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

the upper end of the uk 37 temperature calibration revisited 1 being able to decipher paleo sea surface temperatures for warm oceanic waters is of the utmost importance to further evaluate the role of the tropics in global climate change the uk 37 index is one of such paleothermometers although the warm range of temperatures often poses serious analytical challenges this paper discusses and reviews several important aspects of the uk 37 index calibration for waters warmer than 26 27 c amongst them insights into the possible existence of a limit above which the uk 37 index is not able to accurately record temperature variations are presented some warnings are also given on the misleading practice and expected consequences of reporting uk 37 index values of unity in the cases when abundances of the minor triunsaturated alkenone below detection limit are encountered future directions toward an improved knowledge of the behaviour of the uk 37 calibration for warm waters are suggested

influence of ionospheric electron density fluctuations on satellite radar interferometry evidence is presented that auroral zone ionospheric disturbances can influence satellite radar interferometry sri obtained with the radarsat ers and jers 1 satellites fluctuations in ionospheric electron density can lead to an azimuth shift modulation in synthetic aperture radar sar imagery which can be detected using sri measurements of azimuth shift in sri can help to differentiate ionospheric from tropospheric propagation problems and to understand better the impact of the ionosphere on spaceborne sar further sri azimuth shift modulation may be useful in mapping patterns of polar auroral zone ionospheric disturbances over large distances

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

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

complete three dimensional near field surface displacements from imaging geodesy techniques applied to the 2016 kumamoto earthquake abstract the recent development of imaging geodesy an advanced technique with a high spatial resolution and large scale coverage has enabled researchers to obtain multiple high quality surface displacement estimates at low labor cost thereby improving the capability to monitor and manage geological disasters the different sources e g radar optical and lidar sensors and analysis approaches e g differential interferometric synthetic aperture radar dinsar multiple aperture insar pixel offset tracking and iterative closest point icp in imaging geodesy used to derive displacement estimates have unique benefits and drawbacks however the inherent differences among these data sources and methods in the construction of three dimensional 3d deformation maps particularly in the near field remain poorly understood and require further discussion in this study we acquired three pairs of alos 2 stripmap mode images two pairs of sentinel 1 tops mode images and pre and post event lidar data for the 2016 kumamoto earthquake to explore the 3d near field displacements using various imaging geodesy techniques with different types of image information i e sar phase data sar amplitude data and lidar point cloud data our results show that each image type is independently capable of producing a high quality 3d deformation map for the 2016 kumamoto earthquake with an on fault accuracy of

quantitative clay mineralogy as provenance indicator for recent muds in the southern north sea abstract the origin of recent mud deposits as well as the coastal turbidity maximum in the french belgian dutch nearshore area of the southern north sea is still under debate in the literature some models favor the erosion of the cretaceous chalk cliffs along the english channel and subsequent ne ward directed transport other models focus on the erosion of eocene to earliest oligocene and pleistocene to holocene clays outcropping on the seafloor off the belgian coast in order to validate these hypotheses the detailed qualitative and quantitative clay mineral composition of these sediments was used as a provenance indicator by comparing the clay mineral composition of the mud deposits and the associated suspended particulate matter spm with the composition of potential nearby and more remote sources such as the present day marine environment estuaries and rivers coastal erosion areas and the geological substratum the origin of the mud deposits and the spm could be traced results showed that only the clay composition of the scheldt estuary coincides with those of the mud deposits and the coastal turbidity maximum and that all other potential sources could be excluded our data suggest that the clay mineral composition of the mud deposits has a similar composition since at least about 100 000 years indicating that these deposits originate from a paleo scheldt river rather than from the recent river system as the present day scheldt estuary is not source of fine grained sediments the present day spm in the belgian dutch nearshore area originates mainly from the erosion and resuspension of the existing mud deposits situated in the belgian nearshore this study demonstrates the value and suitability of quantitative bulk and clay mineralogy techniques in sediment provenance studies and highlights the importance of incorporating the recent geological history in hydrodynamic studies of sedimentary basins

decorrelation in interferometric radar echoes a radar interferometric technique for topographic mapping of surfaces implemented utilizing a single synthetic aperture radar sar system in a nearly repeating orbit is discussed the authors characterize the various sources contributing to the echo correlation statistics and isolate the term which most closely describes surficial change they then examine the application of this approach to topographic mapping of vegetated surfaces which may be expected to possess varying backscatter over time it is found that there is decorrelation increasing with time but that digital terrain model generation remains feasible the authors present such a map of a forested area in oregon which also includes some nearly unvegetated lava flows such a technique could provide a global digital terrain map

reducing ionospheric effects in insar data using accurate coregistration interferometric synthetic aperture radar insar is a valuable tool for the study of geophysical phenomena such as crustal deformation ice motion and structure and vegetation canopy depths but it is adversely affected by uncharacterized inhomogeneities in ionospheric propagation delay ionospheric disturbances distort both insar phase and correlation maps here we present a method to compensate ionospheric propagation variations using accurate image coregistration this significantly improves both the interferometric coherence and phase accuracy an azimuth gradient in the total electron content tec from a spatially variable ionosphere results in a range dependent azimuth phase gradient being added to the phase histories of the pixels being imaged these phase gradients are equivalent to doppler shifts and thus they cause azimuth offsets between the actual and imaged positions of the pixels measuring these offsets accurately permits estimation of the gradient and correction of the interferograms for much of the phase distortion resulting in more accurate estimates of coherence we show an example over greenland where the tec variation causes the correlation to drop from about 0 7 to about 0 2 in one region if spatially varying offsets are not accounted for it also adds an estimated 4 4 radians of interferometric phase over an 80 km insar scene after applying our algorithm we find that the correlation in regions affected by the ionospheric inhomogeneity becomes comparable to correlation in the rest of the image in a more challenging example over iceland we show that our method improves the correlation from 0 15 to 0 25 in some areas

palsar radiometric and geometric calibration this paper summarizes the results obtained from geometric and radiometric calibrations of the phased array l band synthetic aperture radar palsar on the advanced land observing satellite which has been in space for three years all of the imaging modes of the palsar i e single dual and full polarimetric strip modes and scanning synthetic aperture radar scansar were calibrated and validated using a total of 572 calibration points collected worldwide and distributed targets selected primarily from the amazon forest through raw data characterization antenna pattern estimation using the distributed target data and polarimetric calibration using the faraday rotation free area in the amazon we performed the palsar radiometric and geometric calibrations and confirmed that the geometric accuracy of the strip mode is 9 7 m root mean square rms the geometric accuracy of scansar is 70 m and the radiometric accuracy is 0 76 db from a corner reflector analysis and 0 22 db from the amazon data analysis standard deviation polarimetric calibration was successful resulting in a vv hh amplitude balance of 1 013 0 0561 db with a standard deviation of 0 062 and a phase balance of 0 612deg with a standard deviation of 2 66deg

insar bias and uncertainty due to the systematic and stochastic tropospheric delay we quantify the bias and uncertainty of interferometric synthetic aperture radar insar displacement time series and their derivatives the displacement velocities by analyzing the systematic and stochastic components of the temporal variation of the tropospheric delay the biases due to the systematic seasonal delay depend on the sar acquisition times whereas the uncertainties depend on the standard deviation of the random delay the number of acquisitions the total time span covered and the covariance of the time series of the stochastic delay between a pixel and the reference we study the contribution of the wet delay to the insar observations along the western india plate boundary using i moderate resolution imaging spectroradiometer precipitable water vapor ii stratified tropospheric delay estimated from the era i global atmospheric model and iii seven envisat insar swaths our analysis indicates that the amplitudes of the annual delay vary by up to 10 cm in this region equivalent to a maximum displacement bias of 24 cm in insar line of sight direction between two epochs assuming envisat is6 beam mode the stratified tropospheric delay correction mitigates this bias and reduces the scatter due to the stochastic delay for 7 years of envisat acquisitions along the western india plate boundary the uncertainty of the insar velocity field due to the residual stochastic wet delay after stratified tropospheric delay correction using the era i model is in the order of 2 mm yr over 100 km and 4 mm yr over 400 km we discuss the implication of the derived uncertainties on the full variance covariance matrix of the insar data

sediment provenance in the western pacific warm pool from the last glacial maximum to the early holocene implications for ocean circulation and climatic change abstract sedimentary records including clay minerals major elements rare earth elements ree and 14c ages were analyzed in one core from the western pacific warm pool wpwp in order to identify the sources of sediments in the warm pool region from the last glacial maximum lgm to the early holocene the results showed that the sedimentation rate at the studied core site has decreased continuously since the lgm both major elements and clay minerals experienced staged changes in the study area in the studied core most major elemental concentrations decreased prior to 22 kyr bp but increased gradually after 13 kyr bp sediment provenance based on clay minerals and rees further revealed that sediments were likely a mixture of dominant new guinea sediments and asian dust the south equatorial current was the main force transporting new guinea particles while the east asian winter monsoon and the correlated north equatorial countercurrent might have loaded the asian dust into the study area moreover heinrich events were well imprinted in the western pacific and another cold climatic event that occurred at approximately 21 kyr bp was also recorded in the study area these events were similarly documented in ice from greenland but were undistinguished in ice from the antarctic and stalagmites from the hulu cave china a frequency analysis of multi proxies confirmed that sun irradiance essentially controlled the variation in sedimentary records in the western pacific from the lgm to the early holocene

reevaluation of the oxygen isotopic composition of planktonic foraminifera experimental results and revised paleotemperature equations cultured planktonic foraminifera orbulina universa symbiotic and globigerina bulloides nonsymbiotic are used to reexamine temperature 18o relationships at 15 25 c relationships for both species can be described by linear equations equations for o universa grown under low light ll and high light hl share a slope of 4 80 0 21 c 1 with a hl ll offset of 0 33 due to symbiont photosynthetic activity the effect of co32 on o universa is 0 002 mol 1 kg 1 and is insensitive to temperature for g bulloides ontogenetic effects produce size related trends in temperature 18o whereby larger shells are enriched in 18o relative to smaller specimens the o universa temperature 18o relationships are more accurate than previously published equations for describing plankton tow data our equations do not explain planktonic core top data with the same precision but provide a good fit to benthic cibicidoides data below 10 c temperature 18o relationships for g bulloides provide good agreement with field data for this species from the northeast pacific

understanding fine grained river sediment dispersal on continental margins studies of fine grained sediment dispersal in the marine environment have documented diversity in the behavior of depositional systems on continental margins with different oceanographic conditions and morphologies based on the pattern and nature of sediment accumulation for twenty three case studies we propose there are five basic types of dispersal systems and these are related to river wave tide and margin characteristics data suggest that the type of dispersal system on any margin can be predicted with knowledge of sediment load mean significant wave height tidal range and continental shelf width at a river mouth and from these a hierarchical decision tree is developed analysis of the dispersal system type of more than 100 river mouths reveals that proximal accumulation dominated pad and marine dispersal dominated mdd systems are most abundant but estuarine accumulation dominated ead systems also are anticipated to be numerous globally research quantifying marine sediment dynamics in these system types is needed although less common the size and nature of subaqueous delta clinoform sdc and canyon captured cc systems also warrant future attention to their study strong correlations between physical characteristics i e significant wave height and tidal range and the depth and distance to the nearest maximum shelf depocenter provide evidence that in reality a continuum exists between the system types the process related partitioning of sediment in the five different types of marine dispersal systems has important implications for understanding the stratigraphic record and the cycling of carbon

past glaciation in the tropics abstract tropical glaciers are considered along three meridional profiles for the australasian sector africa and the americas evaluated are the annual mean freezing level 0 c modern equilibrium line altitude mel and past equilibrium line altitude pel the calculation of 0 c is based on a 1958 1997 global data set mel refers to estimates concerning the first half of the 20th century and the timing of the pel is not generally known 0 c stands around 4000 5000 m with lower levels in the outer tropics mel is reached in the australasian sector on four mountains and in africa on three mountains near the equator near or above 0 c in the american cordilleras many peaks are still glaciated above 0 c but in the arid southern tropical andes even summits above 6000 m do not reach mel the pel stands between 3000 m and 5000 m high in the equatorial zone but highest in the arid southern tropical andes the height difference between mel and pel is of order 1000 m with regional differences deglaciation dates range between 15 000 and 8000 years bp with later timing towards the higher elevations this synopsis suggests priority targets for further research morphological mapping and age determination in the high atlas of morocco timing of deglaciation in the high semyen of ethiopia and the altos de cuchumatanes of guatemala exploration in the highlands of lesotho and of the dominican republic and glaciation in the arid southern tropical andes

mineralogy of the ganges and brahmaputra rivers implications for river switching and late quaternary climate change late quaternary sediments of the bengal basin contain a history of river switching and climate change as revealed from sand and clay size mineralogy of boreholes and modern riverbed grabs epidote to garnet ratios e g in sand fraction sediments are diagnostic of source with high 1 e g indicating brahmaputra provenance and low 1 e g indicating ganges provenance in the clay fraction of surficial sediments smectite is diagnostic with high values 39 in the ganges and low values 3 in the brahmaputra in contrast the brahmaputra contains more kaolinite 29 vs 18 more illite 63 vs 41 and more chlorite 3 vs 1 than the ganges analysis of mineralogic and stratigraphic data indicates that the two rivers have changed position several times during the holocene extended periods of mixed river inputs appear to be isolated to the early holocene suggesting rapidly migrating braided channels during sea level lowstand tectonically driven accommodation in the sylhet basin may have contributed to the favored easterly course of the brahmaputra during much of the holocene relative abundances of illite and chlorite ic vs smectite and kaolinite sk record varying degrees of physical and chemical weathering respectively high ic values in early post glacial deposits suggest a dominance of physical weathering at that time however a general increase in sk concentrations throughout the holocene appears to reflect enhanced chemical weathering under increasingly warmer and more humid conditions notably a peak in sk concentrations that corresponds to an early holocene warm period 10 7 ka suggests that weathering patterns in the catchment respond quickly to climatic shifts

estimates of sea surface temperature in the coral sea at the last glacial maximum the climap 1981 reconstruction of the coral sea found relatively little cooling 2 c in the low latitudes 10 s but a warming off australia at about 25 s the small low latitude changes are of interest because terrestrial pollen and snowline data from the new guinea highlands imply that surface temperatures may have been 6 to 9 c colder at the last glacial maximum lgm the purpose of this paper is to evaluate these conclusions on the basis of additional core sites new oxygen isotope stratigraphy and new sea surface temperature sst estimates using the modern analog technique mat in the northern coral sea planktonic foraminifer assemblages consist of tropical subtropical species that show little change over the past 20 kyr quantitative estimates of sst using the modern analog technique mat confirm the climap 1981 conclusion that little or no temperature change occurred in this tropical region at the lgm thus reinforcing the conflict with terrestrial evidence in the southern region 25 s two cores indicate that foraminifer faunas became more subtropical at the lgm the mat estimates for the lgm are 3 to 4 c colder than modern producing a steeper thermal gradient in the southern coral sea these data remove the warm sst anomaly along the eastern coast of australia and indicate that during the lgm cool high latitude waters were displaced northward along the coast of australia into the southern coral sea

a novel proxy for terrestrial organic matter in sediments based on branched and isoprenoid tetraether lipids we propose a novel tracer for terrestrial organic carbon in sediments based on the analysis of tetraether lipids using high performance liquid chromatography mass spectrometry hplc ms analysis of terrestrial soil and peats shows that branched tetraether lipids are predominant in terrestrial environments in contrast to crenarchaeol the characteristic membrane lipid of non thermophilic crenarchaeota which is especially abundant in the marine and lacustrine environment based on these findings an index was developed the so called branched and isoprenoid tetraether bit index based on the relative abundance of terrestrially derived tetraether lipids versus crenarchaeol this bit index was applied to surface sediments from the angola basin where it was shown to trace the outflow of the congo river furthermore analyses of particulate organic matter from the north sea showed relatively higher bit indices in water column particulate organic matter near large river inputs a survey of globally distributed marine and lacustrine surface sediments shows that the bit index in these environments correlates with the relative fluvial input of terrestrial organic material making this index generally applicable the new proxy allows the rapid assessment of the fluvial input of terrestrial organic material in immature sediments up to 100 ma old

rapid rise of sea level 19 000 years ago and its global implications evidence from the irish sea basin supports the existence of an abrupt rise in sea level meltwater pulse at 19 000 years before the present b p climate records indicate a large reduction in the strength of north atlantic deep water formation and attendant cooling of the north atlantic at this time indicating a source of the meltwater pulse from one or more northern hemisphere ice sheets warming of the tropical atlantic and pacific oceans and the southern hemisphere also began at 19 000 years b p these responses identify mechanisms responsible for the propagation of deglacial climate signals to the southern hemisphere and tropics while maintaining a cold climate in the northern hemisphere

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

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

source parameters of the 2017 m w 6 2 yukon earthquake doublet inferred from coseismic gps and alos 2 deformation measurements we investigated an m w 6 2 earthquake doublet on the border of the usa and canada using alos2 light of sight displacements and gps measurements we selected three l band alos 2 interfergorams with temporal baselines of one yr to extract coseismic deformation maps in which master and slave images were both acquired in july a subpixel based alignment and another range spectral splitting techniques under the gamma insar software framework were applied to improve the interferometric coherence and reduce the effects of phase anomalies in two of the three interferometric pairs due to either ionospheric delay or a potential focusing issues in the generation of the alos2 slc data the updated interferograms convincingly reveal deformation fringe patterns produced by the two earthquakes we conducted a nonlinear geophysical inversion to estimate the geometric parameters of the earthquakes with the insar and gps measurements the best fitting model shows that a thrust faulting on a reverse fault and left lateral strike slip faulting on a nearly vertical fault with the centroid depths of 9 3 0 6 and 8 4 0 7 km respectively are most likely responsible for the earthquake doublet the eastern denali fault edf and duke river fault are major active faults in the region and the earthquake doublet could be due to reactivation of the part of the two faults system

insar time series estimation of the ionospheric phase delay an extension of the split range spectrum technique repeat pass interferometric synthetic aperture radar insar observations may be significantly impacted by the propagation delay of the microwave signal through the ionosphere which is commonly referred to as ionospheric delay the dispersive character of the ionosphere at microwave frequencies allows one to estimate the ionospheric delay from insar data through a split range spectrum technique here we extend the existing split range spectrum technique to insar time series we present an algorithm for estimating a time series of ionospheric phase delay that is useful for correcting insar time series of ground surface displacement or for evaluating the spatial and temporal variations of the ionosphere s total electron content tec experimental results from stacks of l band sar data acquired by the alos 1 japanese satellite show significant ionospheric phase delay equivalent to 2 m of the temporal variation of insar time series along 445 km in chile a region at low latitudes where large tec variations are common the observed delay is significantly smaller with a maximum of 10 cm over 160 km in california the estimation and correction of ionospheric delay reduces the temporal variation of the insar time series to centimeter levels in chile the ionospheric delay correction of the insar time series reveals earthquake induced ground displacement which otherwise could not be detected a comparison with independent gps time series demonstrates an order of magnitude reduction in the root mean square difference between gps and insar after correcting for ionospheric delay the results show that the presented algorithm significantly improves the accuracy of insar time series and should become a routine component of insar time series analysis

orbital and sea level changes regulate the iron associated sediment supplies from papua new guinea to the equatorial pacific abstract iron fe supplied to the equatorial pacific are thought to play a critical role in marine biogeochemical cycle and the related air sea co2 flux previous studies have shown that papua new guinea png is a major fe contributor for the western equatorial pacific however key issues of this fe supply including the exact sources transport processes and distribution range remain unclear especially its long term variability associated with hydroclimatic and paleoceanographic changes using a set of cores collected offshore the northern png and from the ontong java plateau ojp shown to situate along the pathway of fe delivery by undercurrents here we compile high resolution records to explore how the fe associated sediment supplies varied and distributed on orbital time scale during the past 400 ka the chronologic frameworks of these cores are established by using 14c datings and stratigraphic correlations of foraminiferal 18o records and carbonate contents the sedimentary fe and clay mineral smectite in the offshore png sites show a prominent precession cycle in phase with the march insolation change at 5 s such precessional predominance suggests the control of local precipitation and river runoff on the offshore deposition of the fe associated sediment for the ojp sites the proxies derived from terrigenous detrital component give a spectral pattern however prevailed by 100 ka cycle with secondary precessional highs the significant 100 ka cycle can best be attributed to glacial interglacial changes in oceanic transports likely caused by sea level regulated variability in the strength and or route of the coastal undercurrents off png this variability may have influenced the long distance transport of fe rich particulates from the png to the ojp and further eastwards via the equatorial undercurrent

evidence for indonesian throughflow slowdown during heinrich events 3 5 we present sea surface and upper thermocline temperature records 60 100 year temporal resolution spanning marine isotope stage 3 similar to 24 62 ka b p from international marine global change study core md01 2378 121 degrees 47 27 e and 13 degrees 04 95 s 1783 m water depth located in the outflow area of the indonesian throughflow within the timor sea stable isotopes and mg ca of the near surface dwelling planktonic foraminifer globigerinoides ruber white and the upper thermocline dwelling pulleniatina obliquiloculata reveal rapid changes in the thermal structure of the upper ocean during heinrich events thermocline warming and increased delta o 18 seawater p obliquiloculata record during heinrich events 3 4 and 5 reflect weakening of the relatively cool and fresh thermocline flow and reduced export of less saline water from the north pacific and indonesian seas to the tropical indian ocean three main factors influenced indonesian throughflow variability during marine isotope stage 3 1 global slowdown in thermohaline circulation during heinrich events triggered by northern hemisphere cooling 2 increased freshwater export from the java sea into the indonesian throughflow controlled by rising sea level from similar to 60 to 47 ka and 3 insolation related changes in the australasian monsoon with associated migration of hydrological fronts between indian ocean and indonesian throughflow derived water masses at similar to 46 40 ka

230th normalization an essential tool for interpreting sedimentary fluxes during the late quaternary there is increasing evidence indicating that syndepositional redistribution of sediment on the seafloor by bottom currents is common and can significantly affect sediment mass accumulation rates notwithstanding its common incidence this process generally referred to as sediment focusing is often difficult to recognize if redistribution is near synchronous to deposition the stratigraphy of the sediment is not disturbed and sediment focusing can easily be overlooked ignoring it however can lead to serious misinterpretations of sedimentary fluxes particularly when past changes in export flux from the overlying water are inferred in many instances this problem can be resolved at least for sediments deposited during the late quaternary by normalizing to the flux of 230th scavenged from seawater which is nearly constant and equivalent to the known rate of production of 230th from the decay of dissolved 234u we review the principle advantages and limitations of this method notwithstanding its limitations it is clear that 230th normalization does provide a means of achieving more accurate interpretations of sedimentary fluxes and eliminates the risk of serious misinterpretations of sediment mass accumulation rates

turbidite emplacement on the southern balearic abyssal plain western mediterranean sea during marine isotope stages 1 3 an application of itrax xrf scanning of sediment cores to lithostratigraphic analysis the upper part 0 20 m of a long piston core from the se balearic abyssal plain spanning the past 50 ka has been studied using the itrax micro xrf core scanner to obtain downcore elemental profiles the ca fe ratio was found to be an effective parameter to distinguish between turbidites and pelagites because turbidites generally have higher fe contents and lower ca contents compared with pelagic intervals beds that were obscure when visually logged could be identified as turbidites or pelagites on their geochemical characteristics allowing more complete subdivision of the sequence into genetic units the itrax xrf data also provide useful information on textural grading bioturbative mixing identification of geochemically distinctive marker beds indications of differences in provenance and confirm or query the presence of early arrivals during turbidite emplacement a chronostratigraphic framework for the core based on accelerator mass spectrometry ams radiocarbon dating and correlation with oxygen isotope stages of pelagic intervals in other cores using calcium carbonate stratigraphy was also established this shows that turbidite emplacement on this part of the balearic abyssal plain has been modulated strongly by climate and sea level change with turbidite emplacement most frequent during the early holocene when the rate of post glacial sea level rise was greatest deposition of the coarsest i e sand and silt based turbidites at the core site was restricted to the full and late glacial 11 25 ka turbidite emplacement during oxygen isotope stage 3 was rare most of the turbidites at the site are distal but some coarse grained based turbidites are characterized by higher sr ca ratios possibly indicating a higher aragonite content higher ca and lower fe contents compared to other turbidites and are interpreted as having a more proximal shelf source such turbidites are generally rare however and restricted to full glacial and younger dryas time there is little evidence for large scale seismogenic turbidites expected to be seen as randomly timed emplacement seemingly independent of eustatic control at the core site despite proximity to the seismically active algerian margin 100 km to the south this suggests that seismogenic turbidites must largely bypass this part of the plain although the itrax core scanner provides a rapid and non destructive means of characterizing downcore geochemical distributions in great detail interpretation of the data requires caution and assessment from an informed standpoint analytical artefacts such as those caused by water or organic content degree of compaction grain size and mineral effects unevenness of the cut core surface and poor discrimination of closely spaced element xrf peaks need identification and elimination

high resolution record of northern hemisphere climate extending into the last interglacial period high resolution record of northern hemisphere climate extending into the last interglacial period

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

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

geodetically accurate insar data processor we present a new interferometric synthetic aperture radar insar processing approach that capitalizes on the precise orbit tracking that is available with modern radar satellites our method uses an accurate orbit information along with motion compensation techniques to propagate the radar echoes to positions along a noninertial virtual orbit frame in which the location and focusing equations are particularly simple so that images are focused without requiring autofocus techniques and are computed efficiently motion compensation requires two additional focus correction phase terms that are implemented in the frequency domain if the images from an interferometric pair or stack are all computed along the same reference orbit flat earth topographic correction is not needed and image coregistration is simplified obviating many difficulties that are often encountered in insar processing we process several data sets collected by the alos palsar instrument and find that the geodetic accuracy of the radar images is 10 20 m with up to 20 m of additional image distortion needed to align 100 km 100 km scenes with reference digital elevation models we validated the accuracy by using both known radar corner reflector locations and by the registration of the interferograms with digital maps the topography corrected interferograms are free from all geometric phase terms and they clearly show the geophysical observables of crustal deformation atmospheric phase and ionospheric phase

factors controlling 13c contents of sedimentary organic compounds principles and evidence the carbon isotopic composition of any naturally synthesized organic compound depends on 1 the carbon source utilized 2 isotope effects associated with assimilation of carbon by the producing organism 3 isotope effects associated with metabolism and biosynthesis and 4 cellular carbon budgets these factors are reviewed and quantitative considerations summarized particularly with regard to active and passive modes of carbon assimilation by phytoplankton and the existence of discernible regularities in isotope effects associated with lipid biosynthesis it is concluded that n alkyl lipids are in general depleted in 13c by about 1 5 relative to polyisoprenoid lipids produced by the same organism the effects of biological reworking on isotopic compositions of organic carbon are examined and it is suggested that enrichment of 13c in sedimentary organic carbon may result from loss of ch4 from zooplanktonic gut communities isotopic methods for estimation of ancient co2 levels are considered and a hyperbolic form favored for the relationship between concentrations of dissolved co2 and isotopic fractionation

ice flow dynamics of the greenland ice sheet from sar interferometry synthetic aperture radar sar interferograms produced from esa s ers 1 satellite provide the first synoptic view of ice flow dynamics of the western sector of the greenland ice sheet glacial motion is detected in the radar ranging direction at millimetric scales across a complete sequence of snow accumulation and melting regimes despite significant variations in their radar scattering properties ice flow evolves from a slow regular motion at the higher elevations at lower elevations motion is strongly convoluted by meter scale undulations in surface topography which have a unique interferometric signature that enables a novel approach for retrieving flow direction inferred flow directions combined with surface displacements in the radar ranging direction yield ice velocity estimates that are within 6 of in situ measurements gathered along a 40 km survey line application of repeat pass sar interferometry to the entire greenland ice sheet should enable precise mapping of its ice flow dynamics at an unprecedented level of spatial detail

provenance and accumulation rates of pliocene and quaternary sediments from the western coral sea seven sediment cores were investigated from areas in the western coral sea where a thin sediment cover above acoustic basement or above marked unconformities was visible in reflection seismic records implying low accumulation rates consequently in five of the cores pliocene strata were reached in less than 4 meters depth subbottom the remaining cores reached pleistocene strata at similar shallow depths cores from the queensland plateau and the coral sea abyssal plain are composed of mainly calcareous nannofossil and foraminiferal oozes indicating a calcareous biological primary production in the western coral sea at least since the pliocene the younger quaternary sections of two cores from the northeastern slope of the queensland plateau show a high abundance of siliceous microfossils resulting from the influence of silica rich seawater of the eastern coral sea sediments cored in the moresby canyon are terrigenous muds the carbonate content of the quaternary sediments depends strongly on the waterdepth and on the input of terrigenous material the quaternary calcium carbonate compensation depth of the western coral sea was estimated to be at 4600 m which is close to that of the equatorial pacific ocean the sediments from the moresby canyon the coral sea abyssal plain and the northeastern slope of the queensland plateau have received their terrigenous components mainly quartz feldspar chlorite and muscovite illite from mainland new guinea the western slope of the queensland plateau and the western coral sea abyssal plain very likely have received terrigenous components also from mainland australia as indicated by admixed kaolinite the frequent fine grained volcanic glass in the sediments probably was provided by drift pumice rafts which derived from volcanic eruptions in the southwestern pacific region

high resolution greenland ice core data show abrupt climate change happens in few years the last two abrupt warmings at the onset of our present warm interglacial period interrupted by the younger dryas cooling event were investigated at high temporal resolution from the north greenland ice core project ice core the deuterium excess a proxy of greenland precipitation moisture source switched mode within 1 to 3 years over these transitions and initiated a more gradual change over 50 years of the greenland air temperature as recorded by stable water isotopes the onsets of both abrupt greenland warmings were slightly preceded by decreasing greenland dust deposition reflecting the wetting of asian deserts a northern shift of the intertropical convergence zone could be the trigger of these abrupt shifts of northern hemisphere atmospheric circulation resulting in changes of 2 to 4 kelvin in greenland moisture source temperature from one year to the next

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

seismotectonics of new guinea a model for arc reversal following arc continent collision the structure and evolution of the northern new guinea collision zone is deduced from international seismological center isc seismicity 1964 1985 new and previously published focal mechanisms and a reexamination of pertinent geological data a tectonic model for the new guinea margin is derived which illustrates the sequential stages in the collision and suturing of the bewani toricelli adelbert finisterre huon new britain arc to central new guinea followed by subduction polarity reversal in the west east of 149 e the solomon plate is being subducted both to the north and south bringing the new britain and trobriand forearcs toward collision west of 149 e the forearcs have collided and together they override a fold in the doubly subducted solomon plate lithosphere which has an axis that is parallel to the strike of the ramu markham suture and that plunges westward at an angle of 5 beneath the coast ranges of northern new guinea active volcanism off the north coast of new guinea is related to subduction of the solomon plate beneath the bismarck plate active volcanism of the papuan peninsula and quaternary volcanism of the new guinea highlands are related to slow subduction of the solomon plate beneath the indo australian plate along the trobriand trough and the trough s former extension to the west respectively from 144 148 e seismicity and focal mechanisms reveal that convergence between the sutured bismarck and indo australian plates is accommodated by thrusting within the finisterre and adelbert ranges and compression of the new guinea orogenic belt together with basement involved foreland folding and thrusting to the south the finisterre block overthrusts the new guinea orogenic belt whereas the adelbert block is sutured to new guinea and overthrusts the oceanic lithosphere of the bismarck sea along the new guinea trench west of 144 e seismicity defines a southward dipping wadati benioif zone and focal mechanisms indicate oblique subduction only this oldest westernmost portion of the collision has progressed past suturing to a full reversal in subduction polarity

measuring azimuth deformation with l band alos 2 scansar interferometry we analyze the methods for measuring azimuth deformation with the l band advanced land observing satellite 2 alos 2 scanning synthetic aperture radar scansar interferometry to implement the methods we extract focused bursts from the alos 2 full aperture product which is the only product available for scansar interferometry at present the extracted bursts are properly processed to measure azimuth deformation using interferometric phase we apply the range split spectrum method to scansar to estimate the differential ionospheric phase of the interferogram and take the azimuth derivative of the differential ionospheric phase to mitigate the relative azimuth shift caused by ionosphere for the first time azimuth deformation of a large earthquake april 25 2015 nepal earthquake is nearly completely measured by the l band scansar interferometry with moderate precision the result is validated by the azimuth deformation measured by incoherent cross correlation using a pair of high resolution radarsat 2 images in addition to the final azimuth deformation we show the possibility of processing full aperture scansar product using a burst by burst approach to form regular interferograms we also show the recent strong large scale ionospheric effects on the l band alos 2 scansar interferograms other possible applications of this paper include measuring the movement of glaciers

the onset and early evolution of life the tension between co 2 dissolved at relatively high atmospheric pressure in the hadean ocean and h 2 generated as ocean water oxidized ferrous iron during convection in the oceanic crust was resolved by the onset of life we suggest that this chemosynthetic life emerged within hydrothermal mounds produced by alkaline solutions of moderate temperature in the relative safety of the deep ocean fl oor exothermic reaction between hydrothermal h 2 hcoo and ch 3 s with co 2 was catalyzed in inorganic membranes near the mound s surface by mackinawite fes nanocrysts and ready made clusters corresponding to the greigite fe 5 nis 8 structure such clusters were precursors to the active centers e g the c cluster fe 4 nis 5 of a metalloenzyme that today catalyzes acetate synthesis viz the bifunctional dehydrogenase enzyme acs codh the water and some of the acetate h 3 c coo produced in this way were exhaled into the ocean together as fl uid waste glycine h 3 n ch 2 coo and other amino acids as well as tiny quantities of rna generated in the same milieu were trapped within tiny iron sulfi de cavities energy from the acetate reaction augmented by a proton gradient operating through the membrane was spent polymerizing glycine and other amino acids into short peptides upon the phosphorylated mineral surface in turn these peptides sequestered and thereby protected the catalytically and electrochemically active pyrophosphate and iron nickel sulfi de clusters from dissolution or crystallization intervention of rna as a polymerizing agent for amino acids also led to an adventitious though crude process of regulating metabolism a process that was also to provide genetic information to offspring the fl uxes of energy and nutrient available in the hydrothermal mound commensurate with the requirements of life encouraged differentiation of the fi rst microbes into two separate domains at the bifurcation the bacteria were to specialize in acetogenesis and the archaea into methanogenesis representatives of both these domains left the mound by way of the ocean fl oor and crust to colonize the deep biosphere once life had emerged and evolved to the extent of being able to reduce nitrogen for use in peptides and nucleic acids light could have been used directly as an energy source for biosynthesis certain bacteria may have been able to do this where protected from hard uv by a thin coating of chemical sediment produced at a subaerial hot spring operating in an obducted and uplifted portion of the deep biosphere

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

satellite radar interferometry time series analysis of surface deformation for los angeles california 1 the los angeles california metropolitan area is a tectonically active region with surface deformation that is a combination of fault related tectonics plus a variety of natural and anthropogenic signals we apply the small baseline subset sbas algorithm to produce an interferometric synthetic aperture radar insar time series analysis for the los angeles area using data acquired by the ers satellites from late 1995 into 2002 the result is a space time deformation product that can be exploited to view not only the smoothly varying long term surface motion but also its time varying patterns large seasonal oscillations of the santa ana aquifer observed in southern california integrated gps network scign data are accurately matched in the insar time series moreover correlations of the insar time series with an annual sinusoid allows us to investigate the dynamics of the hydrologic system index terms 1243 geodesy and gravity space geodetic surveys 1294 geodesy and gravity instruments and techniques 1803 hydrology anthropogenic effects citation lanari r p lundgren m manzo and f casu 2004 satellite radar interferometry time series analysis of surface deformation for los angeles california geophys res lett 31 l23613 doi 10 1029 2004gl021294

itcz rather than enso signature for abrupt climate changes across the tropical pacific latitudinal movements of the intertropical convergence zone itcz analogous to its present day seasonal shifts and el nino southern oscillation enso type variability both potentially impacted rainfall changes at the millennial timescale during the last glacial period in this study we compare tropical pacific sedimentary records of paleoprecipitation to decipher which climate mechanism was responsible for the past rainfall changes we find that latitudinal movements of the itcz are consistent with the observed rainfall patterns challenging the enso hypothesis for explaining the rapid rainfall changes at low latitudes the itcz related mechanism appears to reflect large scale atmospheric rearrangements over the tropical belt with a pronounced heinrich dansgaard oeschger signature this observation is coherent with the simulated tropical rainfall anomalies induced by a weakening of the atlantic thermohaline circulation in modeling experiments c 2009 university of washington published by elsevier inc all rights reserved

single baseline polarimetric sar interferometry examines the application of single baseline polarimetric sar interferometry to the remote sensing and measurement of structure over forested terrain for this a polarimetric coherent scattering model for vegetation cover suitable for the estimation of forest parameters from interferometric observables is introduced discussed and validated based on this model an inversion algorithm which allows the estimation of forest parameters such as tree height average extinction and underlying topography from single baseline fully polarimetric interferometric data is addressed the performance of the inversion algorithm is demonstrated using fully polarimetric single baseline experimental data acquired by dlr s e sar system at l band

radiocarbon simulations for the glacial ocean the effects of wind stress southern ocean sea ice and heinrich events simulations of oceanic radiocarbon for the last glacial maximum are presented using a three dimensional global ocean circulation model forced with glacial background states according to various reconstructions we investigate the influence of sea surface temperatures sea ice margins wind stress and antarctic sea ice formation on the glacial tracer distribution and meridional overturning circulation the aim of these sensitivity studies is to reconcile available radiocarbon data from marine sediments with reconstructed sea surface temperatures and estimated sea ice production rates model runs with a modified freshwater balance in the southern ocean mimicking increased brine release due to enhanced divergence of antarctic sea ice arrive at radiocarbon values close to observations these experiments also yield abyssal temperatures and salinities which are consistent with recent inferences in the simulation with the best agreement with radiocarbon observations north atlantic deep water export is reduced by 40 compared to present day while antarctic bottom water flow is intensified to similar strength in the south atlantic transient simulations show that glacial freshwater discharge into the north atlantic can cause abrupt increases of atmospheric radiocarbon as observed during heinrich event 1 however the effect is only significant in scenarios with a massive short time discharge at the beginning which is followed by low level freshwater input for the rest of the event or if it is assumed that the meridional overturning circulation was already in a modern operational mode

massive expansion of marine archaea during a mid cretaceous oceanic anoxic event biogeochemical and stable carbon isotopic analysis of black shale sequences deposited during an albian oceanic anoxic event 112 million years ago indicate that up to 80 weight percent of sedimentary organic carbon is derived from marine nonthermophilic archaea the carbon 13 content of archaeal molecular fossils indicates that these archaea were living chemoautotrophically their massive expansion may have been a response to the strong stratification of the ocean during this anoxic event indeed the sedimentary record of archaeal membrane lipids suggests that this anoxic event marks a time in earth history at which certain hyperthermophilic archaea adapted to low temperature environments

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

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

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

provenance of oligocene miocene alluvial and fluvial fans of the northern ebro basin ne spain an xrd petrographic and sem study abstract this paper combines stratigraphic and sedimentological data with xrd petrographic and sem techniques in order to investigate the fluvial and alluvial fans that were developed during the oligocene and the lower miocene in the central area of the northern ebro basin spain and their respective source areas the proximal sectors of the coeval depositional systems can be separated on the basis of lithofacies criteria conglomerate features reveal that the source areas for the alluvial fans were limited to the south pyrenean sierras whereas those of the fluvial fans included more northern pyrenean areas such as the axial zone or the clastic tremp graus basin far from the basin margin the distal alluvial facies interdigitate with the middle distal fluvial deposits in these areas only detailed mineralogical and petrographic analysis of the rocks can determine their origin thus the methods used have allowed us to differentiate between authigenic and detrital phases on the basis of these observations three different types of coarse sandstone petrofacies have been distinguished 1 carbonate rich sandstone 2 high quartz sandstone and 3 high lithic fragment sandstone rich in shale and feldspars grains the first corresponds to the alluvial samples and corroborates the south pyrenean sierras as alluvial fans source area the high quartz and the high lithic fragment sandstone correspond to the fluvial samples and evidence that the drainage basin of the fluvial fans included the clastic tremp graus basin and the axial zone the high lithic fragment petrofacies is representative of the most ancient fluvial rocks whereas the high quartz sandstone corresponds to the recent and nonconforming fluvial rocks this change in the fluvial petrofacies allows us to recognise the changing importance of each region as a source area of the fluvial fans over time which can be correlated with pyrenean tectonic activity during the oligocene

tectonic controls on carbonate platform evolution in southern papua new guinea passive margin to foreland basin the middle oligocene collision of the northern margin of the australian craton with a complex subduction system resulted in emplacement of a thrust mass and formation of a foreland basin that extended from the coral sea to the indian ocean the distribution of carbonate platform facies in southwestern papua new guinea reflects the transition from an eocene passive margin setting to the early stages of foreland basin evolution the initial basin configuration with terrigenous sedimentation confined to the proximal foredeep allowed carbonate deposition in the shallow environment adjacent to the peripheral forebulge subsequent southward migration of the basin resulted in a rapid increase in the area and thickness of carbonate platform deposition when the proximal foredeep became filled by detritus shed from the emerging orogen clastic sediments buried the platform and terminated carbonate deposition the history of the southern papua new guinea carbonate platform illustrates the paradox of carbonate deposition within the foreland basin whereby basin configuration initially encourages thick and extensive carbonate deposition but inevitably leads to terrigenous inundation and the demise of the carbonate platform

warm pool hydrological and terrestrial variability near southern papua new guinea over the past 50k here we presenta 50k archiveof u37 seasurface temperature sst planktic foraminifera oxygen isotopes and terrestrial input indicators including branched and isoprenoid tetraether bit biomarkers 232 th activity and non biogenic sediment components recorded in core md052928 from the wpwp near southern papua new guinea png the planktic foraminifer oxygen isotopes in the core show millennial scale changes indicating fresher seawater during the nh cold periods i e heinrich events hes and suggesting hydrological changes that are most likely linked to the strength of the boreal winter asian australian monsoon aam our observations are corroborated by evidence from the same core that indicates increased terrestrial input caused by higher precipitation on land and more river runoff from southern png during the cold periods consistent with other nearby hydrological records from land our study indicates persistent millennial scale hydrological changes within the past 50k in the western tropical pacific and southeast asia the timing of the millennial scale changes appears to have been determined by the latitudinal displacement of the intertropical convergencezone itcz thatreflectsahistoryofheattrans

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

topographic mapping from interferometric synthetic aperture radar observations interferometric synthetic aperture radar observations provide a means for obtaining high resolution topographic terrain maps from data acquired simultaneously at two slightly displaced antennas calculation of the three dimensional coordinates of all the points in a radar image can be made from the combination of along track slant range and interferometer fringe measurements thus the result compensates for the layover exhibited by conventional radar maps and removes the false targets generated by multiple signal paths to a given object in the scene we have derived a topographic map of a portion of the san francisco bay area utilizing data that were recorded by a radar system mounted on a nasa cv990 aircraft and processed by a general purpose digital computer this map displays the height above sea level of a region approximately 11 km by 10 km in size sampled on an 11 m pixel grid uncertainties in the estimated height result from imprecise knowledge of the observational geometry radar bandwidth limitations and finite signal to noise ratios for our system each factor contributed approximately 3 4 m to a relative rms error of about 6 m additional global errors of the order of 10 m can result from inaccurate monitoring of aircraft attitude the statistical variation of the height measurements from the ocean portion of the map which we can presume to be quite flat is 2 10 m rms which is consistent with the theoretical estimate comparison of our results with u s geological survey contour maps indicates a high degree of correlation between the two sets of altitude data

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

building the holocene clinothem in the gulf of papua an ocean circulation study received 31 august 2006 revised 21 august 2007 accepted 15 november 2007 published 28 march 2008 1 this paper investigates the role that tidal and wind driven flows and buoyant river plumes play in the development of the holocene clinothem in the gulf of papua time series data from bottom tripods and a mooring were obtained at four locations near the mouth of the fly river during portions of 2003 and 2004 flows in the gulf of papua during calendar year 2003 were hindcast every 3 h using the navy coastal ocean model ncom with boundary conditions from the navy atmospheric prediction system the east asian seas implementation of ncom and the otis tidal inversion system results show that tidal flows on the modern clinoform are strong and are landward and seaward directed peak spring tidal velocities can provide the shear stresses necessary to keep sediment up to sand size in motion as the wind driven and baroclinic currents distribute it from the river mouths across and along the shelf in two circulation states during the monsoon season the clinoform topset is swept by a seaward surface flow and landward bottom flow reflecting river plumes and coastal upwelling seaward this structure evolves into a sw directed surface current over the clinothem foreset with accompanying landward directed near bed currents that trend obliquely up the foreset to the wsw over much of the clinothem during the trade wind season the inner and outer topset are swept by ne directed contour parallel surface currents underneath which lie obliquely landward near bed currents these modeled 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 modern gulf of papua clinothem

late quaternary vegetation change in the tari basin papua new guinea the changes in late quaternary vegetation at two sites in the tari basin central highlands of new guinea are presented haeapugua basin 1650 m altitude and tugupugua basin 2300 m altitude lie within the lower montane forest belt where the climate is characterised by high relative humidity and low seasonality pollen analysis mineral magnetics carbonised particle analysis and dating by radiocarbon and thermoluminescence techniques are employed to reconstruct the vegetation and sediment history the sequences include fragmentary interglacial interstadial records from before 50 000 yr b p and a continuous record from at least 28 000 yr b p to the present the study shows that prior to 21 000 yr b p vegetation in the basin was dominated by fluctuating proportions of tree taxa indicative of a forested environment the montane forest taxon nothofagus is important throughout the record although other tree taxa including castanopsis myrtaceae dacrydium and pandanus attain dominance at different times under the influence of a range of environmental factors the creation of an open environment around 21 000 yr b p is considered to be a consequence of the arrival of humans in the region the late glacial transition between 14 500 and 8500 yr b p is a period of climatic instability with landscape and vegetation adjustments proceeding at different rates across the highlands vegetational adjustments match modern ranges by about 8500 yr b p when swamp forest developed across the sites at the lower altitude site there are indications of anthropogenic forest disturbance associated with swamp forest clearance commencing around 1700 yr b p and intensifying through to the present forest clearance is recorded only after 700 yr b p at the higher site where agriculture was probably only sustainable after the introduction of sweet potato ipomoea batatas

indirect climatic control of the clay mineral composition of quaternary sediments from the cariaco basin northern venezuela odp site 1002 abstract variations in the clay mineral composition of mid late quaternary sediments recovered from the cariaco basin are interpreted in terms of changes in paleoclimate the results indicate the changing contribution of regional and local sediment sources during interglacial high stands vs glacial low stands the relative contribution of illite increases during interglacial stages and decreases during glacial stages illite smectite shows a much weaker negative relationship to glacial eustacy the abundances of kaolinite and chlorite show no correlation with paleoclimate sediments sourced from rivers adjacent to the cariaco basin contain low illite and provide a significant influx of illite smectite during low sea level stands but during interglacial periods they are probably deposited on the shallow continental shelf bordering the local coastline clays sourced from the amazon and orinoco rivers are richer in illite and their contribution is reduced in times of low sea level stands as the continental shelf becomes much narrower and sediment is discharged directly onto the continental rise during the last glacial period changes in clay mineral composition were magnified relative to previous glaciations possibly due to tectonic evolution of the region the sill depth between the cariaco basin and the open caribbean sea was reduced to a minimum decreasing further the relative importance of the amazon orinoco contribution

millennial scale dynamics of the east asian winter monsoon during the last 200 000 years the primary productivity dynamics of the last 200 000 years in the sulu sea was reconstructed using the abundance of the coccolithophore florisphaera profunda in the images md97 2141 core we find that primary productivity was enhanced during glacial periods which we suggest is due to a stronger east asian winter monsoon during the last 80 kyr eight significant increases in primary productivity pp in the sulu sea are similar to east asian winter monsoon changes recorded in chinese loess the pp maxima are not linked with heinrich events he in the north atlantic although four pp peaks are synchronous with he the pp oscillations have frequencies near those of the dansgaard oeschger cycles in northern hemisphere ice records and indicate a teleconnection of the east asian winter monsoon with greenland climate in this sulu sea record the east asian winter monsoon oscillates with periodicities of6 4 2 3 4 2 3 and 1 5 kyr in particular the 1 5 kyr cycle exhibits a strong and pervasive signal from stage 6 to the holocene without any ice volume modulation this stationarity suggests that the 1 5 kyr cycle is not driven by some high latitude forcing

molecular geomicrobiology genes and geochemical cycling core geosciences concepts are being fundamentally revised as the result of breakthroughs in geomicrobiology revolutionary discoveries have resulted from increased effort devoted to study of microorganisms in the context of their environments much recent progress has been made possible by genetic data particularly those that allow the description of microbial populations in situ new gene and genome sequences are elucidating previously unexpected or unexplained interactions between microorganisms and earth materials with implications for key geological phenomena such as the formation of ore deposits and the regulation of global climate and surface oxidation state genetic data have also led to extensive revision of our understanding of the pace and mechanisms by which evolution occurs yet the field of molecular geomicrobiology remains in its infancy in the foreseeable future merging of modern biogeochemistry with molecularly resolved ecological studies will inspire the development of integrated models for the processes that shape the earth 2002 elsevier science b v all rights reserved

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

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

correcting distortion of polarimetric sar data induced by ionospheric scintillation a correction methodology for distortions induced by ionospheric scintillation on fully polarimetric synthetic aperture radar sar data is proposed the correction is based on deriving the phase distortion induced by the ionosphere from faraday rotation estimates the estimated phase distortion is then used for correction in order to compensate the phase and time doppler history distortions the correction has to be performed at the slant range of the ionospheric layer i e on partially focused single look complex data accordingly the performance of the proposed correction methodology depends among other factors on knowledge of the altitude of the effective ionospheric layer assuming the thin ionospheric layer model its estimation from the sar data itself is therefore also addressed the methodology was applied and validated on simulated p band data for various ionospheric conditions and on real l band data acquired by the advanced land observation satellite phased array l band sar palsar

formation of holocene sedimentary laminae in the black sea and the role of the benthic flocculent layer holocene black sea sediments recovered in 1988 and 1993 from box cores and gravity cores were analyzed geochemically microscopically and with backscattered electron imagery bsei in order to determine the temporal geochemical and sedimentological relationships between the benthic flocculent layer often referred to as the fluff layer and the formation of underlying laminated unit i sediments existence of a permanent benthic fluff layer in the black sea basin is suggested acting as a geochemical transition layer within which all sedimentary particles are hydraulically sorted and particles subject to dissolution or organic remineralization are altered prior to accumulation we propose that particle residence time within the benthic fluff layer is a key factor in determining sedimentary microfabric and geochemical composition of laminated unit i sediments we present a schematic model depicting the above relationships and use it to propose a paleoflux scenario for laminae formation in the unit ii sapropel

possible evidence for wet heinrich phases in tropical ne australia the lynch s crater deposit unarguably one of the most significant paleoclimatological discoveries of the last two decades has been that of abrupt climate events dansgaard oeschger cycles and heinrich events most evidence for these events has originated from the high latitude northern hemisphere with few records documenting the response of the low latitude southern hemisphere here we present new data from lynch s crater a unique terrestrial record from ne australia that may show evidence for southward propagations of the intertropical convergence zone itcz during abrupt climate perturbations as a result of alteration of the low latitude air masses proxies for precipitation wetness indicate enhanced rainfall in the region during heinrich events h events 1 3 and the 8 2 ka northern hemisphere cold event a fully coupled atmosphere ocean climate model simulating a 1 sv freshwater influx to the north atlantic ocean produces a scenario which agrees with the climate changes shown by the lynch s crater record the model shows precipitation anomalies that include a southward migration of the itcz and a zonal shift in mid latitude storm tracks over the southern hemisphere equatorial region these data indicate large scale shifts of the austral summer itcz position that is known to control monsoonal precipitation in ne australia this terrestrial record from australia may demonstrate the involvement of the tropical western pacific ocean in itcz migrations during abrupt climate events of the last glacial period defining such past migrations offers insight into the importance and role of the equatorial region in global climate dynamics

increasing australian indonesian monsoon rainfall linked to early holocene sea level rise the australian indonesian summer monsoon affects rainfall variability across the indo pacific region reconstructions of monsoon strength from stalagmites show that precipitation increased from 11 000 to 7 000 years ago as rising global sea level caused the flooding of the indonesian continental shelf the australian indonesian summer monsoon affects rainfall variability and hence terrestrial productivity in the densely populated tropical indo pacific region it has been proposed that the main control of summer monsoon precipitation on millennial timescales is local insolation1 2 3 but unravelling the mechanisms that have influenced monsoon variability and teleconnections has proven difficult owing to the lack of high resolution records of past monsoon behaviour here we present a precisely dated reconstruction of monsoon rainfall over the past 12 000 years based on oxygen isotope measurements from two stalagmites collected in southeast indonesia we show that the summer monsoon precipitation increased during the younger dryas cooling event when atlantic meridional overturning circulation was relatively weak4 monsoon precipitation intensified even more rapidly from 11 000 to 7 000 years ago when the indonesian continental shelf was flooded by global sea level rise5 6 7 we suggest that the intensification during the younger dryas cooling was caused by enhanced winter monsoon outflow from asia and a related southward migration of the intertropical convergence zone8 however the early holocene intensification of monsoon precipitation was driven by sea level rise which increased the supply of moisture to the indonesian archipelago

ionospheric correction of insar data for accurate ice velocity measurement at polar regions abstract interferometric synthetic aperture radar insar has become an essential tool for measuring ice sheet velocity in the polar regions at low radar frequencies e g l band 1 2 ghz but also at higher frequency e g c band 5 6 ghz the ionosphere has been documented to be an important source of noise in these data in this paper we employ a split spectrum technique and investigate its performance for correcting ionospheric effects in insar based ice velocity measurements in greenland and antarctica three case studies using alos palsar data are used to assess the performance of the split spectrum technique for ionosphere correction over a range of environmental parameters we employ several approaches to evaluate the results including visual inspection profile analysis comparison of experimental and theoretic errors comparison with reference data from other sources generation of double difference interferograms and analysis of time series of multi temporal data our experiments show that ionospheric distortions are observed regularly and in our analyzed greenland dataset and antarctic dataset the ionospheric noise reaches 14 m yr and 10 m yr respectively which exceeds the signal associated with ice motion our analysis using several different approaches demonstrates that the split spectrum technique provides an effective correction the split spectrum technique is also found to be superior to currently used approaches such as baseline fitting and multi temporal averaging the noise level is reduced by a factor of 70 in greenland test areas and 90 in antarctic test areas

oceanographic currents differential subsidence and physiography control three dimensional clinothem growth in the gulf of papua papua new guinea abstract a regional high resolution chirp seismic survey in the gulf of papua gop extends the geographic scope of previous studies by 125 km and reveals that the holocene clinothem along margin geometries surfaces of lap and steepness of foreset slopes appear less dependent on eustatic sea level changes and sediment supply than previously suggested clinothems imaged by chirp profiles and sampled by sediment cores include two older relict clinothems and a younger holocene clinothem divided into three units by two surfaces of lap new radiocarbon ages from this study establish that depositional timing is more recent than previously proposed for the transgressive deposits the holocene clinothem units and surfaces of lap while previous ages suggested that observed stratal relationships could coincide with meltwater pulses or sea level stillstands the younger ages from this study question these results and suggest the dominant control on holocene clinothem architecture may be inherited physiography sw ne differential subsidence along margin currents and seasonal variations in wave energy inherited physiography underlying the holocene clinothem consists of valleys incised during relative lowstands of marine isotope stages mis 4 and 2 valleys in the relict clinothem potentially served as across margin conduits for an older holocene clinothem unit after the older holocene unit filled valleys and accommodation younger holocene units preferentially grew along rather than across margin as bottom shear stresses increased relict clinothems have undergone differential subsidence since deposition due to foreland basin loading which has engendered more accommodation in the northeast gop that systematically decreases toward the southwest areas with less accommodation are more likely to experience toplap as they are exposed to increased shear stresses therefore the surfaces of lap are caused by interactions between accommodation and oceanographic currents examining stratal relationships along the holocene clinothem has broad implications for sequence stratigraphy as many clinothems exhibit a three dimensional stacking pattern measurements of seafloor slopes yield complicated results illustrating that seafloor steepness within lobes is influenced by a complex interplay of accommodation sediment supply underlying physiography and oceanographic currents this suggests that clinothem architecture in the gop cannot simply be interpreted as a rate related problem between rates of sediment supply and relative sea level

a geochemical application of the itrax scanner to a sediment core containing eastern mediterranean sapropel units the itrax micro x ray fluoresence xrf core scanner has been applied in a sediment geochemistry investigation the core sections selected contain examples of the organic rich sedimentary units sapropels that form periodically in the eastern mediterranean basin sapropels are visually obvious from their dark coloration but the itrax x radiograph also reveals physical property changes that result mainly from the high pore water content of sapropels a consideration of wavelength dispersive xrf data from discrete samples of the most recent sapropel s1 was made along with the set of elements reported by the itrax instrument s energy dispersive xrf system over core sections containing s1 this allowed selection of a suite of eight inter element ratios or element integrals through which characteristic features of sapropel development and geochemistry were revealed while recognizing that the measured xrf element integrals from the itrax do not have an exact constant relationship with element concentration over changing sediment types this combination of ratios provides significant information for geochemical interpretation these include evidence for i the presence of high corg contents in the visual sapropel from ba ti and br cl ratios ii a thinning of the original sapropel thickness by post depositional oxidation from mn ti and cu ti ratios iii pyrite authigenesis in the residual visual sapropel from fe ti and s cl ratios and the as integral and iv aragonite formation in and around the sapropel from the sr ca ratio these same ratios were then used to interpret itrax data from a deeper section of the same core containing the older sapropel s3 where the same characteristics including the relict post depositional oxidative thinning of the original unit could be identified with only minor differences of detail directions of supply of fe as and cu into the sapropels could be inferred from profile shapes

asian summer monsoon influence on chemical weathering and sediment provenance determined by clay mineral analysis from the indus submarine canyon clay minerals from the indus canyon and eastern clinoform since 12 ka are uniformly rich in smectite and illite similar to those from the holocene indus flood plains a systematic enrichment of smectite in the proximal delta compared to the canyon and eastern clinoform argues for preferential capture of smectite close to the river mouth since 12 ka there is a rapid shift to a more smectite rich assemblage in the canyon and eastern clinoform after 5 ka this change is probably caused by a change in sediment source with less direct flux from the himalaya and more erosion of older weathered smectite rich sediment from the indus river flood plains driven by incision of the indus and its tributaries into the floodplain as summer monsoon rains weakened this influx of smectite is consistent with lower kaolinite smectite values since 5 ka the onset of large scale agricultural activities since 5 ka especially starting with the harappan civilization may also have enhanced incision and erosion of floodplain sediments over the same time period this study reports for the first time how monsoon strength variations since 12 ka affected the clay mineral assemblages and sediment provenance in a major submarine canyon

correlation between climate events in the north atlantic and china during the last glaciation episodes of massive iceberg release heinrich events 1 3 into the north atlantic ocean during the last glaciation were associated with recurring episodes of unusually cold north atlantic surface water bond cycles 4 and cold air temperatures over greenland dansgaard oeschger events 5 6 four of the youngest of these cold events have also been reported in climate records from sites outside the north atlantic region7 but until now the entire suite has been identified only in north atlantic marine sediments greenland ice core records and tentatively in french lake sediments8 here we examine grain size data from chinese loess and intercalated accretionary palaeosols of last glacial age for evidence of similar climate signals remote from the north atlantic region we see grain size maxima with ages that match those of the last six heinrich events which we interpret as an indication of the changing strength of the east asian winter monsoon which largely controls the transport and deposition of central asian aeolian dust thus it seems that these heinrich events have left their signature in the chinese loess record this is consistent with simulations of the glacial climate9 which imply that the climates of the north atlantic and china were linked by the effect of westerly winds