phytodetritus entering the benthic boundary layer and aggregated on the sea floor in the abyssal ne pacific macro and microscopic composition abstract phytodetritus which can originate in surface waters following seasonal phytoplankton blooms is considered to be an important food resource for abyssal fauna we analyzed the composition of phytodetritus sampled discretely in situ at an abyssal station in the ne pacific the phytodetritus was collected during two time periods straddling a seasonal maximum in the flux of particulate matter into a sediment trap moored within the benthic boundary layer using the sediment trap record and concurrent time lapse photographs of the sea floor in addition to the results for the composition of sea floor phytodetritus we created a scenario for the origin accumulation and degradation of phytodetritus at the study site it appeared that the sediment trap record did not entirely account for the accumulation and composition of phytodetritus on the sea floor likely due to the undersampling of large sinking aggregates by the sediment trap within each sea floor sampling period two types of aggregated phytodetritus were identified based on macroscopic appearance loosely or strongly cohesive the loosely cohesive phyto detritus collected just before the maximum sinking flux was flocculent and contained large numbers of chain forming diatoms the bulk of the loosely cohesive phytodetritus collected one month later consisted of phaeodarians that appeared to have entrained both older and new diatom floc material the strongly cohesive discrete aggregates collected during both sampling periods appeared to be derived from zooplankton mucous webs although samples within each time period were heterogeneous microscopic composition of phytodetritus in terms of several phytoplankton and protozooplankton components differed significantly between sampling periods these results suggest that phytodetritus can change dramatically over a short time period this may have implications for the potential food resource and feeding behavior of abyssal fauna

magnetobiostratigraphy of the spathian to anisian lower to middle triassic kcira section albania summary magnetobiostratigraphic data are presented from three early middle triassic hanbulog limestone successions from kqira northern albania a total of 206 standard palaeomagnetic samples were obtained for thermal demagnetization and statistical analysis from the 42 10 and 5m thick sections the reversal bearing characteristic component carried by haematite and magnetite defines a composite sequence of six main polarity intervals kqln to kq3r in which are embedded four short polarity intervals one at the base of kqln and three towards the top of kqlr the early acquisition of the characteristic remanence is supported by the lateral correlation of magnetozones between sections the early middle triassic boundary approximated by the first occurrence of the conodont chiosella timorensis falls close to the kqlr kq2n polarity transition this is in good agreement with recently published magnetobiostratigraphic data from the coeval chios greece sections the palaeomagnetic pole calculated from the kqira characteristic directions lies close to the triassic portion of the apparent polar wander path for laurussia in european coordinates however a 40 45 clockwise rotation of the external zone of the albano hellenic belt to the south of the scutari pec line is thought to have occurred since the early middle miocene the kqira pole acquires a west gondwana affinity when restored for the neogene clockwise rotation if the clockwise rotation was entirely related to neogene tectonics the kqira area was evidently associated with west gondwana and located at 12 16 n of the western tethys margin

sensitivity of the extended ugamp general circulation model to the specification of gravity wave phase speeds two simulations made using the extended ugamp general circulation model eugcm are compared the first uses a gravity wave parametrization scheme that only includes orographically forced gravity waves with zero phase speeds whilst the second uses a similar scheme except that it includes a gravity wave with a phase speed of 20 ms 1 results from the first simulation show that wintertime westerlies are reasonably estimated but summertime and equatorial easterlies are excessive owing to an absence of gravity wave drag in these region this absence of gravity wave drag also means that the summertime mean meridional circulation is too weak and summer mesospheric model temperatures are accordingly warmer than observations by up to 35 degc inclusion of gravity waves with phase speeds of 20 ms 1 reduces summer and equatorial easterlies and decreases summer mesophere temperatures because unlike zero phase speed waves these waves can propagate into the summer and equatorial middle atmosphere and thus of the 20 ms 1 gravity wave also improves the simulation of the semiannual oscillation both at the stratopause and at the mesopause

the fold test in palaeomagnetism summary the fold test suggested by mcelhinny is shown to be inappropriate more correctly one should determine whether the mean direction of a group of sites from one limb of a fold may be distinguished statistically from the mean direction of a group of sites from another limb details of the application of this test are given with examples it is shown that the test indicates significance under far less severe folding than does the test suggested by mcelhinny

in situ studies of megafaunal mounds indicate rapid sediment turnover and community response at the deep sea floor sediment mounds composed of faecal material from megafaunal deposit feeders1 2 occur in virtually all deep sea environments forming the dominant decimetre scale topography on the ocean floor3 4 mounds are often zones of deep convective bioturbation1 2 and their formation is thought to disturb infaunal benthos5 6 we are studying mounds in the deep sea to evaluate rates and patterns of megafaunal sediment mixing and to assess the disturbance effects of mound building on the infaunal community with the goal of using mounds to investigate natural processes of succession at the deep sea floor7 our results indicate that sediment turnover associated with mound building by echiuran worms can be very rapid and that bathyal infauna can respond quickly to this type of disturbance these findings suggest that spatially rare but dynamic elements in the sediment fabric such as mounds may be important in controlling microstratigraphy chemical diagenesis and community structure at the deep sea floor

tracing abyssal food supply back to upper ocean processes over a 17 year time series in the northeast pacific detrital aggregates episodically deposited on the seafloor represent an underestimated food source to deep sea communities a 17 yr time series study was conducted from 1990 to 2006 in the abyssal northeast pacific sta m 4100 m in depth to evaluate the importance of this food source and its temporal relationship to water column and surface ocean processes detrital aggregates appeared on the seafloor from june through december with the highest peaks in 1990 1994 2001 and 2002 reaching a maximum density of 23 m22 in fall 2001 a total of 15 816 aggregates were measured most less than 20 cm2 in area and with a mode of 9 cm2 density of detrital aggregates was highly correlated with particulate organic carbon poc flux at 600 and 50 m above the bottom p 0 001 with no time lag export flux of organic carbon from the euphotic zone was significantly correlated with aggregate density lagged earlier by 1 4 months p 0 001 zooplankton displacement volume was significantly correlated with poc flux p 5 0 023 and with detrital aggregate density p 5 0 028 on the seafloor when lagged earlier by 1 month the bakun upwelling index computed for the region around sta m was significantly correlated with detrital aggregate density when lagged earlier by 2 5 months p 0 001 a strong correlation exists between surface ocean processes and abyssal food supply including poc flux and detrital aggregates this direct coupling through the entire water column must be considered in resolving the marine carbon cycle

paleomagnetic evidence for rotation in opposite senses of adjacent blocks in northeastern aegea and western anatolia paleomagnetic data from western anatolia and from the island of lesbos demonstrate significant counterclockwise clockwise or null rotations of coherent blocks which occurred during the neotectonic period these results suggest that the brittle carapace of the lithosphere may not everywhere follow the motion of the ductile lower part but that its movement arises from adjustment to the extensional tectonic regime

bioturbation short lived radioisotopes and the tracer dependence of biodiffusion coefficients bioturbation refers to the mixing of sediment particles resulting from benthic faunal activity it is the dominant particle mixing process in most marine sediments and exerts an important control on diagenetic processes in models bioturbation is usually treated as a diffusive process where the biodiffusion coefficient db characterizes the biological mixing intensity biodiffusion coefficients are classically computed by fitting a diffusive model to vertical profiles of particle bound radioisotopes one peculiar observation is tracer dependence db values from short lived tracers tend to be larger than those obtained from long lived tracers from the same site recent theoretical work based on random walk theory and lattice automaton bioturbation simulations labs has suggested that this tracer dependence is simply a model artifact and has concluded that the biodiffusion model is not applicable to the short observational time scales associated with short lived radioisotopes here we have compiled a global dataset of db values obtained from different radiotracers to assess tracer dependence from a data perspective tracer dependence is significant in low mixing environments like slope and deep sea sediments but is not present in intensely mixed coastal areas tracer dependence is absent when the number of mixing events is larger than 20 or the potential length scale is greater than 0 5 cm roughly this comes down to tracer derived db values greater than 2 cm2 yr 1 this condition is met for 68 50 and 8 of published db values obtained from coastal continental slope and abyssal environments respectively these results show that short lived radioisotopes are suitable to quantify biodiffusion mixing in sedimentary environments featuring intense bioturbation

deep sea epibenthic echinoderms and a temporally varying food supply results from a one year time series in the n e pacific abundance and distribution of epibenthic echinoderms and detrital material at an abyssal site 4100 m in the n e pacific were examined between june 1994 and june 1995 camera sled surveys time lapse photographs and observations from the submersible alvin revealed a sequence of detrital deposition events detrital aggregates were present in summer and fall of 1994 but rare in winter and spring 1995 a layer of white flocculent material covered the sea floor from july through november 1994 constituting the first direct observations of a detrital carpet in this area large radiolarian patches also were observed from august 1994 through february 1995 distribution and abundance of echinoderm species were estimated from camera sled surveys and showed few consistent temporal patterns abundance varied spatially and distributions generally could not be distinguished from random in contrast to the clumped pattern observed for detrital aggregates statistically the spatial distributions of several echinoderm species correlated significantly with the distributions of detrital aggregates but these correlations were not consistent across transects or taxa the lack of consistent correlation between echinoderm distribution and abundance and the presence of aggregate material is not surprising when the long duration of extensive detrital coverage of the sea floor is considered

234th and 21pb evidence for rapid ingestion of settling particles by mobile epibenthic megafauna in the abyssal ne pacific particle scavenged 234 th and 210 pb can be used to trace the fate of particulate matter reaching the deep sea floor we used this technique to demonstrate rapid ingestion of particles arriving at the sea floor at a depth of 4 100 m by mobile epibenthic holothuroids abyssocucumis abyssorum and oneirophanta mutabilis excess 234 th and 210 pb activities of sediment trap material detrital aggregates from the sea floor and animal gut contents all were similar while activities of surface sediments top 0 5 mm were considerably lower a simple calculation using the excess 210 pb concentration of two potential food sources sediment trap material and surface sediments shows that 91 of gut content material of a abyssorum must have come from material similar to that found in the sediment trap cups by setting the sediment trap material as age 0 apparent ages of 100 d and 12 13 d were estimated for the aggregates surface sediments and a abyssorum guts respectively the population of a abyssorum at this site could potentially process 0 2 4 of the vertical mass flux m 2 d 1 during the high particle flux period between june and october 1994 the percentage of vertical flux processed could be substantially greater when all of the mobile epibenthic megafauna species are considered

upper palaeozoic subduction accretion processes in the closure of palaeotethys evidence from the chios melange e greece the karaburun melange w turkey and the teke dere unit sw turkey abstract during late palaeozoic time a wide ocean known as palaeotethys separated the future eurasian and african continents this ocean closed in europe in the west during the variscan orogeny whereas in asia further east it remained open and evolved into the mesozoic tethys only finally closing during late cretaceous early cenozoic three upper palaeozoic lithological assemblages the chios melange on the aegean greek island the karaburun melange westernmost aegean turkey and the teke dere unit lycian nappes sw turkey provide critical information concerning sedimentary and tectonic processes during closure of palaeotethys the chios and karaburun melanges in the west are mainly terrigenous turbidites with blocks and dismembered sheets of silurian upper carboniferous platform carbonate rocks shallow water and slope facies and poorly dated volcanic rocks the teke dere unit to the southeast begins with alkaline within plate type volcanics depositionally overlain by upper carboniferous shallow water carbonates this intact succession is overlain by a tectonic slice complex comprising sandstone turbidites that are intersliced with shallow water slope and deep sea sediments locally dated as early carboniferous sandstone petrography and published detrital mineral dating imply derivation from units affected by the panafrican cadomian and variscan orogenies all three units are interpreted as parts of subduction complexes in which pervasive shear zones separate component parts silurian lower carboniferous black cherts lydites and slope carbonates accreted in a subduction trench where sandstone turbidites accumulated some blocks retain primary depositional contacts showing that gravitational processes contributed to formation of the melange detached blocks of upper palaeozoic shallow water carbonates e g chios are commonly mantled by conglomerates which include water worn clasts of black chert the carbonate blocks are restored as one or several carbonate platforms that collided with an active margin fragmenting into elongate blocks that slid into a subduction trench this material was tectonically accreted at shallow levels within a subduction complex resulting in layer parallel extension shearing and slicing the accretion mainly took place during late carboniferous time alternative sedimentary tectonic models are considered in which the timing and extent of closure of palaeotethys differ and in which subduction was either northwards towards eurasia or southwards towards gondwana or both terrane displacement is also an option a similar but metamorphosed accretionary unit the konya complex occurs hundreds of kilometres further east all of these units appear to have been assembled along the northern margin of gondwana by permian time followed by deposition of overlying tauride type carbonate platforms northward subduction of palaeotethys beneath eurasia is commonly proposed however the accretionary units studied here are more easily explained by southward subduction towards gondwana palaeotethys was possibly consumed by long lived late palaeozoic northward subduction beneath eurasia coupled with more short lived late carboniferous southward subduction near gondwana during or soon after closure of palaeotethys in the balkan region to the west

magnetostratigraphy and biostratigraphy of an anisian ladinian middle triassic boundary section from hydra greece on the island of hydra the anisian ladinian boundary is exposed in a 24 m thick section of nodular reddish han bulog limestone this paper is focused on the magnetostratigraphy and conodont biostratigraphy of this section the anisian ladinian boundary is defined by the first appearance datum fad of the conodont species gondolella trammeri kozur base of the nevadites ammonoid zone and occurs in a normal polarity zone microfacies analysis has distinguished a lower and upper lithofacies recording gradual shallowing from pelagic conditions to a platform margin paleoenvironment

a mesozoic time scale we present an integrated geomagnetic polarity and stratigraphic time scale for the triassic jurassic and cretaceous periods of the mesozoic era with age estimates and uncertainty limits for stage boundaries the time scale uses a suite of 324 radiomenc dates including high resolution 40 ar 39 ar age estimates this framework involves the observed ties between 1 radiometric dates biozones and stage boundaries and 2 between biozones and magnetic reversals on the seafloor and in sediments interpolation techniques include maximum likelihood estimation smoothing cubic spline fitting and magnetochronology

the effect of horizontal resolution on gravity waves simulated by the gfdl skyhi general circulation model to examine the effects of horizontal resolution on internal gravity waves simulated by the 40 level gfdl skyhi general circulation model a comparison is made between the 3 and 1 resolution models during late december the stratospheric and mesospheric zonal flows in the winter and summer extratropical regions of the 1 model are much weaker and more realistic than the corresponding zonal flows of the 3 model the weaker flows are consistent with the stronger eliassen palm flux divergence epfd

middle triassic magnetostratigraphy and biostratigraphy from the dolomites and greece abstract magnetostratigrapic and biostratigraphic data across the anisian ladinian middle triassic boundary were obtained from the frotschbach seceda section from the dolomites region of northern italy and the vlichos section from the greek island of hydra where the aghia triada published section was also resampled the frotschbach seceda section includes two radiometrically dated u pb tuff levels and covers two of the three chief candidates for the position of the base of the ladinian namely at the base of the secedensis zone or the subsequent curionii zone the aghia triada section yields biochronological evidence for the base of the secedensis zone whose significance is however critically discussed in the light of the magnetostratigraphic correlation with frotschbach seceda the vlichos section can be correlated with aghia triada and frotschbach seceda by means of magnetic polarity stratigraphy and sparse fossil occurrences the satisfactory correlation of the magnetozones allows us to construct a composite geomagnetic polarity sequence tied to tethyan ammonoid and conodont biostratigraphy for about a 2 4 myr interval across the anisian ladinian boundary

magnetostratigraphy of a lower middle triassic boundary section from chios greece the marmarotrapeza formation at chios island northern aegean sea greece is renowned for its lower middle triassic boundary sections in a marine tethyan setting two sections have been sampled bed by bed to develop a magnetostratigraphic framework for the ammonoid and conodont biostratigraphy the boundary sections occur within a lower normal a reverse b upper normal c polarity sequence the lower middle triassic boundary placed at the first occurrence of the ammonoid genera aegeiceras ugra diener paracrochordiceras spp paradanubites depressus fantini sestini and japonites sp and close to the first appearance of the conodont species gondolella timorensis nogami occurs in normal polarity zone chios c the overall mean direction of the reversal bearing characteristic component whose early acquisition is suggested by a tilt test is d 271 2 i 33 2 t 95 11 7 k 112 5 n 3 the inferred paleolatitude of the sampling sites is about 18 n consistent with either an african or stable european affinity although the declinations suggest large scale counter clockwise rotations with respect to africa or stable europe since the early middle triassic

bioturbation in the abyssal arabian sea influence of fauna and food supply abstract in order to evaluate bioturbation in abyssal arabian sea sediments of the indus fan profiles of 210 pb half life 22 3 yr and 234 th half life 24 1 d were measured in cores collected during september and october 1995 and april 1997 respectively the density and composition of epibenthic megafauna and lebensspuren were determined in vertical seafloor photographs during april 1997 mean eddy diffusive mixing coefficients according to the distribution of excess 210 pb 210 pb db were 0 072 0 028 0 068 0 055 0 373 0 119 0 037 0 009 and 0 079 0 119 cm2 yr 1 in the northern western central eastern and southern abyssal arabian sea respectively mean eddy diffusive mixing coefficients according to the distribution of excess 234 th 234 th db were 0 53 1 64 and 0 47 cm2 yr 1 in the northern western and central abyssal arabian sea respectively mobile epibenthic megafauna at the western northern central and southern study sites were dominated by ophiuroids holothurians ophiuroids and natant decapods the respective densities were 100 82 29 and 6 individuals 1000 m 2 the northern study site was characterized by a high abundance of spoke traces and fecal casts the central site showed spoke traces and many tracks the southern site displayed the highest abundance of spoke traces whereas at the western site hardly any lebensspuren were observed there is evidence for at least two functional endmember communities in the arabian sea in the northwestern arabian sea wast vertical particle displacement seems to be dominated by macrofauna and primarily eddy diffusive in the southern arabian sea sast non local and incidental mixing due to spoke trace producers might become more important and superimpose reduced eddy diffusive mixing with respect to biological data cast is an intermediate location given the biological data average 210 pb db is higher and decimeter scale variability of 210 pb db smaller at cast than expected these findings indicate that in a mixture of both endmember communities the organisms may interact in way that increases values of biodiffusivity as reflected by 210 pb db and reduces decimeter scale 210 pb db heterogeneity in comparison to the simple sum of the isolated effects of the endmembers for time scales 210 pb db and 234 th db bioturbation intensity should be controlled primarily by the composition of the benthic fauna its specific adaptation to the environmental setting and the abundance of each species of the benthic community food supply can have only an indirect influence on bioturbation intensity in certain parts of the ocean the a priori overall positive relationship between poc flux and biodiffusivity might include restricted intervals displaying no or even negative relations

phytodetritus at the abyssal seafloor across 10 of latitude in the central equatorial pacific fresh phytoplankton detritus or phytodetritus has been reported from numerous deep seafloor sites in the temperate north atlantic and pacific oceans following seasonal phytoplankton blooms here we report the first strong evidence for abyssal accumulations of phytodetritus in the tropics in the central equatorial pacific in november december 1992 we obtained photographs and or sediment core samples from 61 abyssal stations water depths of 4280 5012 m between 12 s and 9 n along 140 w greenish flocculent material was recovered from the top of multiple core samples from 5 s to 5 n this material was most abundant from 2 s to 2 n in some areas forming continuous layers at least 5 mm thick and individual aggregates 1 cm in diameter the greenish material was clearly visible in bottom photographs as a green veneer that covered 95 of the seafloor near the equator and as individual cm scale aggregates covering 1 of the seafloor occasionally thick accumulations of cm scale aggregates occurred in biogenic pits cleared trails and feeding traces suggest that surface deposit feeding holothurians and echiurans grazed the greenish material microscopic examination of greenish material recovered from core tops and a burrow lumen revealed relatively intact diatoms including rhizosolenia sp and other microalgae with chloroplasts containing chlorophyll the greenish material was 1 12 5 organic carbon by weight i e 5 39 times richer than associated seafloor sediments it also contained high excess activities of 234th suggesting arrival from the water column in the previous 100 days samples of the greenish flocculent material from 0 and 5 n incubated at simulated environmental pressure and temperature with 14c labeled glutamate exhibited 5 fold higher rates of microbial activity than underlying sediments or brown floc from 9 n surface sediment samples which included the greenish flocculent material from 5 s to 5 n also contained significant concentrations of chlorophyll a and other chloropigments the chloropigment concentrations were roughly comparable to deep sea phytodetritus collected in the north atlantic we conclude that fresh organic rich phytodetritus was present on the seafloor from 5 s to 5 n along 140 w in november december 1992 with highest concentrations within 2 3 of the equator this material is likely to be a concentrated high quality food resource for deep sea microbes and metazoans we estimate an upper limit for the standing stock of this phytodetritus to be 2 6 mmol corg m2 this corresponds to 3 of the annual flux of organic carbon to the seafloor at these latitudes in 1992 because the degradation rate of this material appears to be very high its presence at the seafloor for several months per year could yield significant phytodetrital contributions to the annual seafloor organic carbon budget we also suggest that the phytodetrital aggregates are formed at intense convergence zones resulting from seasonal passage of tropical instability waves within 5 of the equator if so phytodetrital accumulations are likely to recur seasonally over broad areas of the abyssal equatorial pacific

alleviation of a systematic westerly bias in general circulation and numerical weather prediction models through an orographic gravity wave drag parametrization systematic westerly biases in the northern hemisphere wintertime flow of the meteorological office 15 layer operational model and 11 layer general circulation model are described evidence that the failure to parametrize subgrid scale orographic gravity wave drag may account for such biases is presented this evidence is taken from aircraft studies surface pressure drag measurements and studies of the zonally averaged momentum budget a parametrization scheme is described in which the surface stress is proportional to the near surface wind speed and static stability and to the variance of subgrid scale orography the stress is absorbed in the vertical by considering the influence of such gravity wave activity on static stability and vertical wind shear a richardson number dependent wave breaking formulation is devised and the vertical stress profile determined by a saturation hypothesis whereby the breaking waves are maintained at marginal stability it is shown that wave breaking preferentially occurs in the boundary layer and in the lower stratosphere results from a simple zonally symmetric model show how the adjustment to thermal wind balance with a wave drag in the stratosphere warms polar regions by adiabatic descent and decelerates the mean westerlies in the troposphere the influence of the parametrization scheme on integrations of the 11 layer model is described and found to be generally beneficial in a discussion of the reasons why this problem has only recently emerged it is suggested that the satisfactory northern hemisphere winter circulations of previous coarser general circulation models were due to a compensation implied by underestimating both the surface drag and the horizontal flux of momentum by explicitly resolved large scale eddies

focusing of phytodetritus deposition beneath a deep ocean front chatham rise new zealand in october 2001 we observed a deep ocean phytodetritus deposition event on chatham rise beneath the subtropical front stf the origin of this phytodetritus was probably an extensive phytoplankton bloom that occurred in the stf in the preceding weeks we assessed the spatial distribution of the deposition event using video images from benthic lander and epibenthic trawl deployments and sediment pigment analyses at six sites on a north south transect across chatham rise high surficial sediment chlorophyll a concentrations were restricted spatially to the southern flank of chatham rise 350 1 200 m depth with the highest values centered at 750 m water depth 750 s this southern 750 s site was also the only site where macroscopic phytodetritus was observed coincident with elevated benthic biomass and sediment community respiration rates at 750 s phytodetritus resuspension was observed on video and corroborated by current meter sediment trap and optical

formation of the late palaeozoic konya complex and comparable units in southern turkey by subduction accretion processes implications for the tectonic development of tethys in the eastern mediterranean region abstract the southern margin of eurasia from the balkan region eastwards is widely envisaged as an active continental margin related to northward subduction at least during late carboniferous early cenozoic time by contrast the late palaeozoic setting of the southern gondwana margin was previously interpreted as an intra continental marginal basin related to southward subduction beneath the northern margin of gondwana or as part of a forearc complex e g forearc basin related to northward subduction beneath eurasia palaeotethyan evolution is recorded in the konya complex new name an assemblage of palaeozoic silurian carboniferous meta sedimentary and meta igneous rocks that is exposed beneath metamorphosed upper permian mesozoic shelf type sediments in central southern turkey to the north of the tauride mountains the konya complex is dominated by large thrust slices of mainly devonian shallow water platform carbonates bozdag unit there is also a melange that is made up of lenticular sheets and blocks of mainly lower carboniferous shallow water limestones silurian devonian black chert lydite pelagic limestones and rare blocks of mid ocean ridge type and within plate type basaltic rocks the blocks are set in a mainly terrigenous derived siliciclastic matrix locally including siliceous tuff the matrix is interpreted as mainly deep water turbidites and debris flow deposits an overlying intact volcanic sedimentary sequence includes chemically enriched extrusives e g trachyandesites that also exhibit a negative nb anomaly suggesting a subduction influence dykes crosscutting the carbonate platform units are relatively depleted and also show a subduction influence shallow marine carbonates and terrigenous quartzose sediments of mainly late permian age are exposed above the konya complex in the west of the area in contrast triassic non marine to shallow marine clastic sediments unconformably overlie the konya complex in the east of the area both the permian and the triassic sediments pass upwards without a break into a middle triassic upper cretaceous platform carbonate succession which was overthrust by accretionary melange and ophiolites during latest cretaceous time the mesozoic carbonate platform and the underlying konya complex experienced polyphase deformation and partial high temperature low pressure metamorphism related to alpine late cretaceous early cenozoic closure of tethys comparison of tauride and pontide units suggests the deformed konya complex upper palaeozoic carbonate platform has gondwanan affinities we also compare the complex with other upper palaeozoic units in southern turkey including the tekedere unit lycian nappes and the karaburun and chios melanges all of these units are interpreted to have formed by subduction accretion processes alternative possible settings involve northward subduction southward subduction or terrane displacement strike slip northward subduction beneath eurasia requires collisional assembly with gondwana possibly during the latest triassic cimmerian orogeny for which there is little evidence a southward dipping subduction zone would need to be located some distance outboard of the gondwana margin as there is little evidence of upper palaeozoic arc magmatism in the tauride platform emplacement as an exotic terrane probably derived from further west in the balkan region is also possible

magnetostratigraphy of the permo triassic boundary section at shangsi guangyuan sichuan province china continous marine sedimentation characterizes many late permian to early triassic sections on the yangtze terrane in south china the permo triassic p tr boundary section at shangsi sichuan province consists of limestones intercalated with clays and mudstones which belong to the wuchiapingian and changxingian upper permian and the griesbachian and dienerian lower triassic stages the p tr boundary is formed by a clay horizon with an unusually high iridium concentration the intensity of natural remanent magnetization is very low with a mean of 0 15 ma m 1 about 40 of the samples contain secondary or unstable magnetization components only whereas the remaining samples carry a characteristic remanent magnetization thought to reflect the polarity of the geomagnetic field during deposition with sufficient accuracy normal and reversed polarity of the characteristic magnetization constitute a pattern of at least six polarity zones the p tr boundary being situated very close to the transition from a reversed to a normal polarity zone the shangsi polarity sequence represents part of the illawarra interval of mixed polarity the exact beginning of which has still to be determined

palaeomagnetism of permo triassic rocks in the iberian cordillera spain acquisition of secondary and characteristic remanence magnetostratigraphy is widely used as a tool for stratigraphical correlation but there are problems in its application to rocks which have suffered complex diagenesis particularly sandy continental red beds in such cases the complete magnetic record should be studied in relation to its depositional diagenetic and structural history to this end a detailed palaeomagnetic study has been made of permian and triassic rocks in the northern iberian cordillera spain four stratigraphical units comprising the autunian 9saxonian9 buntsandstein and muschelkalk have been studied in a single section near molina de aragon which is well documented sedimentologically autunian rocks have a characteristic remanence which is exclusively reversed and corresponds to the kiaman interval of lower permian age a pole position 49 n 167 w is consistent with previous studies which indicate the rotation of iberia in post triassic times relative to the stable european plate the saxonian facies show complex multicomponent magnetizations no polarity zonation can be resolved but individual components were acquired prior to the rotation of iberia the buntsandstein is remarkable in that much of it is completely remagnetized in a direction similar to the present local geomagnetic direction this secondary remanence is carried by fine grained hematite which has been formed as a result of carbonate dissolution and other diagenetic reactions initially these iron oxides were probably superparamagnetic and remanence was only blocked in by structural inversion of the iberian cordillera in tertiary times and after rotation of the iberian plate some of the primary remanence is preserved in some fine grained lithologies of the buntsandstein indicating that normal and reversed zones of magnetization were originally present the magnetization of the muschelkalk carbonates is also complex secondary components similar to those of the buntsandstein are present but there is evidence that primary components were mainly normal during karnian times

simulation of the semi annual oscillation of the equatorial middle atmosphere using the extended ugamp general circulation model the semi annual oscillation sao is examined in two runs of a middle atmosphere general circulation model the first run pgw includes a parametrization of gravity waves with zero phase speed only whilst the second run agw also includes gravity waves with phase speeds of 20 m s 1 run pgw successfully simulates equatorial saos near the stratopause and in the mid to upper mesosphere however the zonal winds at all heights are easterly and the amplitude of the oscillation is too weak by up to 15 m s 1 near the stratopause and too strong by about 45 m s 1 in the upper mesosphere the corresponding saos in run agw however have amplitudes that are within 5 m s 1 of those observed by rocketsondes and have a pattern of easterly and westerly winds that are in reasonable agreement with the observations zonal mean momentum budget studies show that both at the stratopause and in the mid to upper mesosphere the westerly phase of the oscillation in run agw is stronger than in run pgw owing to an increase in total eddy forcing associated with the introduction of the 20 m s 1 phase speed gravity wave the easterly phase of the stratopause oscillation on the summer side of the equator is driven by advection of easterlies across the equator however on the winter side of the equator the net zonal forcing is westerly in may but easterly in november since easterly eddy forcing associated with extratropical planetary waves is stronger in november than in may the easterly phase of the mid to upper mesosphere oscillation is forced by contributions from both the residual circulation and eddy forcing the eddy forcing contribution is more easterly than in other modelling studies owing to weaker kelvin wave activity and to easterly forcing associated with model diurnal tides introduction of the 20 m s 1 gravity waves also improves the simulation of an n2o like tracer in run agw a double peak of tracer is present in april in reasonable agreement with observations but this feature is absent in run pgw

the benthic silica cycle in the northeast atlantic annual mass balance seasonality and importance of non steady state processes for the early diagenesis of biogenic opal in deep sea sediments within the framework of the eu funded bengal programme the effects of seasonality on biogenic silica early diagenesis have been studied at the porcupine abyssal plain pap an abyssal locality located in the northeast atlantic ocean nine cruises were carried out between august 1996 and august 1998 silicic acid dsi increased downward from 46 2 to 213 m mean of 27 profiles biogenic silica bsi decreased from ca 2 near the sediment water interface to 1 at depth benthic silicic acid fluxes as measured from benthic chambers were close to those estimated from non linear dsi porewater gradients some 90 of the dissolution occurred within the top 5 5 cm of the sediment column rather than at the sediment water interface and the annual dsi efflux was close to 0 057 mol si m 2 yr 1 biogenic silica accumulation was close to 0 008 mol si m 2 yr 1 and the annual opal delivery reconstructed from sedimentary fluxes assuming steady state was 0 065 mol si m 2 yr 1 this is in good agreement with the mean annual opal flux determined from sediment trap samples averaged over the last decade 0 062 mol si m 2 yr 1 thus ca 12 of the opal flux delivered to the seafloor get preserved in the sediments a simple comparison between the sedimentation rate and the dissolution rate in the uppermost 5 5 cm of the sediment column suggests that there should be no accumulation of opal in pap sediments however by combining the bengal high sampling frequency with our experimental results on bsi dissolution we conclude that non steady state processes associated with the seasonal deposition of fresh biogenic particles may well play a fundamental role in the preservation of bsi in these sediments this comes about though the way seasonal variability affects the quality of the biogenic matter reaching the seafloor hence it influences the intrinsic dissolution properties of the opal at the seafloor and also the part played by non local mixing events by ensuring the rapid transport of bsi particles deep into the sediment to where saturation is reached

testing the foodbancs hypothesis seasonal variations in near bottom particle flux bioturbation intensity and deposit feeding based on 234th measurements abstract naturally occurring 234th 24 d half life was used on the west antarctic continental shelf to evaluate temporal variations in the flux of particulate material reaching the seabed bioturbation intensity the seasonal continuity of feeding by benthic fauna and trends in particle selection during ingestion for six common detritivores four surface deposit feeders and two subsurface deposit feeders these measurements were made at three stations during the five foodbancs cruises december 1999 march june and october 2000 and march 2001 to assess the nature of pelagic benthic coupling on the shelf and to evaluate the seabed as a potential food bank for deposit feeders when surface primary production is minimal two summer regimes were sampled march 2000 and march 2001 with the latter exhibiting a distinct 1 2 cm thick phytodetritus layer in nearly all sediment core samples at site b the 234th fluxes into the near bottom 150 170 mab sediment traps were indistinguishable for the december march 2000 march june 2000 and june october 2000 sampling intervals fluxes ranging from 170 to 280 dpm m 2 d 1 however the sediment trap 234th flux measured for the october 2000 march 2001 interval 1000 dpm m 2 d 1 was 5 fold greater than during the other three sampling periods consistent with the deposition of a phytodetritus layer the steady state 234th fluxes derived from seabed inventories at site b were 2 4 2 7 times greater than the sediment trap 234th fluxes indicating substantial scavenging of this particle reactive radiotracer in the bottom 150 m of the water column and or lateral transport near the seabed the seabed 234th inventories at the three stations showed no variation during the first four cruises but were significantly greater during cruise fb v march 2001 when the phytodetritus layer occurred based on 234th distributions in the seabed bioturbation intensities quantified using the diffusive mixing coefficient db varied from 0 5 to 97 cm2 yr 1 mixing coefficients were significantly lower during fb ii than during fb iii but no other time comparisons were statistically significant p 0 05 234th dbs showed no distinct seasonality and no correlation with either organic carbon flux into the sediment traps or 234th inventory in the seabed the four surface deposit feeders examined an echiuran worm and three holothurians protelpidia murrayi bathyplotes fuscivinculum and peniagone vignoni exhibited greater particle selection for recently deposited sediment during ingestion than the two subsurface deposit feeders studied a head down deposit feeding holothurian molpadia musculus and an irregular urchin amphipneustes lorioli all six deposit feeders contained excess 234th activity in gut sediments during all five cruises indicating sediment ingestion year round even during the austral winter the lack of seasonal variation in bioturbation intensity and the demonstration of year round feeding in deposit feeders are consistent with the hypothesis that the seafloor sediments accumulate labile organic matter produced during periods of high primary production and that deposit feeders utilize this food source as a food bank on a year round basis

upper anisian to lower carnian magnetostratigraphy from the northern calcareous alps austria we present a magnetostratigraphic study of three pelagic limestone sections gamsstein mendlingbach and mayerling from the eastern part of the northern calcareous alps together these sections which contain a rich conodont fauna yield a sedimentary record encompassing the uppermost anisian the ladinian and the lower carnian thermal demagnetization and isothermal remanent magnetization experiments indicate that the magnetization is essentially carried by a mineral of the magnetite family the high unblocking temperature components isolated from the three sections provide clear magnetic polarity zonations correlations between these results based on the biostratigraphic data and tephrochronology allow the construction of a composite magnetic polarity sequence from the illyrian substage upper anisian to the julian 2 zone lower carnian this sequence contains 17 well defined polarity reversals and eight more poorly defined intervals correlations can be suggested between the new data and other magnetostratigraphic results previously obtained from marine sections we estimate that the magnetic reversal frequency was 2 5 to 3 6 reversals per million years during the ladinian

interactions between gravity waves and planetary scale flow simulated by the gfdl skyhi general circulation model abstract in order to study interactions between gravity waves and planetary flow in the middle atmosphere a 3 latitude by 3 6 longitude version of the 40 level gfdl skyhi general circulation model is analyzed using bihourly sampled output data it is shown by a space time spectral analysis that gravity waves in the mean zonal westerlies easterlies mainly consist of westward eastward moving components and carry easterly westerly momentum upward and decelerate the mean zonal westerlies easterlies in the mesosphere zonal momentum flux convergence due to gravity waves accounts for nearly all of the eliassen palm e p flux divergence in the summer mesosphere this convergence accounts for 30 50 of that in the winter upper mesosphere however this percentage is probably an underestimate since the convergence is significantly enhanced in a high resolution 1 1 2 model currently being integrated vertical propagation of gravity waves is affected not only by the mean zonal wind but also

general circulation model simulation of the semiannual oscillation of the tropical middle atmosphere abstract a study has been made of the evolution of the zonal mean zonal wind and temperature in a multiyear integration of the 40 level 3 3 6 resolution skyhi general circulation model gcm that has been developed at gfdl in the tropical upper stratosphere the mean wind variation is dominated by a strong semiannual oscillation sao the peak sao amplitude in the model is almost 25 m s 1 and occurs near the 1 mb level the phase of the sao near the stratopause is such that maximum westerlies occur shortly after the equinoxes these features are in good agreement with the available observations in addition the meridional width of the stratopause sao in the gcm compares well with observations a diagnostic analysis of the zonal mean momentum balance near the tropical stratopause was performed using the detailed fields archived during the gcm integration it appears that the easterly accelerations in the model sao are provided by a combination of i divergence of the meridional component of the el