diviner lunar radiometer observations of cold traps in the moon s south polar region diviner lunar radiometer experiment surface temperature maps reveal the existence of widespread surface and near surface cryogenic regions that extend beyond the boundaries of persistent shadow the lunar crater observation and sensing satellite lcross struck one of the coldest of these regions where subsurface temperatures are estimated to be 38 kelvin large areas of the lunar polar regions are currently cold enough to cold trap water ice as well as a range of both more volatile and less volatile species the diverse mixture of water and high volatility compounds detected in the lcross ejecta plume is strong evidence for the impact delivery and cold trapping of volatiles derived from primitive outer solar system bodies

abrupt onset and termination of the african humid period rapid climate responses to gradual insolation forcing a detailed ca 100 yr resolution and well dated 18 ams 14 c dates to 23 cal ka bp record of latest pleistocene holocene variations in terrigenous eolian sediment deposition at odp site 658c off cap blanc mauritania documents very abrupt large scale changes in subtropical north african climate the terrigenous record exhibits a well defined period of low influx between 14 8 and 5 5 cal ka bp associated with the african humid period when the sahara was nearly completely vegetated and supported numerous perennial lakes an arid interval corresponding to the younger dryas chronozone punctuates this humid period the african humid period has been attributed to a strengthening of the african monsoon due to gradual orbital increases in summer season insolation however the onset and termination of this humid period were very abrupt occurring within decades to centuries both transitions occurred when summer season insolation crossed a nearly identical threshold value which was 4 2 greater than present these abrupt climate responses to gradual insolation forcing require strongly non linear feedback processes and current coupled climate model studies invoke vegetation and ocean temperature feedbacks as candidate mechanisms for the non linear climate sensitivity the african monsoon climate system is thus a low latitude corollary to the bi stable behavior of high latitude deep ocean thermohaline circulation which is similarly capable of rapid and large amplitude climate transitions

recent benthic foraminifera from the continental margin of northwest africa community structure and distribution abstract sediment grab samples were collected at 107 locations along the continental margin of northwest africa these samples form a series of depth transects between the straits of gibraltar and dakar senegal the greater than 250 m size fraction was retained for a census of both the live and dead foraminifera after deleting trace occurrences jaccard and correlation coefficient based cluster analyses were performed to decipher the community structure for this margin the geographic distribution of the four major faunal provinces recognized is conventional in that for both the live and dead assemblages three are related to depth upper slope and shelf middle slope and lower slope and continental rise the biotopes and thanatotopes within these provinces are strongly restricted along vertical or latitudinal boundaries when the data are analysed using jaccard coefficients dendrograms constructed from correlation coefficients emphasize depth related faunal communities dominant species such as cibicides lobatulus trifarina fornasinii planulina ariminensis uvigerina finisterrensis and c wuellerstorfi are generally distributed within a definite depth range along this margin and strongly influence the correlation coefficient based dendrograms other distributions are clearly not depth related but correspond to various environmental variables for example cancris auriculus coarse substrate bolivina subaenariensis oxygen minimum cibicidoides kullenbergi and hoeglundina elegans low organic carbon uvigerina peregrina is also a notable exception to depth dependence in that this dominant species and the province it represents are generally confined to the continental slope south of cape blanc its preference for that region may arise from the high organic carbon and fine grain size of the sediment there from low salinity of the bottom water or from other unknown variables the most important vertical faunal boundary occurs between cape barbas and cape blanc between 22 and 21 n latitude in contrast the canary island ridge intersects the continental margin at a saddle depth of about 1500 m but that physiographic barrier has little effect on provincialism of the deep water benthic foraminifera

dating transitionally magnetized lavas of the late matuyama chron toward a new 40ar 39ar timescale of reversals and events the k ar based geomagnetic polarity timescale was constructed using data from lavas and tuffs that bracketed but rarely dated the transitions between polarity intervals subsequent 40ar 39ar dating indicated that the ages of some polarity transitions had been underestimated by about 6 although the accepted ages of the polarity chron boundaries have increased their precise temporal definition remained uncertain we have taken a different approach and used incremental heating techniques to obtain 18 new 40ar 39ar ages from basaltic lavas within flow sequences at punaruu valley tahiti and haleakala volcano hawaii these lavas record transitional paleomagnetic directions corresponding to four mid pleistocene polarity reversals or events three lavas from punaruu valley previously thought to record the cobb mountain normal polarity subchron cmns gave a mean age of 1 105 0 005 ma indicating that they were erupted about 76 kyr after the cmns this period of transitional field behavior is designated the punaruu event in addition seven new 40ar 39ar ages from the punaruu valley indicate that the jaramillo normal polarity subchron jns lasted about 67 kyr starting at 1 053 0 006 ma and ending 0 986 0 005 ma this agrees with astronomical estimates but conflicts with jns ages proposed by spell and mcdougall 1992 and izett and obradovich 1994 on the basis of 40ar 39ar dating of rhyolite domes in the valles caldera indistinguishable 40ar 39ar ages of seven lavas including one from punaruu valley and six from haleakala that record broadly similar intermediate paleodirections suggest that the kamikatsura event occurred at 0 886 0 003 ma moreover these data indicate that the kamikatsura event occurred 20 40 kyr after another geomagnetic event most probably taking place at 0 92 ma we designate this earlier field behavior the santa rosa event adopting its name from that of a transitionally magnetized rhyolite dome which happened to figure prominently in the original definition of the end of the jns in the 1968 study of doell et al 1968 the discovery of these new short lived polarity events during the matuyama reversed chron suggests that the 400 kyr period between 1 18 and 0 78 ma experienced no less than 7 and perhaps more than 11 attempts by the geodynamo to reverse this newly determined higher frequency of geomagnetic activity illustrates vividly the importance of obtaining precise age control directly from transitionally magnetized rocks

low latitude dusty events vs high latitude icy heinrich events it has been proposed that tropical events could have participated in the triggering of the classic high latitude iceberg discharge heinrich events he we explore low latitude heinrich events equivalents at high resolution in a piston core recovered from the tropical north western african margin they are characterized by an increase of total dust lacustrine diatoms and fibrous lacustrine clay minerals thus low latitude events clearly reflect severe aridity events that occurred over africa at the saharan latitudes probably induced by southward shifts of the inter tropical convergence zone at a first approximation it seems that there is more likely synchronicity between the high latitude heinrich events hes and low latitude events lle rather than asynchronous behaviours

clay mineral evidence of nepheloid layer contributions to the heinrich layers in the northwest atlantic abstract the clay fraction of four cores drilled in the north atlantic ocean was studied at a very high resolution over the last 150 ka in order to record the mineralogical signature of heinrich events factor analysis of clay mineralogy establishes that three independent factors represent the main variations a detrital factor illite chlorite kaolinite a smectite factor and a mixed layer factor ivml illite vermiculite mixed layered clay the clay mineral fraction of core su90 38 drilled in the northeastern atlantic basin did not record any heinrich event whereas large changes in the clay mineral fraction occurred during heinrich events h1 h2 h4 and h5 in the three cores from the northwestern atlantic basin cores su90 08 su90 11 and su90 12 heinrich layers are characterized by increases in the detrital factor in cores su90 08 and su90 11 and sharp increases in the mixed layer factor in cores su90 11 and su90 12 the geographical setting of the cores the pattern of surface intermediate and deep water circulation and the main sources of clay minerals allow recognition of two major mechanisms involved in the deposition of the heinrich layers 1 an increased supply of detrital clay minerals by the icebergs and 2 a specific input of illite vermiculite mixed layer clay minerals by a nepheloid layer

geochemical and micropaleontological impacts caused by the 2011 tohoku oki tsunami in matsushima bay northeastern japan abstract we present stratigraphic geochemical cns elemental analysis and micropaleontological ostracode assemblages evidence for the 2011 tohoku oki tsunami impact in matsushima bay northeastern japan and examine the recovery process after the impact to the bay environment using short sediment cores from two different topographic settings at a water depth of approximately 4 m at both sites tsunami deposits are composed of two sedimentary layers that recorded the first tsunami run up and backwash at the western site near the channel that connects the bay with the pacific ocean the first tsunami wave eroded the bay floor sediments and left the tsunami deposits composed of medium sand rich in shell fragments but with sparse numbers of meiobenthic ostracodes by contrast at the eastern site which is surrounded by many small islands the first wave eroded very little of the bay floor sediments and left tsunami deposits consisting of sandy mud rich in exotic ostracodes such as phytal species shallow marine sand dwelling species and brackish water species overlying post tsunami deposits are composed mainly of organic rich mud in which organic matter was derived primarily from marine plankton ostracode assemblages in the tsunami deposits lack the offshore species that live in water depths 50 m and are dominated by the species from matsushima bay and its adjacent nearshore upper sublittoral areas and brackish water environments the distance from deep water offshore areas to the core sites is too far to transport ostracode valves by tsunami waves

connection between south mediterranean climate and north african atmospheric circulation during the last 50 000 yr bp north atlantic cold events abstract high resolution clay mineralogical analyses were performed on sediment deposited during the last 50 000 yr in the alboran sea odp site 976 the clay mineral record is compared with pollen assemblages and with annual precipitation pann and mean temperatures of the coldest month mtco reconstructed with the modern analog technique mat enhanced contribution of palygorskite a typical wind blown clay mineral characterizes the north atlantic cold climatic events coeval development of the semi arid vegetation artemisia rich associated with a drastic fall of reconstructed precipitations and temperatures suggest cold and arid continental conditions in the west mediterranean area during north atlantic cold events the clay mineral association especially the palygorskite content and the illite to kaolinite ratio indicate western morocco as one of the major source of the clay size fraction during the north atlantic cold events the maximum abundance of artemisia associated with the presence of argania pollen both indicate morocco as the main origin for pollen during these cold periods the comparison of these pollen and clay mineral specific features allows us to pinpoint western morocco as the dominant source of wind blown particles during north atlantic cold events these specific mineralogical composition and palynological assemblages reveal enhanced aridity over north africa and intensification of winds favouring dust erosion and transport from north africa toward the alboran sea during the north atlantic cold events according to atmospheric models such a meridian transport 1 likely results from the development of strong and stable anticyclonic conditions over the tropical atlantic and north africa similar to today s summer meteorological configuration and 2 implies a northward position of the westerly winds during north atlantic cold events finally the synoptic situation over the west mediterranean during the north atlantic cold events is compared with the north atlantic oscillation nao suggesting that during the cold atlantic events weather regimes over europe and north africa may have been systematically shifted towards a positive nao situation

african climate change and faunal evolution during the pliocene pleistocene abstract environmental theories of african faunal evolution state that important evolutionary changes during the pliocene pleistocene interval the last ca 5 3 million years were mediated by changes in african climate or shifts in climate variability marine sediment sequences demonstrate that subtropical african climate periodically oscillated between markedly wetter and drier conditions paced by earth orbital variations with evidence for step like 0 2 ma increases in african climate variability and aridity near 2 8 ma 1 7 ma and 1 0 ma coincident with the onset and intensification of high latitude glacial cycles analysis of the best dated and most complete african mammal fossil databases indicates african faunal assemblage and perhaps speciation changes during the pliocene pleistocene suggesting more varied and open habitats at 2 9 2 4 ma and after 1 8 ma these intervals correspond to key junctures in early hominid evolution including the emergence of our genus homo pliocene pleistocene shifts in african climate vegetation and faunal assemblages thus appear to be roughly contemporary although detailed comparisons are hampered by sampling gaps dating uncertainties and preservational biases in the fossil record further study of possible relations between african faunal and climatic change will benefit from the accelerating pace of important new fossil discoveries emerging molecular biomarker methods for reconstructing african paleovegetation changes tephra correlations between terrestrial and marine sequences as well as continuing collaborations between the paleoclimatic and paleoanthropological communities

saharan wind regimes traced by the sr nd isotopic composition of subtropical atlantic sediments last glacial maximum vs today new nd sr isotopic data on the 30 m lithic particles of surface and last glacial maximum sediments recovered along the african margin between the equator and the gibraltar strait are presented in combination with grain size measurements this 30 m size fraction allows us to eliminate any hemipelagic contribution that could occur in the coarser fractions in the eolian fraction both sr and nd isotopic tracers reveal the same major northwestern origin mauritania mali southern algeria and morocco the archaean formations of the western saharan shield could be the source of the very unradiogenic ratios observed here the more southern regions senegal guinea act only as secondary sources a similar pattern is observed for the lgm lithic particles are mostly transported by both trade and saharan air layer sal winds along an approximate ne sw axis this main feature matches the southern plume characterizing the dust transport observed during winter no significant latitudinal shift of the belt winds is observed between the lgm and today at the lgm however dust fluxes were 2 4 times higher than today leading to a more archaean type imprint in the deposits we do not observe any clear relationship between the latitudinal variability of the upwelling systems identified in this region at the lgm and the location of the major wind systems both enhanced aridity on the continent and increased wind speed probably occurred together over western tropical africa during the last glacial period

anthropogenic changes in the landscape of west java indonesia during historic times inferred from a sediment and pollen record from teluk banten palynological and charcoal analyses of shallow marine core 98 28 from the northern coastal area of west java provide a regional vegetation history during the last few centuries reliable chronostratigraphical control is provided by 210pb analyses and the occurrence of the 1883 krakatau ash tsunami layer as a time marker the results permit the distinction of four successive stages reflecting increased disturbance and land clearance with some evidence for the presence of deciduous lowland forests in the banten area during the early holocene the establishment of coconut and pine plantations and the severe loss of biodiversity in the last few decennia are also echoed in the pollen record the effect of the krakatau eruption was insignificant compared with human impact on vegetation in the banten area copyright 2004 john wiley sons ltd

late quaternary paleoproductivity and deep water circulation in the eastern south atlantic ocean evidence from benthic foraminifera abstract two late quaternary sediment cores from the northern cape basin in the eastern south atlantic ocean were analyzed for their benthic foraminiferal content and benthic stable carbon isotope composition the locations of the cores were selected such that both of them presently are bathed by north atlantic deep water nadw and past changes in deep water circulation should be recorded simultaneously at both locations however the areas are different in terms of primary production one core was recovered from the nutrient depleted walvis ridge area whereas the other one is from the continental slope just below the coastal upwelling mixing area where present day organic matter fluxes are shown to be moderately high recent data served as the basis for the interpretation of the late quaternary faunal fluctuations and the paleoceanographic reconstruction during the last 450 000 years nadw flux into the eastern south atlantic ocean has been restricted to interglacial periods with the strongest dominance of a nadw driven deep water circulation during interglacial stages 1 9 and 11 at the continental margin high productivity faunas and very low epibenthic 13c values indicate enhanced fluxes of organic matter during glacial periods this can be attributed to a glacial increase and lateral extension of coastal upwelling the long term glacial interglacial paleoproductivity cycles are superimposed by high frequency variations with a period of about 23 000 yr enhanced productivity in surface waters above the walvis ridge far from the coast is indicated during glacial stages 8 10 and 12 during these periods cold nutrient rich filaments from the mixing area were probably driven as far as to the southeastern flank of the walvis ridge

the nature of lunar volatiles as revealed by mini rf observations of the lcross impact site 1 on 9 october 2009 the lunar crater observation and sensing satellite lcross impacted cabeus crater located near the south pole of the moon prior to that impact the mini rf instruments on isro s chandrayaan 1 and nasa s lunar reconnaissance orbiter lro obtained s band 12 6 cm synthetic aperture radar images of the impact site at 150 and 30 m resolution respectively these observations show that the floor of cabeus has a circular polarization ratio cpr comparable to or less than the average of nearby terrain in the southern lunar highlands furthermore 2 of the pixels in cabeus crater have cpr values greater than unity this observation is not consistent with the presence of thick deposits of nearly pure water ice within a few meters of the lunar surface but it does not rule out the presence of small 10 cm discrete pieces of ice mixed in with the regolith in addition mini rf on lro acquired a postimpact s band image of the region surrounding the lcross impact site providing important geologic context for the site registering the lro image to a near infrared nir image taken by the lcross shepherding spacecraft we find that the impactor landed in the ray of a fresh radar bright 1 km crater however the difference between preimpact and postimpact images is not above the speckle noise this implies that the size of the lcross impact crater is less than mini rf s resolution 30 m and or that the impact did not excavate more decimeter size blocks than were already present at the impact site

eight glacial cycles from an antarctic ice core the antarctic vostok ice core provided compelling evidence of the nature of climate and of climate feedbacks over the past 420 000 years marine records suggest that the amplitude of climate variability was smaller before that time but such records are often poorly resolved moreover it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records here we report the recovery of a deep ice core from dome c antarctica that provides a climate record for the past 740 000 years for the four most recent glacial cycles the data agree well with the record from vostok the earlier period between 740 000 and 430 000 years ago was characterized by less pronounced warmth in interglacial periods in antarctica but a higher proportion of each cycle was spent in the warm mode the transition from glacial to interglacial conditions about 430 000 years ago termination v resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases but there are significant differences in the patterns of change the interglacial stage following termination v was exceptionally long 28 000 years compared to for example the 12 000 years recorded so far in the present interglacial period given the similarities between this earlier warm period and today our results may imply that without human intervention a climate similar to the present one would extend well into the future

the santa rosa event 40ar 39ar and paleomagnetic results from the valles rhyolite near jaramillo creek jemez mountains new mexico the jaramillo event was originally defined by doell and dalrymple in 1966 on the basis of k ar ages from sanidine in the normally transitionally and reversely magnetized rhyolite domes named cerro del abrigo cerro santa rosa i and cerro santa rosa ii respectively that erupted following collapse of the archetypal valles caldera new mexico we have collected new paleomagnetic data from the three domes and new 40 ar 39 ar laser fusion and furnace incremental heating experiments on sanidine crystals from the cerro santa rosa i rhyolite step wise alternating field and thermal demagnetization techniques applied to 52 samples from seven sites indicate that the original paleomagnetic results of doell and dalrymple science 152 1966 1060 1061 are valid cerro del abrigo is normally magnetized whereas the santa rosa i dome is transitional with an inclination of 363 toward the east and the santa rosa ii dome is of reversed polarity twenty five laser fusion experiments on sanidine crystals from the the cerro santa rosa i dome together with the saddle shaped spectrum obtained by incrementally heating the sanidine in a furnace reveal that this rhyolite contained a small but significant component of excess argon prior to eruption our preferred age of 936 8 ka 2c for the santa rosa i rhyolite is based on the concordant laser fusion isochron and incremental heating plateau ages this age is significantly older than was inferred on the basis of earlier laser fusion 40 ar 39 ar results that suggested a trapped component characterized by a 40 ar 36 ar ratio lower than the atmospheric value of 295 5 our new age distinguishes the santa rosa i dome by 65 kyr from the termination of the jaramillo normal subchron 1001 10 ka and by 37 kyr from basaltic lavas at haleakala and tahiti which record the kamikatsura event 899 6 ka moreover this determination is a factor of three more precise than the best previous estimate for a proposed geomagnetic event in this time period the cerro santa rosa i rhyolite dome once intimately linked with the end of the jaramillo event and the acceptance of plate tectonic theory now defines a highly resolved feature the santa rosa event in a terrestrial geomagnetic reversal time scale that is consistent with the global record of magnetic field intensity from marine sediments fl 2002 elsevier science b v all rights reserved

spatial distribution of lunar polar hydrogen deposits after kaguya selene 1 although controversial in its physical form there is mounting evidence of hydrogen enhancements at the lunar poles the permanently shadowed locales are potential sites for significant concentrations of cold trapped volatiles including water ice we derive maps of the lunar hydrogen distribution near the poles by applying a pixon image reconstruction algorithm to the lunar prospector epithermal neutron data coupled with a new map of cold trap locations derived from the kaguya selene altimetry measurements the results presented in this article require the hydrogen to be concentrated into cold traps

the middle pleistocene transition characteristics mechanisms and implications for long term changes in atmospheric pco2 abstract the emergence of low frequency high amplitude quasi periodic 100 kyr glacial variability during the middle pleistocene in the absence of any significant change in orbital forcing indicates a fundamental change internal to the climate system this middle pleistocene transition mpt began 1250 ka and was complete by 700 ka its onset was accompanied by decreases in sea surface temperatures ssts in the north atlantic and tropical ocean upwelling regions and by an increase in african and asian aridity and monsoonal intensity during the mpt long term average ice volume gradually increased by 50 m sea level equivalent whereas low frequency ice volume variability experienced a 100 kyr lull centered on 1000 ka followed by its reappearance 900 ka although as a broad band of power rather than a narrow persistent 100 kyr cycle additional changes at 900 ka indicate this to be an important time during the mpt beginning with an 80 kyr event of extreme sst cooling followed by the partial recovery and subsequent stabilization of long term north atlantic and tropical ocean ssts increasing southern ocean sst variability primarily associated with warmer interglacials the loss of permanent subpolar sea ice cover and the emergence of low frequency variability in pacific ssts and global deep ocean circulation since 900 ka ice sheets have been the only component of the climate system to exhibit consistent low frequency variability with the exception of a near universal organization of low frequency power associated with marine isotope stages 11 and 12 all other components show an inconsistent distribution of power in frequency time space suggesting a highly nonlinear system response to orbital and ice sheet forcing most hypotheses for the origin of the mpt invoke a response to a long term cooling possibly induced by decreasing atmospheric pco2 none of these hypotheses however accounts for the geological constraint that the earliest northern hemisphere ice sheets covered a similar or larger area than those that followed the mpt given that the mpt was associated with an increase in ice volume this constraint requires that post mpt ice sheets were substantially thicker than pre mpt ice sheets indicating a change in subglacial conditions that influence ice dynamics we review evidence in support of the hypothesis that such an increase in ice thickness occurred as crystalline precambrian shield bedrock became exposed by glacial erosion of a thick mantle of regolith this exposure of a high friction substrate caused thicker ice sheets with an attendant change in their response to the orbital forcing marine carbon isotope data indicate a rapid transfer of organic carbon to inorganic carbon in the ocean system during the mpt if this carbon came from terrigenous sources an increase in atmospheric pco2 would be likely which is inconsistent with evidence for widespread cooling apparently rapid carbon transfer from terrestrial sources is difficult to reconcile with gradual erosion of regolith a more likely source of organic carbon and nutrients which would mitigate pco2 rise is from shelf and upper slope marine sediments which were fully exposed for the first time in millions of years in response to thickening ice sheets and falling sealevels during the mpt modeling indicates that regolith erosion and resulting exposure of crystalline bedrock would cause an increase in long term silicate weathering rates in good agreement with marine sr and os isotopic records we use a carbon cycle model to show that a post mpt increase in silicate weathering rates would lower atmospheric pco2 by 7 12 ppm suggesting that the attendant cooling may have been an important feedback in causing the mpt

fluxes of fast and epithermal neutrons from lunar prospector evidence for water ice at the lunar poles maps of epithermal and fast neutron fluxes measured by lunar prospector were used to search for deposits enriched in hydrogen at both lunar poles depressions in epithermal fluxes were observed close to permanently shaded areas at both poles the peak depression at the north pole is 4 6 percent below the average epithermal flux intensity at lower latitudes and that at the south pole is 3 0 percent below the low latitude average no measurable depression in fast neutrons is seen at either pole these data are consistent with deposits of hydrogen in the form of water ice that are covered by as much as 40 centimeters of desiccated regolith within permanently shaded craters near both poles

late holocene evolution of the southwestern donana national park guadalquivir estuary sw spain a multivariate approach four phases are distinguished in the late holocene evolution of the southwestern donana national park sw spain based on a multidisciplinary analysis of the sediments present in drill cores in the oldest phase 2400 2500 cal yr bp a coastal lagoon the roman lacus ligustinus was recognized in the central part of this area partly closed by the donana spit and limited by fluvial levees the following phase 2400 2200 cal yr bp is characterized by high energy events which caused the breakthrough of the donana spit and the creation of new littoral strands in the inner areas in the third phase 2200 2050 cal yr bp this new outlet was closed coinciding with the progradation of the donana spit the last phase 2050 cal yr bp recent comprises three periods a an unstable period 2050 1950 cal yr bp with the deposit of cheniers over the previous levees b an infilling period with a diminution of the marine influence and c the appearance of temporary ponds between the emerged levees and cheniers

underlying causes for long term global ocean δ13c fluctuations over the last 1 20 myr pleistocene stable carbon isotope 13c records from surface and deep dwelling foraminifera in all major ocean basins show two distinct long term carbon isotope fluctuations since 1 00 ma the first started around 1 00 ma and was characterised by a 0 35 decrease in 13c values until 0 90 ma followed by an increase of 0 60 lasting until 0 50 ma the subsequent fluctuation started with a 0 40 decrease between 0 50 and 0 25 ma followed by an increase of 0 30 between 0 25 and 0 10 ma here we evaluate existing evidence and various hypotheses for these global pleistocene 13c fluctuations and present an interpretation where the fluctuations most likely resulted from concomitant changes in the burial fluxes of organic and inorganic carbon due to ventilation changes and or changes in the production and export ratio our model indicates that to satisfy the long term stability of the pleistocene lysocline the ratio between the amounts of change in the organic and inorganic carbon burial fluxes would have to be close to a 1 1 ratio as deviations from this ratio would lead to sizable variations in the depth of the lysocline it is then apparent that the mid pleistocene climate transition which apart from the glacial cycles represents the most fundamental change in the pleistocene climate was likely not associated with a fundamental change in atmospheric pco2 while recognising that high frequency glacial interglacial cycles are associated with relatively large 100 ppmv changes in pco2 our model scenario with burial changes close to a 1 1 ratio produces a maximum long term variability of only 20 ppmv over the fluctuation between 1 00 and 0 50 ma

phase relationships between millennial scale events 64 000 24 000 years ago a core recovered on the iberian margin off southern portugal can be correlated with greenland ice cores using oxygen isotope variability in planktonic foraminifera which closely matches the ice core records of temperature over greenland our age model identifies the base of every interstadial between 64 000 and 24 000 years ago and uses the greenland ice core project grip timescale the oxygen isotope signal in benthic foraminifera on this grip based timescale is quite different from the planktonic record and resembles the temperature record over antarctica when this is synchronized with greenland using the record of methane in the atmospheric air in the polar ice cores we interpret the benthic record as indicating significant fluctuations in ice volume during millennial events and we suggest that antarctic temperature changed as a function of ice volume

expanding the proxy toolkit to help identify past events lessons from the 2004 indian ocean tsunami and the 2009 south pacific tsunami article i nfo some of the proxies used to identify palaeotsunamis are reviewed in light of new findings following the 2004 indian ocean tsunami and the 2009 south pacific tsunami and a revised toolkit provided the new application of anisotropy of magnetic susceptibility ams to the study of tsunami deposits and its usefulness to determine the hydrodynamic conditions during the emplacement of tsunami sequences together with data from grain size analysis are presented the value of chemical proxies as indicators of saltwater inundation associated marine shell and or coral high energy depositional environment and possible contamination is demonstrated and issues of preservation addressed we also provide new findings from detailed studies of heavy minerals new information gathered during the unesco international oceanographic commission ioc international tsunami survey of fine onshore sediments following the 2009 south pacific tsunami is presented and includes grain size chemical diatom and foraminifera data the tsunami deposit varied ranging from fining upward sand layers to thin sand layers overlain by a thick layer of organic debris and or a mud cap grain size characteristics chemical data and microfossil assemblages provide evidence for marine inundation from near shore and changes in flow dynamics during the tsunami

glacial water mass geometry and the distribution of δ13c of σco2 in the western atlantic ocean 1 oxygen and carbon isotopic data were produced on the benthic foraminiferal taxa cibicidoides and planulina from 25 new piston cores gravity cores and multicores from the brazil margin the cores span water depths from about 400 to 3000 m and intersect the major water masses in this region these new data fill a critical gap in the south atlantic ocean and provide the motivation for updating the classic glacial western atlantic 13c transect of duplessy et al 1988 the distribution of 13c of co2 requires the presence of three distinct water masses in the glacial atlantic ocean a shallow 1000 m southern source water mass with an end member 13c value of about 0 3 0 5 vpdb a middepth 1500 m northern source water mass with an end member value of about 1 5 and a deep 2000 m southern source water with an end member value of less than 0 2 and perhaps as low as the 0 9 values observed in the south atlantic sector of the southern ocean ninnemann and charles 2002 the origins of the water masses are supported by the meridional gradients in benthic foraminiferal 18o a revised glacial section of deep water 13c documents the positions and gradients among these end member intermediate and deep water masses the large property gradients in the presence of strong vertical mixing can only be maintained by a vigorous overturning circulation

the avaatech xrf core scanner technical description and applications to ne atlantic sediments abstract x ray fluorescence xrf core scanning provides rapid high resolution down to 1 mm records of chemical composition on split sediment cores the measurements are non destructive and require very limited sample preparation the new avaatech xrf core scanner operational since 2002 covers the atomic mass range from al to u instrument parameters especially tube voltage can be adjusted to provide optimum settings for selected elements or sets thereof owing to the nature of the surface of split sediment cores particularly effects resulting from sample inhomogeneity and surface roughness results are semiquantitative yet provide reliable records of the relative variability in elemental composition downcore selected case studies from diverse sedimentary settings in the ne atlantic ocean illustrate a range of applications of xrf logging data these include preliminary stratigraphic interpretations glacial interglacial cycles provenance studies of the terrigenous sediment fraction lithological characterization early diagenetic processes and distinction between carbonate phases aragonite v calcite

high energy marine flood deposits on astypalaea island greece possible evidence for the ad 1956 southern aegean tsunami high energy marine sediments are described from livadia and stavros astypalaea island greece which are tentatively interpreted to be associated with the southern aegean tsunami of 9th july ad 1956 at livadia the marine provenance of imbricated pebble deposits referred to here as the imbricated clast unit or icu are inferred from two observations firstly the similarity between the clasts comprising the icu and contemporary beach sediments and secondly the inclusion of foraminiferal tests within the sediment matrix derivation from the ad 1956 tsunami rather than from a storm surge is inferred from the uniqueness of the deposits within the sedimentary record their distinct imbrication and 137cs and 210pb dating of overlying and underlying sediments the top of the icu occurs at 2 00 metres above sea level m a s l indicating a minimum flood level at this location at stavros a gravel with rounded clasts incorporating marine mollusca is found on exposed cliff surfaces up to an elevation of 10 00 m a s l these gravels are also interpreted as having been deposited by the ad 1956 tsunami the elevation of the deposits and topographic observations indicate that previously reported run up elevations were over estimated the results shown here represent the first systematic investigation into sedimentary deposits possibly associated with a modern tsunami within the aegean sea region of greece

a high energy deposit in the byzantine harbour of yenikapi istanbul turkey abstract a byzantine harbour theodosian harbour has been uncovered during excavations at yenikapi with a stratigraphic sequence spanning the past 7000 bp in the marine part of the sedimentary sequence a high energy deposit has been interpreted as being of tsunami origin and related to the earthquake of 557 ad this paper presents a bio sedimentological analysis of this facies the unit is characterised by coarse sands and gravels containing reworked material such as woods bones marble blocks amphora fragments ceramics coins shells and plant remains the thickness of the facies varies between 10 and 100 cm the sediment matrix is poorly sorted with skewness values indicative of a sub tidal fine sand environment many of the marine taxa have been reworked and diverse ecological assemblages are represented lagoonal coastal and open marine species this unit is divided into three facies consistent with different phases of the tsunami drowning and water retreat the basal facies corresponds to two tsunami wave trains and the upper facies indicates the backwash flow

sedimentary and microfossil imprint from historical earthquakes and tsunamis jalisco coast mexican subduction abstract tsunamis are high energy events capable of leaving their imprint in the geological record the western mexican pacific coast located in the mexican subduction zone is prone to large earthquakes m 8 0 where tsunami hazard has been underrated the geologic archive obtained in a sheltered coastal lagoon was analyzed applying a multi proxy approach to reveal the occurrence of historical earthquakes in the jalisco coast foraminifera and ostracoda aid identifying earthquake and tsunami geologic evidence in this section of the mexican pacific coast where tropical conditions prevail we present the evidence of changes in stratigraphy grain size biostratigraphy supported by archaeomagnetic dating they were complemented with published 210pb dating magnetic properties and historical data we identified three events the tsunami deposit left by the june 3rd 1932 tsunami produced by the largest earthquake m 8 2 recorded in instrumental history in mexico and the coseismic deformation resulting from the 1932 event also a probable tsunami deposit likely produced by an historical earthquake in 1900 and the coseismic deformation associated to this event and the coseismic deformation resulting produced by the 1563 earthquake the site geomorphology with a marginal lagoon closed by a little barrier 7 m 1 m above sea level precludes tropical storms as responsible for marine incursions this work contributes to strengthening the earthquake and associated tsunamis chronology aiming to improve coastal hazard assessment for the area

balancing the deglacial global carbon budget the hydrate factor abstract the discovery that methane from dissociation of gas hydrates could be an important factor in the global carbon cycle resolves the major discrepancy in estimates of the increase of terrestrial biomass from the last glacial period to the present carbon isotope budgeting using the marine carbon isotopic record results in an estimate centered around 500 gtc whereas palaeovegetation reconstruction with biosphere models gives averages around 1000 gtc the discrepancy may be resolved by considering release of isotopically light methane through destabilization of gas hydrates this provides a unique means of estimating the contribution of gas hydrates to the deglacial rise in atmospheric methane a release of 120 gtc methane makes a biospheric carbon transfer of 1000 gtc compatible with the marine carbon isotope data this however represents less than 30 of the enhanced atmospheric methane production between 18 and 8 ka observed in ice cores supporting the theory that glacial interglacial variations in atmospheric methane were driven primarily by changes in the extent of tropical and temperate wetlands and not by methane release from clathrates by balancing the deglacial carbon budget we demonstrate that global carbon models will have to incorporate glacial interglacial vegetation shifts of at least 1000 gtc which many currently find difficult

the mid pleistocene climate transition a deep sea carbon isotopic perspective five 13c records from the deep ocean extending back to 1 3 ma were examined in order to constrain changes in mean ocean carbon isotope composition and thermohaline circulation over the 41 to 100 ka climate transition these data show that significant perturbations in mean ocean carbon chemistry were associated with the mid pleistocene climate transition notable features of the last 1 3 myr are 1 a pronounced 0 3 decrease in mean ocean 13c between 0 9 and 1 0 myr followed by a return to pre 1 0 ma values by 400 ka b p which we propose was due to the onetime addition of isotopically depleted terrestrial carbon to the ocean possibly associated with an increase in global aridity and decrease in the size of the biosphere across the 41 to 100 ka transition 2 no change in the atlantic pacific a p 13c gradient over the last 1 3 myr suggesting no change in mean ocean nutrient content accompanied the addition of light carbon and 3 stronger vertical nutrient fractionation in the north atlantic in the middle pleistocene between sites 607 and 552 suggesting weaker north atlantic deep water formation at this time relative to the early and late pleistocene we also find evidence for a more pronounced deep recirculation gyre in the western north atlantic basin in the early brunhes as evidenced by aging of deep northern basin water site 607 relative to deep water in the equatorial atlantic site 664

holocene coastal change and geoarchaeology at howick northumberland uk the recent discovery of one of the earliest mesolithic occupation sites in northern britain at howick on the northumberland coast in association with multiperiod archaeological evidence nearby highlights the importance of uk coastal settings as focii of human occupation through the holocene environmental evidence from a nearby river valley 8 15 m of sediment ranging in age from about 12 000 cal bp to the present records local and regional environmental change twenty four radiocarbon dates based on plant macrofossils provide a strong chronological framework calcareous microfossil assemblages foraminifera ostracods have been recovered from the fine grained sediments recording a change from marine through to brackish and eventually freshwater conditions between about 8200 and 6500 cal bp a preliminary pollen study of the core has permitted a reconstruction of the regional vegetation as it responded to climatic amelioration and human influence upon the landscape radiocarbon dating and sedimentological evidence indicates a major hiatus between approximately 11 000 and 8000 years bp including the period of mesolithic occupation represented by a 30 cm layer of coarse sands and sandstone pebbles probably the result of a significant high energy event dated to about 8300 cal bp although not a typical tsunami deposit the age and context suggests that this may be associated with the storegga slide event already well documented along the eastern coast of scotland the sedimentary and biological remains at howick record environmental change over much of the holocene and are compared with other environmental change records from the region to provide an environmental framework for the archaeology of this coastline

sedimentologic and geomorphologic tsunami imprints worldwide a review abstract tsunami events with extreme effects on sedimentary transport or considerable alterations of the coastal configuration are rather rare regarding human history but considering geological timescales they occur frequently at least 100 megatsunami in different parts of the world have been recorded in the past 2000 years but presumably far more have failed to be noticed during historical times and are not mentioned either in written or oral ancient records therefore the topic of paleotsunami requires inevitable sedimentological and geomorphological research however field research concerning paleotsunami is astonishingly rare within the scientific approach and only 5 of the existing tsunami literature is related to this subject future efforts in paleotsunami research should focus on the geological evidence of these mega events to clarify their contribution to coastal forming processes this paper reviews the state of the art knowledge of sedimentologic and geomorphic imprints of tsunami along the world s coastlines in order to highlight the need for more detailed studies of paleotsunami depositional and geomorphological traces

facies analysis foraminiferal record and chronostratigraphy of holocene sequences from saltes island tinto odiel estuary sw spain the origin of high energy deposits abstract a multidisciplinary analysis of holocene sediments from la cascajera tinto odiel estuary sw spain has allowed to differentiate five sedimentary facies sandy tidal flat clayey tidal flat washover fan salt marsh edaphic horizon according to their granulometric characteristics internal structure mineralogical composition clay mineral assemblage and paleontological record these data coupled to 14c ams dating suggest an evolution from a sandy tidal plain to a chenier before 2100 cal yr bp this initial chenier was partially eroded later by regional storms between 2100 cal yr bp and 1900 cal yr bp leading to the deposition of two washover fans these facies have been eroded in the last centuries by the action of an ebb tide channel

upwelling intensification as part of the pliocene pleistocene climate transition a deep sea sediment core underlying the benguela upwelling system off southwest africa provides a continuous time series of sea surface temperature sst for the past 4 5 million years our results indicate that temperatures in the region have declined by about 10 c since 3 2 million years ago records of paleoproductivity suggest that this cooling was associated with an increase in wind driven upwelling tied to a shift from relatively stable global warmth during the mid pliocene to the high amplitude glacial interglacial cycles of the late quaternary these observations imply that atlantic ocean surface water circulation was radically different during the mid pliocene

deep sea benthic foraminiferal assemblage response to a surface ocean productivity gradient a test a transect of samples from the eastern equatorial pacific where surface ocean productivity is the only changing environmental variable was used to test the response of benthic foraminiferal assemblages to an open ocean productivity gradient the transect runs along the east pacific rise from the highly productive waters near the equator to the oligotrophic south pacific subtropical gyre surface sediment benthic assemblages show progressive change along the transect with strong compositional shifts corresponding to the rapid productivity gradient near the equator and to the position of the southern convergence near 18 19 s the relationship of the assemblages to surface ocean productivity was tested by statistical regression of quantitative estimates of productivity on the assemblage principal component scores calculated for each sampling location the regression yielded an r squared of 0 87 demonstrating a clear relationship between surface ocean productivity and deep sea benthic foraminiferal assemblage composition the species most important to this relationship display a consistent response to oceanic productivity for long stretches of geologic time this conservative behavior and the results of the regression analysis indicate that benthic foraminiferal assemblages can be used to estimate surface ocean productivity for the geologic past

changes in east atlantic deepwater circulation over the last 30 000 years eight time slice reconstructions using 95 epibenthic 13c records eight time slices were reconstructed to trace the distribution of east atlantic deepwater and intermediate water masses over the last 30 000 years our results show that there have been three distinct modes of deepwater circulation near the stage 3 2 boundary the origin of north atlantic deep water nadw was similar to today mode 1 however after late stage 3 the source region of the nadw end member shifted from the norwegian greenland sea to areas south of iceland mode 2 a reduced nadw flow persisted during the last glacial maximum with constant preformed 13c values the nutrient content of nadw increased markedly near the azores fracture zone from north to south probably because of the mixing of upwelled antarctic bottom water aabw from below which then advected with much higher flux rates into the northeast atlantic later the spread of glacial meltwater over the north atlantic led to a marked short term ventilation minimum below 1800 m about 13 500 14c years ago mode 3 the formation of nadw recommenced abruptly north of iceland 12 800 12 500 years ago and reached a volume approaching that of the holocene in the younger dryas 10 800 10 350 years b p another short term shutdown of deepwater formation followed between 10 200 and 9 600 years b p linked to a further major meltwater pulse into the atlantic each renewal of deepwater formation led to a marked release of fossil co2 from the ocean the likely cause of the contemporaneous 14c plateaus over the last 9000 years deepwater circulation varied little from today apart from a slight increase in aabw about 7000 14c years ago it is also shown that the oxygenated mediterranean outflow varied largely independent of the variations in deepwater circulation over the last 30 000 years

coherent high and low latitude control of the northwest african hydrological balance variability in northwest african humidity has been documented for the holocene period but less is known about the development of the hydrological balance during the pleistocene period sedimentary records and numerical simulations for the past 120 000 years show abrupt millennial scale changes in humidity which may be related to changes in the strength of the north atlantic meridional overturning circulation

diatom biostratigraphy of tsunami deposits examples from the 1998 papua new guinea tsunami abstract distinctive diatom assemblages may be associated with tsunami sediments and may often contrast with the assemblages found within sediments underlying the tsunami deposit as well as those associated with the modern coastal environment sediments associated with the 1998 tsunami that destroyed much of the sissano lagoon area in northern papua new guinea have been investigated surface sediments from three transects across the sediment spit near warapu have been examined for diatom content and preservation the preservation is variable and the data show an often chaotic assemblage that can be attributed to the tsunami waves incorporating and depositing diatoms from distinctive habitat zones during their runup and subsequent backwash the diatoms identified within the warapu sediments indicate an origin from within the inter tidal and offshore area rather than from the beach sand spit complex the sand deposits disclose a high percentage in excess of 75 of broken diatom valves and a predominance of centric circular species due to preferential preservation the study demonstrates that the application of diatom biostratigraphy to modern tsunami deposits can be used in conjunction with other stratigraphical lines of evidence to interpret the source and provenance of historical and palaeo tsunami deposits

the paleoclimatic record provided by eolian deposition in the deep sea the geologic history of wind the mineral component of pelagic sediment is brought to the deep sea by transport in the wind extraction and analysis of this dust allows estimation of the past aridity of the eolian source region via flux determinations and of the intensity of the transporting winds from grain size data these two parameters the grain size and mass flux of dust vary independently there are three significant sources of modern dust eastern and central asia northwest africa and arabia all in the northern hemisphere as the rainfall associated with the intertropical convergence zone is an effective barrier to southerly transport of dust the northern hemisphere is an order of magnitude more dusty than is the southern an asymmetry that has characterized most of the cenozoic eolian flux data show that most of the northern hemisphere was more arid during glacial maxima with 3 to 5 times as much dust transported during glacial stages than during interglacials only northwestern south america varied in the opposite sense the periodicity of quaternary variation in both eolian flux and eolian grain size data is strongly influenced by the milankovitch cycles of orbital variability wind intensities vary on a shorter time scale than the general 100 kyr cycles of glaciation and general aridity eolian grain sizes display forcing at precessional 19 and 23 kyr tilt 41 kyr and at approximately 30 kyr periodicities as a result the generalization that winds are uniformly stronger during glacial times is not valid whole cenozoic records show that the largest change in dust flux an order of magnitude increase occurred in the northern hemisphere and reflects continental drying associated with the late pliocene onset of northern hemisphere glaciation southern hemisphere eolian records show no sign of paleoclimatic changes in the late pliocene the most important change in cenozoic atmospheric circulation was a severalfold reduction in wind intensity that occurred at the time of the paleocene eocene boundary before then latest cretaceous and paleocene winds were essentially as strong as those of the late cenozoic this shift appears to be one of several climatic responses to a change in the nature and amount of global heat transport at about 55 ma

models of the distribution and abundance of hydrogen at the lunar south pole 1 permanently shadowed locations at the lunar poles are potential sites for significant concentrations of cold trapped volatiles including water ice hydrogen enhancements are seen at the poles but the physical form abundance and distribution of this hydrogen remains controversial using a pixon based image reconstruction algorithm to effectively improve spatial resolution we derive maps of the lunar south polar water equivalent hydrogen concentration that are fully consistent with the orbital neutron measurements with abundances greater than 0 5 wt in some permanently shadowed locations this is much greater than the highest solar wind hydrogen abundance in returned lunar samples and may indicate ice between regolith grains if the hydrogen distribution is inhomogeneous within a permanently shadowed crater then even higher abundances are implied in shackleton crater for example the derived count rates are consistent with 10 of the crater floor area having 20 wt water equivalent hydrogen and the remainder at 0 25 wt

deepwater source variations during the last climatic cycle and their impact on the global deepwater circulation the degree of similarity of the 13c records of the planktonic foraminiferal species n pachyderma and of the benthic foraminiferal genus cibicides in the high latitude basins of the world ocean is used as an indicator of the presence of deepwater sources during the last climatic cycle whereas continuous formation of deep water is recognized in the southern ocean the norwegian sea stopped acting as a sink for surface water during isotope stage 4 and the remainder of the last glaciation however deep water formed in the north atlantic south of the norwegian sea during the last climatic cycle as early as isotope substage 5d and this area was also the only active northern source during stages 4 2 a detailed reconstruction of the geographic distribution of 13c in benthic foraminifera in the atlantic ocean during the last glacial maximum shows that the most important deepwater mass originated from the southern ocean whereas the glacial north atlantic deep water cannot be traced south of 40 n at shallower depth an oxygenated 13c rich intermediate water mass extended from 45 n to 15 s in the pacific ocean a ventilation higher than the modern one was also found in open ocean in the depth range 700 2600 m and is best explained by stronger formation of intermediate water in high northern latitudes

ostracods as tsunami tracers in holocene sequences this review analyses the ostracod record in holocene tsunami deposits using an overview of the 2004 indian ocean tsunami impact on its recent populations and the associated tsunamigenic deposits together with results from numerous investigations of other holocene sequences different features such as the variability of the local assemblages population density species diversity age population structure e g percentages of adults and juvenile stages or taphonomical signatures suggest that these microorganisms may be included amongst the most promising tracers of these high energy events in marshes lakes lagoons or shallow marine areas

improvements in long core measurement techniques applications in palaeomagnetism and palaeoceanography we report on new developments in the long core measurement techniques using u channels in connection with new small access cryogenic magnetometers with these new instruments u channel samples allow us to measure a wide range of magnetic parameters along entire core length with a spatial resolution and accuracy virtually equivalent to that obtained using discrete cubic samples an additional advantage is that the sediment disturbance when sampling is significantly less when using u channels we present comparisons of results from both continuous and discrete measurements and examine the effectiveness of minimal deconvolution using various techniques examples of continuous measurements of low field susceptibility nrm arm irm hrc from north atlantic deep sea cores show that it is possible to generate logs of combination of parameters related to rock magnetic characteristics of the sediments useful in palaeoceanography in particular the continuous method allows us to rapidly detect core regions with fast changing magnetic parameters useful for correlation between cores and also for understanding changes in palaeo environmental conditions the fast scan also allows us to detect regions of the core where the rock magnetic parameters are suitable or not suitable for palaeomagnetic studies related to changes in the geomagnetic field such as the relative changes in palaeointensity

the impact of african aridity on the isotopic signature of atlantic deep waters across the middle pleistocene transition abstract a high resolution analysis of benthic foraminifera as well as of aeolian terrigenous proxies extracted from a 37 m long marine core located off the mauritanian margin spanning the last 1 2 ma documents the possible link between major continental environmental changes with a shift in the isotopic signature of deep waters around 1 0 0 9 ma within the so called mid pleistocene transition mpt time period the increase in the oxygen isotopic composition of deep waters as seen through the benthic foraminifera 18o values is consistent with the growth of larger ice sheets known to have occurred during this transition deep water mass 13c changes also estimated from benthic foraminifera show a strong depletion for the same time interval this drastic change in 13c values is concomitant with a worldwide 0 3 decrease observed in the major deep oceanic waters for the mpt time period the phase relationship between aeolian terrigeneous signal increase and this 13c decrease in our record as well as in other paleorecords supports the hypothesis of a global aridification amongst others processes to explain the deep water masses isotopic signature changes during the mpt in any case the isotopic shifts imply major changes in the end member 18o and 13c values of deep waters

response of global deep water circulation to earth s climatic change 135 000 107 000 years ago the response of deep ocean circulation to major climatic events of the past 135 000 years is inferred using carbon 13 analyses of benthic foraminifera from the major ocean basins the results demonstrate that the circulation of the world ocean deep water is very sensitive to climate and that it changes drastically during climatic transitions

sedimentary record of a tsunami during roman times bay of cadiz spain abstract historical data show that the gulf of cadiz has been exposed to destructive tsunamisduring at least the past 2000 yr the last tsunami was generated by the ad 1755 lisbon earthquake which affected the atlantic coasts of spain portugal and morocco today these littoral areas areintensely populated and the expected damage could be much greater tsunami studies are of greatimportance in helping to determine the recurrence interval of these events the presence of washover fan deposits on the inland margin of the valdelagrana spit bar cadiz spain indicates the occurrence of a high energy marine event ca 2300 cal yr bp historical geomorphological sedimentological palaeontological and geochronological data suggest that atsunami could have affected the area during roman times copyright 2002 john wiley sons ltd journal of quaternary science keywords tsunami deposits grain size palaeontology gulf of cadiz south spain introduction investigations of the geological records of past tsunamis arean important tool in helping to determine the recurrenceinterval of such events in a region these investigations arealso the only way of determining the prehistoric occurrenceand tsunami hazard in areas of infrequent seismic activity however at present it is dif cult to distinguish betweentsunami deposits and those laid down by other high energyevents such as a storm surge or hurricane recent work bygoff et al 2001 has helped to identify a series of diagnosticcriteria for tsunami deposits and research is underway tohighlight the differences between these and other high energyevents goff and chagu e goff in preparation j goff personalcommunication 2002 wave hydrodynamics the speci ccoastal setting morphology orientation availability and typeof sediments depositional environments tsunami magnitudeand tidal range are all factors that help to de ne the type andpreservation of tsunami deposits furthermore the ability todetermine the tsunamigenic source largely depends upon thepalaeoseismic and historical record e g goff et al 2001

two dimensional distribution of volatiles in the lunar regolith from space weathering simulations 1 we present simulations of space weathering effects on ice deposits in regions of permanent shadow on the moon these monte carlo simulations follow the effects of space weathering processes on the distribution of the volatiles over time the model output constrains the coherence of volatile deposits with depth lateral separation and time the results suggest that ice sheets become broken and buried with time as impacts begin to puncture an initially coherent surficial ice sheet small areas with a deficit of ice compared to surrounding areas are formed first as time progresses holes become prevalent and the anomalous regions are local enhancements of ice concentration in a volume the 3 d distribution is also heterogeneous because the ice is buried to varying depths in different locations analysis of the coherence of ice on 10 cm scales predicts that putative ice sheets in anomalous radar craters are 1000 myr old for future in situ analysis of cold trap volatiles a horizontal range of 10 m is sufficient to acquire surface based measurements of heterogeneously distributed ice these results also support previous analyses that mercury s cold traps are young

diatoms as an aid in identifying late holocene tsunami deposits diatoms bacillariophyta help identify the onshore deposits of tsunamis from earthquakes on the cascadia subduction zone along the pacific coast of oregon washington and british columbia and on faults high in the north american plate in the puget sound area of washington at the copalis river washington diatom analyses suggest that a tsunami deposit about 300 calendric years old 300 yr bp originated from sandy shoals of the lower estuary rather than nearby beaches or coastal dunes at cultus bay and west point washington well preserved benthic estuarine diatoms in sand sheets overlying tidal marsh peat indicate that the deposits came from intertidal or nearshore areas of puget sound on an abruptly uplifted mudflat at the landward end of hood canal at lynch cove washington tidal flat diatoms refute the possibility of a terrestrial source for the sand diatoms in 300 yr bp tsunami deposits on the niawiakum river washington confirm that the sand in these deposits had a marine source and help

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

distinguishing tsunami and storm deposits an example from martinhal sw portugal abstract geological identification of past tsunamis is important for risk assessment studies especially in areas where the historical record is limited or absent the main problem when using the geological evidence is to distinguish between tsunami and storm deposits both are high energy events that may leave marine traces in coastal stratigraphic sequences at martinhal sw portugal both storm surge and tsunami deposits are present at the same site within a single stratigraphic sequence which makes it suitable to study the differences between them excluding variations caused by local factors the tsunami associated with the lisbon earthquake of november 1st 1755 ad had a major impact on the geomorphology and sedimentology of martinhal it breached the barrier and laid down an extensive sheet of sand as described in eyewitness reports besides the tsunami deposit the stratigraphy of martinhal also displays evidence for storm surges that have breached and overtopped the barrier flooding the lowland and leaving sand layers both marine derived flood deposits show similar grain size characteristics and distinctive marine foraminifera the most important differences are the rip up clasts and boulders exclusively found in the tsunami deposit and the landward extent of the tsunami deposit that everywhere exceeds that of the storm deposits identification of both depositional units was only possible using a collection of different data and extensive stratigraphical information from cores as well as trenches

stratigraphic and microfossil evidence for late holocene tsunamis at swantown marsh whidbey island washington abstract four muddy sand sheets occur within a tidal marsh peat at swantown on the west coast of whidbey island washington the two largest sand sheets pinch out about 100 m inland and became thinner and finer grained landward all four sand sheets contain marine microfossils and have internal stratification they record repeated inundation of the marsh over a short time period by distinct pulses of sediment laden ocean water consistent with deposition by a tsunami wave train the layers have been radiocarbon dated to 1160 1350 1400 1700 1810 2060 and 1830 2120 cal yr b p the overlap in age between the two youngest layers and inferred great earthquake events at the cascadia plate boundary some 250 km to the west suggests they were emplaced by tsunamis from this source area the two older layers do not correlate with plate boundary events they may be products of tsunamis caused by earthquakes on local faults in the strait of juan de fuca or by submarine landslides in this area

an integrated view of inorganic and organic biogeochemical indicators of palaeoproductivity changes in a coastal upwelling area in order to evaluate the role of the continental margin areas in the changes of atmospheric co2 during past climatic cycles it is crucial to reconstruct reliably export palaeoproductivity changes in such areas this paper examines and discusses the specific relationships between various productivity dependent geochemical signals recorded in a single sediment core from the northwestern africa continental slope including both major and trace parameters of inorganic and organic origin this paper clearly shows that the export productivity flux as well as its composition e g the relative contribution of calcareous siliceous and mineral free producers have changed these changes have subsequently modified benthic conditions which can have had in turn a retroaction on major biogenic element contents this effect seems however to be only minor compared to that one directly induced by changes in biogenic fluxes these results indicate that direct palaeoproductivity transfer functions which are based on present day statistical calibrations of one single parameter and which are valid to some extent for sediments from abyssal open ocean cannot be properly applied in marginal areas which are much more complex and in particular highly affected by sea level changes in such areas quantitative palaeoproductivity reconstructions should be only considered at a regional scale including off shoreward on shoreward and latitudinal migration or extension of the productive areas as well as the palaeoproductivity intensity and composition

a geologic model for lunar ice deposits at mining scales abstract water ice has been detected at the lunar poles but existing and near future orbital datasets do not have the capabilities to determine its horizontal and vertical distribution at meter to hundred meter scales relevant for mining operations additionally there has not yet been a coherent geologic model put forward for how ice deposits have formed and evolved that can be used to assist in planning prospecting campaigns or developing relevant hardware here we propose a system model for understanding these deposits at scales of meters to hectares the model considers sources of water ice capture at and below the surface and retention it focuses heavily on impact gardening as a modifying process that drives changes in how ice is distributed 3 dimensional stochastic impact simulations are then used to test the system model and explore how ice deposits might evolve over an area the size of a potential mining outpost the simulation results showed ice concentrations should eventually become fairly homogeneous at meter to hectare scales due to impact gardening and high concentrations are distributed randomly rather than clustered in earth like ore bodies we found the best ice deposits for extracting likely exist 10s of cm deep or more even in locations where ice is currently stable at the very surface terrestrial mining software was then used to create block models and grade tonnage curves that can inform future in situ resource utilization demonstration missions and future mining operations planning

sedimentology of the december 26 2004 sumatra tsunami deposits in eastern india tamil nadu and kenya the december 26 2004 sumatra tsunami caused severe damage at the coasts of the indian ocean we report results of a sedimentological study of tsunami run up parameters and the sediments laid down by the tsunami at the coast of tamil nadu india and between malindi and lamu kenya in india evidence of three tsunami waves is preserved on the beaches in the form of characteristic debris accumulations we measured the maximum run up distance at 580 m and the maximum run up height at 4 85 m flow depth over land was at least 3 5 m the tsunami deposited an up to 30 cm thick blanket of moderately well to well sorted coarse and medium sand that overlies older beach deposits or soil with an erosional unconformity the sand sheet thins inland without a decrease of grain size the deposits consist frequently of three layers the lower one may be cross bedded with foresets dipping landward and indicating deposition during run up the overlying two sand layers are graded or parallel laminated without indicators of current directions thus it remains undecided whether they formed during run up or return flow thin dark laminae rich in heavy minerals frequently mark the contacts between successive layers benthic foraminifera indicate an entrainment of sediment by the tsunami from water depths less than ca 30 m water depth on the indian shelf these depths are present at distances of up to 5 km from the coast in kenya only one wave is recorded which attained a run up height of 3 m at a run up distance of ca 35 m from the tidal water line at the time of the tsunami impact only one layer of fine sand was deposited by the tsunami it consists predominantly of heavy minerals supplied to the sea by a nearby river the sand layer thins landward with a minor decrease in grain size benthic foraminifera indicate an entrainment of sediment by the tsunami from water depths less than ca 30 m water depth reaching down potentially to ca 80 m the presence of only one tsunami related sediment layer in kenya but three in india reflects the impact of only one wave at the coast of kenya as opposed to several in india grain size distributions in the indian and kenyan deposits are mostly normal to slightly positively skewed and indicate that the detritus was entrained by the tsunami from well sorted pre tsunami deposits in nearshore swash zone and beach environments

the use of ostracods from marginal marine brackish waters as bioindicators of modern and quaternary environmental change abstract ostracoda microscopic aquatic crustacea from brackish waters have a great potential for ecological monitoring and palaeoenvironmental analyses in highly variable environments this has been proven in many articles during recent decades but their potential has yet to be fully developed or utilised the analysis of ostracod assemblage composition species distributions eco phenotypic variability and the analysis of stable isotopes and trace elements in ostracod shells provide valuable information on present and past water salinity temperature and chemistry hydrodynamic conditions substrate characteristics climate sea level variations oxygen and nutrient availability this article provides an overview on the application of ostracods from brackish waters for palaeoenvironmental reconstruction in the quaternary and for environmental studies in present day environments

changes in the distribution of δ13c of deep water σco2 between the last glaciation and the holocene carbon isotopic measurements on the benthic foraminiferal genus cibicidoides document that mean deep ocean 13c values were 0 46 lower during the last glacial maximum than during the late holocene the geographic distribution of 13c was altered by changes in the production rate of nutrient depleted deep water in the north atlantic during the late holocene north atlantic deep water with high 13c values and low nutrient values can be found throughout the atlantic ocean and its effects can be traced into the southern ocean where it mixes with recirculated pacific deep water during the glaciation decreased production of north atlantic deep water allowed southern ocean deep water to penetrate farther into the north atlantic and across low latitude fracture zones into the eastern atlantic mean southern ocean 13c values during the glaciation are lower than both north atlantic and pacific 13c values suggesting that production of nutrient depleted water occurred in both oceans during the glaciation enriched 13c values in shallow cores within the atlantic ocean indicate the existence of a nutrient depleted water mass above 2000 m in this ocean

sedimentation and hydrodynamic processes associated with the tsunami generated by the 1755 lisbon earthquake abstract an unusual sedimentary horizon believed to have been deposited by the tsunami associated with the 1755 lisbon earthquake has been identified at boca do rio in southern portugal this horizon marks a distinct sedimentological and micropalaeontological break from the deposits enclosing it the sedimentary characteristics of the horizon which consists of several distinct sub units vary greatly in both vertical and horizontal section detailed textural analysis through vertical sections of these sub units shows abrupt changes in particle size characteristics the highly variable nature of the horizon appears to be due to rapid variation in the hydrodynamic characteristics of the depositional event the lowermost section of the deposit appears to have been deposited from a highly turbulent water mass which was able to transport gravel sized clasts as well as gravel sized mud balls eroded from underlying material the water mass rapidly lost energy leading to the deposition of predominantly sand silt and clay particles sharp breaks in textural characteristics are likely to be due to changes in current direction caused by wave reflection or swash backwash interference the main sources of sand sized material within the deposit are the seaward barrier beach foredune system the tsunami deposit at boca do rio shares many of the sedimentary characteristics of tsunami deposits from other sites around the world

stability of north atlantic water masses in face of pronounced climate variability during the pleistocene 1 geochemical profiles from the north atlantic ocean suggest that the vertical 13c structure of the water column at intermediate depths did not change significantly between glacial and interglacial time over much of the pleistocene despite large changes in ice volume and iceberg delivery from nearby landmasses the most anomalous 13c profiles are from the extreme interglaciations of the late pleistocene this compilation of data suggests that unlike today an extreme interglaciation the two primary sources of northern deep water norwegian greenland sea and labrador sea subpolar north atlantic had different characteristic 13c values over most of the pleistocene we speculate that the current open sea ice conditions in the norwegian greenland sea are a relatively rare occurrence and that the high 13c deep water that forms in this region today is geologically unusual if northern source deep waters can have highly variable 13c then this likelihood must be considered when inferring past circulation changes from benthic 13c records

evidence of high energy events in the geological record mid holocene evolution of the southwestern donana national park sw spain abstract four phases are distinguished in the mid holocene evolution of the southwestern donana national park sw spain based on the multidisciplinary study of sediments in drill cores in the oldest phase 5500 5400 cal years bp a coastal brackish lagoon occupied the central part of the study area partly enclosed by the donana spit and limited by fluvial levees an evolution from subtidal to intertidal conditions characterized the areas located close to the inner side of the donana spit during the same phase the following phase 5400 5200 cal years bp is characterized by a high energy event tsunami which caused the breakthrough of the donana spit and the creation of new littoral strands in the inner areas in the first period of the third phase 5200 4200 cal years bp estuarine infilling was probably the dominant process with the accumulation of phyllosilicate rich clays in the lagoon bed this was followed by a renewed phase of instability 4200 4100 cal years bp indicated by the presence of fine storm lain deposits and thicker probably tsunami induced shelly deposits the last phase 4100 3700 cal years bp comprises a an infilling period with a diminution of the marine influence and b two new high energy events which caused the erosion of the donana spit and the creation of new cheniers in the last 7000 years the comparison of these results with a revision of both geological and historical records has revealed the occurrence of twenty tsunamis at least during this period in portugal and southern spain evidences of these high energy events are washover fans bioclastic coarse sized layers within salt marsh deposits or the presence of giant boulders and pebbles the determination of the recurrence period is very difficult owing to the very scarce data although our data and other authors do not discard a possible periodicity of 2000 years for a cycle of two events separated by 300 400 years

a tsunami ca 6300 years bp and other holocene environmental changes northern hawke s bay new zealand abstract sediment cores collected in a coastal lagoon a few kilometres east of wairoa northern hawke s bay new zealand were examined using sedimentological geochemical palynological and micropaleontological analyses a distinct short lived catastrophic saltwater inundation csi about 6300 years bp and possibly other minor marine incursions are preserved in the coastal estuarine to lagoonal freshwater sedimentary sequences which have been deposited in the last 6500 years the csi is characterised by a gravel unit that thins landward and decreases in particle size to sand within a sequence consisting mainly of brackish estuarine muds diatom assemblages indicate a marked change from the shallow brackish estuarine muds to marine gravels and sands to brackish estuarine muds the marine influence in the gravel and sand is also shown by the presence of marine dinoflagellates and a peak in na rb sedimentological chemical and paleontological in particular diatoms evidence indicates it is a csi we conclude that this was a tsunami and propose the most likely propagating mechanisms marine influence decreases upcore and totally freshwater conditions are evident in the upper section of the cores the geochemistry of the sediments mainly reflects the change in stratigraphy with distinct signatures for tephra na fe cr organic rich and peat units as br and the coarse gravel sand csi unit na rb cr fe but it is also indicative of changes in depositional environment the change in chemistry na rb in the csi event is indicative of a saltwater influence whereas a marked change in s content suggests a sudden change from brackish to freshwater conditions shortly after 4800 years bp another peak in s and br content about 3200 years bp may indicate another temporary change to brackish conditions

ostracod palaeolimnological analysis reveals drastic historical changes in salinity eutrophication and biodiversity loss in a coastal mediterranean lake the albufera of valencia one of the largest oligohaline coastal lagoons of the iberian peninsula has suffered hydrological and landscape modifications since medieval times this paleolimnological study clears up the controversy about the factors which drove the lake to its present state lithological descriptions ostracod paleoassemblages and cyprideis torosa jones 1850 shell morphological variations and geochemistry 18o 13c and sr ca have been used to reconstruct the lake ecosystem evolution during the last two centuries the sandy sediments at the bottom of l antina core 63 cm presented a typical assemblage of brackish water ostracods with shell derived 18o values inferred salinity and sr cawater characteristic of waters with marine influence however 10 cm above coinciding with a drastic change in lithology ostracod palaeoassemblages and decreased shell 18o indicated a shift to freshwater influences at the top of the sequence inferred salinity suggests oligohaline waters and ostr

tsunami deposits in holocene bay mud in southern kanto region pacific coast of central japan abstract tsunami have probably deposited sand sheets that are intercalated in holocene bay floor mud exposed on the boso and miura peninsulas facing the convergent boundary of the pacific philippine sea and eurasian plates we have identified seven sand sheets at four drowned valleys and correlated these by 137 radiocarbon dates of shells and wood the sheets consist of poorly sorted muddy sand and well sorted sand layers in fining upward sequences containing abundant transported shells rip up clasts and wood fragments the sheets erosionally overlie bioturbated bay floor mud that contains molluscan shells in life position most of the sheets are less than 20 cm thick and rarely more than 50 cm thick some molluscan shells are older in these layers than in underlying mud both landward and seaward paleocurrents are shown in a few cases by imbrication of shells and by low angle wedge shaped lamination at least five of the sand sheets contain molluscan fossils derived from rocky coasts or shore platforms although they intercalated in mud deposited within bays at depths of 10 15 m two other sand sheets are dominated by open seashore ostracode assemblages although they were deposited in the brackish inner bay and muddy central bay five of the layers may correlate with emergences recorded by nearby holocene marine terraces these correlations suggest that great earthquakes triggered the inferred tsunami the tsunami occurred at intervals of 300 2000 years beginning about 10 000 years ago

millennial scale northwest african droughts related to heinrich events and dansgaard oeschger cycles evidence in marine sediments from offshore senegal 1 we present a suite of new high resolution records 0 135 ka representing pulses of aeolian fluvial and biogenic sedimentation along the senegalese continental margin a multiproxy approach based on rock magnetic element and color data was applied on three cores enclosing the present day northern limit of the itcz a strong episodic aeolian contribution driven by stronger winds and dry conditions and characterized by high hematite and goethite input was revealed north of 13 n these millennial scale dust fluxes are synchronous with north atlantic heinrich stadials fluvial clay input driven by the west african monsoon predominates at 12 n and varies at dansgaard oeschger time scales while marine productivity is strongly enhanced during the african humid periods and marine isotope stage 5 from latitudinal signal variations we deduce that the last glacial itcz summer position was located between core positions at 12 26 and 13 40 n furthermore this work also shows that submillennial periods of aridity over northwest africa occurred more frequently and farther south than previously thought

ostracods from a marmara sea lagoon turkey as tsunami indicators abstract a 352 cm long sediment core from hersek lagoon gulf of izmit was investigated for its ostracod species composition in order to evaluate the potential of ostracods to detect tsunami deposits in coastal environments the gulf of izmit is the eastern bay of the marmara sea which is tectonically controlled by the north anatolian fault ostracod shells are rare in the lower third of the core which probably represents a coastal wetland environment according to radiocarbon dating of terrestrial plant remains this unit was deposited between ad 500 and ad 800 above ostracod shells are abundant and dominantly monospecific composed almost exclusively of the widespread brackish water ostracod cyprideis torosa this almost monospecific occurrence indicates the establishment and maintenance of the hersek lagoon after ad 800 three distinct layers of mollusc shells and fragments contain ostracod shells of marine and to a lesser extent non marine origin in addition to those of c torosa the shell layers are further characterized by significant maxima in total ostracod shell numbers the high concentration of ostracod shells the higher species numbers and the mixture of marine lagoonal and non marine ostracod shells shows that shell layers were formed as high energy deposits resulting from tsunamis or large storms in the marmara sea the partial occurrence of non marine ostracod shells in the shell layers possibly indicates that tsunamis with extensive run ups and significant backwash flows caused the high energy deposits rather than large storms the investigated sediments show that lagoonal ostracods can serve as good proxies for tsunamis or large storms through significant variations in total shell numbers species numbers and the mixing of shells of different origin

abrupt environmental changes within a late holocene lacustrine sequence south of the marmara sea lake manyas n w turkey possible links with seismic events abstract a coring campaign in lake manyas kus golu on the southern coast of the sea of marmara turkey has provided insights into basin infilling processes during the upper 11 metres of the sedimentary record combined sedimentary features between 5 and 4 m depth have been explained by a seismite a brittle mixed layer uniquely rich in seeds and ostracod valves was widely detected at 4 m downcore this has been interpreted as being the result of a seiche either through a salt inundation linked to a tsunami in the sea of marmara the large scale scenario or a local hydrothermal fluid discharge the small scale scenario ostracod valves which are usually not preserved in lake manyas sediment are either incorporated here as tsunami debris providing a spatially averaged snapshot of the regional assemblage or are locally preserved following a temporary geochemical hydrochemical change of the water of unknown duration but probably several decades the brittle mixed layer overlies cracks resulting from the direct effects of the seismic shock wave on slightly compacted sediment at around 964 cm depth palynological and particle size analyses indicate a change from backswamp to open lacustrine conditions the end of the backswamp has been correlated with a decrease in the level of the sea of marmara from 4000 to 3000 2800 yr ago uncal caused by regional tectonic movements an age depth model is presented based on two ams radiocarbon dates on the palynological detection of the end of the beysehir occupation phase 130 cm above the event and on maximal sedimentation accumulation rates obtained by radionuclide analyses the entire study sequence covers the last 4300 yr the paper examines the possibility of an early byzantine age for the seismic event this may have been the historical event at ad 460 that destroyed cyzicus the ancient erdek 20 km north of the lake and various villages in the interior and was felt widely in the then known world other possibilities include various local and regional events in that same period the early byzantine tectonic paroxysm and the large earthquake in ad 447 that affected the entire sea of marmara region

sediments deposited by the 2004 indian ocean tsunami along the malaysia thailand peninsula stratigraphy grain size distribution and foraminiferal assemblages of pre tsunami and tsunami sediment from the indian ocean tsunami at five sites along the malaysia thailand peninsula were analyzed to gain information on tsunami sediment source and deposition style between three and five stratigraphic units were identified at each site and contained between one and three fining upward sequences reflecting waning flow or pre backwash deposition coarser sand layers reflecting uprush high energy flow separated the fining upward sequences with the exception of one site sungai burong which contained a coarsening upward sequence all contacts between the pre tsunami and tsunami sediment were sharp or erosional medium and coarse sand dominated all of the tsunami sediment deposits and often contained shell fragments foraminiferal assemblages were able to differentiate pre tsunami sediment from tsunami sediment where no lithological or grain size distribution change was evident between two and four foraminiferal zones were identified at each of the five sites and provided estimates of sediment source and wave characteristics

mid pleistocene environmental change in tropical africa began as early as 1 05 ma palynological records from the congo fan reveal environmental change in equatorial africa occurring 1 05 ma ago 100 k y before the mid pleistocene climatic shift at 0 9 ma prior to 1 05 ma a glacial interglacial rhythm is not obvious in the african vegetation variation afterwards podocarpus spread in the mountains of central africa mainly during glacials and congo river discharge decreased the sequence of vegetation variation associated with the mid pleistocene glacials and interglacials differed from that observed during the late pleistocene between 0 9 and 0 6 ma interglacials were characterized by warm dry conditions and glacials were characterized by cool humid conditions while during the past 0 2 ma glacials were cold and dry and interglacials warm and humid our data indicate that before the northern hemisphere ice caps dramatically increased in size 0 9 0 6 ma low latitude climate forcing and response in the tropics played an important role in the initiation of 100 k y ice age cycles during the mid to late pleistocene however the climate conditions in the tropics were increasingly influenced by the glacialinterglacial variations of continental ice sheets

paleoceanography of the mauritanian margin during the last two climatic cycles from planktonic foraminifera to african climate dynamics abstract the last 220 ka of the md03 2705 18 05 81 n 21 09 19 w sedimentary sequence retrieved off the cape verde islands was investigated using a multiproxy approach planktonic foraminifera assemblage analyses coupled with isotopic measurements 18 o from benthic planulina wuellerstorfi and planktonic globigerinoides ruber foraminifera monospecific samples were conducted along the topmost 11 m of the sequence high resolution x ray fluorescence measurements 0 5 cm resolution giving access to major element ratio have completed the geochemical analyses along the core seasonal and annual past sea surface temperatures sst were quantitatively reconstructed local sea surface salinity sss changes were then estimated by coupling sst with planktonic 18 o data our data provide a set of both oceanic and continental markers of environmental changes along the north western african margin the major changes detected in our record are discussed in the light of the regional paleoceanographic and paleoclimatic history of the last 220 ka coupled oceanographic and atmospheric processes portray the climatic evolution of the area and show strong links among the regional oceanography water mass advection the upwelling dynamics and the intertropical convergence zone itcz migration an increased upwelling activity or influence of upwelling filaments is noted at the end of the two last glacial periods probably in response to a more southerly position of the itcz higher sss are recorded over the area during arid intervals and were tentatively interpreted as signing a southward shift of the cape verde frontal zone a detailed coupling between dust advection and sss values over the site of study was noted during mis6 5

ostracodes reveal the sea bed origin of tsunami deposits 1 in rikuzentakata city ostracode assemblages in sediment deposited by the tohoku oki earthquake and tsunami of 11 march 2011 revealed that the sediment was derived from the seafloor from at least 9 m water depth and was transported inland more than 1 km the tsunami wave height at this location was higher than 10 m four hundred fifty seven modern ostracode assemblages were used in the modern analogue technique to estimate the depth source of the tsunami deposited assemblages the application of this method to paleo tsunami deposits may provide insight into past tsunami wave height and potentially earthquake slip and magnitude

shallow marine sediment cores record climate variability and earthquake activity off lisbon portugal for the last 2000 years abstract sea surface temperature sst river discharge and biological productivity have been reconstructed from a multi proxy study of a high temporal resolution sedimentary sequence recovered from the tagus deposition center off lisbon portugal for the last 2000 years sst shows 2 c variability on a century scale that allows the identification of the medieval warm period mwp and the little ice age lia high iron fe and fine sediment deposition accompanied by high n alkane concentrations and presence of freshwater diatoms during the lia 1300 1900 ad science 292 2001 662 suggest augmented river discharge whereas higher total alkenone concentrations point to increased river induced productivity during the mwp 550 1300 ad science 292 2001 662 larger mean grain size and low values of magnetic susceptibility and concentrations of fe n alkanes and n alcohols are interpreted to reflect decreased runoff at the same time increased benthic and planktonic foraminifera abundances and presence of upwelling related diatoms point to increased oceanic productivity on the basis of the excellent match found between the negative phases of the north atlantic oscillation nao index and the intensified tagus river discharge observed for the last century it is hypothesized that the increased influx of terrigenous material during the lia reflects a negative nao like state or the occurrence of frequent extreme nao minima during the milder few centuries of the mwp stronger coastal upwelling conditions are attributed to a persistent positive nao like state or the frequent occurrence of extreme nao maxima the peak in magnetic susceptibility centered at 90 cm composite core depth ccd is interpreted as the result of the well known 1755 ad lisbon earthquake the lisbon earthquake and accompanying tsunami are estimated to have caused the loss of 39 cm of sediment 355 years of record most of the lia and the instantaneous deposition of a 19 cm sediment bed

13c record of benthic foraminifera in the last interglacial ocean implications for the carbon cycle and the global deep water circulation the 13c 12c ratios of upper holocene benthic foraminiferal tests genera cibicides and uvigerina of deep sea cores from the various world ocean basins have been compared with those of the modern total carbon dioxide tco2 measured during the geosecs program the 13c difference between benthic foraminifera and tco2 is 0 07 0 04 for cibicides and 0 83 0 07 for uvigerina at the 95 confidence level 13c analyses of the benthic foraminifera that lived during the last interglaciation isotopic substage 5e about 120 000 yr ago show that the bulk of the tco2 in the world ocean had a 13c value 0 15 0 12 lower than the modern one at the 95 confidence level reflecting a depletion compared to the present value of the global organic carbon reservoir regional differences in 13c between the various oceanic basins are explained by a pattern of deep water circulation different from the modern one the antarctic bottom water production was higher than today during the last interglaciation but the eastward transport in the circumpolar deep water was lower

astronomical timescale and palaeoclimatic implication of stacked 3 6 myr monsoon records from the chinese loess plateau abstract magnetic susceptibility and grain size records from two continuous red clay and loess palaeosol sequences on the chinese loess plateau have been generated to investigate the evolution and variability of the east asian monsoon eam during the late pliocene and pleistocene tuning the grain size records to orbital obliquity and precession yields an improved astronomical timescale for the loess palaeosol sequence 0 2 6 ma and an extended age model for the upper red clay formation 2 6 3 6 ma this timescale indicates older ages for a number of the magnetic polarity boundaries consistent with lock in depth offsets in loess sequences good site to site correlation enables generation of stacked grain size and susceptibility records spanning the last 3 6 myr these records indicate that monsoon evolution since the late pliocene can be subdivided into three phases 0 1 25 1 25 2 72 and 2 72 3 4 ma each phase is characterized by unique amplitude and frequency characteristics for both summer monsoon magnetic susceptibility and winter monsoon grain size spectral analyses of the stacked monsoon proxies indicate that characteristics of both the summer and winter monsoons are dominated mainly by variance in the eccentricity 410 and 100 kyr obliquity 41 kyr and precession 23 and 19 kyr bands over the past 3 4 myr implying a non linear response of the long term eam evolution to orbital and glacial forcing

crater degradation on the lunar maria topographic diffusion and the rate of erosion on the moon landscape evolution on the moon is dominated by impact cratering in the post maria period in this study we mapped 800 m to 5 km diameter craters on 30 of the lunar maria and extracted their topographic profiles from digital terrain models created using the kaguya terrain camera we then characterized the degradation of these craters using a topographic diffusion model because craters have a well understood initial morphometry these data provide insight into erosion on the moon and the topographic diffusivity of the lunar surface as a function of time the average diffusivity we calculate over the past 3 ga is 5 5 m2 myr with this diffusivity after 3 ga a 1 km diameter crater is reduced to approximately 52 of its initial depth and a 300 m diameter crater is reduced to only 7 of its initial depth and craters smaller than 200 300 m are degraded beyond recognition our results also allow estimation of the age of individual craters on the basis of their degradation state provide a constraint on the age of mare units and enable modeling of how lunar terrain evolves as a function of its topography

early middle pleistocene transitions linking terrestrial and marine realms abstract marked by a progressive increase in the amplitude of climate oscillations an evolving waveform and a shift towards a quasi 100 ky frequency the early middle pleistocene transition empt previously known as the mid pleistocene transition or mid pleistocene revolution 1 4 0 4 ma represents a fundamental transformation in the earth s climate state the empt began with a substantial change in climate dynamics and ended with the mid brunhes event signaling the establishment of a new steady state the reasons for the empt while uncertain appear to involve a non linear response of the earth climate system the physical and biotic responses to this transition amplified by the growth of northern hemisphere ice sheets have been profound two important chronostratigraphic markers characterize the empt the jaramillo subchron 1 070 0 988 ma and the matuyama brunhes chron boundary 773 ka the latter has been chosen as the primary guide for the lower middle pleistocene subseries boundary as it lies at the approximate midpoint of the empt and aids in global recognition both in marine and terrestrial deposits the jaramillo subchron has received less attention but the late early pleistocene is important in europe because it saw the progressive transition from the villafranchian to galerian mammal faunas and expansion of hominins into western and northern europe the jaramillo subchron is represented by marine isotope stages mis 31 to 28 with mis 30 already showing the asymmetrical sawtooth pattern characteristic of the middle pleistocene indeed while variation in the 40 ky band obliquity remains strong throughout the empt low frequency variability begins at around 1250 1200 ky which coincides with a progressive increase in global ice volume against a backdrop of increasingly severe glacial cycles notably during mis 36 34 24 22 the so called 0 9 ma event 16 and 12 pronounced phases of warming are also documented globally including the super interglacial mis 31 the early phase of the empt is characterized by important glaciations beginning with mis 36 and continuing to mis 24 22 a major intensification of the east asian monsoon system intensification of loess deposition in northern europe development of open landscapes in western siberia increased fluvial incision higher amplitude sea level change and spread of large mammals across northern eurasia and a strong reduction in the north atlantic thermohaline circulation in europe the loss of thermophilous plant taxa during the empt and indeed throughout the quaternary is a reminder of the progressive cooling that took place here and elsewhere

recursive plasma wake formation on the moon and its effect on polar volatiles abstract solar wind plasma flows almost horizontally in near terminator regions of the moon one question is how does this plasma flow around topographic features like near terminator mountains and polar craters we present kinetic simulations of plasma inflow into a complicated polar crater having a second child crater within the parent crater i e a crater in a crater model we find that the effect on the inflowing ions of this second child feature is a function of its position downstream relative to the primary crater wall close to the wall where the solar wind is occulted there is little ion inflow and thus not a significant perturbation from the child obstruction however beyond about two crater wall heights downstream there is substantial ion flow and the child obstruction will create a second ambipolar wake region similar to that created by the first obstruction we also present a general analytical formalism that explains the most critical properties of the inflow perturbations finally we consider the effect of the ion inflow into polar craters with 1 water frost mixed within the top micron layers of the regolith we find that in order to maintain equilibrium a persistent frost most likely has to be maintained by a dynamic water source of 10 9 molecules m 2 s 1 in polar craters to offset solar wind ion inflow sputtering losses

ostracoda crustacea as indicators of subaqueous mass movements an example from the large brackish lake tangra yumco on the southern tibetan plateau china abstract a conceptual model of subaquaeous mass movements and ostracod distribution in lacustrine sediment event layers was tested integrated methods geophysical sedimentological and microfossil analyses were performed on a short sediment core retrieved from 220 m water depth in the large brackish lake tangra yumco on the southern tibetan plateau central asia the event layers of the core and their underlying and overlying sediments were investigated four major event layers composed of sandy silt with graded bedding are interpreted as turbidites the fifth layer consisting of fine sand and silt and without graded bedding is characterized as a debrite the ostracods small bivalved aquatic crustaceans identified are leucocytherella sinensis huang 1982 leucocythere dorsotuberosa huang 1982 limnocythere inopinata baird 1843 and fabaeformiscandona gyirongensis huang 1982 ostracod evidence is a good proxy for the evaluation of massive sediment event layers formed by subaqueous mass movements four assumptions of a conceptual model were confirmed i fine grained sediments of event layers turbidite deposits contain very low numbers of ostracods compared to the underlying and overlying sediments ii ostracods are sorted according to size and display high abundance and high proportion of adult valves of leucocytherella sinensis at the base of event layers iii a relatively low number of carapaces is present within the event layers and iv the recolonization of newly event generated habitats by pioneer assemblages transforming into pre event association gradually

megatsunami deposits on kohala volcano hawaii from flank collapse of mauna loa the origin of coastal and high elevation marine gravels on the hawaiian islands of lanai and molokai is controversial because the vertical tectonics of these islands is poorly constrained the gravels are either from eustatic highstands or were left by massive tsunamis from offshore giant landslides in contrast at kohala on the island of hawaii where continuous subsidence is well established lithofacies analysis and dating of a fossiliferous marine conglomerate 1 5 61 m above present sea level support a tsunami origin and indicate a runup of 400 m 6 km inland the conglomerate age 110 10 ka suggests a tsunami caused by the ca 120 ka giant alika 2 landslide from nearby mauna loa volcano

north atlantic intermediate to deep water circulation and chemical stratification during the past 1 myr benthic foraminiferal carbon isotope records from a suite of drill sites in the north atlantic are used to trace variations in the relative strengths of lower north atlantic deep water lnadw upper north atlantic deep water unadw and southern ocean water sow over the past 1 myr during glacial intervals significant increases in intermediate to deep 13c gradients commonly reaching 1 2 are consistent with changes in deep water circulation and associated chemical stratification bathymetric 13c gradients covary with benthic foraminiferal 18o and covary inversely with vostok co2 in agreement with chemical stratification as a driver of atmospheric co2 changes three deep circulation indices based on 13c show a phasing similar to north atlantic sea surface temperatures consistent with a northern hemisphere control of nadw sow variations however lags in the precession band indicate that factors other than deep water circulation control ice volume variations at least in this band

sedimentological and geoarchaeological evidence of multiple tsunamigenic imprint on the bay of palairos pogonia akarnania nw greece abstract this paper presents evidence of multiple tsunami impact on the bay of palairos pogonia nw greece during the holocene based on detailed geo scientific studies altogether 41 vibracores were drilled to detect high energy influence in the stratigraphical record layers of coarse grained allochthonous marine deposits were found intersecting autochthonous fine grained back beach sediments in the palairos coastal plain on top of beach or marly bedrock units at pogonia beach and along the pogonia cliff section high energy deposits are associated with specific sedimentary structures such as fining upward sequences rip up clasts basal erosional contact bi to multimodal grain size distribution lamination and co existence of both well rounded and angular sharply edged components all of them typical of tsunami impact macro and microfaunal analyses revealed tsunami related input of numerous ex situ marine species and mostly angular shell debris into quiescent fresh to brackish water environments by high energy and long distance transport geophysical methods helped to find subsurface structures and to seize the lateral extent of tsunami layers ca fe ratios derived from xrf measurements were used to trace tsunami influence inland most important is the widespread spatial distribution of the tsunamites with a lateral extent between 70 m at the pogonia cliff section 200 m at pogonia beach and 1 km in the central palairos plain and overall tendencies of fining and thinning towards inland highest elevations of tsunamites were found around pogonia village at ca 7 5 m a s l vibracore data give evidence that the overall coastal evolution has been strongly affected locally even controlled by multiple high energy impact a conspicuous geoarchaeological tsunamite up to 1 5 m thick was found at pogonia cliff consisting of mixed marine sand pebbles bio erosively altered stones shell debris foraminifers and terrigenous material abundant ceramic fragments bones building material it is directly associated with the submerged remains of an ancient mole which was destroyed and its building material partly dislocated by the same event dating of tsunamites was accomplished by archaeological age determination of diagnostic sherds and by radiocarbon and luminescence dating techniques strong tsunami events were dated to the beginning of the 6th the mid 5th the 4th 3rd and the late 2nd millennia bc as well as to the 4th 3rd century bc on a regional scale the recurrence interval for large events is ca 500 1000 years at least twice during the late holocene the palairos coastal plain was flooded quasi contemporaneously from both the northern and southern side

sahel megadroughts triggered by glacial slowdowns of atlantic meridional overturning 1 the influence of the large scale ocean circulation on sahel rainfall is elusive because of the shortness of the observational record we reconstructed the history of eolian and fluvial sedimentation on the continental slope off senegal during the past 57 000 years our data show that abrupt onsets of arid conditions in the west african sahel were linked to cold north atlantic sea surface temperatures during times of reduced meridional overturning circulation associated with heinrich stadials climate modeling suggests that this drying is induced by a southward shift of the west african monsoon trough in conjunction with an intensification and southward expansion of the midtropospheric african easterly jet

arecibo radar mapping of the lunar poles a search for ice deposits the arecibo 12 6 centimeter wavelength radar system was used to image the polar regions of the moon at a resolution of 125 meters in a search for ice deposits in areas of possible permanent shadow from the sun no areas greater than 1 square kilometer were found with high radar backscatter cross sections and high circular polarization ratios properties suggestive of the presence of ice a number of areas smaller than 1 square kilometer were found with these properties but optical images from spacecraft missions have shown some of these features to be in sunlight arecibo radar images of sinus iridum at latitude 47 n also showed a number of small features with similar properties the coincidence of some of these features with the radar facing slopes of craters and their presence in sunlit areas suggests that very rough surfaces rather than ice deposits are responsible for their unusual radar properties