify it 3 accommodation is not an independent factor with respect to sediment input type efficiency and area of the carbonate factory depend on sea level changes and sea floor morphology the base level for sediment to accumulate accommodation depends on the type and locus of sediment being produced the upper miocene carbonate platforms of the balearic islands illustrate how changes in intrabasinal environmental conditions nutrients and or temperature produce changes in stratal patterns and facies architecture if they affect the biological system during early tortonian carbonate production occurred both in the shallow euphotic zone foramol and in the deeper oligophotic zone rhodalgal originating a distally steepened ramp during late tortonian and early messinian carbonate production mainly occurred in the euphotic zone where framework producing biota coral reefs formed a rimmed platform although deposited under similar conditions of high frequency sea level fluctuations these two types of platforms exhibit different internal facies architecture and distribution of heterogeneities because of differences in base level in carbonates base level for sediment accumulation depends on the type and amount of sediment being produced on the production loci and on the processes controlling sediment dispersal base level for the loose foramol rhodalgal sediment associations of the ramp was controlled by wave and storm base and the associated currents whereas base level for the framework dominated reef complex was sea level furthermore the increase on effective accommodation space to allow the reef rimmed shelf to prograde onto the distally steepened ramp both platforms being depositional sequences resulted from an ecological change rather than significant relative sea level change namely by the shift from grain to framework producing biota the euphotic framework producing biota was able to fill the accommodation space existing between wave and storm base level and sea level that was not previously filled by the loose bioclasts

ancient upwelling record in a phosphate hardground tortonian of menorca balearic islands spain abstract the tortonian sedimentary succession of menorca island balears spain includes two stratigraphic sequences the lower tortonian distally steepened carbonate ramp and the coral reef complex of late tortonian early messinian age the boundary between the two sequences corresponds to heterostegina rich sediments in the western part of menorca and to a phosphatic hardground in the eastern part of the island in the field the hardground is represented by a dark brown layer and a rough surface on top of the tortonian ramp deposits dark phosphate precipitates infill cracks and borings in the underlying limestone to a depth of up to 50 cm the phosphatic hardground is overlain by planktonic rich wackestone to packstone which penetrates downward into the fissures borings and vugs this deposit is characterized also by grains of reworked phosphate glauconite grains small benthic foraminifers and is followed by tabular beds of bioclastic packstone to wackestone with abundant thin crusts of coralline algae based on the amphistegina tests shapes and red algal assemblage of sediments below and above the hardground and the lateral correlation with heterostegina deposits the bathymetry for the development of the phosphatization is estimated less than 100 m the limited localization of the phosphatic hardground at the eastern side of the ramp indicates that a dynamic upwelling of deeper and nutrient enriched waters favored development of a phosphatic hardground this upwelling episode is representative of the paleoceanographic settings induced by the climate conditions of the mediterranean area during the tortonian

electric fields and charges near 0 c in stratiform clouds abstract earlier studies of mesoscale convective system stratiform regions have shown that large electric fields and charge densities are found near the 0 c level here 12 soundings of the electric field were analyzed through the 0 c level in various types of electrified stratiform clouds for each electric field sounding the thermodynamic sounding and supporting radar data were also studied for comparison five soundings not from stratiform clouds were included charge densities were found at or near 0 c in the stratiform clouds of at least 1 nc m 3 in eight of the soundings and four of those had charge densities of at least 2 nc m 3 of the stratiform soundings 11 had an electric field magnitude of greater than 50 kv m 1 near 0 c and 7 of those had an electric field magnitude of at least 75 kv m 1 the evidence suggests that melting may be the primary cause of the charge density found at and below 0 c in electrified stratiform clouds in all 12 of the stratiform soundings positive charge density w

environmental factors influencing skeletal grain sediment associations a critical review of miocene examples from the western mediterranean the presence of foramol rhodalgal and bryomol skeletal grain associations in ancient shallow marine limestones is commonly interpreted as evidence for non tropical palaeoclimate despite temperature being only one of several factors influencing skeletal grain associations such interpretations neglect the multitude of factors other than temperature that influence carbonate producing biota these include nutrients water energy water transparency depth of the sea floor salinity oxygen ca2 and co2 concentrations mg ca ratio alkalinity substrate requirements competitive displacement as well as biological and evolutionary trends this uniformitarian approach also disregards the probability that conditions of present day biological systems may not be representative of past conditions of analogous systems here the importance of considering these other factors is illustrated through two examples of carbonate platforms in the western mediterranean these platforms are dominated by foramol rhodalgal and bryomol associations of miocene age in spite of having formed in tropical conditions the platforms discussed are 1 the lower tortonian ramp on menorca balearic islands and 2 the lower middle miocene ramps of the central apennines italy evidence for tropical conditions in the mediterranean during the period of growth of these platforms is provided by species of red algae and larger foraminifera by data from coeval continental basins and by global oxygen isotope data

electrical structure in thunderstorm convective regions 2 isolated storms electric field e soundings through the convective regions of two types of isolated thunderstorms are examined analysis of seven soundings through strong updrafts of isolated supercell storms show that the basic e structure there has three e peaks a positive peak near 8 km height a negative peak near 10 5 km and a positive peak near 12 km strong updraft soundings are those with average balloon ascent rates in excess of 10 m s 1 the basic charge structure in strong updrafts of supercells has four charge regions of alternating polarity the lowermost charge is positive between about 4 and 8 km and the uppermost region is negative all the supercell updraft soundings are incomplete due to balloon burst or lightning induced instrument destruction below cloud top six supercell soundings that ascended outside strong updrafts are used to show that the e and charge structures there are more complex than within the strong updrafts analysis of 15 new or previously published soundings through small new mexican mountain thunderstorms indicates that the basic e structure in or near their convective cores consists of three e peaks a lower positive peak at about 5 km height a midlevel negative peak near 6 5 km and an upper positive peak near 9 5 km the basic charge structure near the center of new mexican storm convection has four charge regions alternating in polarity with a positive charge region lowest soundings in new mexican convection that did not ascend near the convective cores show more complex e profiles and charge structures

terrigenous dolomite in the miocene of menorca spain provenance and diagenesis abstract miocene calcarenites of menorca spain exhibit abundant terrigenous dolomite both as medium grained polycrystalline rock fragments and as fine grained individual abraded crystals petrographically this detritus looks both like neighboring jurassic dolostones and like triassic muschelkalk dolostones of the same general area in order to determine which stratigraphic unit s provided this terrigenous dolomite the iron contents of triassic and jurassic dolostones were analyzed with an electron microprobe and compared with that of the miocene terrigenous dolomite as was expected from their present greater surface exposure jurrassic dolostones proved to be the principal source the trace of probable triassic dolomite detritus in miocene samples analyzed is proportionate to the smal area of triassic exposure relative to that of the jurassic diagenetic dolomite in miocene host calcarenites occurs as l pervasive crystals of fine to medium crystalline dolomite and 2 overgrowths on the terrigenous dolomite crystals these two varieties commonly occur together but overgrowths occur in some samples in the absence of the pervasive variety which indicates that seeding by terrigenous dolomite promoted diagenetic dolomitization calcitization of miocene dolomite favored centers of the pervasive variety of dolomite crystals and the inner margins of dolomite overgrowths these patterns of dedolomite indicate that the two varieties of dolomite are behaviorly correlative which suggests that they are temporally correlative as well

short paper a standardized model for tethyan tertiary carbonate ramps low latitude carbonates in massive and clinoform bedded sheets termed ramps occur throughout the tertiary tethyan realm and are characterized by recurring biofacies usually including large foraminifera rhodolithic algae coralgal patch reef and gastropod dominated sequences all can be interpreted broadly within a standardized tertiary carbonate ramp model biota can be used to define precise palaeobathymetric zones which have a predictive utility in palaeoenvironmental modelling especially where data are limited the carbonate ramp model of earlier authors has been elaborated by read 1982 and ramp formation occurs mostly in passive margin and extensional tectonic settings ramps are characterized by slope gradients of less than 1 degree and once established are conservative to change much use has been made of the ramp model for palaeozoic and mesozoic lithofacies modelling in contrast published work on cenozoic ramps is limited however tethyan ramps are particularly widespread and extend tens to hundreds of kilometres along strike and occupy tens of kilometres of slope many studies have dealt with cenozoic ramp associations and sequences e g pedley 1983 reiss hottinger 1984 purser 1973 and have demonstrated the diversity of biotal and sediment detail but without ascribing them to a ramp model biota were quick to adapt to the tertiary environments left vacant after the k t boundary extinction events new genera of foraminifera mollusca bryozoa and echinoder mata rapidly replaced the extinct forms in bursts of innovative opportunism codiacean algae rhodophyta and marine angiosperms were equally adaptive colonizers of the carbonate platforms novel biofacies associations were derived from

genesis of limestone megabreccias and their significance in carbonate sequence stratigraphic models a review a re appraisal of the factors controlling the deposition of carbonate megabreccias and their sequence stratigraphic significance is presented based on an examination of the mechanisms for instigating carbonate seafloor slope instability and a review of the depositional settings of these distinctive rock deposits limestone megabreccias have classically been interpreted as formed by the catastrophic collapse of high angle metastable oversteepened carbonate platform margins however a review of megabreccia occurrence shows that these deposits formed on a broad range of carbonate slope angles and that metastable oversteepened slopes are not necessary for their genesis a re evaluation constructed from first principles of mechanisms promoting submarine gravitational instability indicates that pore water overpressure of confined aquifer horizons beneath the seafloor rather than slope oversteepening is the critical control on megabreccia deposition catastrophic release of overpressure may initiate gravitational instability of previously kinematically stable slopes the relative importance of endogenic processes intrinsically linked to the depositional system and exogenic processes operating independently in generating megabreccias is assessed two particularly important mechanisms in generating megabreccias are endogenic processes causing overpressure at discrete hydrologically confined horizons beneath the seafloor during relative sea level falls and increases in stress as pore fluid drains from the sediment when the platform top becomes subaerially exposed during relative lowstands of sea level the increased likelihood of megabreccia genesis during relative sea level falls is supported by an empirical trend identified from a review of the stratigraphic distribution of documented megabreccias exogenic causes of gravitational instability with inherently random periodicity especially seismicity may account for the small number of documented megabreccias that do not conform to this underlying trend the proposed endogenic pattern favouring megabreccia deposition during relative sea level falls is important in a sequence stratigraphic context megabreccia deposits may build volumetrically significant toe of slope wedges and aprons during relative lowstands of sea level partially compensating for the decrease loss in the supply of fresh granular sediment as the platform top carbonate factory contracts lowstand wedges and aprons in carbonate systems therefore generally differ in composition from equivalent highstand deposits in being composed not of calciturbidite deposits but of megabreccias cannibalized from the upper slope

rocket and wire triggered lightning in 2012 tropical storm debby in the absence of natural lightning 1 lightning mapping array source locations channel base currents and electric field waveforms are presented for a lightning flash triggered in the rainbands of 2012 tropical storm debby the national lightning detection network reported no natural cloud to ground discharges within 60 km of the north florida triggering site for at least 20 h before and 8 h after the triggered flash additionally local electric field mill and wideband antenna networks show no close cloud or cloud to ground flashes the triggering rocket was launched with negative charge overhead producing an electric field at the ground of 5 kv m 1 and in coordination with x band dual polarimetric radar observations of streamers of enhanced precipitation descending from the melting level as they approached the site the debby flash consisted of an initial stage is followed by eleven leader return stroke sequences the flash exhibited all the processes of normal triggered and natural cloud to ground lightning leader return stroke sequences continuing currents k events and m components additionally the flash exhibited several exceptional characteristics three return stroke peak currents greater than 25 ka one very long 352 ms continuing current that transferred about 35 c of charge to ground and a relatively short 202 ms is containing no initial continuous current pulses following a near vertical upward positive leader attaining 2 8 km height the is branched and propagated horizontally at 3 5 km altitude the flash exhibiting strokes and continuing current then ascended to and propagated horizontally at 5 5 km extending about 25 km south and 15 km east the 0 c level was near 4 5 km above sea level it follows from the above that clouds that are not producing natural lightning can represent a triggered lightning hazard to launch vehicles and aircraft

composition and temporal variability of particle fluxes in an insular canyon of the northwestern mediterranean sea abstract particle fluxes have been widely studied in canyons located in continental margins conversely particle fluxes in canyons in sediment starved margins incising small island margins have received very little attention and remain poorly understood the menorca canyon is the largest canyon system in the balearic archipelago despite the high oligotrophic conditions of the balearic archipelago the canyon and surrounding areas host diverse communities dominated by benthic suspension feeders understanding the magnitude and variability of environmental factors influencing these communities thus remain crucial in order to characterize the temporal variability of particle fluxes analyze its geochemical and macroscopic composition and identify the main processes that modulate particle fluxes in the menorca canyon one instrumented line with a sediment trap and a current meter was deployed at 430 m water depth from september 2010 to october 2012 particle fluxes ranged between 190 and 2300 mg m2 d 1 being one of the lowest ever registered in a mediterranean submarine canyon s head the caco3 fraction was the major constituent contrasting with the general trend observed in other mediterranean canyons macroscopic constituents fecal pellets posidonia oceanica detritus and pelagic and benthic foraminifera presented a wide variability throughout the sampling period and were not significantly correlated with the total mass flux the low magnitude of the registered fluxes and the lack of correlation with the observed environmental variables e g currents winds wave height chlorophyll a biomass suggest that there is no evident controlling mechanism however we could infer that resuspension processes and the presence of different hydrodynamic features e g eddies interchange of water masses condition the magnitude and composition of particle fluxes

lightning location relative to storm structure in a leading line trailing stratiform mesoscale convective system 1 horizontal and line normal vertical cross sections and composite images of dallas fort worth lightning detection and ranging ldar ii vhf radiation sources and radar reflectivity over a 30 min period provide a unique perspective on lightning pathways within a leading line trailing stratiform llts mesoscale convective system mcs on 16 june 2002 the overwhelming majority of vhf lightning sources occurred within the leading convective line in a bimodal pattern in the vertical assuming that vhf source density maxima were most likely associated with positive charge then the ldar ii observations suggest that the gross charge structure of the convective region of the mcs was characterized by a tripole with net positive charge centered at 4 5 km agl 3 c and 9 5 km agl 35 c and net negative charge centered roughly in the relative minimum of the vhf source density maximum at 7 km agl 17 c a persistent lightning pathway and inferred positive charge zone sloped rearward by 40 50 km and downward by 4 5 km from the upper vhf source maximum in the convective line through the transition zone and into the radar bright band of the stratiform region in the stratiform region vhf lightning sources and inferred positive charge were concentrated in three layers centered at 4 5 6 and 9 km agl 2 c 11 c and 31 c respectively consistent with past electric field studies of symmetric llts mcss positive cloud to ground lightning flashes in the stratiform region were initiated in the convective line and followed the slanting pathway from the top of convective cores to the stratiform precipitation where they were horizontally extensive layered and highly branched the sloping lightning pathway was identical to hypothetical trajectories taken by snow particles these observations provide further support for the advection of charge on snow along the sloping pathway and the in situ generation of charge in the horizontal lightning layers as primary contributors to electrification and positive lightning production rearward of the convective line

composite sedimentary record of falling stages of pleistocene glacio eustatic cycles in a shelf setting crotone basin south italy abstract a thick pleistocene shelf and nearshore cyclical succession was deposited in the s mauro sub basin of the crotone basin southern italy the regressive units of the cycles are mostly represented by coastal siliciclastic and bioclastic prograding wedges showing a clinoform geometry these are separated by blanket like deposits of high lateral persistence recording major transgressive episodes the aim of this paper is 1 to describe facies patterns and depositional setting of two prograding wedges particularly focussing on their polycyclic internal architecture 2 to analyze these units within a sequence stratigraphic framework and 3 to speculate on the possible origin of the small scale cyclicity the two wedges analyzed in this paper consist of a number of shingles individual shingles consist of two physically connected units 1 a relatively thin package of sigmoid clinoforms grading into 2 a volumetrically dominant package of oblique tangential clinoforms with toplap terminations the shingles are bounded by seaward dipping surfaces with sigmoid clinoform geometry which are ravinement surfaces updip passing into conformable flooding surfaces downdip the wedges are thus organized into high frequency small scale sequences each comprising transgressive highstand and falling stage systems tracts as a whole individual prograding wedges are interpreted as forced regressive units as the shoreline was subject to an overall shift basinwards and downwards along a low angle trajectory in spite of the repeated minor relative sea level rises tectonic subsidence and particularly the syndepositional growth of gentle synclines are thought to have been the key factors allowing the preservation of these forced regressive units progradation of the wedges took place in a high energy wave climate characterized by high frequency of storms and very efficient alongshore redistribution of sediments recurrent storm driven offshore currents led to intense reworking of sediments on the topset platform and gravity spreading on the foreset slope of the prograding wedges well oxygenated conditions over the shelf due to intensified storm activity during glacial periods may have enhanced the rate of production of skeletal foramol type carbonates it can reasonably be assumed that progradation took place from a line source and that the sand bodies are to be regarded as coastal prograding bodies in spite of active syndepositional tectonics the cycles can be correlated to pleistocene high amplitude sea level oscillations the older of the two wedges can be correlated through bio magnetostratigraphy to the major climatic transition which occurred from the marine oxygen isotope stage 25 to 24 22 rio et al 1996 the younger probably developed during the sea level fall that ended with substage 18 2 as suggested by sequence and bio stratigraphic data the prograding wedges are thus interpreted to record long lived sea level falls of fourth order cycles due to the particular depositional setting we are inclined to exclude authigenic mechanisms in the origin of small scale cyclicity although the concomitance and interaction of different controlling factors may be taken into account it is tempting to ascribe this cyclicity to minor eustatic changes punctuating long lived erratic falling stages possibly accompanied by climate driven fluctuations of sediment supply shelf perched and shelf edge prograding units consisting of foramol type carbonates are apparently a common falling stage to lowstand depositional feature in the mediterranean area during the late pliocene and pleistocene

triassic sea level change and the ladinian carnian stage boundary time stratigraphie correlations are difficult in many middle and upper triassic sedimentary sections either because the sections do not contain diagnostic fossils or because of ambiguities in biostratigraphic resolution recently it has been suggested that some triassic stage boundaries are associated with eustatic changes in sea level1 2 here evidence is presented to support that view three widely separated examples indicate that the local sea level falls were due to a worldwide change in sea level at any locality the response to the global fall in sea level was controlled by the interaction between initial water depth sedimentation rate and local subsidence rate in the examples presented here areas characterized by late ladinian shallow water sedimentation show either an erosional unconformity or a seaward shift of facies belts at the ladinian carnian boundary late ladinian slope or basinal settings exhibit shallowing upward trends an increase in sedimentation rates or subtle lithological changes across the boundary these types of lithostratigraphic relationships can be used to improve correlations in areas where middle and upper triassic sedimentary sections are difficult to date