spatial and temporal variation in european neogene large mammals diversity abstract large mammals diversity i e ungulates or hoofed mammals is investigated over the whole european geographic area and through a period extending from the late oligocene around 27 ma ago to the early pliocene around 3 ma ago qualitative and quantitative spatial and temporal patterns are discussed thanks to the analysis of a large dataset of localities 695 that yielded large mammals and distributed over this period and area we show that the miocene is a key period in the installation of modern faunas in europe modern ruminants mainly cervids and bovids largely develop during the period considered and replace the oligocene inherited dominant faunas these replacements are triggered by different factors often extrinsic and constitute the roots of the present situation indeed a complex interplay between geographic palaeogeographic reorganisations and climatic factors warming and cooling events can be invoked to understand how faunas change geography seems to play a crucial role in the early miocene when it allows migration routes to open between europe asia and africa and in turn leads to a drastic increase of ungulate diversity that seems to be maintained in the middle miocene under the warm equable climates of the miocene climatic optimum the late miocene sees a global climatic deterioration leading to a decline in large mammals diversity and represents the root of the extant depleted situation regional comparisons indicate that endemism was already strong in the miocene especially in south eastern europe and that strong climatic belts already seem to have an impact on mammal communities since the late miocene the roots of the extant situation endemism and low diversity are therefore more complex and probably older than previously thought they are to be looked for before the quaternary climatic cycles and are the by product of deep time geographic and climatic events

size sorting in marine muds processes pitfalls and prospects for paleoflow speed proxies the basis for and use of fine grain size parameters for inference of paleoflow speeds is reviewed here the basis resides in data on deposited sediment taken in conjunction with flow speed measurements in the field experimental data on suspended sediment transport and deposition and theoretical treatments of the generation of size distributions of deposits from suspension controlled by particle settling velocity and flow speed in the deep sea sorting events occur under resuspension deposition events in benthic storms at flow speeds below 10 15 cm s 1 size in the noncohesive sortable silt 10 63 m range is controlled by selective deposition whereas above that range removal of finer material by winnowing also plays a role the best particle size instruments to measure a flow speed related grain size employ the settling velocity method while laser diffraction sizers can yield misleading results because of particle shape effects potential problems including source effects downslope supply on continental margins spatial variability of flow over bedforms and influence of ice rafted detritus are examined a number of studies using the sortable silt flow speed proxy are reviewed and inverse modeling of grain size distributions is examined outstanding problems are that corroboration is sparse because almost no studies have yet used the full range of proxies for flow rate and water mass identification and that the sortable silt mean size is not yet properly calibrated in terms of flow speed

deglacial sea level record from tahiti corals and the timing of global meltwater discharge the timing of the last deglaciation is important to our understanding of the dynamics of large ice sheets1 and their effects on the earth s surface2 3 moreover the disappearance of the glacial ice sheets was responsible for dramatic increases in freshwater fluxes to the oceans which probably disturbed the ocean s thermohaline circulation and hence global climate4 7 sea level increases bear witness to the melting of continental ice sheets but only two such records from barbados8 9 and new guinea10 11 corals have been accurately dated but these corals overlie active subduction zones where tectonic movements are large and often discontinuous especially in new guinea so the apparent sea level records may be contaminated by a complex tectonic component here we date fossil corals from tahiti which is far from plate boundaries and thus is likely to be tectonically relatively stable and remote from the locations of large former ice sheets the resulting record indicates a large sea level jump shortly before 13 800 calendar years bp which corresponds to meltwater pulse 1a in the barbados coral records8 9 the timing of this event is more accurately constrained in the tahiti record revealing that the meltwater pulse coincides with a short and intense climate cooling event12 15 that followed the initiation of the bolling allerod warm period12 16 but preceded the younger dryas cold event by about 1 000 years

a geophysical study of the manila trench luzon philippines 1 crustal structure gravity and regional tectonic evolution the manila trench subduction zone is an active convergent plate margin between the south china sea and the northern philippines the trench trends northerly and is associated with a volcanic arc an east dipping benioff zone beneath luzon and a well developed fore arc basin system the luzon trough fore arc basins lie landward of the manila trench and contain up to 4 5 km of cenozoic sediments offscraping and accretion of turbidite sediments deposited in the manila trench have resulted in the upbuilding and outbuilding of an accretionary prism which forms the seaward margin of the fore arc basin system the uplifted zambales ophiolite and its offshore extension form the landward side of the fore arc basin multichannel seismic reflection profiles reveal that folding and thrust faulting of trench strata occur at the base of the trench slope the major structural decollement at the manila trench usually forms near the unconformity separating the hemipelagic sediments from the turbidite sediments subduction and perhaps underplating of the basal hemipelagic trench sediments accompany the deformation and accretion of the overlying clastic deposits faulting and uplift occur within a narrow zone of the fore arc where seamounts associated with the relict spreading center of the south china sea basin have presumably been subducted north of lingayan gulf the fore arc is disrupted by active fault systems that trend north and northwest offshore from the luzon central valley and from the southern cordillera central based on regional geological and tectonic observations we infer that subduction probably began at the manila trench in late oligocene to middle miocene time the long term average convergence rate at the manila trench is estimated to be between 10 and 20 mm yr and may be slowing in the north owing to the collision of taiwan with eurasia

discovery of the oldest european ruminant in the late eocene of bulgaria did tectonics influence the diachronic development of the grande coupure abstract we describe the oldest known european ruminant bachitherium thraciensis sp nov from late eocene latest bartonian or early priabonian strata in bulgaria the new specimen which possesses the most primitive dental morphology known in the bachitheriidae family predates its western european relatives by at least 4 5 myr the discovery suggests that ruminants dispersed into europe in a series of east to west waves preceding and following the eocene oligocene boundary probably originating from asia the oldest ruminant reported here migrated into southeastern europe during a second wave comprising the grand coupure dispersal event ruminants moved into western europe at the eocene oligocene boundary a third wave composed by bachitheriidae and tragulidae arrived in western europe 2 myr later in the earliest oligocene the origin of this east to west diachronism was probably facilitated by orogenesis that episodically allowed dispersal of ruminants from asia through southeastern europe and into western europe in what we herein term the bachitherium dispersal event however none of the abundant perissodactyl fauna from southeastern europe migrated to western europe during this time because like their relatives in central asia they may not survive to terminal eocene cooling and aridity

a new chalcolithic era tsunami event identified in the offshore sedimentary record of jisr al zarka israel abstract tsunami field evidence is a critical resource for determining coastal risk however in many cases there is low potential for long term preservation of such deposits on land a growing body of evidence suggests that tsunami deposits can be present in the shallow offshore realm and may present a largely untapped but important worldwide sedimentological reference set for investigating past tsunami events here different proxies for tsunami sediment identification and differentiation granulometry xrd xrf ft ir were used to determine the presence or absence of such deposits in a core collected offshore at jisr al zarka midway between tel aviv and haifa the study aimed to recognize anomalous deposits and test different analytical methods to define their origins five anomalous sedimentological horizons were identified four of which were interpreted as tsunamigenic by comparison to previously identified poorly sorted shell rich tsunamites found nearby in caesarea and contrast to the fine sand nile derived background sediments the remaining anomaly was distinctive but not determined to be tsunamigenic due to a lack of coarse shell in the matrix the oldest tsunamigenic layer coinciding with the chalcholithic cultural period 5 7 ka is the oldest such deposit identified offshore israel to date and the non tsunamigenic anomalous horizon may correspond with a transitional climatic phase 5 5 ka this research reinforces the importance of offshore investigations as a means of improving tsunami catalogues and identifying environment altering events

floristic changes indicate a cooling climate in the eocene of southern england a major climatic cooling at the close of the eocene the terminal eocene event is suggested by studies of leaf floras in north america1 2 and by oxygen isotope studies of mollusc shells from the north sea3 and of planktonic and benthic foraminifera from the north and south pacific4 climatic fluctuations in the french palaeogene5 8 inferred from palynological studies are difficult to interpret in terms of this single event the pacific faunal studies4 and preliminary palynological evidence from the isle of wight southern england9 indicates an onset of cooling earlier in the eocene we have therefore examined fossil floras fruits seeds pollen and spores from the palaeogene deposits of the london and hampshire basins of southern england which form a continuous sequence from the early eocene we find no evidence for a sudden climatic change at the end of the eocene taken to be near the base of the bembridge marls in the hampshire basin10 our evidence in the form of two major periods of floristic change suggests a more gradual cooling commencing in the latest early eocene

sedimentary succession and evolution of the mediterranean ridge western sector as derived from lithology of mud breccia clasts abstract rock fragments from mud breccia extruded by mud volcanoes discovered during the ttr 4 cruise of the r v gelendzhik on the western mediterranean ridge are represented by a number of different lithologies they provide important information on the composition genesis and age of the deep seated sedimentary series of the basin lithological description and age determination of the main rock types obtained as clasts from mud breccia were made on the basis of a study of ninety seven samples depositional processes and environments of their accumulation were determined using sedimentological criteria the sedimentary section through which mud volcanoes erupted on the western mediterranean ridge includes aptian albian claystones late cretaceous limestones paleogene siliciclastic rocks and a variety of miocene limestones and mudstones the rock clasts studied throw insight into the evolution of the western sector of the eastern mediterranean basin from at least aptian time the aptian albian clayey series have been deposited in the marine conditions of a relatively narrow basin with a high input of terrigenous clayey material during the late cretaceous the basin enlarged terrigenous input into deep parts of the basin decreased and carbonate pelagic sedimentation became prevalent regression in paleogene time led to the deposition of thick terrigenous siliciclastic series of deltaic prodeltaic sediments extensive turbidite systems were emplaced in the western sector of the eastern mediterranean during the miocene along with predominantly carbonate pelagic sedimentation

the eocene oligocene ungulates from western europe and their environment abstract a survey of paleogene ungulates from western europe is drawn up from the results of previous work on the ungulate lineages of this period and from new data on two groups particularly representative of the oligocene ungulate fauna the ruminants and the cainotheriidae based on new material collected in localities of the quercy phosphorites the history of ungulates from western europe at the eocene oligocene transition is marked by different phases of extinction and origination related to environmental changes in this perspective the relative diversity of groups and the modifications of their tooth morphology which reflect a diet change resulting from vegetation modifications are analysed from the early eocene to the late oligocene in western europe the late eocene and the early oligocene was a period of transition with an important change in faunal and floral composition the diversity analysis of ungulates suggests that the grande coupure is the result of gradual climatic and geographic events that occurred from the middle eocene mammalian paleogene mp 13 14 reference levels to the early oligocene mp 21 22 reference levels during this period it has been demonstrated that important adaptive changes occurred in the ungulate dental pattern selenodonty in artiodactyls semihypsodonty in perissodactyls and appendicular skeleton fusion of the cuboid and navicular bones of the tarsus in artiodactyls these morphological modifications coincided with environmental changes that were less extreme than in north america

holocene tsunamis from mount etna and the fate of israeli neolithic communities 1 field evidence reveals that the neolithic village of atlit yam israeli coast was destroyed in an event which also caused the sudden death of tens of inhabitants archaeological evidence and numerical simulations support the notion that the village was destroyed 8 3 ka b p by a tsunami triggered by a known holocene flank collapse of mt etna volcano italy the filling of a water well within the village confirms inundation by a tsunami wave train and a sediment layer composed of a clayed sandy matrix and other detritus including reworked marine sediment indicates tsunami inundation this scenario shows that tsunamis generated by sector collapses from coastal volcanoes can seriously threaten near shore settlements thousands of kilometres distant from the tsunami source

fossil horses and carbon isotopes new evidence for cenozoic dietary habitat and ecosystem changes in north america abstract the transformation from low crowned to high crowned horse teeth during the miocene has traditionally been interpreted as an adaptive response to the spread of savanna grasslands during the middle miocene by about 15 m y ago carbon isotope data from 50 north american horse teeth spanning eocene to pleistocene age indicate that savanna grasslands presumably dominated by c 4 grasses as they are today first became widespread much later than do horses with high crowned teeth prior to 7 m y horses had a c 3 based diet and after 7 m y horses started eating c 4 grasses this change in diet occurred when the major drop in the diversity of horses occurs during the late miocene the change in vegetation reflected in horses diet may be related to a significant reduction in atmospheric co 2 level toward the end of the miocene which provided the c 4 grasses with an adaptive advantage and led to their expansion at the expense of c 3 plants

historical and pre historical tsunamis in the mediterranean and its connected seas geological signatures generation mechanisms and coastal impacts abstract the origin of tsunamis in the mediterranean region and its connected seas including the marmara sea the black sea and the sw iberian margin in the ne atlantic ocean is reviewed within the geological and seismotectonic settings of the region a variety of historical documentary sources combined with evidence from onshore and offshore geological signatures geomorphological imprints observations from selected coastal archeological sites as well as instrumental records eyewitnesses accounts and pictorial material clearly indicate that tsunami sources both seismic and non seismic e g volcanism landslides can be found in all the seas of the region with a variable tsunamigenic potential local regional and basin wide tsunamis have been documented an improved map of 22 main tsunamigenic zones and their relative potential for tsunami generation is presented from west to east the most important tsunamigenic zones are situated offshore sw iberia in the north algerian margin in the tyrrhenian calabria and messina straits in the western and eastern segments of the hellenic arc in the corinth gulf of central greece in the levantine sea offshore the dead sea transform fault and in the eastern side of the marmara sea important historical examples including destructive tsunamis associated with large earthquakes are presented the mean recurrence of strong tsunamis in the several basins varies greatly but the highest event frequency 1 96 years is observed in the east mediterranean basin for most of the historical events it is still unclear which was the causative seismic source and if the tsunami was caused by co seismic slip by earthquake triggered submarine landslides or by a combination of both mechanisms in pre historical times submarine volcanic eruptions i e caldera collapse massive pyroclastic flows volcanogenic landslides and large submarine landslides caused important tsunamis although little is known about their source mechanisms we conclude that further investigation of the tsunami generation mechanisms is of primary importance in the mediterranean region inputs from tsunami numerical modeling as well as from empirical discrimination criteria for characterizing tsunami sources have been proved particularly effective for recent well documented aseismic landslide tsunamis e g 1963 corinth gulf 1979 cote d azur 1999 izmit bay 2002 stromboli volcano since the tsunami generation mechanisms are controlled by a variety of factors and given that the knowledge of past tsunami activity is the cornerstone for undertaking tsunami risk mitigation action future interdisciplinary research efforts on past tsunamis are needed

impact of the minoan tsunami of santorini simulated scenarios in the eastern mediterranean 1 we have simulated the impact of the tsunami generated by the late bronze age lba volcanic eruption of santorini on the eastern mediterranean two different tsunami triggering mechanisms were considered a caldera collapse and pyroclastic flows surges entering the sea simulations include the worst input conditions in order to evaluate the maximum possible impacts but also lighter input conditions compatible with the lack of any tsunami trace on the northern coasts of crete in all the simulations tsunami propagation is mainly confined to the southern aegean outside the aegean the tsunami impact was negligible and not responsible for the slide slumping of fine grained pelagic and or hemipelagic sediments considered the sources of the sporadically located sea deposits in the ionian sea and of the widespread megaturbidite deposits localized in the ionian and sirte abyssal plains

abrupt climate change and transient climates during the paleogene a marine perspective detailed investigations of high latitude sequences recently collected by the ocean drilling program odp indicate that periods of rapid climate change often culminated in brief transient climates with more extreme conditions than subsequent long term climates two examples of such events have been identified in the paleogene the first in latest paleocene time in the middle of a warming trend that began several million years earlier the second in earliest oligocene time near the end of a middle eocene to late oligocene global cooling trend superimposed on the earlier event was a sudden and extreme warming of both high latitude sea surface and deep ocean waters imbedded in the latter transition was an abrupt decline in high latitude temperatures and the brief appearance of a full size continental ice sheet on antarctica in both cases the climate extremes were not stable lasting for less than a few hundred thousand years indicating a temporary or transient climate state geochemical and sedimentolog

les rongeurs de l eocene terminal et de l oligocene d europe comme indicateurs de leur environnement abstract palaeoecological interpretation of the occurrence of certain rodents in late eocene and oligocene strata from western europe is based on the establishment of five dental categories roughly linked with diet and environment time changes in species diversity and relative abundance in these categories are analyzed for the late eocene and oligocene periods the sequence is geographically limited quercy auvergne to avoid the mixing of environments that results from too general compiling cooling at the beginning of the late eocene created open areas testified by the occurrence of hypsodont rodents the great decrease in rodent diversity and species turnover at the grande coupure is probably related to the important decrease in temperature at the eocene oligocene boundary the less important diversity decrease at the mas de pauffie level mp 26 is perhaps an indication of a recurrent cooling at the beginning of the late oligocene maximum aridity also occurred at this level the calibration and correlation of these events with global events like the 29 ma decrease in temperature or the 30 ma great marine regression are discussed the decrease in abundance of issiodoromys with the great increase in species iversity of categories i and ii no to weakly hypsodont teeth during the late oligocene mark the development of forests related to increased moisture and temperature the analysis of time specific changes in the theridomyidae from their first occurrence to their extinction is related to the principal environmental events

palaeoenvironmental implication of resedimented limestones shed from mississippian permian mid oceanic atoll type buildup into slope to basin facies akiyoshi japan abstract for better understanding of long term environmental changes in a mid oceanic atoll type buildup akiyoshi limestone group we examined the atoll derived carbonate sediments that were contemporaneously shed into the spicular chert of slope to basin facies ota group in the akiyoshi area southwest japan both of these two units are dated as upper visean to capitanian and interpreted as having laterally passed into each other on and around a mid oceanic seamount the resedimented limestone occurs as slab like bodies and isolated and laterally discrete smaller pods and thin beds and laminae in the spicular chert of the ota group the composite succession ca 105 m thick measured in slab like bodies is divided into the lower and upper units each of which consists of the sharp based calcarenite siliceous lime mud siltstone and spicular chert with blocks beds and laminae of calcarenite and siliceous limestone in ascending order the calcarenite forming slabs and smaller blocks are massive and dominantly comprises densely packed coarse crinoid debris and subordinate bryozoan fragments with no or sparse matrix the siliceous lime mud siltstone consists of siliceous sponges spicules minute calcitic skeletal debris and peloidal particles with the matrix of a mixture of lime mud and microcrystalline quartz the calcarenite and siliceous lime mud siltstone beds and laminae in the spicular chert occasionally contain graded and parallel laminae the massive calcarenite and graded calcarenite and siliceous limestone were formed by redeposition mainly of skeletal sands presumably by grain flows with minor debris flows and by mixing of sponge spicule rich siliceous sediments and redeposited lime mud and skeletal debris by muddy turbidites of distal facies respectively these redeposited carbonate sediments were exported from the akiyoshi limestone group onto the spicular sediments of slope to basin facies conodonts fusulinids and smaller foraminifers from the resedimented limestone indicate that the redeposition of the carbonate sediments took place dominantly in late visean to late bashkirian and subordinately in sakmarian to capitanian time the absence of the moscovian to asselian resedimented limestone implies much reduced carbonate shedding during this period the correlation with the interpreted palaeoenvironmental episodes in the akiyoshi buildup shows that late visean to late bashkirian and sakmarian to capitanian carbonate shedding events correspond to the times of generally warm climate and high sea levels in the akiyoshi buildup moscovian to asselian time which lacks records of carbonate shedding nearly corresponds to the moscovian to gzhelian cooling and sea level lowering in the akiyoshi buildup we consider that the shedding of carbonate sediments from the akiyoshi atoll is its depositional response to the warm climate and elevated sea levels and is compared with a sedimentary system of the highstand shedding of carbonates atoll type carbonates equivalent to the akiyoshi limestone group in the akiyoshi terrane also show comparable responses of carbonate shedding into slope and slope to basin facies

comment on holocene tsunamis from mount etna and the fate of israeli neolithic communities by maria teresa pareschi enzo boschi and massimiliano favalli

refined numerical modeling of the 1979 tsunami in nice french riviera comparison with coastal data 1 the 16 october 1979 landslide at nice airport france produced tsunami waves observed in several harbors and the city of antibes was significantly flooded a new simulation of this event is presented in this paper to assess the sensitivity of the tsunami to the properties of the slide and to evaluate how local bathymetry and harbor resonance influence the effects of the tsunami at the coast a study of slide viscosity and water incorporation is performed using a detailed numerical model with a single initial volume of about 107 m3 the propagation of the tsunami is then simulated with a multigrid finite difference code using high resolution bathymetry in the harbors to a greater level of detail than previous studies we show that while the slide parameters are of great importance to properly model the later stages of the slide the initial volume and early dynamics of the slide are the relevant factors for determining the characteristics of the tsunami numerical results are compared with tide recordings in nice and villefranche as well as a mapping of the flood computed maximum elevation maps are compared with witness reports highlighting a focusing of the waves on antibes which explains its vulnerability this kind of focusing pattern should be considered when assessing the tsunami hazard for coastal regions calculated resonant periods in nice villefranche port vauban and la salis are matched with components present in both observed and computed waveforms most of the observed waves in nice and villefranche can be attributed to resonance

faunal stability during the early oligocene climatic crash abstract traditional neo darwinism views species as highly flexible entities which adapt to climatic change by gradually evolving new morphologies of the 177 species of mammals from the upper eocene lower oligocene 37 30 ma white river group in the high plains most species are static for 2 4 million years on average and some persist much longer only three examples of gradualism can be documented in the entire fauna and these are mostly size changes contrary to expectations most mammalian species show no change during the earliest oligocene climatic crash 33 2 ma in spite of the fact that the vegetation changed from dense forests to open forested grassland mean annual temperatures dropped 13 c and conditions got much drier and more seasonal only a few mammalian lineages speciated a few more went extinct and the vast majority 62 out of 70 persisted through this climatic event with no observable response whatsoever this evidence shows that organisms are much less responsive to the environment than short term neontological studies suggest

late miocene atmospheric co2 concentrations and the expansion of c4 grasses the global expansion of c4 grasslands in the late miocene has been attributed to a large scale decrease in atmospheric carbon dioxide co2 concentrations this triggering mechanism is controversial in part because of a lack of direct evidence for change in the partial pressure of co2 pco2 and because other factors are also important determinants in controlling plant type distributions alkenone based pco2 estimates for the late miocene indicate that pco2 increased from 14 to 9 million years ago and stabilized at preindustrial values by 9 million years ago the estimates presented here provide no evidence for major changes in pco2 during the late miocene thus c4 plant expansion was likely driven by additional factors possibly a tectonically related episode of enhanced low latitude aridity or changes in seasonal precipitation patterns on a global scale or both

tsunami hazard evaluation of the eastern mediterranean historical analysis and selected modeling seismic sea waves in the eastern mediterranean have been reported since written history first emerged several thousand years ago we collected and investigated these ancient and modern reports to understand and model the typical tsunamigenic sources with the ultimate purpose of characterizing tsunami hazard along the levant coasts surprisingly only 35 of the tsunami reports could be traced back to primary sources with the balance remaining questionable the tsunamis varied in size from barely noticeable to greatly damaging and their effects ranged from local to regional overall we list 21 reliably reported tsunamis that occurred since the mid second century b c along the levant coast along with 57 significant historical earthquakes that originated from the local continental dead sea transform dst system an in depth evaluation shows that 10 tsunamis are clearly associated with on land dst earthquakes and therefore as formerly suggested they probably originated from offshore seismogenically induced slumps eight tsunamis arrived from the remote hellenic and cypriot arcs one from italy and two are left with as yet unrecognized sources a major conclusion from this work is that onshore earthquakes commonly produce tsunamis along the levant coastline and that analogous situations are present elsewhere in the mediterranean as well as along the california coast and in another regions with active faults near the coast we modeled three typical scenarios and in light of the sumatra experience we examined the more likely severe magnitudes this of course leads us toward the upper range of expected run ups the models show that sooner than five minutes after a strong earthquake produces an offshore slump which occurs after close to a third of the large dst earthquakes a 4 to 6 m run up may flood part of the syrian lebanese and israeli coasts tsunamis from remote earthquakes however arrive later and produce only 1 to 3 m run ups but are more regional in extent online material tsunami modeling and reports

chlorite chemical composition change in response to the eocene oligocene climate transition on the northeastern tibetan plateau abstract the eocene oligocene climate transition eoct at 34 ma is a pronounced environmental reorganization that occurred in the cenozoic era and has been extensively studied via marine archives however to date there is still a less well dated continental record across the eoct which can mostly be attributed to a lack of suitable proxies used in the varied continental settings in terms of sedimentary facies provenance and climate thus resulting in a poor understanding of the continental response to this transition located on the northeastern tibetan plateau the qaidam basin is filled with continuous and well exposed cenozoic fluvio lacustrine sediments cenozoic lacustrine sediment has been proven to be an ideal archive to study the continental climatic response to the eoct here we present the detailed mineralogical and elemental composition of chlorite a widespread clay mineral in continental sediments formed by rock weathering collected from a lacustrine sequence in the northern qaidam basin to constrain the onset of the eoct and the related climatic response the results show that chlorite abundance crystallinity indices intensity ratios of chlorite diagnostic peaks and chemical composition collectively exhibit remarkable changes at 34 3 ma to be more specific the well crystallized fe mg rich chlorites were characterized by a high fe content before the eoct and turned into high mg content mg chlorites with poor crystallinity the chlorite chemical composition change is assumed to have been related to regional drying after the eoct thus providing new insights into the continental paleoenvironmental change based on this novel proxy

activation of gas bubble emissions indicated by the upward decreasing lead 210 activity at a submarine mud volcano ty1 offshore southwestern taiwan abstract a submarine mud volcano mv known as ty1 is one of the largest conical structures found offshore southwestern taiwan active gas bubble emissions at the flat crest of the mud volcano disperse sediment particles into the water column changes in the mud volcanism of ty1 were revealed by radiograph and grain size analysis of the sediment cores 210 pb geochronology was applied to the near seafloor sediments to reveal the detailed mud volcanism from the deposition rate in a 58 cm long sediment core taken from the northern margin of the crest known as ty1 n 170 the size and frequency of the mud clasts decrease upward the clasts are smaller than 8 mm above a sediment depth of 34 cm below the sea floor cmbsf sediments between 0 and 19 cmbsf are massive and particles larger than 2 mm are absent an enrichment of coarse silt sized particles in the massive sediment unit and the restricted distribution of the unit suggest that the massive unit was generated by re deposition of sediment particles that were dispersed into the water column by gas bubble emission these characteristics suggest that during the last mud volcanism of ty1 there was a decrease in mud eruption energy and gas bubble emission became the main activity in core ty1 s 440 taken from the southern slope a massive sediment unit enriched with coarse silt sized particles is intercalated between mud breccia structures this suggests repeated mud breccia flows caused by ty1 the excess 210 pb activity present in the massive sediment unit of ty1 n 170 suggests activation of gas bubble emission in the massive unit a decrease in excess 210 pb activity appears upward toward the seafloor the highest value is 3 1 dpm g at 19 8 cmbsf 26 4 g cm 2 in cumulative mass values lower than 1 0 dpm g are distributed 2 8 6 8 cmbsf 3 6 8 8 g cm 2 the upwardly decreasing trend is opposite that of the reference core from which a reasonable areal sedimentation rate was obtained using a constant flux constant sedimentation model the anomalous depth profile at the massive unit indicates an increasing rate of sediment deposition which originated from the activation of gas bubble emission

evolution of early cenozoic marine temperatures the equator to high southern latitude sea surface and vertical temperature gradients are reconstructed from oxygen isotope values of planktonic and benthic foraminifers for the following five time intervals late paleocene early eocene early middle eocene late eocene and early oligocene paleotemperatures are calculated using standard oxygen isotope temperature equations with adjustments to account for 1 variations in sea water 18o related to changes in global ice volume over time and 2 latitudinal gradients in surface water 18o these reconstructions indicate that sea surface temperatures sst of the southern oceans in the early eocene were as high as 15 c whereas temperatures during the late paleocene and early middle eocene reached maximum levels of 10 12 c by the late eocene and early oligocene high latitude sst had declined to 6 and 4 c respectively for most of the early paleogene low latitude sub tropical temperatures remained constant and well within the range of holocene temperatures 24 ndash 25 c but by the late eocene and early oligocene declined to values in the range of 18 to 22 c the late paleogene apparent decline in tropical temperatures however might be artificial because of dissolution of near surface foraminifera tests which biased sediment assemblages toward deeper dwelling foraminifera moreover according to recent plate reconstructions it appears that the majority of sites upon which the late eocene and early oligocene tropical temperatures were previously established were located either in or near regions likely to have been influenced by upwelling global deepwater temperature on average paralleled southern ocean sst for most of the paleogene we speculate based on the overall timing and character of marine sea surface temperature variation during the paleogene that some combination of both higher levels of greenhouse gases and increased heat transport was responsible for the exceptional high latitude warmth of the early eocene

in situ measurements of particle settling velocity in the deep sea two instruments the remote optical settling tube and the benthic autonomous settling tube have been deployed on the nova scotian continental rise at a depth of 4820 m the few results obtained suggest that optical and gravimetric methods give comparable results assumptions about particle density little affect the settling velocity distribution but do scale the total magnitude by using a distribution of declining density with increasing size indicating increasing water content the total concentration inferred from the light attenuation by using mie theory is quite close to the total found from gravimetric data the coarser end of the size distribution changes more with overall change in concentration than the fine end the settling velocity distribution shows the presence of several modes the two principal ones can be matched with modal sizes of 3 3 m and 60 m in coulter counter data allowing inference of stokes density contrasts of 1 5 and 0 061 g cm 3 respectively at concentrations of about 200 mg m 3 more than 50 of the material has a settling velocity less than 2 10 4 cm s 1 probably 3 m in size but this percentage appears to decrease with an increase in total concentration

relating sulfate and methane dynamics to geology accretionary prism offshore sw taiwan geochemical data ch4 so42 i cl particulate organic carbon poc 13c ch4 and 13c co2 are presented from the upper 30 m of marine sediment on a tectonic submarine accretionary wedge offshore southwest taiwan the sampling stations covered three ridges tai nan yung an and good weather each characterized by bottom simulating reflectors acoustic turbidity and different types of faulting and anticlines sulfate and iodide concentrations varied little from seawater like values in the upper 1 3 m of sediment at all stations a feature that is consistent with irrigation of seawater by gas bubbles rising through the soft surface sediments below this depth sulfate was rapidly consumed within 5 10 m by anaerobic oxidation of methane aom at the sulfate methane transition carbon isotopic data imply a mainly biogenic methane source a numerical transport reaction model was used to identify the supply pathways of methane and estimate depth integrated turnover rates at the three ridges methane gas ascending from deep layers facilitated by thrusts and faults was by far the dominant term in the methane budget at all sites differences in the proximity of the sampling sites to the faults and anticlines mainly accounted for the variability in gas fluxes and depth integrated aom rates by comparison methane produced in situ by poc degradation within the modeled sediment column was unimportant this study demonstrates that the geochemical trends in the continental margins offshore sw taiwan are closely related to the different geological settings

relevance of the chiancone volcaniclastic deposit in the recent history of etna volcano italy abstract the chiancone ch deposit is a volcaniclastic fan on the eastern flank of mt etna it crops out from the exit of the depression of the valle del bove 350 m a s l to the sea in an area which covers about 40 km 2 with a maximum thickness of about 30 m and a slope of 3 4 towards the east the total volume of the deposit is unknown because the base does not crop out but some geophysical data suggest a maximum thickness of about 300 m leading to an estimated maximum volume of about 12 km 3 which is comparable to the volume of the valle del bove vdb since this horseshoe shaped valley is considered to be the ch s source region a study of this deposit may allow an understanding of the mechanisms responsible for the origin of the vdb on the basis of stratigraphic and sedimentary studies we divided the ch sequence into two main parts the basal portion lithofacies 1 is visible only along the coast and has a width of about 6 5 km a thickness of 1 4 m and appears as an indurated horizontal deposit with a flat locally eroded upper surface we consider lithofacies 1 as a huge mud flow which may be associated with an important eruptive event the upper part lithofacies 2 5 is mainly composed of fluvial beds 63 of measured thicknesses that we attribute to events reworking the previously deposited layers the less abundant 23 very coarse grained lenses were caused by fluvial floods thin and discontinuous pyroclastic layers are accidentally 3 interbedded into the sequence the upper portion of the ch sequence is up to 30 m thick and formed after 7590 130 yr b p as established by our new radiocarbon dating when the chemical data obtained on lava blocks sampled from lithofacies 1 4 are compared with products of older eruptive centres it may be argued that the major direction of transport occurred from west to east and involved erosion of those old eruptive centres which were located in the central northern part of the vdb our data suggest the occurrence of an important eruptive event at least 7590 yr b p which may be associated with the deposition of the huge basal mud flow this event was followed by fluvial reworking and deposition at a rate of at least 4 mm yr extending this deposition rate to the whole thickness of the ch deposit 300 m would imply a maximum age of 80 000 70 000 yr b p however the deposition rate of the hidden part of the ch deposit was almost certainly much greater than 4 mm yr implying an age for the onset of the ch sequence significantly less than 80 000 70 000 yr b p this very strongly suggests that the trifoglietto volcano which is older than 80 000 yr was not involved in the opening of the vdb and the formation of the ch deposit it also suggests that the first event of the opening of the vdb was much older than the 5000 yr proposed by some authors it is possible that the ch was deposited during or slightly later than the life span of the ellittico volcano 40 000 15 000 yr b p