preliminary results from the sprites94 aircraft campaign 2 blue jets initial observations of a newly documented type of optical emission above thunderstorms are reported blue jets or narrowly collimated beams of blue light that appear to propagate upwards from the tops of thunderstorms were recorded on b w and color video cameras for the first time during the sprites94 aircraft campaign june july 1994 the jets appear to propagate upward at speeds of about 100 km s and reach terminal altitudes of 40 50 km fifty six examples were recorded during a 22 minute interval during a storm over arkansas we examine some possible mechanisms but have no satisfactory theory of this phenomenon

transionospheric attenuation of 100 khz radio waves inferred from satellite and ground based observations 1 around fifty loran long range navigation transmitters in the northern hemisphere currently launch continuously pulsed 100 khz radio waves into the earth s atmosphere for marine navigation it is discovered that the 100 khz radio waves from the loran transmissions can be detected by the demeter satellite at an altitude of 660 km above the transmitters these novel electric field measurements in space enable the determination of the nocturnal transionospheric attenuation by comparison with ground based electric field measurements the electric field measurements on the satellite indicate that the nocturnal transionospheric attenuation of 100 khz radio waves from loran transmissions is equivalent to a nocturnal subionospheric attenuation of the 100 khz radio waves at a distance of 7 9 mm the radio waves exhibit an average subionospheric attenuation of 5 db mm and it is concluded that the nocturnal transionospheric attenuation of 100 khz radio waves is 35 45 db this result enables future space missions to quantify the intensity of lightning discharges associated with transient luminous events and terrestrial ray flashes

slope apron deposition in an ordovician arc related setting the vuelta de las tolas member suri formation famatina basin northwest argentina abstract the ordovician suri formation is part of the infill of the famatina basin of northwest argentina which formed in an active setting along the western margin of early paleozoic gondwana the lower part of this formation the vuelta de las tolas member records sedimentation on a slope apron formed in an intra arc basin situated on a flooded continental arc platform the coincidence of a thick arenig llanvirn sedimentary succession and volcanic plutonic arc rocks suggests an extensional or transtensional arc setting and is consistent with evidence of an extensional regime within the volcanic are in the northern puna region the studied stratigraphic sections consist of volcanic rocks and six sedimentary facies the facies can be clustered into four facies associations association 1 composed of facies a laminated siltstones and mudstones and b massive mudstones and siltstones is interpreted to have accumulated from silty muddy high and low density turbidity currents and highly fluid silty debris flows with subsequent reworking by bottom currents and to a lesser extent hemipelagic suspension in an open slope setting facies association 2 is dominated by facies c current rippled siltstones strata these deposits are interpreted to record overbank sedimentation from fine grained turbidity currents facies e matrix supported volcanic breccias interbedded with andesitic lava units comprises facies association 3 deposition was contemporaneous with subaqueous volcanic activity and accumulated from cohesive debris flows in a coarse grained wedge at the base of slope facies association 4 is typified by facies d vitric fine grained sandstones and siltstones and f channelized and graded volcanic conglomerates and breccias deposits these strata commonly display thinning and fining upward trends indicating sedimentation from highly concentrated volcaniclastic turbidity currents in a channelized system the general characteristics of these deposits of fresh pyroclastic detritus suggest that their accumulation was contemporaneous with or post dated shallow water or subaereal explosive volcanism the vuelta de las tolas member tends to show an overall random facies patterns reflecting the strong influence of non cyclical episodic processes related to arc volcanism and slope sedimentation the scarcity of resident ichnofaunas and the presence of thick packages of uniform mudstones suggest deposition under oxygen depleted conditions in a topographically confined ponded sub basin interbasinal correlations favor comparison with middle arenig slope apron successions formed in the northern puna basin and suggest a southward prolongation of the arenig volcanic arc

olenelloid trilobites from cambrian series 2 of devon island nunavut arctic canada four species of olenelloid trilobites characterized by advanced or robust genal spines are described from the lower cambrian rabbit point formation cambrian series 2 stage 4 of eastern devon island representing the most diverse assemblage of olenelloids yet described from arctic canada new taxa bristolia kurtzi n sp paranephrolenellus cowiei n sp siciliolenellus fritzi n gen and n sp

vertical distribution of radiolaria in the eastern equatorial atlantic analysis of a multiple series of closely spaced plankton tows radiolaria from the upper 101 and 202 m of eastern equatorial atlantic waters were collected with multiple opening closing nets in combination with an environmental sensing system mocness the abundance and vertical distribution of 40 polycystine and phaeodarian species were measured and compared with physical and chemical water properties measured at the tow sites highest concentrations of radiolaria radiolaria unit volume of water filtered in the upper 100 m occur at depths encompassing thechlorophyll a maximum and thermocline abundance peaks of many of the spumellarian taxa are recorded in samples taken from nets towed at depths at or directly above thechlorophyll a maximum zone six of the nine colonial radiolarians identified are present in highest concentrations in surface waters 0 25 m where the highest levels of dissolved oxygen were recorded most of the nassellarian and phaeodarian taxa counted in these samples reach maximum abundances at depths well below thechlorophyll a maximum the relationships between radiolaria distribution and physical and or chemical properties measured at the two tow sites are statistically significant

radiolarian responses to paleoceanographic events of the southern south china sea during the pleistocene abstract a quantitative radiolarian study at core 17957 2 from the south china sea scs allows reconstructing two paleoceanographic events occurring during the last 1500 ka based on the abundance variations of siliceous microfossils radiolarian diatom and sponge spicule the definitions of the productivity and thermocline indexes dar diatom accumulation rate and tsr thermocline surface radiolarian indexes as indicators for productivity and thermocline changes as well as changes in the species composition two distinct changes at 900 ka and 600 ka could be detected being related to the multiple transition phenomena of the mid pleistocene revolution mpr the change in the species composition at 900 ka indicated by an increase in subtropical radiolarians and a decrease in tropical radiolarians exhibits a lowering of the sea surface temperatures in the scs that can be related to a southward shift of the north equatorial current induced by variations in the northern trade wind system increasing subsurface and intermediate species and dar and tsr indexes at 700 600 ka may reflect higher sea surface productivity and shallowing thermocline caused by stronger upwelling and nutrient supply the comparison of the radiolarian signal recovered from core 17957 2 with the magnetic susceptibility signal obtained from the chinese loess plateau reveals the close connection of the climatic transitions at 700 600 ka in the southern scs to strengthening of the east asian summer monsoon circulation the spectral analyses indicate that ice mass fluctuations oxygen isotope record have clear 100 ka eccentricity dominated and processional signals after the mpr but with a more significant obliquity related response before the mpr the surface productivity e g dar and thermocline depth e g tsr index show the 100 ka dominant cyclicity before the mpr the 32 ka significant regional cyclicity for the last 1500 ka responds to the surface productivity e g dar and thermocline depth e g tsr index signals

polycystine radiolarians in surface sediments from the bering sea green belt area and their ecological implication for paleoenvironmental reconstructions radiolarians in surface sediments along transects from the shelf edge along the slope into the deep basin of the northern bering sea are dominated by stylochlamydium venustum antarctissa sp 1 the spongodiscidae juvenile pseudodictyophimus gracilipes ceratospyris borealis the plagoniidae phormacantha group and plectacantha group siphocampe arachnea cycladophora davisiana and spongotrochus glacialis this dominance is most extreme on the shelf edge and slope where s venustum antarctissa sp 1 the spongodiscidae juvenile the plagoniidae and s glacialis have their highest relative abundance there is thus a close relation between radiolarian distribution and the high productivity of the bering sea green belt bsgb due to periodic sea ice melt the radiolarian depth distribution patterns indicate that some radiolarian species have specific ecological preferences s venustum the spongodiscidae juvenile and s glacialis live close to the surface water under relatively low temperature and low salinity conditions due to sea ice melting or melt water influx antarctissa sp 1 appears to dwell mainly in surface to subsurface waters but has not been recorded in trap samples of the bering sea the plagoniidae probably live in subsurface and intermediate waters s arachnea and c davisiana are intermediate to deep dwellers the close association of these radiolarians with the bsgb and specific water depths provides a valuable reference for paleoenvironmental reconstruction in the region

quaternary palaeoceanographic changes in the northern south china sea odp site 1146 radiolarian evidence the abundance and accumulation rates of siliceous microfossils in the northern south china sea including radiolarians diatoms and sponge spicules increased during most glacial intervals within the past 1100 kyr similar trends are observed in the index of thermocline surface radiolarians tsr diatom accumulation rates dar charcoal accumulation rates car and the abundance of radiolarian species cycladophora davisiana davisiana decreasing sea surface temperature accompanied by increased seasonality since 900 ka is indicated by a decline in the tropical radiolarian assemblage including tetrapyle octacantha and octopyle stenozona and by an increase in the subtropical assemblage including pterocotys zancleus peromelissa phalacra and ommatartuts tetrathalamus tetrathalamus rapid increases at about 800 to 700 ka of siliceous microfossils charcoal subsurface and intermediate radiolarians as well as the tsr index and the dar imply a fundamental shift in climate and a shoaling thermocline although these fundamental changes in the silicious fauna and flora of the south china sea take place within the context of a developing 100 kyr cycle they do not change in step with changing sea level as indicated by marine delta 18 o this is most clearly illustrated by the step like increase in silica accumulation radiolaria diatoms and sponge spicules at 680 ka rather these fundamental changes probably reflect intensified surface productivity associated with enhanced east asian winter monsoon circulation copyright c 2003 john wiley sons ltd

penetration of lightning mf signals to the upper ionosphere over vlf ground based transmitters 1 the mf data recorded by the low altitude satellite demeter have been used to survey the mf waves around the earth a global map of the mf emissions indicates that there exists a wave activity in the frequency range 2 2 5 mhz above the main powerful vlf ground based transmitters operating in the frequency range 18 50 khz it is shown that this is due to the high frequency part of whistlers induced by the thunderstorm activity they can penetrate trough the ionosphere at the locations of the transmitters because these transmitters induce large ionospheric perturbations this means that an integrated map over several months is able to show these mf emissions above all main vlf transmitters the discrepancy between intensities of the emissions in winter and summer in the northern hemisphere is explained by considering the geographic variations of the plasma frequency below the satellite it is shown that the mf waves spread in longitude in the hemisphere opposite to the vlf transmitters

preliminary results from the sprites94 aircraft campaign 1 red sprites the dual jet aircraft sprites94 campaign yielded the first color imagery and unambiguously triangulated physical dimensions and heights of upper atmospheric optical emissions associated with thunderstorm systems low light level television images in both color and in black and white b w obtained during the campaign show that there are at least two distinctively different types of optical emissions spanning part or all of the distance between the anvil tops and the ionosphere the first of these emissions dubbed sprites after their elusive nature are luminous structures of brief 16 ms duration with a red main body that typically spans the altitude range 50 90 km and possessing lateral dimensions of 5 30 km faint bluish tendrils often extend downward from the main body of sprites occasionally appearing to reach cloud tops near 20 km in this paper the principal characteristics of red sprites as observed during the sprites94 campaign are described the second distinctive type of emissions blue jets are described in a companion paper wescott et al this issue

biogenic silica in surface sediments of the south china sea controlling factors and paleoenvironmental implications abstract we mapped the spatial distribution of biogenic silica bsi based on a total of 355 surface sediment samples from the south china sea to provide a basin wide bsi data set for paleoenvironmental reconstruction in the region the results show that bsi relative abundance calcium carbonate percentage siliceous test total abundance grain size and sediment magnetic susceptibility all show distinct spatial distribution patterns that are affected by environmental drivers the gradual increase in bsi from the continental shelf to the abyssal plain suggests that decreased dilution of terrigenous sediments plays a greater role in bsi preservation than does increasing dilution by caco3 decreasing productivity or siliceous dissolution the bsi correlation is weak for diatom abundance but relatively good for radiolarians confirming that radiolarians are the primary contributor to bsi fluxes in the low latitude south china sea in contrast increased dissolution results in a decrease in caco3 with increasing water depth reflecting the different preservation patterns of these two biogenic components correlation analysis also reveals a positive correlation between bsi and fine grain size perhaps reflecting the ability of clay minerals to protect bsi from dissolution volcanic ash and glass also can retard dissolution by increasing the pore water saturation of sio2 in abyssal basin sediments

television image of a large upward electrical discharge above a thunderstorm system an image of an unusual luminous electrical discharge over a thunderstorm 250 kilometers from the observing site has been obtained with a low light level television camera the discharge began at the cloud tops at 14 kilometers and extended into the clear air 20 kilometers higher the image which had a duration of less than 30 milliseconds resembled two jets or fountains and was probably caused by two localizd electric charge concentrations at the cloud tops large upward discharges may create a hazard for aircraft and rocket launches and by penetrating into the ionosphere may initiate whistler waves and other effects on a magnetospheric scale such upward electrical discharges may account for unexplained photometric observations of distant lightning events that showed a low rise rate of the luminous pulse and no electromagnetic sferic pulse of the type that accompanies cloud to earth lightning strokes an unusually high rate of such photometric events was recorded during the night of 22 to 23 september 1989 during a storm associated with hurricane hugo

lower ordovician graptolite biozonation and lithofacies of southern bolivia relevance for palaeogeographic interpretations the interpretation of the lithofacies and basin evolution of the early ordovician of southern bolivia is based on a number of sections on an e w transect lithostratigraphic units are extremely diachronous and only the available data on the graptolite biostratigraphy enabled an interpretation of the basin evolution the newly proposed graptolite biozonation includes the biozones of rhabdinopora flabelliformis adelograptus sp araneograptus murrayi hunnegraptus copiosus tetragraptus phyllograptoides expansograptus protobalticus expansograptus holmi baltograptus minutus azygograptus lapworthi and isograptus victoriae isograptus victoriae is the first isograptid identified from gondwanan south america the early ordovician succession of southern bolivia is the most complete one documented from south america and can be used as a standard for this continent the faunas are most easily correlated with the faunal succession of scandinavia and without doubt belong to the atlantic graptolite faunal province they show distinct differences from coeval faunas of the argentine precordillera referable to the pacific faunal province

gigantic jets between a thundercloud and the ionosphere transient luminous events in the atmosphere such as lighting induced sprites and upwardly discharging blue jets were discovered recently in the region between thunderclouds and the ionosphere in the conventional picture the main components of earth s global electric circuit include thunderstorms the conducting ionosphere the downward fair weather currents and the conducting earth thunderstorms serve as one of the generators that drive current upward from cloud tops to the ionosphere where the electric potential is hundreds of kilovolts higher than earth s surface it has not been clear however whether all the important components of the global circuit have even been identified here we report observations of five gigantic jets that establish a direct link between a thundercloud altitude approximately 16 km and the ionosphere at 90 km elevation extremely low frequency radio waves in four events were detected while no cloud to ground lightning was observed to trigger these events our result indicates that the extremely low frequency waves were generated by negative cloud to ionosphere discharges which would reduce the electrical potential between ionosphere and ground therefore the conventional picture of the global electric circuit needs to be modified to include the contributions of gigantic jets and possibly sprites

upward electrical discharges from thunderstorms blue jets gigantic jets cloud to cloud discharges and cloud to ground lightning are all electrical discharges from thunderclouds an analysis of numerical simulations and observations of these phenomena places them all in a unifying framework thunderstorms occasionally produce upward discharges called blue jets and gigantic jets that propagate out of the storm top towards or up to the ionosphere1 2 3 4 whereas the various types of intracloud and cloud to ground lightning are reasonably well understood the cause and nature of upward discharges remains a mystery here we present a combination of observational and modelling results that indicate two principal ways in which upward discharges can be produced the modelling indicates that blue jets occur as a result of electrical breakdown between the upper storm charge and the screening charge attracted to the cloud top they are predicted to occur 5 10 s or less after a cloud to ground or intracloud discharge produces a sudden charge imbalance in the storm an observation is presented of an upward discharge that supports this basic mechanism in contrast we find that gigantic jets begin as a normal intracloud discharge between dominant mid level charge and a screening depleted upper level charge that continues to propagate out of the top of the storm observational support for this mechanism comes from similarity with bolt from the blue discharges5 and from data on the polarity of gigantic jets6 we conclude that upward discharges are analogous to cloud to ground lightning our explanation provides a unifying view of how lightning escapes from a thundercloud

development of east asian summer monsoon environments in the late miocene radiolarian evidence from site 1143 of odp leg 184 abundant radiolarians are preserved in the relatively complete upper miocene section of odp site 1143 three radiolarian zones rn6 rn7 and rn8 are recognized on the basis of diartus petterssoni total range in rn6 6 7 ma variations in the abundance of radiolarians especially pyloniid forms radiolarian flux and species diversity are good proxies of upwelling which similar to today s was likely driven by summer monsoons these radiolarian paleomonsoon proxies indicate that the east asian summer monsoon first initiated close to the middle late miocene boundary at similar to 12 11 ma and reached a maximum strength at similar to 8 24 ma therefore the initiation of the east asian summer monsoon was likely earlier than the first indian monsoon which appeared similar to 8 myr ago c 2003 elsevier b v all rights reserved

mapping the radio sky with an interferometric network of low frequency radio receivers 1 the structure of the 100 khz radio sky is determined with two interferometric networks of 10 radio receivers which are distributed over local areas of 1 1 km2 and 10 10 km2 the radio waves arrive at individual receiver pairs with small time differences which are used to determine the arrival direction of the electromagnetic waves including both the bearing and the elevation angle the results show that the major part of the 100 khz radio wave energy comes from the horizon at bearings which are consistent with known locations of long range navigation loran transmitters some part of the radio wave energy arrives from the sky at elevation angles which are consistent with the first and second sky hop waves of loran transmissions a minor part of the 100 khz radio wave energy comes from lightning discharges at distances up to 1000 km with bearings which are consistent with lightning locations reported by the arrival time difference atd lightning detection network of the uk met office the angular resolution for mapping the radio sky depends on the network geometry the instrumental timing accuracy and on the signal to noise ratio of the radio waves the resulting angular resolution of the interferometric networks used in this study is 1 in bearing at zero elevation and several degrees in elevation

proterozoic early paleozoic evolution in western south america a discussion abstract the hypothesis of exotic terranes in peru bolivia argentina and chile generated discussions on the mode of transfer and extent of accretional events that may have occurred in the southern andes during the late proterozoic early paleozoic initially a tectogenesis based on autochthonous mobile fold belts was discussed following ideas emphasised the fragmentation of the supercontinent rodinia laurentia moving along the west gondwana border and colliding with the gondwana western margin the most important effect of this laurentia gondwana relationship was attributed to the argentine precordillera or cuyania terrane splitting off from laurentia and docking to gondwana in the early paleozoic in this study the most cited arguments for this laurentia precordillera relationship are discussed emphasising paleontological considerations it is shown that these arguments do not exclude a close original vicinity of the precordillera terrane to gondwana the precordillera terrane is suggested to be part of a hypothetical platform which developed between south america africa and antarctica safran platform and which was displaced to its actual position by transcurrent faults the collisional events in the sierras pampeanas ensued from strike slip movements and were responsible for the s and i type transpressional magmatism along the pampean and famatinian terranes the final result of this continent parallel movement of terrane slices is similar to that of a terrane split off from laurentia but the first named way of formation easier explains the general continuity of plate convergence at the western border of gondwana than the laurentia precordillera connection does

map of low frequency electromagnetic noise in the sky the earth s natural electromagnetic environment is disturbed by anthropogenic electromagnetic noise here we report the first results from an electromagnetic noise survey of the sky the locations of electromagnetic noise sources are mapped on the hemisphere above a distributed array of wideband receivers that operate in a small aperture configuration it is found that the noise sources can be localized at elevation angles up to 60 in the sky well above the horizon the sky also exhibits zones with little or no noise that are found toward the local zenith and the southwest of the array these results are obtained by a rigorous analysis of the residuals from the classic dispersion relation for electromagnetic waves using an array analysis of electric field measurements in the frequency range from 20 to 250 khz the observed locations of the noise sources enable detailed observations of ionospheric modification for example caused by particle precipitation and lightning discharges while the observed exclusion zones enable the detection of weak natural electromagnetic emissions for example from streamers in transient luminous events above thunderclouds

spatial distribution pattern of living polycystine radiolarian taxa baseline study for paleoenvironmental reconstructions in the southern ocean atlantic sector the horizontal and vertical distribution of living polycystine radiolarian taxa was investigated at seven locations on a n s transect between the antarctic zone 54 s in the southern ocean and the subtropical zone 30 s in the southeastern south atlantic during austral autumn four to five depth intervals from 0 to 1000 m depth were sampled with 55 m mesh opening closing nets in combination with a hydrographic ctd survey a factor analysis for the delineation of specific assemblages and the relation between different taxa and taxa groups resulted in eight factors of which five represent surface and subsurface factors and three deep water factors the spatial distribution pattern of the factors shows that distinct radiolarian assemblages are closely related to water depth distribution of water masses hydrographic boundaries such as frontal systems and nutrients this documents that the distribution of individual radiolarian assemblages is controlled by specific hydrographic conditions and water depth and allows the definition and consolidation of the autecological demands these data are crucial for the paleoenvironmental interpretation of fossil polycystine radiolarian assemblages the comparison of living polycystine radiolarian taxa with those preserved in surface sediments shows general similarities this study includes the first documentation on the distribution of living cycladophora davisiana in circumpolar deep water and supports previous studies stating that c davisiana also lives in deep water masses

radiolarian distribution in the water column southern gulf of california and its implication in thanatocoenose constitution abstract the geographical and depth distributions of five radiolarian plankton assemblages defined through q mode factor analysis of 24 plankton samples demonstrate a direct correspondence to the distribution of oceanographic water masses in the southern gulf of california two assemblages are associated exclusively with water masses of the mixed layer two represent only subsurface water masses and one is important in both surface and subsurface environments the lithomelissa thoracites group and peridium spinipes are predominant species in water that is formed at the surface of the guaymas basin and subsequently is subducted southward into the carmen basin plagiocantha panarium is the predominant species in upwelled surface water at the carmen basin while tetrapyle octhacanta and botryostrobus scutum follow the incursion of the subtropical water mass into the gulf of california through the pescadero and farallon basins druppatractus variabilis and porodiscus sp b occur conspicuously in the upper layer of the pacific intermediate water between approximately 400 and 700 m water depth statistical correlation between plankton and sediment assemblages supports previous evidence that the radiolarian thanatocoenose in the gulf of california is composed primarily of species from the surface mixed layer two exceptions to this are observed in the data first the upwelling plankton assemblage was not well correlated to the sediment assemblage and second input to the sediment during glacial stages appears to be dominated by subsurface forms

hf signatures of powerful lightning recorded on demeter 1 emissions in the hf range 1 7 3 mhz are observed at the times of powerful lightning on the low altitude satellite demeter at 700 km wave activity observed on the e field spectrograms recorded on demeter during nighttime is mainly dominated by upgoing 0 whistlers and higher order dispersed whistlers over a period of 30 months 130 events with hf emissions at frequency 2 mhz have been observed at the time of intense 0 whistlers on vlf spectrograms a global map of the distribution of events indicates that they do not occur above regions of most thunderstorm activity such as the upper part of south america or the middle of africa this lack of occurrence above these two near equatorial regions is consistent with the high value of the critical frequency of the f layer which prevents the transionospheric propagation of the hf component of the lightning pulses up to 700 km the time location intensity and polarity of the lightning discharges related to a subset of these hf events are determined above the north american region with the national lightning detection network as most of the events are recorded in survey mode when full resolution of the data is not available the neural network on board demeter is used to determine the times of the 0 whistlers recorded by the satellite with a time accuracy of 0 1 s the impulsive hf events correspond to intense lightning discharges occurring in regions immediately below the satellite it is assumed that the propagation of these hf pulses up to the altitude of the satellite is favored by local ionospheric heating due to high thunderstorm activities

the vertical distribution of radiolaria in the waters surrounding japan abstract geographic and vertical distribution patterns of living radiolaria are closely related to the characters of the water column we studied living radiolaria in samples collected at closely spaced depth intervals in the waters surrounding japan in order to understand their vertical distribution and its controlling factors such information is needed to reconstruct past vertical water mass structure the japanese islands are surrounded by the marginal japan sea and the north pacific ocean and from approximately 46 n to 26 n they thus extend across a large latitudinal range and are exposed to a similarly wide range of environmental conditions inducing the warm kuroshio tsushima and tsugaru currents and the cold oyashio current we performed plankton tows mesh size 63 mm from late may to early june 2002 at eight sites sampling the upper 200 m of the water column at seven depth intervals we recognized five radiolarian assemblages the upper surface assemblage 0 40 m the lower surface assemblage 40 80 m the surface assemblage 0 80 m the subsurface assemblage 80 200 m and the lower surface subsurface assemblage 40 200 m groups pseudodictyophimus gracilipes and tetrapyle octacantha juvenile show tropical submergence i e they live at the surface in high latitudes and at greater depth in low latitudes four taxa live at specific temperature and salinity acrosphaera spinosa larcopyle butschlii challengeron diodon and stichocorys seriata four taxa are associated with characteristic temperatures neosemantis distephanus arachnocorys umbellifura antarctissa sp 1 and saccospyris conithorax

radiolarian assemblage distributions and paleoceanography of the eastern equatorial pacific ocean during the last 127 000 years abstract mathematical treatment q mode factor analysis of radiolarian species abundance data in equatorial pacific core tops yields four oceanographically meaningful assemblages the distribution of these assemblages in surface sediments can be related to the major surface and subsurface characteristics of the equatorial circulation system western tropical mixed layer flow coastal upwelling and the oxygen minimum layer eastern equatorial divergence upwelling and the equatorial undercurrent and the subtropical water masses of both hemispheres changes in the distribution of radiolarian assemblages during the glacial interglacial cycle spanning the last 127 000 yr are observed in two equatorial pacific piston cores these changes reflect fluctuations in the boundaries of equatorial water masses in response to variations in the position and strength of the tradewind system and tend to precede major glacial interglacial transitions by several thousand years a history of atmospheric circulation in the equatorial pacific has been developed for the last 127 000 yr fluctuations in tradewind intensity north south shifts in the latitudinal position of the tradewind maxima and perhaps a change in the zonality of the tradewinds during the last 127 000 yr have been inferred from downcore quartz abundance and radiolarian assemblage distribution patterns oxygen isotopic fluctuations during the last 127 000 yr indicate that continental ice volume was much greater during glacial stage 2 29 000 b p to 11 000 b p than during glacial stage 4 73 000 b p to 61 000 b p large changes in atmospheric and oceanic circulation patterns also are indicated by the distribution of radiolarian assemblages during the two glacial periods during stage 2 oceanic circulation was more intense the southeast tradewind maximum was closer to the equator and wind stress was more meridional than during stage 4

comparison of radiolarian vertical distributions in the okhotsk sea near the kuril islands and in the northwestern north pacific off hokkaido island abstract the vertical distribution of radiolarians was investigated by using a closing type net with 63 m mesh in the okhotsk sea station nu 2 near bussol strait down to 1000 m depth and in the northwestern north pacific oyashio region station x down to 500 m depth both stations were sampled in september 1995 radiolarian standing stocks were high between 50 and 200 m at both stations and generally decreased with depth the depth integrated living total radiolarian standing stock from 0 to 500 m at station nu 2 was more than three times higher than that at station x the maximum standing stocks of polycystine radiolarians occurred in the 50 100 m depth interval but there were also significant abundance peaks of phaeodarian radiolarians in the 100 200 m interval at both stations the radiolarian production is likely to be associated with not only phytoplankton production in upper waters but also with microbial production in intermediate waters a total of 79 taxa were encountered 25 spumellaria 41 nassellaria and 13 phaeodaria five radiolarian groups were obtained based on r mode cluster analysis group a lower intermediate water dwellers 300 1000 m group b taxa with different distributions in the okhotsk sea 300 1000 m and in the oyashio region 0 100 m group c upper intermediate water dwellers 200 500 m group d surface subsurface water dwellers 0 200 m and group e taxa with pronounced 200 m

radiolarians in the sea of okhotsk and their ecological implication for paleoenvironmental reconstructions to assess the relationship of radiolarian production species distribution in water and surface sediment to water mass characteristics biological productivity and export regimes in the sea of okhotsk sok we accomplished a quantitative analysis of radiolarian assemblages obtained from 35 surface sediment samples and 115 plankton samples recording the radiolarian depth distribution in the upper 1000 m of the water column at 23 locations this study augments the knowledge on the autecological demands of radiolarians dwelling in a specific hydrographic and biological environment and extracts new information on the significance of radiolarians for the assessment of past oceanographic and climatic development in high latitudes highest radiolarian accumulation rates and seasonal radiolarian standing stocks are encountered in the western part of the sok close to sakhalin marking the environmental conditions in this area as most favorable for radiolarian production maximum standing stocks occur during summer indicating that the radiolarian signal preserved in the sediment record is mainly produced during this season when the mesopelagic biomass is at highest activity we identified seven radiolarian species and groups related to specific water mass characteristics depth habitats and productivity regimes of those dictyophimus hirundo and cycladophora davisiana are most prominent in the sea of okhotsk intermediate water 200 1000 m the latter representing an indicator of the occurrence of cold and well ventilated intermediate deep water and enhanced export of organic matter from a highly productive ocean surface while antarctissa sp 1 is typically related to the cold water sea of okhotsk dicothermal layer sodl ranging between 50 and 150 m water depth the surface waters above the sodl affected by strong seasonal variability are inhabited predominantly by taxa belonging to the spongodiscidae having a broad environmental tolerance taxa only found in the sediment record show that the plankton study did not cover all assemblages occurring in the modern sok this accounts for an assemblage restricted to the western kurile basin and apparently related to environmental conditions influenced by north pacific and japan sea waters other important taxa include species of the plagoniidae group representing the most prominent contributors to the sok plankton and surface sediments these radiolarians show a more opportunistic occurrence and are indicative of high nutrient supply in a hydrographic environment characterized by pronounced stratification enhancing heterotrophic activity and phytodetritus export r 2005 elsevier ltd all rights reserved

salterella in the argentine precordillera an early cambrian palaeobiogeographic indicator of laurentian affinity abstract this paper documents salterella maccullochi murchison in the precordillera of western argentina in the present day southern hemisphere the record of these early cambrian small conical shaped fossils assigned to the extinct phylum agmata provides further palaeobiogeographic evidence to consider the argentine precordillera an exotic terrane to gondwana that originally rifted from laurentia for palaeogeographic reconstructions salterella can be considered as an organism equally important and biogeographically as meaningful as the olenellid trilobites due to their limited dispersal and demonstrated link to laurentian shallow water inner shelf facies it has not been found anywhere in gondwana salterella existed for only a very short interval of time but spread almost instantaneously around laurentia on this basis the early cambrian of the precordillera terrane remains the more conclusive palaeobiogeographical link to laurentia salterella provides another line of evidence supporting palaeontological sedimentologic stratigraphic palaeomagnetic and isotopic evidence for a laurentia origin of the precordillera terrane

polypleuraspis arthropoda trilobita from the middle cambrian miaolingian series around kane basin nunavut and greenland polypleuraspis poulsen 1927 originally established on the basis of a single trilobite pygidium from the cape wood formation of inglefield land northwestern greenland is redescribed on the basis

temporal and spatial flux changes of radiolarians in the northwestern pacific ocean during 1997 2000 abstract in order to examine the radiolarian fluxes and evaluate their relationship to the physical and biological environments time series sediment traps were deployed at three stations stations 50n knot and 40n in the northwestern north pacific from 1997 to 2000 station 50n 50 n 165 e 3260 m is located in the center of western subarctic gyre wsag station knot 44 n 155 e 2957 m is located toward the margin of wsag and station 40n 40 n 165 e 2986 m is located in the subarctic boundary total radiolaria fluxes at station 40n showed higher values than those at the other two stations and were mainly attributed to the influence of relatively high temperature and high salinity subtropical gyre waters correlation coefficients between total mass fluxes mainly composed of diatoms and radiolarian fluxes at three stations were relatively low this is primarily because of the wide vertical distribution of radiolarians and various trophic patterns corresponding to their niche radiolarian species were classified according to their geographic water mass and vertical distributions based on previous studies using sediment samples as a result seasonal changes of radiolarian fluxes in each water mass showed patterns corresponding to particular controlling factors such as physical hydrography and food conditions among these patterns temporal changes in radiolarian taxonomic composition in the upper layer 0 100 m seemed to reflect well the sea surface temperature anomaly ssta changes affected by el nino and la nina events at station 40n therefore radiolarian assemblages can be used to reconstruct past ssta changes and to understand the past el nino and la nina teleconnection in the kuroshio oyashio extension region

early palaeozoic brachiopods and associated shelly faunas from western gondwana their bearing on the geodynamic history of the pre andean margin

the palaeogeography of early ordovician iapetus terranes an integration of faunal and palaeomagnetic constraints abstract new and existing fossil data from ireland britain newfoundland and scandinavia emphasize a significant degree of latitudinal variation in biogeographic patterns across the ordovician iapetus ocean platform provinces together with marginal belts and island complexes can be recognised with increasing clarity on the basis of palaeontological information statistical analysis of the distribution patterns of about 70 early ordovician brachiopod genera across some 25 sites using both cladistic and phenetic methods together with a critical analysis of their geological settings combined with current palaeogeographic and palaeomagnetic data reaffirm the existence of the celtic brachiopod province during the early ordovician the majority of sites assigned to the celtic province define a high latitude peri gondwanan belt shadowing the distribution of the low latitude circum laurentian toquima table head faunas rapidly changing ordovician faunal signals across the baltic province and exploits zone of central newfoundland track the cross latitude movement of these terranes from high temperate to near tropical belts during the period new fossil information together with continuing statistical appraisal of an expanding database are providing more accurate and sophisticated models for the dynamics of the iapetus ocean system

distribution of polycystine radiolarians in the northern south china sea in september 2005 we studied the distribution of polycystine radiolarians in the northern south china sea scs in september 2005 in order to document the relation between radiolarian assemblages and environmental parameters vertical plankton tows were collected at depth intervals from 0 to 250 m at thirteen stations using a closing net 62 pm mesh the highest abundance of polycystine radiolarians generally occurred at depths of 0 75 m i e above the chlorophyll a maximum and thermocline in contrast the maximum polycystine abundance occurred below the chlorophyll a maximum at station e105 75 150 m possibly as a result of down welling of warm waters and the maximum fell within the chlorophyll a maximum at station e702 as a result of upwelling of intermediate cold waters during our sampling period the southwestern monsoon caused upwelling in the northern scs the taiwan bank region as shown by the high abundance of tetrapyle octacantha acanthodesimia vinculata cladococcus cervicoris octopyle octospinosa spongaster tetras streblacantha circumtexta and spongotrochus glacialis the patterns of distribution and the abundances of the species botryocyrtis scutum pterocorys hertwigii collosphaera tuberosa and didymocyrtis tetrathalamus tetrathalamus suggested that western equatorial pacific waters did not yet influence the region at the time of sampling the first two species were dominant in the northern scs during our sampling the species cornutella profunda and cyrtopera laguncula were rare at depths of 150 250 m in the tropical region of the scs and assemblages in northern and southern scs were very similar the relative abundance of b scutum and p hertwigii is an indicator for seasonal changes in monsoonal circulation c 2008 elsevier b v all rights reserved

sprite observations above the u s high plains in relation to their parent thunderstorm systems transient luminous events sprites blue jets elves above large mesoscale convective systems mcss over the u s high plains have been routinely monitored from the yucca ridge field station near fort collins colorado using ground based low light video systems we analyzed 36 sprites above the nebraska mcs of august 6 1994 the results lend further support to the hypothesis that sprites are almost uniquely associated with positive cloud to ground cg lightning flashes sprite associated cgs also averaged substantially larger peak currents than the remaining cg population 81 ka versus 30 ka in this storm system there is some evidence that sprite associated cgs also have higher stroke multiplicity this study yields no evidence of sprites associated with negative cg events in the central united states an additional requirement appears to be that the parent mcs has a contiguous radar reflectivity area exceeding 20 25 000 km 2 the majority of the sprites occur above the large stratiform precipitation region and not the high reflectivity convective core of the mcs triangulation of a limited number of paired images from september 7 1994 suggests that the sprite is generally centered within 50 km of the parent cg assuming the cg provides the range single image photogrammetric analyses provide estimates of the maximum vertical extent of the sprites for this storm the sprite tops averaged 77 km with a maximum of 88 km the bases averaged 50 km but with a few sprite tendrils extending as low as 31 km

radiolaria as indicators of upwelling processes the peruvian connection abstract in the sediments along the coastal region of peru certain radiolarian species have preferences to waters associated with upwelling such is the case forpolysolenia murrayana in the upwelling areas fed by equatorial water and forcenosphaera sp in the upwelling areas fed by temperate subantarctic water cycladophora davisiana appears to frame the upwelling centers suggesting that it prefers regions near thermic fronts the down core records of these species as well as records of quartz and organic carbon are depicted in three14c and 18o dated cores located along the pacific coast of south america between 11 and 13 s they suggest that both the eolian and oceanic circulation were more intense during the last glacial stage approximately between 33 000 and 11 000 years ago than during the present postglacial at these latitudes the intensification in circulation was not only accompanied by an increased coastal upwelling and in turn by an increased primary productivity but also by a larger supply of temperate waters to the area

depth related radiolarian assemblage in the water column and surface sediments of the japan sea plankton tows and surface sediments from the japan sea a marginal sea of the northwestern pacific were examined to study the depth distribution of modern radiolarians the depth distribution patterns between the living assemblage in the water column and the thanatocoenose in surface sediments are similar to each other indicating that the depth related assemblage in sediments is closely related to the living depths of major species four clear restrictions of many species to discrete depth zones are recognized in the water column from the surface down to 2000 m 1 upper subsurface water species which are abundant from 40 to 120 m larcopyle butschlii juvenile form spirocyrtis subscalaris spongodiscus resurgens and lipmanella virchowii 2 lower subsurface water species which are abundant from 40 to 300 m larcopyle butschlii adult form ceratocyrtis histricosa and spongotrochus glacialis 3 intermediate water species which have population maxima from 160 to 300 m ceratospyris borealis and 4 deep water species which have maxima between 1000 and 2000 m cycladophora davisiana and actinomma boreale only a few specimens of a boreale were found in the water column ranging from 1000 to 2000 m depth although this is a dominant species in surface sediments from depths below 2000 m of which the dominance increases with water depth a boreale may live mainly in the bottom water cycladophora davisiana and a boreale which characterize the japan sea deep assemblage are naturally shallow or intermediate dwellers in other oceans on the other hand the typical deep dwellers e g cornutella profunda cyrtopera languncula and peripyramis circumtexta of other oceans have not been found in the japan sea such a peculiar deep assemblage is a result of the deep circulation system in the japan sea and the shallow depths of the sills around it

orbital and millennial scale changes of radiolarian assemblages during the last 220 kyrs in the japan sea abstract significant abundance changes of seven radiolarian species during the last 220 kyrs in the japan sea are reported herein based on three sediment cores during the interglacial periods warm water species the tetrapyle octacantha group and warmer high nutrient water species lithomelissa setosa occurred commonly which may indicate inflows of the tsushima warm current on the other hand cold water species such as ceratospyris borealis and stylochlamydium venustum dominated the assemblage during the glacial periods when the japan sea was mostly isolated from the adjacent seas due to lower eustatic sea level however at glacial maxima the habitat of s venustum was strongly limited due to low salinity surface waters the abundance of the deep water species cycladophora davisiana seems to have changed significantly possibly related to the intrusion of oxygen and organic materials into deeper waters higher abundances of this species in mis marine isotope stage 1 mis 3 and mis 5c resulted from well ventilated deep water and high organic flux while its low abundance during the glacial maxima and mis 5e was probably caused by oxygen poor deep water millennial scale variations of c davisiana abundance show high abundance at the transition intervals from interstadial to stadial periods of the dansgaard oeschger cycles the disappearance events of lychnocanoma nipponica sakaii and amphimelissa setosa were recognized at 54 ka and 85 ka respectively both of these events in the japan sea can be correlated with those in the north pacific bering sea and sea of okhotsk

radiolarian distribution in surface sediments of the northern and central south china sea radiolarian distribution in surface sediments of 104 stations from northern and central south china sea show that the abundance and diversity of radiolarians increase with the water depth and are related to radiolarian concentrations from the water column diminished terrigenous input variability in calcareous shell content and the rate of silica and carbonate dissolution in the deep sea according to the appearances of individual species in surface sediments at particular depths seven faunal boundaries distribution are recognized at water depths of 100 450 650 1000 1200 1400 and 2500 m four radiolarian assemblages in the sediments were identified by applying clustering procedures geographic distributions of these four assemblages coincide with present day hydrologic features of the surface waters in this area

radiolarian assemblage as an indicator of environmental conditions in the marginal seas of the western north pacific abstract in this study we analyzed 45 surface sediment samples collected in the marginal seas of the western north pacific including the south china sea the east china sea and the philippine sea to investigate the radiolarian assemblages and their relationship with upper layer environmental conditions based on the results of q mode cluster analysis the radiolarian assemblages can be divided into four clusters corresponding to the north equatorial current assemblage north equatorial current bifurcation assemblage kuroshio south china sea assemblage and kuroshio east china sea assemblage winter sea surface temperature sstw winter sea surface salinity sssw and annual silicate concentration were the most significant environmental variables associated with the radiolarian assemblages among which sstw showed the highest correlation with the radiolarian fauna the significant influences of sstw and sssw suggested that the seasonal change of the north equatorial current kuroshio current system exerted a crucial effect on the abundance and distribution pattern of the radiolarian fauna

electrical discharge from a thundercloud top to the lower ionosphere for over a century numerous undocumented reports have appeared about unusual large scale luminous phenomena above thunderclouds1 2 3 4 5 6 and more than 80 years ago it was suggested that an electrical discharge could bridge the gap between a thundercloud and the upper atmosphere7 8 since then two classes of vertically extensive optical flashes above thunderclouds have been identified sprites9 10 11 and blue jets12 13 14 sprites initiate near the base of the ionosphere develop very rapidly downwards at speeds which can exceed 107 m s 1 ref 15 and assume many different geometrical forms16 17 18 19 in contrast blue jets develop upwards from cloud tops at speeds of the order of 105 m s 1 and are characterized by a blue conical shape12 13 14 but no experimental data related to sprites or blue jets have been reported which conclusively indicate that they establish a direct path of electrical contact between a thundercloud and the lower ionosphere here we report a video recording of a blue jet propagating upwards from a thundercloud to an altitude of about 70 km taken at the arecibo observatory puerto rico above an altitude of 42 km normally the upper limit for blue jets and the lower terminal altitude for sprites the flash exhibited some features normally observed in sprites as we observed this phenomenon above a relatively small thunderstorm cell we speculate that it may be common and therefore represent an unaccounted for component of the global electric circuit

paleobiogeographic patterns in the middle and late devonian emphasizing laurentia abstract the relative importance of tectonism and sea level change in driving middle to late devonian biogeographic patterns in marine invertebrates is investigated using phylogenetic biogeography taxa considered include two clades of brachiopods one bivalve clade and a suborder of phyllocarid crustaceans these organisms colonized different depositional environments and played different roles in the devonian ecosystem which allows biogeographic patterns to be considered in a cross faunal analysis vicariance patterns are well resolved and may reflect biogeographic relationships developed in the early to early middle devonian due to the uplift of intracratonic arches uplift of tectonic arches is inferred to occur during times of tectonic quiescence during the second and third and possibly also the first tectophase after ettensohn f r 1985 the catskill delta complex and the acadian orogeny a model in woodrow d l sevon w d eds the catskill delta geological society of america boulder co special paper 201 pp 39 49 of the acadian orogeny geo dispersal patterns are not as well resolved but may indicate dispersal across tectonic arches during downwarping associated with increased compressional tectonism during ettensohn s 1985 ettensohn f r 1985 the catskill delta complex and the acadian orogeny a model in woodrow d l sevon w d eds the catskill delta geological society of america boulder co special paper 201 pp 39 49 tectophases ii and iii geo dispersal across relatively low arches may also be coincident with transgressive events iia and iic of johnson et al 1985 johnson j g klapper g sandberg c a 1985 devonian eustatic fluctuations in euramerica geological society of america bulletin 96 567 587 the overall lack of congruence between the vicariance and geo dispersal patterns suggests that singular tectonic events exerted more profound influence on devonian biogeography than cyclical changes in sea level furthermore the offset in perceived timing between vicariance and geo dispersal patterns may indicate a fundamental change in the style of biogeographic patterns during the middle devonian and may have played a major factor in regulating biodiversity dynamics during the late devonian biodiversity crisis

observations of lightning in the stratosphere an examination and analysis of video images of lightning captured by the payload bay tv cameras of the space shuttle provided a variety of examples of lightning in the stratosphere above thunderstorms these images were obtained on several recent shuttle flights while conducting the mesoscale lightning experiment mle the images of stratospheric lightning illustrate the variety of filamentary and broad vertical discharges in the stratosphere that may accompany a lightning flash a typical event is imaged as a single or multiple filament extending 30 to 40 km above a thunderstorm that is illuminated by a series of lightning strokes examples are found in temperate and tropical areas over the oceans and over the land

geology and paleobiology of islands in the ordovician iapetus ocean review and implications a history of islands in the iapetus ocean and their destruction is recorded by widespread occurrences of lower to upper ordovician volcanic and epiclastic rocks and some limestone through the axial parts of the appalachian caledonide orogen in north america and northwestern europe assemblages of arenigian and llanvirnian benthic shelly fossils chiefly brachiopods from these rocks constitute the celtic biogeographic province that is distinguished by its endemic genera and by some that are older than in other biogeographic provinces some that are younger than elsewhere and others that have not hitherto been found together evidence from these fossils and from the geology of the rocks pertaining to them suggests that north american terranes that included islands of arenigian llanvirnian age lay at middle to high latitudes both in mid ocean and within the armorican continental margin whereas coeval rocks in west central ireland and norway that have toquima table head shelly fossils were originally part of the laurentian continental margin eradication of the celtic assemblage and the reduction of ordovician faunal provinciality in the appalachian caledonide region coincide with llanvirnian obduction subduction of hundreds of kilometres of iapetus ocean crust late llanvirnian and younger ordovician rocks in the remnant basin including some of peri insular origin have brachiopods of scoto appalachian affinities no discrete islands of ashgillian age have been recognized although fossiliferous volcaniclastic and polymictic conglomerates indicate intermontane basins in some places shelly fossils in these rocks and those in the siltstones and limestones from the gaspe peninsula are like those of ashgillian age elsewhere

the allochthony of the argentine precordillera ten years later 1993 2003 a new paleobiogeographic test of the microcontinental model abstract recent and new faunal data from the cambrian to silurian rocks of the precordillera famatina and northwest argentina basins are used to discriminate between different paleogeographic models and especially to establish to what extent they are compatible with a previous conclusion that the precordillera is a laurentian derived microcontinent there is no paleontological evidence to support a para autochthonous gondwanan origin of the precordillera the strong differences in the cambrian trilobite faunas and lithologic successions preclude a common origin of the precordillera terrane eastern antarctica and south africa recent discoveries of brachiopods and organisms of the phylum agmata strengthened laurentian affinities during the cambrian the latest cambrian early ordovician faunas that inhabited the autochthonous northwest argentina basin including the western puna volcaniclastic successions are mostly peri gondwanan the early ordovician brachiopods ostracods and trilobites display mixed laurentian baltic and avalonian biogeographical links supporting a drifting of the precordillera across the iapetus ocean increasing gondwanan elements during the llanvirn along with varied geological evidence indicate that the first stages of collision may have begun at that time involving a major change in the plate kinematics the distribution of facies and faunas basin development and timing of deformation are interpreted as resulting from a north to south diachronous closing of the remnant basin during the last phases of convergence and oblique collision of the precordillera terrane with the gondwana margin the high level of endemism of caradoc faunas may be a consequence of the rearrangement and partial isolation of sedimentary areas during the strike slip movement of the colliding precordillera plate with respect to the gondwana margin suggested relationships between facies distribution geographic barriers and faunal migrations before and during the collision are depicted in a series of schematic reconstructions at five time slices from late cambrian to silurian