diurnal tides in the arctic ocean a two dimensional numerical model with a space grid of about 14 km is applied to calculate diurnal tidal constituents k1 and o1 in the arctic ocean calculated corange and cotidal charts show that along the continental slope local regions of increased sea level amplitude highly variable phase and enhanced currents occur it is shown that in these local regions shelf waves topographic waves of tidal origin are generated in the arctic ocean and northern atlantic ocean more than 30 regions of enhanced currents are identified to prove the near resonant interaction of the diurnal tides with the local bottom topography the natural periods of oscillations for all regions have been calculated the flux of energy averaged over the tidal period depicts the gyres of semitrapped energy suggesting that the shelf waves are partially trapped over the irregularities of the bottom topography it is shown that the occurrence of near resonance phenomenon changes the energy flow in the tidal waves first the flux of energy from the astronomical sources is amplified in the shelf wave regions and afterwards the tidal energy is strongly dissipated in the same regions

three dimensional splay fault geometry and implications for tsunami generation megasplay faults very long thrust faults that rise from the subduction plate boundary megathrust and intersect the sea floor at the landward edge of the accretionary prism are thought to play a role in tsunami genesis we imaged a megasplay thrust system along the nankai trough in three dimensions which allowed us to map the splay fault geometry and its lateral continuity the megasplay is continuous from the main plate interface fault upwards to the sea floor where it cuts older thrust slices of the frontal accretionary prism the thrust geometry and evidence of large scale slumping of surficial sediments show that the fault is active and that the activity has evolved toward the landward direction with time contrary to the usual seaward progression of accretionary thrusts the megasplay fault has progressively steepened substantially increasing the potential for vertical uplift of the sea floor with slip we conclude that slip on the megasplay fault most likely contributed to generating devastating historic tsunamis such as the 1944 moment magnitude 8 1 tonankai event and it is this geometry that makes this margin and others like it particularly prone to tsunami genesis

an 15 000 year record of el nino driven alluviation in southwestern ecuador debris flows have deposited inorganic laminae in an alpine lake that is 75 kilometers east of the pacific ocean in ecuador these storm induced events were dated by radiocarbon and the age of laminae that are less than 200 years old matches the historic record of el nino events from about 15 000 to about 7000 calendar years before the present the periodicity of clastic deposition is greater than or equal to 15 years thereafter there is a progressive increase in frequency to periodicities of 2 to 8 5 years this is the modern el nino periodicity which was established about 5000 calendar years before the present this may reflect the onset of a steeper zonal sea surface temperature gradient which was driven by enhanced trade winds

late quaternary deltaic and carbonate sedimentation in the gulf of papua foreland basin response to sea level change abstract the rivers that drain the wet mountainous island of new guinea discharge about 1 5 billion tonnes yr of sediments into the adjacent seas including the foreland basin between new guinea and australia despite this huge sediment input there appears to have been only limited deposition in the gulf of papua during the holocene postglacial rise in sea level seismic and core data indicate that the transgressive systems tract in the gulf of papua is thin and patchy it is confined to regions within and north of an incised east west trending shelf valley system of the possible explanations for the absence of a significant transgressive systems tract inland storage and along and off shelf transport of the sediment are of greatest significance reef growth up to the latitude of the east west trending incised valley system in the southern gulf of papua is considered to have been facilitated by a northward flowing coastal boundary current the coral sea coastal current this current now sweeps turbid brackish waters and terrigenous sediments discharged by the rivers northwards away from the reefs an observed northward offset in transgressive sediments in relation to the axis of the shelf valleys suggests that such a northward flowing shelf current operated during the late pleistocene and early holocene the northern limit of the great barrier reef could thus be controlled by the balance between fluvial sediment supply and northward advection of suspended sediment by the coral sea coastal current this current may also be imp rtant in maintaining a supply of clear water to the eastern gulf of papua thus enabling photosynthesis and the flourishing of calcareous algae halimeda bioherms or biostromes at depths of up to 100 m over much of the middle and outer shelf directly offshore of the modern fly delta these carbonate sediments represent the exposed maximum flooding surface and condensed section modern highstand delta deposits have begun to prograde over this layer on the inner shelf

excess 210pb inventories and fluxes along the continental slope and basins of the gulf of papua 1 sediment samples were collected from continental slopes and marginal basins in the gulf of papua and analyzed for excess 210pb to elucidate transport processes of fine grained particles to this region estimated excess 210pb fluxes of 1 0 12 8 dpm cm 2 a 1 were derived from measured seabed inventories highest sediment accumulation rates 0 28 0 35 cm a 1 were measured along the northeastern shelf edge and they decrease in seaward directions and along isobaths to the southwest the excess 210pb flux could result from either focused deposition of high 210pb activity sediments from the continental shelf and upper slope or scavenging of 210pb brought landward from deep sea waters this sediment flux is concentrated in the northeastern gulf of papua where the shelf is narrow and calcium carbonate contents are lowest analysis of sedimentary fabric and 210pb distributions in cores suggests sediment delivery to the slope occurs on a 100 year timescale as both diffuse hemipelagic deposition as well as turbidity flows the flux of sediment in turbidity flows is not well constrained but may be producing additional deep sea accumulation in the moresby trough as well as export from the study area

late glacial stage and holocene tropical ice core records from huascaran peru two ice cores from the col of huascaran in the north central andes of peru contain a paleoclimatic history extending well into the wisconsinan wurm glacial stage and include evidence of the younger dryas cool phase glacial stage conditions at high elevations in the tropics appear to have been as much as 8 to 12 c cooler than today the atmosphere contained about 200 times as much dust and the amazon basin forest cover may have been much less extensive differences in both the oxygen isotope ratio 18o 8 per mil and the deuterium excess 4 5 per mil from the late glacial stage to the holocene are comparable with polar ice core records these data imply that the tropical atlantic was possibly 5 to 6 c cooler during the late glacial stage that the climate was warmest from 8400 to 5200 years before present and that it cooled gradually culminating with the little ice age 200 to 500 years before present a strong warming has dominated the last two centuries

large submarine landslides in the japan trench a new scenario for additional tsunami generation 1 we describe in detail possible large submarine landslides several tens of kilometers in length and width on the trench landward slope of the japan trench on the basis of high resolution topographic surveys and detailed seafloor observations these slides stopped at the toe of the trench slope after initial movement of the toe along a basal decollement or thrust of the trench landward slope wedge during an earthquake the basal frictional condition s might change drastically from static to dynamic thus reducing the frictional strength as a result rapid submarine landsliding push downward on the toe generating large horizontal displacements for tsunamis this hypothesis should explain suitably the relation between large displacement of the thrust fault and tsunami generation by the 2011 tohoku earthquake as well as tsunami generation by the 1896 tohoku earthquake

rapid flooding of the sunda shelf a late glacial sea level record the increase in sea level from the last glacial maximum has been derived from a siliciclastic system on the tectonically stable sunda shelf in southeast asia the time from 21 to 14 thousand calendar years before the present has been poorly covered in other records the record generally confirms sea level reconstructions from coral reefs the rise of sea level during meltwater pulse 1a was as much as 16 meters within 300 years 14 6 to 14 3 thousand years ago

post glacial sea level rise from a coral record at huon peninsula papua new guinea dating of coral reef terraces can provide a record of changes in sea level which should be pronounced during the transition between glacial and interglacial periods cores drilled from coral reefs at barbados in the equatorial west atlantic1have revealed the sea level changes that occurred during the younger dry as event at the end of the last glacial maximum 11 000 yr bp it has not been known however whether pacific coral reefs can grow at a rate sufficient to keep up with the rise in sea level during such a transition here we report results obtained from a 52 m drill core from the post glacial reef at huon peninsula papua new guinea spanning the interval from 7 000 to 11 000 14c yr bp which show that coral growth kept pace while the relative sea level rose by 50m although the tectonic environment is very different from that at barbados the two records compare well when corrections are made for local tectonic uplift showing that sea level rise was similar at both locations the rate of rise was greatest between 9 000 and 10 00014c yr bp corresponding to the time of the younger dryas

late quaternary palynology in marine sediments a synthesis of the understanding of pollen distribution patterns in the nw african setting abstract after a review of the first steps in marine palynology we show that the understanding of the northwest african setting is crucial to evaluate the potential of marine palynological studies elsewhere we studied distribution patterns of pollen grains in recent marine sediments off nw africa and were able to clearly relate patterns to modern pollen source areas vegetation belts and operating transport systems wind belts and ocean currents in particular patterns of quercus artemisia chenopodiaceae amaranthaceae ephedra gramineae and wet forest trees are very indicative of the position of the vegetation belts on the adjacent continent aeolian pollen transport is carried out by the northeast trade winds and the african easterly jet aej in the rain forest belt transport of pollen and fern spores also occurs by rivers a detailed comparison between recent pollen rain samples from terrestrial and marine sites between 21 and 12 n showed that the latitudinal range of vegetation belts is clearly reflected in the pollen samples of both environments a migration of the southern border of the sahara is reflected by the changing ratio between chenopodiaceae amaranthaceae pollen from the desert and gramineae pollen from the savannah belt distribution patterns of pollen for 9000 and 18 000 14 c yr bp last glacial maximum time slices based on pollen records from eleven marine cores between portugal and the gulf of guinea show significant latitudinal migrations of vegetation belts but a stable position of the main wind trajectories the aej had a stable position around 21 n the belt with trade winds had a stable position from morocco southwards changing vigour of the trade winds is clearly reflected by the patterns of isopollen contours and by changes in pollen influx records

bundled turbidite deposition in the central pandora trough gulf of papua since last glacial maximum linking sediment nature and accumulation to sea level fluctuations at millennial timescale since last glacial maximum 23 19 ka earth climate warming and deglaciation occurred in two major steps bolling allerod and preboreal interrupted by a short cooling interval referred to as the younger dryas 12 5 11 5 ka b p in this study three cores mv 33 mv 66 and md 40 collected in the central part of pandora trough gulf of papua have been analyzed and they reveal a detailed sedimentary pattern at millennial timescale siliciclastic turbidites disappeared during the bolling allerod and preboreal intervals to systematically reoccur during the younger dryas interval subsequent to the final disappearance of the siliciclastic turbidites a calciturbidite occurred during meltwater pulse 1b the holocene interval was characterized by a lack of siliciclastic turbidites relatively high carbonate content and fine bank derived aragonitic sediment the observed millennial timescale sedimentary variability can be explained by sea level fluctuations during the last glacial maximum siliciclastic turbidites were numerous when the lowstand coastal system was located along the modern shelf edge although they did not occur during the intervals of maximum flooding of the shelf during meltwater pulses 1a and 1b siliciclastic turbidites reappear briefly during the younger dryas an interval when sea level rise slowed stopped or perhaps even fell the timing of the calciturbidite coincides with the first reflooding of eastern fields reef an atoll that remained exposed for most of the glacial stages

tropical climates in the game of two hemispheres revealed by abrupt climatic change the climatically sensitive equatorial regions provide important information for evaluation of the phasing between high and low latitude climate variability a high resolution pollen record from northern brazil demonstrates a significant abrupt and rapid environmental change associated with the northern hemisphere younger dryas temperature reversal this finding is consistent with the model in which the younger dryas had a stronger influence on temperature in the northern hemisphere than south of the equator because of the larger temperature gradient between pole and equator in the northern hemisphere than in the southern hemisphere one consequence of the younger dryas changes would be the location of the intertropical convergence zone in a southern position so that even tropical regions would have been under arctic influence

pollen quantitative distribution in marine and fluvial surface sediments from the northern south china sea new insights into pollen transportation and deposition mechanisms in order to improve the understanding of pollen transportation and deposition mechanisms in northern south china sea scs 45 seafloor surface sediment samples from the scs and nine surface sediment samples from the pearl river mouth were analyzed palynologically the spatial distributions of pollen and spore taxa suggest that various transport mechanisms and the production at the source the dominant pollen pinus poaceae cyperaceae and fern spores are most abundant in the river mouth and decrease with increasing distance from the land suggesting they are mainly derived from the pearl river drainage basin and strongly dispersed by river plume and ocean currents which reflects a dominant pollen transportation pattern in the northern scs podoconpus and temperate broad leaved components pollen such as evergreen quercus and castanopsis pollen is common in marine samples and is scattered in the pearl river samples reflecting their extensive source areas and dispersal in more than one route however some pollen types of conifers are mostly deposited close to the shore such as dacrydium picea and abies which are restricted near hainan island and taiwan island excluding evergreen quercus and castanopsis pollen the total tropical and subtropical components poorly reflect their parent plants and fewer such pollen are transported over long distances however the source areas of some other pollen taxa e g phyllociadus artemisia and chenopodiaceae are unclear spatially varying ratios of spores to pollen indicate that spores are relatively easily transported by water over longer distances than are pollen grains this study provides a sound basis for interpreting quaternary pollen deposits from the northern scs and for further evaluation of pollen dispersal and deposition in marine and fluvial deposits c 2013 elsevier ltd and inqua all rights reserved

glacial versus interglacial sedimentation rates and turbidite frequency in the bahamas the southern tongue of the ocean is a 1300 m deep flat floored basin in the bahamas that receives large amounts of sediment from the carbonate platforms surrounding it on three sides we have examined five 8 13 m long piston cores and determined bulk sedimentation rates turbidite frequency and turbidite accumulation rates for the past two glacial and interglacial periods the mean of bulk sedimentation rates is four to six times higher in interglacial periods average accumulation rates of recognizable turbidites are higher by a factor of 21 to 45 and interglacial turbidite frequency is higher by a factor of 6 to 14 sediment composition indicates that increased interglacial rates are due to higher accumulation of platform derived material additional data from other bahamian basins as well as published material from the caribbean strongly suggest that highstand shedding is a general trend in pure carbonate depositional systems carbonate platforms without a siliciclastic component export more material during highstands of sea level when the platform tops are flooded and produce sediment the response of carbonate platforms to quaternary sea level cycles is opposed to that of siliciclastic ocean margins where sediment is stored on the inner shelf during highstands and passed on to continental rises and abyssal plains during lowstands of sea level

potential transport pathways of terrigenous material in the gulf of papua t this work discusses potential transport pathways of plume water may infrequently enter the torres straits terrigenous material in the gulf of papua gop new because of sub tidal water elevation differences between guinea using lagrangian tracers as proxies for clay the gop and the arafura sea modeling studies have been minerals and finer particles the tracers are transported by used in conjunction with measurement programs to elucicurrents from the east asia seas implementation of the date dispersal mechanisms for noncohesive sediments in the navy coastal ocean model the results suggest that clay gop wolanski el al 1984 1995 hemer et al 2004 minerals input from rivers along the northwest coast of the 4 this study complements earlier work by examining gop accumulate on the inner shelf with high concentrations the dispersal of dissolved and fine grained suspended ternear the mouth of the fly and purari rivers finer particles rigenous material within the gop for a year long interval which are also representative of dissolved metals are using a combination of hydrodynamic and lagrangian transported eastward along the gop coast into the solomon tracer modeling furthermore because of the large model sea as well as into the torres strait to the west the results domain used in this study we are able to study the impact of also suggest that some finer particles are entrained by eddies large scale flows on transport patterns without imposing within the northern coral sea these results are in artificial boundary conditions the use of tracers to examine qualitative agreement with observations from the region complex multidisciplinary problems in oceanography has citation keen t r d s ko r l slingerland s riedlinger led to understanding the behavior of both suspended and and p flynn 2006 potential transport pathways of terrigenous dissolved constituents in a range of ocean environments material in the gulf of papua geophys res lett 33 l04608 nakano and povinec 2003 mcmanus and prandle 1997

high resolution last deglaciation record from the congo fan reveals significance of mangrove pollen and biomarkers as indicators of shelf transgression abstract high abundances of mangrove pollen have been associated with transgressive cycles on tropical margins but the detailed relations between systems tracts and the taphonomy of the pollen are unclear we report here the occurrence and high abundance of rhizophora pollen in association with taraxerol a rhizophora sourced biomarker from a high resolution congo fan core covering the last deglaciation an age model based on 14c dates enables the temporal changes in taraxerol content and the percentage frequencies and flux pollen grains pg cm 2 103 yr 1 of mangrove pollen to be compared quantitatively with the lateral rate of transgression across the flooding surface derived from glacio hydro isostatic model output and the bathymetry of the margin rhizophora pollen concentrations and taraxerol content of the sediment are very strongly positively correlated with the lateral rate of transgression and indicate independently of any sequence stratigraphic context that mangrove pollen spikes are associated with the transgressive systems tract rather than the highstand systems tract or maximum flooding surface lower resolution longer term records from this margin indicate an association between taraxerol concentrations and transgressive rather than regressive phases the flux of these materials to the congo fan is interpreted as a function of the erosion of flooded mangrove swamp on the shelf and less importantly changing extent of mangrove habitat during sea level rise congo river palaeoflood events also result in reworking of mangrove pollen and supply to the fan but this mechanism is subdominant rhizophora pollen has been underestimated in many palynological studies undertaken on cores from the african margin because of inappropriate sieve mesh size used during laboratory preparation

hydrologic cycling over antarctica during the middle miocene warming global warmth 20 15 million years ago allowed vegetation to grow on formerly ice covered areas of antarctica leaf wax and pollen data show that this growth was supported by increased hydrologic activity over the antarctic coast derived from a local moisture source

holocene development of the yellow river s subaqueous delta north yellow sea high resolution seismic profiles from the north yellow sea reveal a 20 40 m thick subaqueous clinoform delta that wraps around the eastern end of the shandong peninsula extending into the south yellow sea this complex sigmoidal oblique clinoform containing an estimated 400 km 3 of sediment overlies prominent relict transgressive surfaces the nearshore topset of the clinoform 50 m contain less than 1 m of holocene sediment with low sedimentation rates 1 mm year in contrast to other clinoforms the shandong clinoform appears to be a compound subaqueous deltaic system with what we interpret to be proximal and distal phases of clinoform development the underlying proximal sequence formed proximally between f11 and 9 2 ka in response to a temporary pause in the rapid postglacial sea level rise after the meltwater pulse 1b mwp 1b and increased discharge from the yellow river to the north yellow sea due to intensification of the summer monsoon a flooding surface appears to separate the proximal and distal phases corresponding to the next rapid sea level rise 9 5 9 2 ka bp mwp 1c since 9 2 ka bp an overlying distal sedimentary sequence has accumulated reflecting the backstepping and shifting river mouth westward to the gulf of bohai some inputs from coastal erosion and nearby small streams may be locally important along shore transport cross shelf advection and upwelling in the north yellow sea have reworked post lgm sediment and have helped maintain the morphology of the clinoform in the shandong mud wedge d 2004 elsevier b v all rights reserved

neogene evolution of the mixed carbonate siliciclastic system in the gulf of papua papua new guinea this paper outlines the evolution of the late cenozoic mixed carbonate siliciclastic depositional system in the gulf of papua gop using seismic gravity multibeam bathymetry well data sets and landsat imagery the deposition of the mixed sedimentary sequences was influenced by dynamic interplay of tectonics eustasy in situ carbonate production and siliciclastic sediment supply the roles of these major factors are estimated during different periods of the gop margin evolution the cenozoic mixed system in the gop formed in distinct phases the first phase late cretaceous paleocene was mostly driven by tectonics rifting created grabens and uplifted structural blocks which served later as pedestals for carbonate edifices active neritic carbonate accumulation characterized the second phase eocene middle miocene during this phase mostly eustatic fluctuations controlled the large scale sedimentary geometries of the carbonate system the third phase late miocene early pliocene was characterized by extensive demise of the carbonate platforms in the central part of the study area which can be triggered by one or combination of several factors such as eustatic sea level fluctuations increased tectonic subsidence uplift sudden influx of siliciclastics or dramatic changes in environmental conditions and climate the fourth phase late pliocene holocene was dominated by siliciclastics which resulted in the burial of drowned and or active carbonate platforms although some platforms still remain alive until present day

trapped motion around the pribilof islands in the bering sea observations in the region of the pribilof islands and canyon pic reveal a clockwise circulation around the group of islands and around each of the two largest islands st paul and st george six current meters deployed around st paul island revealed a steady clockwise flow around the island which was strongest south of the island and weakest to the east we use a high resolution tidal model in the pic region to show that this flow pattern results from tidal rectification over the shallow topography tides tidal residual currents of 10 15 cm s were predicted by the model compared to mean currents of 5 20 cm s observed at the mooring sites both diurnal and semidiurnal tidal oscillations contribute to the clockwise circulation around the islands in the diurnal band the enhanced currents occur also at the shelf slope where a tidal wave generates a shelf wave due to resonance with topography in the pic region the main shelf wave occurs in the pribilof canyon where both observations and measurements show enhancement of the diurnal tidal currents

characteristics of a tsunamigenic megasplay fault in the nankai trough 1 slip on the shallow part of a megasplay fault that is an out of sequence thrust and branch of the main subduction plate boundary can cause devastating tsunamis after earthquakes we analyzed the three dimensional geometry including dip amount and azimuths roughness distributions and thickness variations of the shallow part of a megasplay fault in the nankai trough using a three dimensional seismic data set the fault is divided into three zones based on its geometry thick smooth and simply convex in the east complexly curved in the middle and thin and kinked in the west results of scientific drilling indicate that the eastern region of the fault is most active and local heterogeneities in fault geometry including roughness and thickness may control the slip on this part of the fault the present findings can be used to evaluate the risk of future tsunamis arising from movement on shallow thrust faults at subduction margins

the palaeoenvironments of kuk swamp from the beginnings of agriculture in the highlands of papua new guinea pollen phytolith and charcoal records from the archaeological wetland site of kuk swamp wahgi valley papua new guinea spanning the period from 20 000 to 270 cal bp are compiled to reconstruct past vegetation and plant exploitation during the earliest to late phases of agricultural development samples collected from exposed stratigraphic sections associated with archaeological excavations enable detailed reconstructions of local vegetation and fire histories that can be directly linked to archaeological evidence for agricultural activity the record of past environmental change is constructed through detailed chronological control and stratigraphic correlation across the swamp revealing evidence of early holocene vegetation disturbance including short term patchy forest loss and burning considered indicative of plant exploitation it is not until the mid holocene after 7000 cal bp that persistent and widespread forest loss occurs with burning and the transplanting of musa banana into an open grassland environment which is contemporary with local archaeological features representing cultivation practices multi proxy palaeoecological evidence at kuk provides a robust vegetation history and land use chronology for the upper wahgi valley for the late pleistocene and holocene including the emergence of an agricultural landscape by 7000 cal bp subsequent agricultural developments in the highlands of new guinea can be seen as a series of continuing indigenous innovations in agricultural technology in the face of increased land degradation climate change and external influences

modeling of topographically amplified diurnal tides in the nordic seas abstract diurnal tidal constituents k1 and o1 are calculated in the nordic seas with a numerical space grid of about 10 km this allows resolution of the structure of enhanced tidal currents generated by near resonant topographic vorticity waves at the yermak plateau the resonance properties of the yermak plateau are investigated in the period range 20 30 h the main resonance peak is close to the 26 h period and the resonance curve envelops a wide range of periods this broad resonance peak explains the enhancement of both diurnal tidal components separated by a 2 h difference and the stability of the resonance phenomena the model results describe well the observed flow pattern over the yermak plateau including the current ellipse rotation

crustal structure across the coseismic rupture zone of the 1944 tonankai earthquake the central nankai trough seismogenic zone 1 differences in the coseismic rupture process between the 1944 tonankai and the 1946 nankaido earthquakes have been studied by many fault models to understand what factors control coseismic rupture zones it is important to investigate differences in deep crustal structures of the rupture zones between the 1944 and 1946 earthquakes the previously published crustal structure of the rupture zone of the 1946 earthquake shows that the coseismic rupture extends to the neogene quaternary accretionary prism however little is known about the structure of the rupture zone of the 1944 earthquake to obtain a complete image of the seismogenic zone of the 1944 earthquake a wide angle seismic survey was performed across the presumed coseismic rupture zone of the 1944 earthquake from ocean to land our model for the crustal structure is based on ocean bottom seismographic data the crustal structure appears characteristic for subducting oceanic crust and a neogene quaternary accretionary prism bounded by an island arc crust the neogene quaternary accretionary prism reaches a maximum thickness of 7 km at 50 km distance landward from the deformation front the subducting oceanic crust can be traced down to 35 km the subduction angle becomes steeper landward reaching up to 11 beneath the island arc crust the depth of the top of subducting oceanic crust at the downdip limit of the rupture zone is 23 km while the updip limit is located beneath the island arc upper crust similar structures of the updip and downdip limits are also published for several other subduction zones

pollen distribution in marine sediments from the south eastern indonesian waters abstract pollen analysis on box core sediments from the south eastern indonesian waters provide information on trends in pollen transport and on pollen distribution in the marine surface sediments pollen and at a lower rate pteridophyta spore concentration values tend to decrease with increasing distance from the shoreline as a result pteridophyta percentages tend to increase with increasing distance from the shoreline mangrove pollen shows very little export from its distribution area while pollen from the mid upper montane group shows a substantial export from its onshore distribution area in general despite the complex nature of vegetation patterns and pollen transport in this region the onshore distribution of individual taxa and major vegetation types is well reflected in the pollen distribution in the marine sediments

a late holocene palaeoecological record from ambra crater in the highlands of papua new guinea and implications for agricultural history a series of monoliths collected from ambra crater in the upper wahgi valley papua new guinea have been subject to multiproxy pollen microcharcoal and diatom palaeoecological investigation the palaeoecological record enables a relatively high resolution reconstruction from c 4000 500 cal bp throughout the sequence the valley floor and crater area were continuously deforested and carpeted with a grassland disturbance taxa mosaic vegetation communities in the valley were largely unaffected by successive tephra deposition events although some muted effects occurred tephra deposition did have considerable local effects on soil water conditions and hydrology in the base of the crater the ambra crater record is consistent with longer chronologies from wetlands in the upper wahgi valley which document extensive disturbance to dryland forests and their replacement with grasses and other disturbance taxa from the mid holocene the ambra crater record taken in conjunction with previously published multisite data enables critique and dis crimination of different interpretations of agricultural history in the highlands during the late holocene

quantifying structural uncertainty on fault networks using a marked point process within a bayesian framework abstract faults are one of the building blocks for subsurface modeling studies incomplete observations of subsurface fault networks lead to uncertainty pertaining to location geometry and existence of faults in practice gaps in incomplete fault network observations are filled based on tectonic knowledge and interpreter s intuition pertaining to fault relationships modeling fault network uncertainty with realistic models that represent tectonic knowledge is still a challenge although methods that address specific sources of fault network uncertainty and complexities of fault modeling exists a unifying framework is still lacking in this paper we propose a rigorous approach to quantify fault network uncertainty fault pattern and intensity information are expressed by means of a marked point process marked strauss point process fault network information is constrained to fault surface observations complete or partial within a bayesian framework a structural prior model is defined to quantitatively express fault patterns geometries and relationships within the bayesian framework structural relationships between faults in particular fault abutting relations are represented with a level set based approach a markov chain monte carlo sampler is used to sample posterior fault network realizations that reflect tectonic knowledge and honor fault observations we apply the methodology to a field study from nankai trough kumano basin the target for uncertainty quantification is a deep site with attenuated seismic data with only partially visible faults and many faults missing from the survey or interpretation a structural prior model is built from shallow analog sites that are believed to have undergone similar tectonics compared to the site of study fault network uncertainty for the field is quantified with fault network realizations that are conditioned to structural rules tectonic information and partially observed fault surfaces we show the proposed methodology generates realistic fault network models conditioned to data and a conceptual model of the underlying tectonics

inverse modeling of post last glacial maximum transgressive sedimentation using 2d sedflux application to the northern adriatic sea abstract a coupled simulation of the hydrologic model hydrotrend and the stratigraphic model 2d sedflux is applied to transgressive deposits in the north adriatic sea area over the last 21 000 years synthetic sediment discharge from the po river which increases more than 70 during late pleistocene compared to those during holocene due to glacier melt and enlarged drainage area is employed in the simulation of sediment deposition by the process based forward model 2d sedflux paleo morphology is reconstructed in a pseudo inverse manner by comparing the predicted deposit distribution and the modern morphology accommodation for thick prograding deposits in the modern po delta and the po lowstand delta are created by drawing back the modern bathymetric profile the bathymetric profile is then adjusted for aggradational deposits these sequential simulations produced a likely profile of the paleo morphology which had accommodation matching with the sediment supply evaluation of effects of waves however suggested that the predicted rate of sediment input was too low to produce a prograding delta a good match with the observation of the modern po delta was achieved when further adjustments in basin width was properly made

sediment delivery from the fly river tidally dominated delta to the nearshore marine environment and the impact of el nino 1 in tidally dominated deltas sediment discharged from the river sources must transit through an estuarine region located within the distributary channels where particle pathways can undergo significant transformations water column profiles and time series data were collected in the distributaries and shallow nearshore region offshore of the fly river papua new guinea during monsoon conditions of 2003 and 2004 within the distributaries of this tidally dominated delta near bed fluid mud concentrations were observed at the estuarine turbidity maximum discharge and morphology of the distributaries determine the location of estuarine processes and control the sediment flux to the marine environment sediment delivery from the delta to the broad shallow nearshore region northeast of the river mouth and to the steep umuda shelf valley is influenced by the shorter pathway of the northernmost distributary the shallowest portion of the nearshore region 10 m water depth is a zone of temporary storage where unconsolidated sediment is easily resuspended umuda shelf valley constrains and enhances tidal currents and provides a steep conduit to seaward transport of fluid muds comparison of 2003 and 2004 data shows evidence of reduction in freshwater supply to the gulf of papua during the moderate 2003 el nino conditions el nino creates a large negative perturbation i e low flow to the relatively constant sediment discharge this reduction of discharge limits transport of sediment from the distributaries to the nearshore zone of temporary storage as the sediment stored near shore feeds the prograding clinoform found seaward the perturbation propagates throughout the dispersal system

timing and progression of climatic tectonic and glacioeustatic influences on the messinian salinity crisis abstract new palynological analysis of the continuous upper neogene sequence from the rifian corridor at sale morocco permits the deconvolution of climatic tectonic and eustatic control on the messinian salinity crisis via two indices 1 a distance from shore index based on dinoflagellate cyst versus pollen distribution and 2 a land climate index based on detailed pollen analysis this new pollen analysis indicates that the messinian salinity crisis 6 8 ma to 5 3 ma was not associated with major climate change detailed analyses of dinoflagellate cyst ecology at sale correlated to the sale 18o record show that initial shoaling of the rifian corridor after 7 3 ma primarily resulted from tectonic uplift however from 6 5 ma to 5 4 ma the rifian corridor was sufficiently shallow to have experienced significant restriction of atlantic inflow during at least four small amplitude glacioeustatic lowstands at 5 4 ma abrupt increase in the ratio of continental versus marine derived palynomorphs indicates that restriction intensified as tectonic uplift significantly outpaced gradual glacioeustatic rise despite eustatic rise at 5 32 ma the sale palynological data show that the rifian corridor experienced a second major drop in relative sea level tectonic uplift or increased sedimentation therefore termination of the messinian salinity crisis was probably associated with a breach elsewhere along the gibraltar arc

quaternary sea level variations in the pacific indian ocean gateways response and impact abstract the indonesian maritime island also called the maritime continent is situated in a unique geographic setting relating to regional and global climate change tropical monsoons between asia and australia exert a strong influence on this area pacific and indian ocean currents pass through the island corridors and rise to the sunda sahul epicontinental platforms bringing nutrients that support reef development this system may be disturbed during glacial low sea level however the deep passage indian pacific ocean gateways remained open during glaciations allowing deep ocean currents to continue flowing between the emerged sunda and sahul platforms thus the coastal plain of the large lowland area and the large shallow and stable sunda sahul platforms are sensitive to eustatic sea level changes changes in basin volume in the long term may be the primary control on global sea level but in the relatively short term global climate change could be the most significant cause of sea level oscillations based on a study of uplifted coral reefs an upper pleistocene sea level curve has been constructed for the indonesian region this curve had been corrected by using oxygen isotope data from odp hole 677

controls and development of late quaternary periplatform carbonate stratigraphy in walton basin northeastern nicaragua rise caribbean sea the late quaternary sedimentary record in periplatform oozes and muds deposited on the northern nicaragua rise results from the interplay of four main controls 1 input of pelagic carbonates and bank derived fine aragonite and magnesian calcite 2 input of siliciclastic sediments 3 dispersal and removal of sediments by the caribbean current and 4 partial seafloor dissolution of metastable carbonates high accumulation rates of the calcite coarse sediment fraction throughout the study area demonstrate that planktonic foraminiferal productivity peaked during interglacial stages neritic carbonate productivity also peaked during interglacial stages when bank and shelf tops along the nicaragua rise were submerged within the photic zone because the bank and shelf tops remained mostly exposed during glacial stages the surface area available for the neritic carbonate productivity was drastically reduced to a narrow band along the margins of pedro bank and the southern shelf of jamaica a large volume of siliciclastic sediments transported from the coastal area of south america and the eastern and western regions of jamaica were deposited during glacial stages within the eastern and western deep extensions of walton basin this finding contrasts with the input pattern of siliciclastic sediments in walton basin itself where the largest input of siliciclastic sediments occurred at each of the interglacial climatic optima corresponding to intervals of maximum sea level transgression finally cores in water depths exceeding 1100 m display during interglacial stages aragonite accumulation rates systematically lower than rates in cores from water depths shallower than 1100 m this indicates that some bank derived aragonite and magnesian calcite has been partially removed by seafloor dissolution in areas from water depths exceeding 1100 m results from this study on the northeastern nicaragua rise indicate that not only do offbank transport and water column saturation state influence the late quaternary record but also that the variable strength of the caribbean current and the proximity of sources for siliciclastic sediments have played a major role in the development of the late quaternary periplatform high resolution stratigraphy

origin and evolution of a splay fault in the nankai accretionary wedge subduction zones are often characterized by wedge shaped sedimentary complexes called accretionary prisms that form when sediments are scraped off the subducting plate and added to the overriding plate large landward dipping thrust faults can cut through such a prism these faults known as megasplay faults 1 2 originate near the top of the subducting plate and terminate at the shallow landward edge of the prism1 3 4 5 6 megasplay faults have been the subject of numerous geological and geophysical studies4 5 6 7 8 9 10 11 12 13 14 15 but their initiation and evolution through time remains poorly constrained here we combine seismic reflection data from the nankai accretionary wedge with geological data collected by the integrated ocean drilling program iodp and find that the splay fault cutting this wedge initiated approx1 95 million years myr ago in the lower part of the prism as an out of sequence thrust oost after an initial phase of high activity the movement along the fault slowed down but uplift and reactivation of the fault resumed about 1 55 myr ago the alternating periods of high and low activity along the splay fault that we document hint at episodic changes in the mechanical stability of accretionary prisms

origin and tectonic interpretation of multiple fault patterns abstract it is shown that in two dimensional and three dimensional deformation accommodated by fracture the symmetry of the fault patterns is an intrinsic attribute because it reflects the symmetry of either stress or strain tensors the deformation accommodated by sliding along pre existing planes when there is kinematic interaction between that planes forms multiple fault pattern and multiple slickenline sets during a single deformation event these fault patterns have no restrictions with respect to symmetry number of fault sets or fault orientation the kinematic analysis developed here shows that an interacting system is formed by two cross cutting faults and three slickenlines one slickenline must be parallel to the intersection line between the planes also it is demonstrated that the slickenlines generally do not correspond to the shear stress solution on the planes thus the interaction between planes does not satisfy the assumption of parallelism between shear stress and slip vector we conclude that the inversion methods to calculate paleostress tensors can lead to erroneous interpretations in structurally complex zones with many pre existing planes of weakness we propose four possibilities to form multiple fault patterns 1 two or more events of faulting obeying coulomb s law with a change of orientation of the principal stresses in each event 2 reactivation of non interacting planes according to the bott 1959 model 3 one three dimensional strain event that obeys the slip model this mechanism will form an orthorhombic four fault pattern and two slickenline sets in a single strain event and 4 one or more events obeying the interacting block model proposed here with or without rotation of the principal stresses we propose the last origin as the most common in continental regions

fault growth in brittle ductile experiments and the mechanics of continental collisions using laboratory models of continental collisions we study the mechanisms responsible for large scale deformation and the nature of the penetrative deformation localized or homogeneous and its characteristic scales and structure in order to focus the study one of the most spectacular cases of continental collisions namely the india asia collision is considered different models with varying rheologies are analyzed which attempt to respect the brittle ductile stratification corresponding to the crust and mantle structure in the earth each experiment is quantified by studying the strain field and the fault pattern as a function of the position p of the indenter within the system the strain field is characterized by 1 the second invariant of the two dimensional strain tensor and its variation with position for a fixed p the evolution of its average as a function of p 2 the evolution with p of the participation ratio s2 which quantifies the fraction of the system surface area which participates in the deformation 3 the evolution of the escape ratio calculated as the surface increase gained by the system during its eastward lateral escape divided by the surface covered by the indenter penetration qualitatively we find that the deformation first spreads out but later on undergoes localization once the fault pattern is mature the cumulative fault length does not increase anymore we observe that the strain field is essentially controlled by the kinematics of the larger faults each fault pattern is quantified by studying 1 the histograms of fault orientations 2 the capacity and barycenter fractal dimensions 3 the multifractal generalized dimensions and 4 the distribution of fault lengths the fractal dimension d is found to almost constant within experimental uncertainty d 1 7 0 1 and thus appears rather insensitive to the particular chosen rheology we find a correlation between the generalized multifractal dimensions and two exponents the barycenter fractal dimension b and the exponent a of the fault length distribution this shows that the scaling properties of fault patterns can be characterized by the knowledge of only two exponents b and a of the spatial and length distributions of faults our main results are 1 observation of the growth of self similar fault patterns 2 complete characterization of the fault patterns with two scaling exponents a and b 3 wide distribution of undeteriorated domains and large heterogeneity of the deformation field 4 maturation of the fault structure corresponding to a localization of the deformation on a few large faults in the late stage of the deformation

analysis of normal fault populations in the kumano forearc basin nankai trough japan 1 multiple orientations and generations of faults from 3 d coherency mapping 1 analyses of normal faults in the kumano forearc basin of the nankai trough reveal multiple normal fault populations in a region generally thought to be under compression most faults have offsets of less than 20 m and dips of 60 70 and show no growth structures indicating that the faults were active for short periods of time the oldest generation of faults is older than 0 9 ma and strikes 50 60 the next oldest faults strike 160 170 are older than 0 44 ma and are related to local uplift along the western edge of the region the youngest faults cut the seafloor shallow faults near the se margin of the basin curve from 100 in the middle of the survey area to 145 at the se corner of the area the pattern of the two youngest fault populations is consistent with the regional stress pattern maximum horizontal stress subparallel to the trench orientations of older fault populations are caused by uplift of the underlying accretionary prism implying that the forearc basin region is not as stable as previously thought reconstruction of displacements on the youngest faults shows that the overall horizontal extension is less than 2 concentrated near the seaward edge of the basin the active normal faults distributed throughout the basin support the idea that the horizontal stress parallel to the plate convergence direction does not reach the critical stress to activate or form thrust faults and produce horizontal shortening within the shallow portion of the inner wedge

tidal and seasonal dynamics of a muddy inner shelf environment gulf of papua 1 subaqueous delta clinoforms are accretionary features created on the continental shelf where there is a large supply of sediment sediment is transported across the shallow topset region and accumulates rapidly in the deeper foreset region in the gulf of papua papua new guinea the absence of cyclonic storms makes tidal currents and seasonal variation of wind direction primary controls on the timing and magnitude of across shelf sediment transport to investigate processes that disperse sediment across the topset of the fly river clinoform anchor stations were occupied during spring and neap tidal cycles of the trade wind season the monsoon season and the transition period during the energetic trade wind season surface waves coupled to strong spring tide currents generated peaks in suspended sediment concentration 100 g l 1 at some locations however seabed erosion and deposition over tidal timescales could not be discerned indicating that sediment was being advected across the outer topset although seaward gravity flows occur with significant spatial heterogeneity they are important for carrying sediment to the foreset region because the near bed circulation generally has a landward net flow seaward transport is restricted to the energetic trade wind season during the quiescent monsoon season 4 11 cm of erosion occurs on parts of the outer topset as fluvial sediment is temporarily deposited closer to shore seasonal patterns in sediment dispersal are likely impacted by el nino southern oscillation and consideration of el nino conditions of 2002 2003 are reflected in the interpretation of observations

effect of increased shear stress along a plate boundary fault on the formation of an out of sequence thrust and a break in surface slope within an accretionary wedge based on numerical simulations abstract we investigated the effect on accretionary wedge structure of increased shear stress which describes the frictional sliding resistance along a decollement arising from an increase in material friction or reduction in pore pressure to clarify the nature of the effect we performed numerical simulations using two models a stable friction model and an increased friction model the stable friction model produced a low angle smooth surface slope and an in sequence thrust whereas the increased friction model produced a break in surface slope scarp and an out of sequence thrust ost that cuts through the thrust sheet the ost formed via the connection of segments of two adjacent thrusts and its formation resulted in a change in the thickening mode of the wedge from thrust sheet rotation and back thrust activity to underplating this contrast in thickening mode between the landward high friction zone and seaward low friction zone resulted in the formation of a clear break in slope as the landward zone is steeper than the seaward zone consistent with critical taper theory the subduction of a basement slice or seamount can produce similar structures arising from an increase in resistance to basal shear sliding however the distinctive structures arising in an accretionary wedge as a result of increased shear sliding resistance include a flat basal plane and absence of slope failure sediments beneath the ost these structural features are observed in accretionary wedges of the nankai trough off muroto japan the sunda strait and the barbados ridge

late holocene flooding history of a tropical river in western india in response to southwest monsoon fluctuations a multi proxy study from lower narmada valley abstract a multi proxy study on the sediments from lower narmada valley western india records large flooding events and high sediment influx linked to southwest monsoon variations during late holocene on the basis of proxy data and chronology of preserved sediments three major environmental perturbations at 1809 1487 and 1187 cal bp have been identified that corroborate well with the regional fluctuations in southwest monsoon variability a phase of dominant marine influence between 2185 and 1809 cal bp is inferred based on the presence of marine palynomorphs mangrove pollen and amorphous organic matter and is coincident with the phase of weak monsoon in the region a transition from marine marsh environment to a phase of high fluvial influx occurred around 1809 cal bp the fluvial influence is inferred based on the replacement of amorphous organic matter with structured organic matter presence of fresh water algae decrease in the 13c values and dominance of kaolinite clay the fluvial regime stabilized between 1487 and 1187 cal bp as recorded in the overbank sediments palynomorphs and geochemical indices and sedimentation occurred under a highly oxidizing and high energy condition with long distance transport of sediments the later incision of the sediment sequence which post dates 1187 cal bp can be attributed to enhanced precipitation the response of the lower narmada valley to short term southwest monsoon fluctuations is manifest in the shifting deposition environments and a major role of terrestrial sediment influx variability is surmised leading to relative sea level variations in this part of the indian subcontinent a temporal and process based interplay between flooding periods and sediment discharge in river systems and tidal conditions is suggested for the tropical estuarine environments

structure of the nankai trough accretionary zone from multichannel seismic reflection data new multichannel seismic reflection data collected over the nankai trough image the accretionary complex in two areas the international program of ocean drilling leg 87 transect area western area and the region of upcoming ocean drilling program leg 131 eastern area the incoming shikoku basin sedimentary section consists of hemipelagic clays and thin terrigenous turbidites the basin section is overlain by a trench wedge that is 12 16 km wide and 350 750 m thick at the thrust front accretionary deformation begins in a protothrust zone that is characterized by thickening and seaward tilting of the trench wedge the zone in the western area is 4 5 km wide and is characterized by kink folds the zone in the eastern area is only 2 5 km wide and does not exhibit such folds the frontal thrusts in each area are imaged as fault plane reflections and ramp upward from within the basin hemipelagic section the overthrusting sediments form fault bend folds over these ramps thrust spacing at the toe of the slope is 1 5 2 5 km the second thrust cuts up from an inferred decollement within the shikoku basin sedimentary section in the eastern area a reflection marking the top of the basin pelagic sediment section changes from normal to reversed polarity about 6 3 km seaward of the thrust front and underlies the entire protothrust zone this reflector continues with reversed polarity under the accretionary complex and is at the level of the basal decollement the underlying basin pelagic section is apparently thrust undisturbed beneath the accretionary prism the reversal of polarity indicates a change in reflection coefficient that is due to a combination of decreasing seismic velocity and density across the interface this decrease in velocity and density may indicate that the decollement is a zone of high porosity due to fluid expulsion from deeper within the accretionary prism the reflections from the first and second thrusts are also reversed polarity possibly indicating that they also are pathways of fluid expulsion the critical wedge taper of the western area is greater than that of the eastern area an observation that is consistent with the existence of an overpressured decollement in the eastern area

holocene pollen records from caution bay southern mainland papua new guinea this study presents new palynological data from caution bay south central papua new guinea png it explores holocene mangrove transitional events along a tide dominated shoreline and expands reconstructive detail for the wider southern png lowlands coinciding with recent regional archaeological research this study also holds implications for interpretations of the holocene settlement of caution bay and long term people landscape interactions data demonstrate a late holocene mangrove to mudflat transition with vegetation patterns largely a function of low sediment loading sedimentary redistributions and salinisation upon sea level decline c 2000 cal yr bp these trends appear unique to caution bay highlighting a variety of holocene shoreline vegetation changes along the png south coast each dependent on geomorphologic setting and hydrological fluxes further work is required to elucidate vegetation change inland of the coastal zone greater understanding of burning patterns and an archaeological collaboration are required to determine more concisely dryland plant spatial and temporal variability

integrating 3 d seismic data field analogs and mechanical models in the analysis of segmented normal faults in the wytch farm oil field southern england united kingdom we propose a methodology for the analysis of normal fault geometries in three dimensional 3 d seismic data sets to provide insights into the evolution of segmented normal fault systems and to improve recovery efforts in fault controlled oil fields limited seismic resolution can obscure subtle fault characteristics such as segmentation and gaps in fault continuity that are significant for oil migration and thus accurate reservoir characterization detailed seismic data analyses that incorporate principles of normal fault mechanics however can reveal evidence of fault segmentation we integrate seismic attribute analyses outcrop analog observations and numerical models of fault slip and displacement fields to augment the use of 3 d seismic data for fault interpretation we applied these techniques to the wytch farm oil field in southern england resulting in the recognition of significant lateral and to a lesser extent vertical segmentation of reservoir scale faults slip maxima on fault surfaces indicate two unambiguous segment nucleation depths controlled by the lithological heterogeneity of the faulted section faults initiated preferentially in brittle sandstone and limestone units subsequent growth and linkage of segments predominantly in the lateral direction resulted in composite fault surfaces that have long lateral dimensions and multiple slip maxima reservoir compartmentalization is greatest at the level of prevalent segment linkages which corresponds at wytch farm with the predominant hydrocarbon producing unit the sherwood sandstone at relatively shallower depths fault segments are younger and less evolved resulting in a greater degree of segmentation with intact relay zones

mangrove bank sedimentation in a mesotidal environment with large sediment supply gulf of papua the most extensive mangrove forests on earth are associated with major river systems the indo pacific region has numerous large rivers that discharge onto broad continental shelves and mangroves occur widely along these coastlines in the gulf of papua gop alone there are 3350 km2 of mangrove forests the majority of which 2900 km2 are associated with the fly kikori and purari river deltas this study examines data from 28 vibracores to describe preserved sedimentary strata and to determine rates of sediment accumulation in this dynamic coastal environment the observations suggest a common stratigraphy is contained in prograding mangrove banks of the mesotidal western gop and that it is similar to mud dominated and physically stratified stratigraphy recorded by other intertidal areas with and without mangroves experiencing large tidal range 2 m and sediment supply e g ganges brahmaputra and yangtze river deltas grain size sedimentary structure radionuclide and remotely sensed data are analyzed and four stratigraphic facies are identified 1 supratidal to high tidal muds 2 mid tidal sandy muds 3 low tidal sand and mud and 4 subtidal channel sands supratidal and high tidal sediments of gop mangrove forests are typically muddy but can have high sand contents 30 in areas exposed regularly to ocean waves these muds can be homogenous but commonly have physical structures laminations and bedding probably reflecting high rates of sediment accumulation relative to bioturbation mangrove muds may have low water contents due to infrequent inundation and because of their cohesive nature and abundant roots can form steep intertidal banks and erosional scarps mid tidal and low tidal sediments are thinly laminated 2 mm laminations likely deposited from fluid mud transport channel sediments have thin and thick mud and sand laminations but are identified by thick 5 cm sand beds a conceptual model of mangrove bank progradation is created using sedimentological and radionuclide data maximum sediment accumulation rates were determined using steady state 210pb profiles and greatest mean rates are found in mid tidal areas 4 4 cm year 3 9 g cm2 year slower accumulation occurs in high tidal and low tidal areas 1 8 and 1 5 cm year respectively 1 2 and 1 0 g cm2 year respectively remotely sensed data indicate that areas of erosion and accretion co exist in the kikori purari region very large 210pb accumulation rates were measured in areas of significant accretion supporting the validity of the calculated rates in areas of rapid accretion cores can have non steady state or event related 210pb profiles reflecting episodic sedimentation or complex radionuclide scavenging dynamics most cores from the fly river delta are of this type sediment trapping in western gop mangroves is estimated to account for 2 14 of the total gop sediment load

climate impact of late quaternary equatorial pacific sea surface temperature variations magnesium calcium data from planktonic foraminifera in equatorial pacific sediment cores demonstrate that tropical pacific sea surface temperatures ssts were 2 8 0 7 c colder than the present at the last glacial maximum glacial interglacial temperature differences as great as 5 c are observed over the last 450 thousand years changes in sst coincide with changes in antarctic air temperature and precede changes in continental ice volume by about 3 thousand years suggesting that tropical cooling played a major role in driving ice age climate comparison of sst estimates from eastern and western sites indicates that the equatorial pacific zonal sst gradient was similar or somewhat larger during glacial episodes extraction of a salinity proxy from the magnesium calcium and oxygen isotope data indicates that transport of water vapor into the western pacific was enhanced during glacial episodes

barents sea tidal and inertial motions from argos ice buoys during the coordinated eastern arctic experiment a harmonic analysis constrained to estimate separately ice motions forced by tides and inertial oscillations was applied to observed positions of argos buoys deployed on drifting multiyear sea ice in the eastern arctic ocean and barents sea during the coordinated eastern arctic experiment 1988 1989 individual tidal components were estimated at 15 day intervals and inertial oscillations were estimated at 3 day intervals the s2 tidal component was distinguishable from inertial motions south of 79 n and the m2 tidal component was distinguishable from the inertial motion north of 77 5 n computed ice velocities of up to 70 cm s 1 for m2 tidal motion over spitsbergen bank southeast of svalbard agreed reasonably well with the regional tidal models no ice cover of gjevik and of kowalik regional differences in the energy distribution in the arctic basin low barents shelf high and spitsbergen bank extreme were emphasized by this technique the m4 tidal component in the ice motion was typically as large over the barents shelf as the inertial oscillation

distribution of methane hydrate bsrs and its implication for the prism growth in the nankai trough abstract detailed mapping of a bottom simulating reflector bsr which marks the phase transition from the methane hydrate layer above the reflector to free gas below was conducted in the nankai accretionary prism off shikoku and tokai bsrs are widely distributed in the prism slope from the toe region to the forearc basin bsr positions provide us with the regional heat flow variations using pressure temperature conditions for methane hydrate stability estimated heat flows generally show constant values about 50 mw m2 shallower than the middle slope of the prism and gradually increase seaward in the lower prism slope occurrences of bsrs are regarded as accumulation of free gas beneath the base of a gas hydrate stability field bghs and or concentration of methane hydrate above the bghs these conditions can be accomplished by updip migration of methane gas because it is unlikely that such methane concentration is completed by in situ biogenic methanogenesis within sediments including low total organic carbon moreover sedimentation uplifting and sediment stacking by thrust faulting cause upward migration of the bghs and migration of methane from the dissociated hydrate to new bghs such recycling of methane gas may have actively occurred in accretionary prisms in contrast there are five regions of no bsrs the nankai trough floor prism toe slope basin steep slope and deep sea canyon the trough floor the prism toe and the slope basin are characterized by young sediments with low production of methane gas and sub horizontal strata unsuitable for migration of gases and fluids erosion at the steep slope and the canyon causes removal of hydrated sediments and downward movement of the bghs bsr distribution and thermal structure estimated from bsr positions offer information about active processes occurring in accretionary prisms

motion of the philippine sea plate consistent with the nuvel 1a model summary we determine euler vectors for 12 plates including the philippine sea plate ph relative to the fixed pacific plate pa by inverting the earthquake slip vectors along the boundaries of the philippine sea plate gps observed velocities and 1122 data from the nuvel 1 and the nuvel 1a global plate motion model respectively this analysis thus also yields euler vectors for the philippine sea plate relative to adjacent plates our results are consistent with observed data and can satisfy the geological and geophysical constraints along the caroline cr ph and pa cr boundaries the results also give insight into internal deformation of the philippine sea plate the area enclosed by the ryukyu trench nankai trough izu bonin trench and gps stations s102 s063 and okino torishima moves uniformly as a rigid plate but the areas near the philippine trench mariana trough and yap palau trench have obvious deformation

splay fault branching along the nankai subduction zone seismic reflection profiles reveal steeply landward dipping splay faults in the rupture area of the magnitude m 8 1 tonankai earthquake in the nankai subduction zone these splay faults branch upward from the plate boundary interface that is the subduction zone at a depth of approximately 10 kilometers approximately 50 to 55 kilometers landward of the trough axis breaking through the upper crustal plate slip on the active splay fault may be an important mechanism that accommodates the elastic strain caused by relative plate motion

late pleistocene and holocene sedimentation organic carbon delivery and paleoclimatic inferences on the continental slope of the northern pandora trough gulf of papua 1 we investigated sediment and organic carbon accumulation rates in two jumbo piston cores mv 54 mv 51 retrieved from the midslope of the northeastern pandora trough in the gulf of papua papua new guinea our data provide a first assessment of mass fluxes over the past 33 000 14c years b p and variations in organic carbon sources core sediments were analyzed using a suite of physical properties organic geochemistry and micropaleontological measurements mv 54 and mv 51 show two periods of rapid sediment accumulation the first interval is from 15 000 to 20 400 cal years b p mv 51 1 09 m ka 1 and 81 2 g cm 2 ka 1 and the second occurs at 32 000 14c years b p 2 70 m ka 1 and 244 g cm 2 ka 1 extremely high accumulation rates 3 96 m ka 1 428 g cm 2 ka 1 characterize 15 800 17 700 cal years b p in mv 54 and likely correspond to early transgression when rivers delivered sediments much closer to the shelf edge a benthic foraminiferal assemblage in mv 51 from 18 400 to 20 400 cal years b p indicates a seasonally variable flux of organic carbon possibly resulting from enhanced contrast between monsoon seasons the oldest sediments 32 000 14c years b p contain toc fluxes 200 g cm2 ka 1 with 50 of it derived from c3 vascular plant matter magnetic susceptibility values are 2 to 3 times higher and benthic foraminiferal accumulation rates are 6 times higher during this interval than at any younger time indicating a greater influence of detrital minerals and labile organic carbon the ms data suggest more direct dispersal pathways from central and eastern png rivers to the core site

towards incorporating uncertainty of structural data in 3d geological inversion abstract all geological models are subject to several kinds of uncertainty these can be classified into three different types data imprecision and quality inherent randomness and incomplete knowledge with our approach we address uncertainties introduced by input data quality in complex three dimensional 3d models of subsurface structures geological models as input data we consider parameters of geological structures i e formation and fault boundary points and orientation measurements our method consists of five steps construction of an initial geological model with an implicit potential field method assignment of probability distributions to data positions and orientation measurements simulation of several input data sets construction of several model realisations based on these simulated data sets and finally the visualisation and analysis of the uncertainties we test our approach in two generic models a simple graben setting and a complex dome structure the first model shows that our approach can evaluate uncertainties from different structures and their interaction furthermore it indicates that the final uncertainty of the model is not simply the sum of all input data uncertainties but complex interactions exist the second example demonstrates that our approach can handle full three dimensional settings with overturned surfaces results of the uncertainty simulation can be visualised and analysed in several ways ranging from borehole histograms to uncertainty maps for complex 3d visualisation and analysis we use indicator functions when we apply these we can treat the visualisation of uncertainties in complex settings in a self consistent manner with our simulation method it is possible to analyse and visualise the uncertainties directly introduced by imprecision in the input data our approach is intuitive and straight forward and suitable in both simple and complex geological settings it enables detailed insights into the model quality even for the non expert in cases where a geological model is the basis for geophysical simulation it opens up the way to geological data driven ensemble modelling and inversion

palynomorph evidence for tropical climate stability in the gulf of papua papua new guinea over the latest marine transgression and highstand 14 500 years bp to today abstract three sediment cores mv 41 mv 46 and md 50 from the gulf of papua gop papua new guinea were analyzed to assess changes in climatic oceanographic and sedimentological conditions over the last 14 5 kyr palynomorphs which were isolated from sediment core samples were collected at approximately 0 5 m intervals using a strong acid and oxidant md 50 non oxidant mv 41 mv 46 procedure radiocarbon 14c stable isotope geochronology magnetic susceptibility stable isotope analysis md 50 only oxygen 18 18o and carbon 13 13c and clay mineral maturity analysis were also completed for each core palynological data indicate that climatic conditions at sea level have remained warm wet and stable for the past 14 5 kyr with sea surface temperatures in the gop above 14 c potential decreases in vegetative cover marked the younger dryas interval 12 5 11 5 kyr bp as indicated by reduced pollen and spore recovery the end of the latest marine transgression and the subsequent return to eustatic sea level highstand is clearly delineated by increases in marine palynomorph recovery and decreases in mangrove pollen at approximately 5 kyr bp an increase in seasonality and potential el nino southern oscillation variability is observed in md 50 s oxygen isotope results at 5 kyr bp this is not supported by the palynomorph record likely because of the sampling interval and dilution by tropical pollen flora which indicates stable climatic conditions throughout the last 14 5 kyr sediment transport pathways in the gop remained fairly constant throughout the time interval which is supported by the lack of major changes in palynomorph assemblage composition

holocene coral reef terraces and coseismic uplift of huon peninsula papua new guinea abstract as many as six levels of emerged holocene coral terraces occur along 40 km of coastline on the huon peninsula papua new guinea recording uplift history since culmination of the postglacial transgression the holocene reef crest ca 6000 yr b p is tilted down to the northwest parallel to the coast and concordant with the deformation of the last interglacial coral reef terrace and descends from 23 to 12 m in the study area the pattern and rate of deformation have been uniform in the late quaternary because average uplift rates have remained the same since the last interglaciation the holocene terraces described here are erosional features with regressive encrusting corals developed upon the holocene transgressive reef the multiple levels represent episodic probably coseismic uplift which has occurred repeatedly in the last ca 6000 yr significant longshore variation in the age of the lowest terrace from 1700 to 2500 yr b p suggests independent coseismic uplift on different sectors of the coast this is supported by age height relationships of the higher holocene terraces nonlinear uplift during the holocene with recurrence intervals increasing toward the present is clearly recorded by the regressive terraces in each subregion some of the holocene regressive terraces grade laterally into fluvial terraces capped with debris flow deposits probably reflecting seismically triggered mass movement

frontal wedge deformation near the source region of the 2011 tohoku oki earthquake 1 we report an uplift of 5 m with a horizontal displacement of more than 60 m due to the 2011 tohoku oki earthquake the uplift was measured by an ocean bottom pressure gauge installed before the earthquake on a frontal wedge which formed an uplift system near the japan trench horizontal displacements of the frontal wedge were measured using local benchmark displacements obtained by acoustic ranging before and after the earthquake the average displacements at the frontal wedge were 58 m east and 74 m east southeast these results strongly suggest a huge coseismic slip beneath the frontal wedge on the plate boundary the estimated magnitude of the slip along the main fault was 80 m near the trench our results suggest that the horizontal and vertical deformations of the frontal wedge due to the slip generated the tremendous tsunami that struck the coastal area of northeastern japan

timing and distribution of calciturbidites around a deeply submerged carbonate platform in a seismically active setting pedro bank northern nicaragua rise caribbean sea the sedimentological study of thirteen sediment cores from the periplatform setting surrounding pedro bank northern nicaragua rise caribbean sea shows that during the last 300 ka turbidite deposition is controlled by at least four factors 1 late quaternary sea level fluctuations 2 prolific fine grained sediment production and export resulting in oversteepening of the upper slope environment 3 the proximity to the bank margin and 4 local slope and seafloor morphology the most intriguing finding of this study is the paucity of turbidites with only 101 turbidites in 13 cores in this tectonically active setting near the caribbean plate boundary throughout the last 300 ka the frequency of turbidite input during interglacial stages is three times higher than during glacial stages also it is obvious that changes in sea level influence the timing of turbidite deposition this is especially evident during the transgressions resulting in rapid renewed bank top flooding subsequent neritic sediment overproduction and offbank export the flooding event during each transgression is usually recorded by the onset of turbidite deposition at various sites along several platform to basin transects in down and upcurrent slope settings overall however more turbidites are deposited during the regressive rather than the transgressive phases in sea level probably as a result of sediment reorganisation on the slope resulting in slope failure five cores show highstand bundling of calciturbidites i e higher number of turbidites during highstands than during lowstands in sea level

possible strain partitioning structure between the kumano fore arc basin and the slope of the nankai trough accretionary prism 1 a 12 km wide 56 km long three dimensional 3 d seismic volume acquired over the nankai trough offshore the kii peninsula japan images the accretionary prism fore arc basin and subducting philippine sea plate we have analyzed an unusual trench parallel depression a notch along the seaward edge of the fore arc kumano basin just landward of the megasplay fault system this bathymetric feature varies along strike from a single steep walled 3 5 km wide notch in the northeast to a broader 5 km wide zone with several shallower linear depressions in the southwest below the notch we found both vertical faults and faults which dip toward the central axis of the depression dipping faults appear to have normal offset consistent with the extension required to form a bathymetric low some of these dipping faults may join the central vertical fault s at depth creating apparent flower structures offset on the vertical faults is difficult to determine but the along strike geometry of these faults makes predominantly normal or thrust motion unlikely we conclude therefore that the notch feature is the bathymetric expression of a transtensional fault system by considering only the along strike variability of the megasplay fault we could not explain a transform feature at the scale of the notch strike slip faulting at the seaward edge of fore arc basins is also observed in sumatra and is there attributed to strain partitioning due to oblique convergence the wedge and decollement strength variations which control the location of the fore arc basins may therefore play a role in the position where an along strike component of strain is localized while the obliquity of convergence in the nankai trough is comparatively small 15 we believe it generated the kumano basin edge fault zone which has implications for interpreting local measured stress orientations and suggests potential locations for strain partitioning related deformation in other subduction zones

vegetation change following mid holocene marine transgression of the torres strait shelf a record from the island of mua northern australia the pollen and sedimentary record from a coastal backdune swamp on the island of mua torres strait australia is presented a 4 55 m core collected from the swamp centre provides a record of vegetation and landscape change spanning the postglacial marine transgression to present prior to 6000 radiocarbon years before present yr bp results show mangrove vegetation encroaching on the core site periodically displacing non mangrove taxa until the establishment of an extensive mangrove forest between 6000 yr bp and 3000 yr bp within the mangrove community a transition from lower tidal rhizophora forest to an upper intertidal ceriops community is evident this is followed by the development of the current herbaceous freshwater swamp in the late holocene the dryland vegetation record is dominated by sclerophyll and rainforest elements with strongest forest representation occurring around the mid holocene before a decline in tree density and the establishment of open woodlands in the late holocene the data suggest vegetation change accompanied marine transgression and a humid mid holocene climate before stabilization of sea levels and the initiation of dominant on shore catchment processes signalling drier climatic conditions and possible human activity

benthic foraminiferal response to sea level change in the mixed siliciclastic carbonate system of southern ashmore trough gulf of papua 1 ashmore trough in the western gulf of papua gop represents an outstanding modern example of a tropical mixed siliciclastic carbonate depositional system where significant masses of both river borne silicates and bank derived neritic carbonates accumulate in this study we examine how benthic foraminiferal populations within ashmore trough vary in response to sea level driven paleoenvironmental changes particularly organic matter and sediment supply two 11 3 m long piston cores and a trigger core were collected from the slope of ashmore trough and dated using radiocarbon and oxygen isotope measurements of planktic foraminifera relative abundances principal component analyses and cluster analyses of benthic foraminiferal assemblages in sediment samples identify three distinct assemblages whose proportions changed over time assemblage 1 with high abundances of uvigerina peregrina and bolivina robusta dominated between 83 and 70 ka early regression assemblage 2 with high abundances of globocassidulina subglobosa dominated between 70 and 11 ka late regression through lowstand and early transgression and assemblage 3 with high abundances of neritic benthic species such as planorbulina mediterranensis dominated from 11 ka to the present late transgression through early highstand assemblage 1 represents heightened organic carbon flux or lowered bottom water oxygen concentration and corresponds to a time of maximum siliciclastic fluxes to the slope with falling sea level assemblage 2 reflects lowered organic carbon flux or elevated bottom water oxygen concentration and corresponds to an interval of lowered siliciclastic fluxes to the slope due to sediment bypass during sea level lowstand assemblage 3 signals increased off shelf delivery of neritic carbonates likely when carbonate productivity on the outer shelf great barrier reef increased significantly when it was reflooded benthic foraminiferal assemblages in the sediment sink slopes of ashmore trough likely respond to the amount and type of sediment supplied from the proximal source outer gop shelf

development of a bathymetric grid for the gulf of papua and adjacent areas a note describing its development 1 a new bathymetric grid for the gulf of papua and northern australia was produced for the area 140 150 e 6 14 s with a 3 6 110 m cell size new multibeam sonar surveys have added much needed detail to a region of the seabed where previously little was known in shallow australian waters bathymetry derived from landsat satellite imagery was used to supplement traditionally acquired bathymetric data for onshore areas shuttle radar topography mission data were used for topographic control the final grid revealed numerous features not observed in previous compilations of bathymetric data for the region bathymetric surveys on the continental shelf revealed an incised shelf with highly variable valley morphology prograding clinoforms are infilling valleys on the continental shelf and mark the seaward extension of the fly river delta a linear relict shelf edge barrier marks the shelf break in the northern ashmore trough region elsewhere the shelf break is scalloped and incised by canyons large mass transport deposits are widespread on the continental slope and indicate regions where mass wasting is common

mechanical and hydraulic properties of nankai accretionary prism sediments effect of stress path 1 we have conducted triaxial deformation experiments along different loading paths on prism sediments from the nankai trough different load paths of isotropic loading uniaxial strain loading triaxial compression at constant confining pressure pc undrained pc reduction drained pc reduction and triaxial unloading at constant pc were used to understand the evolution of mechanical and hydraulic properties under complicated stress states and loading histories in accretionary subduction zones five deformation experiments were conducted on three sediment core samples for the nankai prism specifically from older accreted sediments at the forearc basin underthrust slope sediments beneath the megasplay fault and overthrust upper shikoku basin sediments along the frontal thrust yield envelopes for each sample were constructed based on the stress paths of pc reduction using the modified cam clay model and in situ stress states of the prism were constrained using the results from the other load paths and accounting for horizontal stress results suggest that the sediments in the vicinity of the megasplay fault and frontal thrust are highly overconsolidated and thus likely to deform brittle rather than ductile the porosity of sediments decreases as the yield envelope expands while the reduction in permeability mainly depends on the effective mean stress before yield and the differential stress after yield an improved understanding of sediment yield strength and hydromechanical properties along different load paths is necessary to treat accurately the coupling of deformation and fluid flow in accretionary subduction zones

fine sediment mineralogy as a tracer of latest quaternary sediment delivery to a dynamic continental margin pandora trough gulf of papua papua new guinea abstract sediment cores and geophysical data from the shelf and slope in the pandora trough and gulf of papua gop papua new guinea northern coral sea have been studied to evaluate timing pathways and sources of sediment delivery to a muddy shelf slope depositional system that developed during the late quaternary marine transgression cores were analyzed for 14 c geochronology clay and bulk mineralogy grain size sedimentary fabric and physical properties observations reveal a shelf edge depocenter and adjacent middle to upper slope sediment wedge that each developed at different times from different sedimentary sources despite close proximity along a down slope gradient clay mineralogy of modern shelf sediments reveals strong longitudinal gradients that appear related to fluvial source composition similar gradients in source composition reveal heterogeneous and shifting sediment sources to the shelf and slope through time from the bolling allerod interstadial 14 5 12 5 kyr bp and the younger dryas 12 5 11 5 kyr bp fluvial sediments accumulated in a muddy inner shelf forming a shelf edge depocenter core mv 41 with high kaolinite chlorite values that are indicative of a local volcanic source consistent with the geology of the nearby lakekamu and vailala river catchments shelf edge sediment accumulation decreased from the time of meltwater pulse 1b mwp 1b to the present due to shelf flooding and inshore trapping of sediment during mwp 1b and possibly earlier sediment transport west of mv 41 was steered obliquely offshore to the northern pandora trough continental margin upper middle slope mv 46 and mv 49 this transport has persisted nearly to the present and has allowed for the development of a holocene upper middle slope sediment wedge cores mv 46 and mv 49 that differs strongly in clay composition and so source from the adjacent up slope shelf edge depocenter mv 41 slope deposits have intermediate illite smectite values similar to the central gop which differ from the very low illite smectite values at mv 41 such heterogeneous dispersal patterns oblique to seabed gradient are likely due to complex interactions of shelf processes with dynamic shelf morphology along the flooding gop shelf rather than a response solely due to rising sea level and down slope transport

the fault shadow problem its nature and elimination the fault shadow problem is what explorationists call the zone of unreliable seismic imaging in the footwalls of faults although it can occur in all types of faults the term is usually applied to extensional faults these problems are common place but much current exploration still relies on images in which they remain in this article i present an example of the fault shadow problem from the wilcox trend eocene paleocene of south texas the stratigraphic velocity alternations in this area cause a distinctive suite of problems in conventional time imaging explorationists can cite numerous examples of wells drilled on time highs but significantly off structure in depth moreover imaging often degrades precipitously at levels below the middle wilcox even when wells indicate an uncomplicated structure i ll begin by demonstrating through schematic and synthetic examples the nature of these problems and their elimination through prestack depth imaging a real data example will then show identical ef

anatomy and growth of a holocene clinothem in the gulf of papua 1 high resolution seismic profiles and sedimentological data from grab samples and long cores provide an unprecedented picture of the structure sedimentology and late quaternary development of two gulf of papua gop clinothems one probably stage 3 and 4 in age and one holocene in age the older was partially eroded during stage 2 and partially covered by the younger clinothem during stage 1 the younger clinothem consists of three stratigraphic units separated by two surfaces of erosion bypass or correlative surfaces of lap the surfaces were formed by changes in accommodation and sediment supply the underlying physiography of the older clinothem also appears to play an important role in governing the shape of the younger clinothem in the northern gulf oblique clinoforms of the younger clinothem suggest that the rate of sediment supply from the northern rivers outstripped the formation of new accommodation whereas in the south sigmoidal clinoforms indicate that accommodation increased faster than sediment supply the origin of the new accommodation remains uncertain because of limited age constraints on the basis of sediment thickness stratal geometry and acoustic character off shelf transport appears to be the dominant sediment transport direction with preferential accumulation on the promontories and bypass in the valleys presently observed and computed modern flows and complex gyres in shallow water coupled with wave and current supported gravity flows or river floods can explain the form internal clinoform shapes and mineralogy of the younger gulf of papua clinothem

crustal velocity field of southwest japan subduction and arc arc collision we investigate crustal deformation in southwest japan over a 3 year period revealed by a permanent dense global positioning system gps array southwest japan is a part of the amurian plate a microplate moving about 10 mm yr toward the east with respect to the eurasian plate it overrides the philippine sea plate at the nankai trough and collides with the northeast japan arc in the central part of japan in this paper we first derive gps site velocities relative to the stable part of the amurian plate in order to isolate signals of crustal deformation caused by the subduction and or the collision the velocity field has a conspicuous feature indicating the interseismic elastic loading by the philippine sea plate slab at the nankai trough characterized by the northwestward movements of points throughout the studied area their amplitudes are the largest at the pacific coast and decay toward the japan sea coast with a subtle systematic shift of azimuths a model assuming an elastic half space the convergence rate at the nankai trough based on a refined euler vector and the strength of the coupling inferred from a thermal model could explain the velocity field in the western part of the studied area to a large extent those in the eastern part systematically deviate from them and the residual components there show east west shortening and north south extension this may represent crustal thickening and trenchward extrusion of crustal blocks caused by the collision between southwest and northeast japan this suggests that the collision between southwest and northeast japan gives rise to not only crustal thickening but also trenchward extrusion of crustal block a velocity contrast was found across the median tectonic line the largest inland active fault in japan but the current permanent gps network is not dense enough for us to discuss its coupling depth

a palynological investigation of holocene vegetation change in torres strait seasonal tropics of northern australia the islands of torres strait occupy a shallow area of submerged continental shelf narrowly separating cape york peninsula australia from new guinea the human history of torres strait is unique with respect to mainland northern australia island vegetation however exhibits a strong affinity with the environments of the western lowlands regions of cape york peninsula and with the vegetation of seasonal tropical australia in general cape york peninsula is both climatically and biologically diverse yet few pollen studies have been carried out in its seasonally tropical environments a summary presentation of palynological results tracing the nature of vegetation change in torres strait offers a possible framework for vegetation changes in similar environments on mainland australia and also provides an opportunity to explore the relationship between quaternary change in humid tropical australian environments and their seasonal tropical counterparts six pollen records from torres strait provide evidence of vegetation change and fire history over approximately the last 8000 years near shore sediments reveal a holocene succession in vegetation incorporating lower tidal mangrove upper tidal mangrove saltmarsh and freshwater swamp communities extensive stable mangrove communities dominated coastal torres strait between approximately 6000 and 3000 radiocarbon years before present yr bp inland the strongest myrtaceae forest and rainforest representation occurs around the mid holocene only to be replaced by open sclerophyll woodlands as tree density and diversity decline in the last 3000 years the development of continuous island freshwater swamp conditions at the coast and inland is similarly restricted to the late holocene c 2600 yr bp and fire as a prominent feature in the torres strait environment is also a relatively recent phenomenon comparisons with regional mainland australian palynological records reveal a degree of consistency in results from torres strait suggesting a similarity in late quaternary trends through australian humid and seasonally tropical environments a number of differences however are also apparent highlighting a degree of diversity which warrants further attention

mangrove vegetation responses to holocene climate change along konkan coast of south western india abstract the pollen signatures preserved in the mangrove sediments provided records of species variation over a period of time with past climate and sea level changes the airoli profile has a late pleistocene sequence and all the other studied profiles and intervals cover the holocene only the absence of mangrove signatures during the late pleistocene interval is attributed to a relatively low sea level the ideal conditions for mangrove development along konkan prevailed during middle holocene when the first extensive mangrove swamps appeared in sindhudurg dhamapur hadi area particularly between 7220 and 4770 yrs bp this period coincides with the holocene climate optimum hco when monsoon asia witnessed much higher precipitation however the mangroves responded to environmental changes due to relative abundance of fresh water leading to change in species composition two different scenarios of mangrove response during the late holocene one in dhamapur and the other in palm beach are found to be significant the rhizophora sonneratia transition from early mid holocene to late holocene is considered to be the most distinctive feature the decline of mangroves since 3500 yrs bp and further degradation has been attributed to the prevailing arid climate and weakening trends of the monsoon until 1500 yrs bp however there seems to be a positive trend in emergence of mangroves in the least disturbed areas of south konkan attributed to strengthening of summer monsoon in the recent past

radiocarbon calibration curve spanning 0 to 50 000 years bp based on paired 230 th 234 u 238 u and 14 c dates on pristine corals abstract radiocarbon dating is the most widely used dating technique in the world recent advances in accelerator mass spectrometry ams and sample preparation techniques have reduced the sample size requirements by a factor of 1000 and decreased the measurement time from weeks to minutes today it is estimated that more than 90 percent of all measurements made on accelerator mass spectrometers are for radiocarbon age dates the production of 14 c in the atmosphere varies through time due to changes in the earth s geomagnetic field intensity and in its concentration which is regulated by the carbon cycle as a result of these two variables a radiocarbon age is not equivalent to a calendar age four decades of joint research by the dendrochronology and radiocarbon communities have produced a radiocarbon calibration data set of remarkable precision and accuracy extending from the present to approximately 12 000 calendar years before present this paper presents high precision paired 230 th 234 u 238 u and 14 c age determinations on pristine coral samples that enable us to extend the radiocarbon calibration curve from 12 000 to 50 000 years before present we developed a statistical model to properly estimate sample age conversion from radiocarbon years to calendar years taking full account of combined errors in input ages and calibration uncertainties our radiocarbon calibration program is publicly accessible at http www radiocarbon ldeo columbia edu along with full documentation of the samples data and our statistical calibration model

timing of the last glacial maximum from observed sea level minima during the last glacial maximum ice sheets covered large areas in northern latitudes and global temperatures were significantly lower than today but few direct estimates exist of the volume of the ice sheets or the timing and rates of change during their advance and retreat here we analyze four distinct sediment facies in the shallow tectonically stable bonaparte gulf australia each of which is characteristic of a distinct range in sea level to estimate the maximum volume of land based ice during the last glaciation and the timing of the initial melting phase we use faunal assemblages and preservation status of the sediments to distinguish open marine shallow marine marginal marine and brackish conditions and estimate the timing and the mass of the ice sheets using radiocarbon dating and glacio hydroisostatic modelling our results indicate that from at least 22 000 to 19 000 calendar years before present land based ice volume was at its maximum exceeding today s grounded ice sheets by 52 5 x 10 exp 6 cu km a rapid decrease in ice volume by about 10 percent within a few hundred years terminated the last glacial maximum at 19 000 250 years

model simulations of the tides in the barents sea a large scale numerical model covering the nordic seas and the arctic ocean with 25 12 5 km grid resolution has been applied to study the tides in the barents sea tidal charts for elevation and phase are presented for the four tidal constituents m2 s2 n2 and k1 computed harmonic constants for elevation and current have been compared with observations from 46 coastal and pelagic tidal stations the agreement between model and field data is good for most stations with an overall standard deviation of 2 5 cm for amplitude 18 30 for phase and 1 3 cm s for current speed calculated tidal residual currents show anticyclonic eddy circulation over the svalbard bank and around bear island and hopen particle trajectories and streaklines due to the tidal flow over svalbardbanken have been calculated and the computed streaklines are found to agree well with observed rifts in the ice cover due to stranded icebergs

a numerical model study of parameters influencing tidal currents in the irish sea the mathematical formulation of a mixed finite difference modal three dimensional tidal model of the irish sea using quadratic bottom friction is briefly presented by using an expansion of modes in the vertical a continuous current profile from sea surface to seabed can be computed and accurate comparisons made with tidal currents measured at a range of positions throughout the water column the sensitivity of current profiles to various eddy viscosity formulations and coefficients of bottom friction are examined in detail also the influence of open boundary conditions and water depths upon computed tidal elevations and currents is examined in common with other earlier published calculations initial results show that with previous formulations of eddy viscosity and friction an accurate distribution of sea surface elevations is accompanied with computed currents which exceed observations by the order of 20 cm s 1 however results from the sensitivity study presented here show that elevations and currents above the bottom boundary in good agreement with observations can be obtained with alternative formulations of viscosity and other friction coefficients together with current input to the radiation condition however computed near bed currents are still larger than those observed although a slight increase in water depth and bottom friction coefficients corrects this calculations clearly show that the computation of near bed currents subject to the constraints of obtaining accurate elevation and current distributions is the most sensitive test of the model excellent agreement between computed and observed currents and elevations was obtained in a final series of calculations using appropriate parameterizations of eddy viscosity and bottom friction

rapid forearc basin uplift and megasplay fault development from 3d seismic images of nankai margin off kii peninsula japan abstract offshore kii peninsula japan a large thrust within the overriding forearc the megasplay fault appears to move coseismically during great earthquakes 3d seismic images of the kumano forearc basin that overlies the megasplay correlated with iodp drilling data are a potential record of the history of large scale motion along this structure in the early quaternary uplift occurred in the southwest portion of the basin that may be a preliminary phase of motion along the megasplay more extensive landward tilting of the outer basin sediments across the seismic volume occurred over 300 kyr in the middle to late quaternary 1 3 1 ma this tilting event may represent the major period of motion along the megasplay that formed the modern fault geometry extensive normal faulting that cuts the forearc basin sediments clearly formed subsequent to the late quaternary tilting and in many cases offset the modern seafloor these faults may form either due to gravitational response to the uplift or as a by product of sediment underthusting these results suggest that the megasplay is a recently formed and transient structure and support the idea that out of sequence thrusts serving as the dominant structure for convergence driven shortening in a subduction zone may be short lived geologically but dominate a margin during these intervals

ocean overturning since the late cretaceous inferences from a new benthic foraminiferal isotope compilation 1 benthic foraminiferal oxygen isotopic d 18 o and carbon isotopic d 13 c trends constructed from compilations of data series from multiple ocean sites provide one of the primary means of reconstructing changes in the ocean interior these records are also widely used as a general climate indicator for comparison with local and more specific marine and terrestrial climate proxy records we present new benthic foraminiferal d 18 o and d 13 c compilations for individual ocean basins that provide a robust estimate of benthic foraminiferal stable isotopic variations to 80ma andtentatively to 110ma first order variations ininterbasinal isotopicgradients delineate transitions from interior ocean heterogeneity during the late cretaceous 65 ma to early paleogene 35 65 ma homogeneity and a return to heterogeneity in the late paleogene early neogene 35 0 ma we propose that these transitions reflect alterations in a first order characteristic of ocean circulation the ability of winds to make water in the deep ocean circulate we document the initiation of large interbasinal d 18 o gradients in the early oligocene and link the variations in interbasinal d 18 o gradients from the middle eocene to oligocene with the increasing influence of wind driven mixing due to the gradual tectonic opening of southern ocean passages and initiation and strengthening of the antarctic circumpolar current the role of wind driven upwelling possibly associated with a tethyan circumequatorial current in controlling late cretaceous interior ocean heterogeneity should be the subject of further research

volcanic disasters and agricultural intensification a case study from the willaumez peninsula papua new guinea abstract environments characterized by frequent volcanic activity provide an excellent opportunity to observe interactions between human land use and ecosystem succession as they unfold over time a case study tracing the history of re colonisation by humans and plants following a series of volcanic disasters during the past 40 000 years in the willaumez peninsula papua new guinea investigates the utility of denevan s models describing variation in the intensity of agricultural practices in wet tropical rainforest environments prior to the introduction of metal tools the archaeological and environmental data obtained to date show that people may have taken advantage of the effects of volcanic activity to establish relatively permanent gardens and therefore avoid the costs associated with shifting cultivation archaeological and plant microfossil data show that humans have been interfering with normal vegetation succession from at least the late pleistocene when long term base camps were established that some patches were used intensively from the early holocene and that groups may have been forced to increase the levels of disturbance after the end of a long period of high magnitude volcanic eruptions

topographic enhancement of tidal motion in the western barents sea a high resolution numerical lattice is used to study a topographically trapped motion around islands and shallow banks of the western barents sea caused both by the semidiurnal and diurnal tidal waves observations and model computations in the vicinity of bear island show well developed trapped motion with distinctive tidal oscillatory motion numerical investigations demonstrate that one source of the trapped motion is tidal current rectification over shallow topography tidal motion supports residual currents of the order of 8 cm s 1 around bear island and shallow spitsbergenbanken the structures of enhanced tidal currents for the semidiurnal components are generated in the shallow areas due to topographic amplification in the diurnal band of oscillations the maximum current is associated with the shelf wave occurrence residual currents due to diurnal tides occur at both the shallow areas and the shelf slope in regions of maximum topographic gradients surface manifestation of the diurnal current enhancement is the local maximum of tidal amplitude at the shelf break of the order of 5 to 10 cm tidal current enhancement and tidally generated residual currents in the bear island and spitsbergenbanken regions cause an increased generation of ice leads ridges and trapped motion of the ice floes

ice production and brine formation in storfjorden svalbard brines which appear as salty and cold bottom water layers on arctic shelves form by salt rejection during sea ice formation high ice production occurs in latent heat polynyas such as the one that appears in storfjorden under northerly winds using ers 2 synthetic aperture radar imagery we observed the ice cover in storfjorden over the winter 1997 1998 revealing an area of over 6000 km 2 of the open water and thin ice that are characteristic of a polynya changes in the polynya extent correlated well with a simple wind driven polynya size algorithm furthermore using a frazil ice formation algorithm and the hypothesis of ice accumulation at the lee side of the polynya we distinguished between open water thin ice and fast pack ice the average polynya width during the 6 winter months was about 30 km with a maximum of 130 km in march thus storfjorden was composed of 5 6 fast and pack ice and 1 6 polynya open water occupied about half of the polynya the other half was composed of brash ice and thin ice involved in ridging and rafting a total ice volume of 40 km 3 was produced in storfjorden between november 15 1997 and may 15 1998 about 57 of it was formed in the open water area 9 in the thin ice area and 34 in the fast pack ice area this ice production released more than 1 gt gigaton of salt able to increase the salinity of the storfjorden waters by 1 4 practical salinity units psu assuming that brine enriched waters are 0 3 psu more saline than the parent waters the above salt release is able to ventilate storfjorden 4 5 times during the course of the productive season

siliciclastic influx and burial of the cenozoic carbonate system in the gulf of papua abstract an extensive carbonate system in the gulf of papua gop developed in the late oligocene middle miocene was buried by huge influx of siliciclastics originated from papua new guinea major episodes of siliciclastic influx in the carbonate system are related to tectonic activity in the fold and thrust belt during the oligocene peninsular orogeny late miocene central range orogeny and late pliocene renewed uplift and exhumation of peninsular region siliciclastics did not influence the carbonate deposition during the late oligocene middle miocene since they were accumulated in the aure trough proximal foreland basin protecting the carbonate system the most significant burial of the carbonate system started during the late miocene early pliocene in the result of the central range orogeny however the largest influx was related to the renewed uplift of the papuan peninsula during the early late pliocene the shelf edge prograded 150 km and formed more than 80 of the modern shelf this high siliciclastic influx was also enhanced by the mid pliocene global warmth period and intensified east asian monsoons at 3 6 2 9 ma although many publications exist on carbonate siliciclastic mixing in different depositional environments this study helps understand the carbonate siliciclastic interactions in space and time especially at basinal scale and during different intervals of the carbonate system burial by siliciclastic sediments

vegetation and palaeoclimatic reconstruction of the sousaki basin eastern gulf of corinth greece during the early pleistocene abstract pollen analysis was performed on a lower pleistocene lacustrine sedimentary sequence outcropping in sousaki basin eastern gulf of corinth greece for the first time the palynological assemblages revealed a stable climate with regard to the glacial interglacial climate variability timescale with minor fluctuations in humidity expressed as a relatively wet phase between 13 1 and 19 3 m and some transient increased aridity and humidity events a mediterranean type of vegetation presenting altitudinal zonation was evidenced for the first time in this region pinus and quercus dominate accompanied by other arboreal and non arboreal plants the presence of rare taxa such as taxodiaceae engelhardia liquidambar tsuga and cedrus in very low percentages shows that these taxa remained in the area as relicts sometime between 2 8 and 1 5ma palaeovegetation patterns from the balkan peninsula are lacking especially during the early pleistocene thus in this study a palaeoclimate reconstruction of the early pleistocene sousaki basin based on palynological data is presented accentuating the effect of global climate changes in an area where no other similar records exist