late cenozoic geodynamic evolution of eastern indonesia this paper presents an internally and globally consistent model of plate evolution in eastern indonesia from middle miocene to present time it is centered on the banda sea region located in the triple junction area between the pacific philippine australia and south east asia plates the geological and geophysical data available from indonesia were until recently insufficient to define a unique plate tectonic model in this paper the new data taken into account clearly restrict the possible interpretations owing to a great number of geological geophysical and geochemical studies the major plate boundaries the sunda banda subduction zone to the south the tarera aiduna fault zone and the seram thrust to the east and the sorong fault zone and molucca sea collision zone to the north are now clearly identified the age of the major tectonic structures is also better known geodetic measurements well constrain the present time plate kinematics we also consider the deformation history within eastern indonesia where numerous short lived microplates and their related microcontinents successively accreted to the asiatic margin moreover magnetic anomalies identification of the north and south banda sea basins allows a precise kinematic reconstruction of the back arc opening we used the plates software to test the coherency of our model presented as a series of 4 plate reconstruction maps from 13 ma to the present finally the origin of oceanic domains restored by our reconstruction is discussed

open system coral ages reveal persistent suborbital sea level cycles sea level is a sensitive index of global climate that has been linked to earth s orbital variations with a minimum periodicity of about 21 000 years although there is ample evidence for climate oscillations that are too frequent to be explained by orbital forcing suborbital frequency sea level change has been difficult to resolve primarily because of problems with uranium thorium coral dating here we use a new approach that corrects coral ages for the frequently observed open system behavior of uranium series nuclides substantially improving the resolution of sea level reconstruction this curve reveals persistent sea level oscillations that are too frequent to be explained exclusively by orbital forcing

phase transformations in serpentine at high pressures and temperatures and implications for subducting lithosphere abstract serpentine may be regarded as a hydrous form of a 1 1 molecular mixture of olivine and pyroxene or a simplified hydrous pyrolite upper mantle composition the phase behaviour of two natural serpentines having the approximate compositions of mg0 99fe0 01 3si2o5 oh 4 and mg0 91fe0 09 3si2o5 oh 4 was investigated between 60 and 280 kbar inclusive at 700 1000 c in a diamond anvil pressure cell coupled with laser heating by incorporating earlier work the results suggest that at pressures greater than 30 kbar and temperatures in the range 600 1000 c serpentine displays the following sequence of phase transformations with increasing pressure serpentine 40 60 kb forsterite talc water 70 80 kbforsterite orthoenstatite water 100 kg forsterite clinoenstatite water 120 kb clinoenstatite phase a water 130 kb stishovite phase a brucite 180 kg stishovite phase b brucite 220 kb none of the high pressure phases expected in olivine and pyroxene such as the spinel modification of olivine the ilmenite and perovskite modifications of pyroxene was observed in serpentine up to about 280 kbar loading pressure on the basis of these results the effect of h2o on phase transformations of olivine and pyroxene at high pressures and high temperatures has been deduced it has been found that the modified spinel phase of mg2sio4 does not occur in the system having a 1 1 mixture of forsterite and enstatite and containing more than about 4 wt h2o the spinel phase of mg2sio4 does not appear at its equilibrium transition boundary modified spinel spinel in the same system containing more than about 3 wt h2o thus if more than about 4 wt h2o is present in the middle portion of a subducting lithosphere the so called 400 km seismic discontinuity observed in the normal mantle may not take place in the downgoing slabs where these transitions do occur at a low h2o content the associated change in density and accordingly the magnitude of discontinuities in the seismic wave velocities would be reduced by a factor of 2 3 if 2 wt h2o is present in the system

surface uplift history of the incipient banda arc continent collision geology and synorogenic foraminifera of rote and savu islands indonesia abstract field mapping and analysis of foraminifera from synorogenic pelagic units of rote and savu islands indonesia reveals high rates of surface uplift of the incipient banda arc continent collision during the past 1 8 myr new geological maps of these islands document accretion to the banda forearc of triassic through tertiary sedimentary cover units from the down going australian continental margin foraminifera rich synorogenic deposits of the batu putih formation unconformably overlie these accreted units we use paleodepth versus time estimates from benthic and planktic foraminifera s to measure long term surface uplift rates for the accretionary wedge although strong currents in the region cause some problems with reworking several distinctive species have been found synorogenic deposits in savu and rote yield foraminifer s of biozone neogene n 18 to n22 5 6 1 0 myr that were deposited at estimated depths of around 3000 m these deposits are unconfomrably overlain by uplifted coral terraces the highest coral terraces in savu are 300 m above sea level and perhaps as old as 0 8 myr in rote the highest coral terrace is 200 above sea level and 0 2 myr old these data indicate that collision of the australian continental margin with the banda arc which initiated much earlier in timor has propagated westward towards rote where it is in the initial stages of accretionary wedge emergence collision of the scott plateau propagated se from sumba 2 3 ma to savu 1 0 0 5 ma and then to rote 0 2 ma average rates of surface uplift of the batu putih formation pelagic deposits during the past 2 myr in rote and savu are 1 5 and 2 3 mm a respectively the rise of these islands is clogging the indo pacific seaway

an 800 kyr record of global surface ocean δ18o and implications for ice volume temperature coupling abstract the sequence of feedbacks that characterized 100 kyr glacial cycles of the past million years remains uncertain hampering an understanding of the interconnections between insolation ice sheets greenhouse gas forcing and climate critical to addressing this issue is an accurate interpretation of the marine 18 o record the main template for the ice ages this study uses a global compilation of 49 paired sea surface temperature planktonic 18 o records to extract the mean 18 o of surface ocean seawater over the past 800 kyr which we interpret to dominantly reflect global ice volume the results indicate that global surface temperature inferred deep ocean temperature and atmospheric co2 decrease early during each glacial cycle in close association with one another whereas major ice sheet growth occurs later in glacial cycles these relationships suggest that ice volume may have exhibited a threshold response to global cooling and that global deglaciations do not occur until after the growth of large ice sheets this phase sequence also suggests that the ice sheets had relatively little feedback on global cooling simple modeling shows that the rate of ice volume change through time is largely determined by the combined influence of insolation temperature and ice sheet size with possible implications for the evolution of glacial cycles over the past three million years

holocene sea level changes in the indo pacific holocene sea level reconstructions exist from many locations in the indo pacific region despite being a large geographical region the nature of holocene sea level change is broadly similar in all locations differences do exist however in the timing and magnitude of the mid holocene high stand mhhs and the nature of late holocene sea level fall across the region when the indo pacific is subdivided into smaller regions these discrepancies do not disappear and in some cases the discrepancies are large within a single coastline it is clear from this analysis that the fundamental criteria to produce accurate local relative sea level curves are hardly ever met there are serious problems associated with the correct interpretation of sea level indicators and their relationship to mean sea level and with the quality of age determinations a consistent methodology throughout the indo pacific for the analysis of sea level data is lacking future sea level analysis from far field locations must involve the application of a consistent methodology in order to allow meaningful comparison between studies this should help to resolve the ongoing debate about the magnitude and timing of the mid holocene high stand and the nature of late holocene sea level fall across the region

the magnitude of a mid holocene sea level highstand in the strait of makassar abstract knowledge on the timing and magnitude of past sea level changes is essential to understand modern and future sea level variability holocene sea level data from literature on the west coast of sulawesi central indonesia suggest that this region experienced two relative sea level highstands over the last 6000 years with magnitudes exceeding two meters however recent datasets from the indo pacific region do not support high magnitude sea level oscillations during the holocene in tectonically stable far field locations here we present a new high precision mid holocene sea level dataset from the spermonde shelf off southwest sulawesi we surveyed 21 fossil microatolls on the reef flats of two coral islands pulau panambungan and pulau barrang lompo and referred their elevations to local mean sea level and to the height of living coral radiometrically calibrated ages from emergent fossil microatolls on pulau panambungan indicate a relative sea level highstand not exceeding 0 5 m above present at ca 5600 cal yr bp the highstand is followed by a relatively rapid sea level fall towards present sea level that was reached at around 4000 cal yr bp fossil microatolls from nearby pulau barrang lompo show the same trend however with a coherent negative vertical offset of about 0 8 m compared to their equivalents on pulau panambungan the largely consistent gradients of both trends 0 14 mm yr 1 the consistent elevation of living microatolls in the spermonde and a number of instructive geomorphic features indicate a localized post formational and probably recent drop of the fossil microatolls on the densely populated island pulau barrang lompo the relative sea level trend inferred from pulau panambungan is well within the range of geophysical predictions based on anice selen ice sheet model which predict a highstand that is significantly lower than those predicted by other gia models for this area although a complete interpretation of the holocene sea level history will require additional high resolution datasets from this and surrounding territories in se asia our results suggest that there was merely a single holocene highstand in central indonesia the magnitude of which was substantially lower than hitherto assumed

decomposition of phase d in the lower mantle and the fate of dense hydrous silicates in subducting slabs abstracthigh pressure high temperature quench type experiments were carried out on serpentine to pressures of 53 gpa andtemperatures between 800 1800oc x ray analyses show that recovered phase assemblages varied considerably for thedifferent high pressure and high temperature studies the dense hydrous magnesium silicate phases decompose sequentiallyas the pressure increases and appear to serve as reservoirs for h 2 o in the mantle eventually releasing it at the highestpressure superhydrous phase b is stable up to pressure equivalent to the boundary between the transition zone and lowermantle phase d decomposes at pressures of 44 gpa equivalent to about 1250 km depth this may de ne the lower depthlimit for the presence of dense hydrous magnesium silicates beyond this pressure only nominally anhydrous phases havebeen recovered in high pressure experiments this may indicate a lack of stoichiometric hydrogen bearing silicate phasesat higher pressure 1998 elsevier science b v all rights reserved keywords x ray diffraction analysis lower mantle serpentine high pressure

multi stage reef development on barbados during the last interglaciation by mapping the vertical and lateral distribution of reefal facies on the west and south coast of barbados we have produced a revised model of reef development for the last interglaciation we find that reef architecture around barbados has significant complexity including evidence for wave exposure related variations in reef geometry and at least 3 stages of reef development that were controlled by variations in sea level during the main stage of development an acropora palmata dominated reef crest aggraded 22 m in response to a minimum sea level rise of 20 m during stage 2 a sea cave was cut 3 4 m above the fossil reef crest possibly indicating that reef growth was terminated before sea level reached the highstand similar sequences elsewhere in the caribbean indicate that this early reef demise may not be a local phenomenon several reefs apparently stopped growing between 2 and 4 m and only in sheltered areas did they reach the highstand at 6 m as recorded by intertidal notches this pattern of reef demise has previously been related to rapid sea level rise at the end of the interglacial but stratigraphic data are equivocal the final stage of reef development on barbados occurred when sea level began to fall this fall was rapid leaving a thin but widespread veneer of reef crest deposits over the proximal reef front and discontinuous intertidal and shallow subtidal deposits capping the distal reef front although further dating is required to differentiate these three stages our only reliable u th tims date indicates that almost 50 of the exposed reef had accreted by 129 ka giving an estimate of 15 ka for the main aggradational stage furthermore reports of relict reef crests buried beneath these exposed deposits indicate that our revised model is incomplete and that earlier stages of reef growth occurred during the last interglaciation these earlier stages imply that sea level was at an interglacial level for as long as 20 ka supporting the devils hole record of interglacial duration unfortunately these estimates could not be verified directly because most of our u th data show major stratigraphic age reversals attributed to diagenesis this pattern is also evident in all other well dated reefal units in the caribbean and leads us to conclude that only diagenetically screened precise stratigraphically consistent coral dates can be used to directly estimate the duration of the last interglaciation

late cenozoic palaeogeography of sulawesi indonesia abstract sulawesi has a remarkable biodiversity an unusually rich endemic fauna and is the largest island in wallacea just west of the wallace line alfred russel wallace himself suggested it could perhaps be the most remarkable island on the globe because of its peculiar fauna it was home to extinct fossil fauna such as dwarf proboscideans records significant pleistocene faunal turnover and evidence of early human occupation suggests an important role in hominid migration through the sunda sahul region information on neogene palaeogeography is essential for understanding biogeographic patterns biodiversity and faunal changes new palaeogeographic maps reflecting recent work on sulawesi s complex geology and changes in tectonic interpretations are presented for intervals from the early miocene to pleistocene at 20 15 10 8 6 5 4 3 2 and 1 ma additional maps illustrate the effects of glacially driven sea level change in the last 1 myr they are based on a field based investigation of sedimentary rocks in sulawesi accompanied by palaeontological petrological and heavy mineral studies and u pb dating of detrital zircons to date and determine depositional environments the new results have been supplemented by re evaluation of previous studies including reports from oil company wells and seismic lines igneous rocks provided ages indications of surface environment of eruptions and location of magmatic activity for most of the neogene from the early miocene sulawesi was a shallow marine area with a number of small islands surrounded by relatively deep marine areas deep inter arm bays began to form in the late miocene and the islands became larger the most significant palaeogeographic change began in the pliocene with an increase in the area and elevation of land accompanied by major subsidence of the inter arm bays the separate islands gradually coalesced in the pleistocene to form the distinctive k shaped island known today

genesis and architecture of sequences of quaternary coral reef terraces insights from numerical models the variety of coral reefs morphologies highlights their sensitivities to several forcings fossil reefs stack in sequences that are accordingly diverse in order to understand their genesis and architectures we devised a numerical approach accounting for quaternary sea level oscillations vertical land motion initial slope wave erosion and reef growth we first test our model on the subsiding sequence of hawaii and on the uplifting sequence of wangi wangi sulawesi that bears active barriers we then construct a parametric study that we analyze based on a comprehensive yet compact description of sequences as barcodes that depict the vertical distribution of a few geometrical characteristics number width and height of the terraces and barriers we find that geological factors suffice to explain the variety of architectures of reefal sequences at first order regardless of additional ecosystemic processes vertical land motion and foundation slopes are the prime players while reef growth rates only play a minor role barriers may develop both in uplift and subsidence mode and their preservation attests for the erosional power last we reappraise the genesis of sequences and find that sequences do not fingerprint discrete events of sea level oscillations but a continuous process harrowed by stochastic events major sea level fluctuations can be overrepresented by several terraces or conversely absent reoccupations may yield composite terraces representing multiple events overall sequences shall not be regarded as stacks of reef bodies forming during sea level highstands which implies that the commonly assumed bijective relationship between sea level highstands and terraces shall be abandoned

a one million year long sequence of marine terraces on sumba island indonesia abstract an exceptional sequence of raised coral reef terraces is visible at cape laundi on the north coast of the island of sumba in the savu sea in which at least eleven terraces wider than 100 m six of them even being over half a kilometer wide are geomorphologically distinguishable between an ancient patch reef now at 475 m and the present sea level esr date estimations of almost unrecrystallized corals most of them in situ make possible a tentative identification of the terraces corresponding to isotope stages 15 ca 600 ka ago and 9 ca 330 ka ago when the uplift trend deduced from the present altitude of dated terraces 0 49 0 01 mm yr is extrapolated to the whole raised section most geomorphological features appear to correspond to interglacial stages of the astronomically calibrated oxygen isotope record up to stage 27 ca 0 99 ma beyond the matuyama jaramillo geomagnetic boundary the upper terraces would in this case be twice as old as previously estimated ca 0 5 ma main terraces seem to correspond to high sea levels at certain interglacial stages and substages but in some cases the action of low sea levels at glacial stages cannot be ruled out for terraces between 30 and 70 m in altitude th u and esr dates reveal that aragonitic corals at similar elevations may differ in age as much as 100 ka this can be explained by taking into account a polycyclic origin for several terraces reconstructions available of changes in the eustatic sea level during the last 250 kyr and the fact that coral reef development may have been scattered at some periods only without totally covering subjacent older formations the sumba sequence of marine terraces at cape laundi is among the longest and most complete for the past million years reported in the literature its relatively good state of preservation will probably give impetus to a number of new studies on the chemical physical isotopic morphological palaeoclimatic pedological ecological and diagenetic changes which have occurred during the past one million years

differential uplift along the northern margin of the central anatolian plateau inferences from marine terraces abstract emerged marine terraces and paleoshorelines along plate margins are prominent geomorphic markers that can be used to quantify the rates and patterns of crustal deformation the northern margin of the central anatolian plateau has been interpreted as an actively deforming orogenic wedge between the north anatolian fault and the black sea here we use uplifted marine terraces across principal faults on the sinop peninsula at the central northern side of the pontide orogenic wedge to unravel patterns of quaternary faulting and orogenic wedge behavior we leveled the present day elevations of paleoshorelines and dated marine terrace deposits using optically stimulated luminescence osl to determine coastal uplift the elevations of the paleoshorelines vary between 4 0 2 and 67 1 4 m above sea level and osl ages suggest terrace formation episodes during interglacial periods at ca 125 190 400 and 570 ka corresponding to marine isotopic stages mis 5e 7a 11 and 15 mean apparent vertical displacement rates without eustatic correction deduced from these terraces range between 0 02 and 0 18 mm a with intermittent faster rates of up to 0 26 mm a we obtained higher rates at the eastern and southern parts of the peninsula toward the hinterland indicating non uniform uplift across the different morphotectonic segments of the peninsula our data are consistent with active on and offshore faulting across the sinop peninsula when integrated with regional tectonic observations the faulting pattern reflects shortening distributed over a broad region of the northern margin of the central anatolian plateau during the quaternary

an open system model for u series age determinations of fossil corals the source of excess 234u in fossil corals and its relationship to u series age determinations has been an outstanding problem in geochronology for more than 20 years with increasing numbers of u series isotope measurements in corals and significant improvements in analytical precision through mass spectrometry it is increasingly apparent that a substantial fraction of observed isotope ratios cannot be reasonably explained by closed system decay moreover observations of a positive correlation between 234u 238u and 230th 238u ratios in corals from the same terrace are difficult to explain however the decay of dissolved uranium and recoil mobilization of uranium daughters produce particle reactive 234th and 230th and the coupled addition of these th isotopes could simultaneously increase coral 234u 238u and 230th 238u here we present a quantitative model based on decay dependent redistribution of 234th and 230th permitting calculation of open system coral ages these equations provide a general solution to the recoil redistribution problem applicable to any alpha decay series while measured isotope ratios of corals from the three youngest stratigraphically defined barbados terraces are inconsistent with closed system decay they fall in broadly linear arrays agreeing with model predictions isotopic arrays of older barbados corals and corals from terraces around the world are also consistent with model predictions suggesting the open system model is generally applicable corals with extreme isotopic compositions that are impossible to produce by closed system decay are consistent with the limited range of isotopic compositions predicted by the model at ages older than 600 ka for corals from a single terrace 234th and 230th redistribution appears to be a source of systematic conventional age error even for corals with slightly elevated 234u however open system ages are consistent even for corals with extremely elevated 234u for the youngest three barbados terraces mean open system terrace ages are consistent with mean conventional terrace ages calculated from pristine samples if the most accurate conventional ages are from corals with an initial 234u 238u identical to modern seawater then the open system model will improve the accuracy of coral u series age determinations and dramatically increase the number of reliable ages

magnetostratigraphic dating of the uplifted atoll of mare geodynamics of the loyalty ridge sw pacific the loyalty islands sw pacific are uplifted as they are progressively affected by the lithospheric flexure of the australian plate before its subduction under the new hebrides arc these geodynamic changes are constrained by magnetostratigraphically dating two sections from mare island where mineral extractions coupled with rock magnetic experiments suggest that the magnetic remanence is mostly carried by a mixture of single domain to multidomain magnetite maghemite with the help of faunal determinations and radiometric dating the sequences of polarity reversals correlated to the geomagnetic polarity timescale range from the top of chron c4n late miocene to the top of the gauss chron late pliocene this new chronostratigraphy refines the timing of two distinctive carbonate units rhodolith platform coral reefs separated by a hardground whose transition is known to coincide approximately with a regional event around the miocene pliocene boundary the magnetostratigraphic dating indicates that the hardground represents about a 1 9 m y hiatus and suggests variable sedimentation rates ranging from 4 7 to 65 4 m m y during the atoll construction the lithospheric bulge seems to have influenced the evolution of mare island some 3 1 m y ago leading to a diachronous emersion of the northeast and southwest rim of the atoll with a mean uplift rate of the order of 4 cm kyr

quaternary raised coral reef terraces on sumba island indonesia a spectacular sequence of coral reef terraces six steps broader than 500 meters and many minor substeps is developed near cape laundi sumba island between an ancient patch reef 475 meters high and sea level several raised reefs have been dated with the electron spin resonance and the uranium series dating methods the uplift trend deduced from these reefs is 0 5 millimeter per year most terraces although polycyclic in origin appear to correspond to specific interglacial stages with the oldest terrace formed 1 million years ago this puts them among the longest and most complete mid quaternary terrace sequences

the anatomy of interglacial sea levels the relationship between sea levels and ice volumes during the last interglacial abstract the elevations and chronology of interglacial shorelines and other sea level indicators provide information on ice volumes for these earlier periods compared with today but as for the holocene the relationship between sea levels and ice volumes for earlier interglacials is not simple because of the planet s deformational gravitational and rotational response to changes in ice water loads glacio hydro isostasy in particular the pattern of global sea level for a particular interglacial will be a function of the earth and ocean response to ice loads applied before during and after the interglacial in question this paper examines the role of glacio hydro isostasy during these glacial cycles to make three key points the first is to demonstrate why interglacial sea levels cannot be interpreted directly in terms of ice volume the second is to illustrate the spatial variability that can be expected in interglacial sea levels because of the earth s isostatic response to changing ice and water loads and to demonstrate why observations from different localities should not be combined into a single sea level function without first correcting for differential isostatic effects the third addresses the question whether in the absence of perfect knowledge of the ice sheets and earth rheology inferences can be made about ice volumes during an interglacial we conclude that if these isostatic factors are ignored interpretations of interglacial sea levels can lead to serious errors in the inferences about ice volumes during the interglacials

a new geomagnetic polarity time scale for the late cretaceous and cenozoic we have constructed a magnetic polarity time scale for the late cretaceous and cenozoic based on an analysis of marine magnetic profiles from the world s ocean basins this is the first time since heirtzler et al 1968 published their time scale that the relative widths of the magnetic polarity intervals for the entire late cretaceous and cenozoic have been systematically determined from magnetic profiles a composite geomagnetic polarity sequence was derived based primarily on data from the south atlantic anomaly spacings in the south atlantic were constrained by a combination of finite rotation poles and averages of stacked profiles fine scale information was derived from magnetic profiles on faster spreading ridges in the pacific and indian oceans and inserted into the south ariantic sequence based on the assumption that spreading rates in the south atlantic were smoothly varying but not necessarily constant a time scale was generated by using a spline function to fit a set of nine age calibration points

on post glacial sea level i general theory summary modern analyses of sea level changes due to glacial isostatic adjustment gia are based on the classic sea level equation derived by farrell clark 1976 geophys j r astr soc 46 647 667 the connection between global sea level variations and changes to ocean height that is assumed within this equation breaks down in the presence of a time varying shoreline geometry we present a generalized sea level equation that overcomes this difficulty we also derive analytic expressions for and present schematic illustrations of the error in the ocean height change over finite time intervals introduced in published efforts to incorporate shoreline evolution into the theory of gia induced sea level change this comparison includes studies of shoreline migration due to either local sea level changes or the growth and ablation of marine based ice we conclude that the theories applied by johnston 1993 geophys j int 114 615 634 milne 1998 phd thesis university of toronto toronto and co workers are more accurate than the procedure advocated by peltier 1994 science 265 195 201 1998a geophys res lett 25 3955 3958 1998b rev geophys 114 615 634 although an improvement in the latter has recently been reported peltier drummond 2002 geophys res lett 29 10 1029 2001gl014273 our generalized theory is valid for any earth model in a companion paper we derive the equations necessary to treat the special case of a spherically symmetric linear viscoelastic and rotating earth and we quantify errors associated with previous work

crustal subsidence rate off hawaii determined from 234u 238u ages of drowned coral reefs a series of submerged coral reefs off northwestern hawaii was formed during largely glacial intervals when the rate of local sea level rise was less than the maximum upward growth rate of the reefs mass spectrometric sup 234 u sup 238 u ages for samples from six such reefs range from 17 to 475 ka and indicate that this part of the hawaiian ridge has been subsiding at a roughly uniform rate of 2 6 mm yr for the past 475 ka the sup 234 u sup 238 u ages are in general agreement with model ages of reef drowning based on estimates of paleo sea level stands derived from oxygen isotope ratios of deep sea sediments but there are disagreements in detail the high attainable precision plus minus 10 ka or better on samples younger than approximately 800 ka large applicable age range relative robustness against open system behavior and ease of analysis for this technique hold great promise for future applications of dating of 50 1 000 ka coral

high precision u series measurements of more than 500 000 year old fossil corals robust independent age constraints on the absolute timing of climate events based on the u series dating of fossil coral are sparse before the last glacial cycle using multiple collector inductively coupled plasma mass spectrometry with multiple faraday protocols we are able to date 600 ka samples with an uncertainty of better than 15 ka 2 representing a three fold improvement in precision compared with previous techniques using these methods we report u series measurements for a suite of 500 thousand year old ka corals from henderson island an emergent atoll in the south central pacific ocean the fossil corals show extraordinarily little diagenetic alteration for their age and the best preserved sample yields a u series age of 600 15 ka 2 which overlaps with the timing of the warm marine isotope stage mis 15 interglacial the open system model of villemant and feuillet villemant b and feuillet n 2003 dating open systems by the 238u 234u 230th method application to quaternary reef terraces earth and planetary science letters 210 1 2 105 118 and the linear regression or open system isochron is clearly limited for such old samples however the open system model developed by thompson et al thompson w g spiegelman m w goldstein s l and speed r c 2003 an open system model for u series age determinations of fossil corals earth and planetary science letters 210 1 2 365 381 appears to reliably correct for open system effects in roughly half of the corals giving a mis 15 origin for these thus the data provide evidence that the systematic addition of 230th and 234u through recoil is a dominant open system process occurring in the henderson island fossil reef system several coral samples yield significantly older thompson et al open system ages between 650 and 750 ka the uncertainty on these ages typically 30 kyrs is too great for precise assignment but most data overlap with the mis 17 interglacial the reliability of these ages is currently unclear it is shown that separate aliquots of the same coral can yield different thompson model ages therefore there appear to be additional diagenetic mechanisms that create further anomalous excursions in the u series systematics limiting the reliability of the thompson et al open system model

experimental and theoretical studies of the stabilities of talc antigorite and phase a at high pressures with applications to subduction processes we have experimentally determined the equilibrium talc enstatite quartz coesite h2o to 40 kbar in the system mgosio2h2o msh using both synthetic and nearly pure mg end member natural talc and other synthetic starting materials for the other solid phases at 40 kbar the equilibrium dehydration boundary lies 150 c higher than that calculated using data from the existing internally consistent thermochemical data bases the reason for this discrepancy lies in the erroneous compressibility data of talc in the data bases we have retrieved the compressibility of talc from the experimental phase equilibrium data and have also calculated sereral other equilibria in the msh system involving talc antigorite and the dense hydrous magnesium silicate dhms commonly referred to as phase a comparison of these equilibria with selected thermal profiles at the leading edge of young and old subducting oceanic slabs along with the dehydration condition of basaltic amphibole and solidus of mantle peridotite provides an explanation for the observed heights of the volcanic fronts above subducting oceanic lithosphere further it is found that in cold oceanic slabs 50 ma with subduction velocity of 10 cm y antigorite will transform to the dhms phase a through a vapor conserved reaction at a depth of 200 km phase a will then serve as a carrier of water into the deeper mantle

coastal staircase sequences reflecting sea level oscillations and tectonic uplift during the quaternary and neogene many coasts feature sequences of quaternary and neogene shorelines that are shaped by a combination of sea level oscillations and tectonics we compiled a global synthesis of sea level changes for the following highstands mis 1 mis 3 mis 5e and mis 11 also we date the apparent onset of sequences of paleoshorelines either from published data or tentatively extrapolating an age for the uppermost purported oldest shoreline in each sequence including the most documented mis 5e benchmark we identify 926 sequences out of which 185 also feature holocene shorelines six areas are identified where elevations of the mis 3 shorelines are known and 31 feature elevation data for mis 11 shorelines genetic relationships to regional geodynamics are further explored based on the elevations of the mis 5e benchmark mean apparent uplift rates range from 0 01 0 01 mm yr hotspots to 1 47 0 08 mm yr continental collision passive margins appear as ubiquitously uplifting while tectonic segmentation is more important on active margins from the literature and our extrapolations we infer ages for the onset of formation for 180 coastal sequences sea level fingerprinting on coastal sequences started at least during mid miocene and locally as early as eocene whether due to the changes in the bulk volume of seawater or to the temporal variations in the shape of ocean basins estimates of eustasy fail to explain the magnitude of the apparent sea level drop thus vertical ground motion is invoked and we interpret the long lasting development of those paleoshore sequences as the imprint of glacial cycles on globally uplifted margins in response to continental compression the geomorphological expression of the sequences matches the amplitude and frequency of glacial cyclicity from middle pleistocene to present day moderately fast 100 000 yrs oscillating sea levels favor the development of well identified strandlines that are distinct from one another pliocene and lower pleistocene strandlines associated with faster cyclicity 40 000 yrs are more compact and easily merge into rasas whereas older cenozoic low frequency eustatic changes generally led to widespread flat lying coastal plains

electron spin resonance dating of the pleistocene coral reef tracts of barbados abstract the reef tracts of barbados have been investigated by electron spin resonance dating all parameters necessary for esr dating including effective efficiency and thermal stability were determined without cross checking with another independent dating method in addition some u series analyses were carried out in order to test the reliability of esr in most cases the results show a satisfactory agreement between esr and both these and previously published u series dates m l bender r g fairbanks f w taylor r k matthews j g goddard and w s broecker 1979 geological society of america bulletin 90 577 594 for the oldest samples esr dates tend to exceed he u dates suggesting that there might have been he loss from aragonite raised reef tracts are assigned to high sea stands from successive interglacial stages 5 7 9 11 13 and 15 esr and u series 230th 234u dates for corals and molluses in north barbados do not support the suggestion of n p james 1971 unpublished thesis mcgill university montreal that this region has subsided during part of the past 125 000 yr whereas the experimentally determined mean life of trapped electrons is only 500 000 yr for the ambient temperature in barbados there is no evidence from the comparison between esr and other dates for thermal fading this emphasizes the difficulty of experimental measurement of

water storage in the mantle the origins of the oceans and earth s volatile atmosphere are major unsolved problems in earth sciences the recent study by finger et al of the crystal chemistry of a water bearing mineral phase cryptically named phase b and grown under conditions equivalent to a depth in the earth of 360 km dramatically demonstrates that several times the earth s visible water budget could be stored in the mantle

evolution of marine terraces and sea level in the last interglacial cave hill barbados the uplifted marine terrace of last interglacial stage 5e age at cave hill barbados has been investigated with views toward terrace architecture developmental processes and sea level history methods include stratigraphic analysis of new deep exposures precise 230th geochronology and geomorphic mapping cave hill was central to earlier studies that led to important ideas on reef and terrace evolution but with which we find significant disagreement we present a new model of terrace evolution that emphasizes the role of marine erosion deposition of carbonate cover during the full eustatic cycle rather than only at highstand and principal reef development during transgression rather than at highstand by keep up rather than catch up growth the new model and geochronology contribute to an improved understanding of surficial processes during emergence of uplifting coral coasts and of global sea level changes in the last interglacial transgression in stage 5e at cave hill was accompanied by progressive marine erosion of a terrace floor and receding seacliff and deposition of a seaward thickening reefal wedge on the floor and above limestones of stage 6 and 7 ages the wedge contains a diachronous basal acropora palmata fringe reef this is overlain by an in place a cervicornis reef that aggraded progressively during sea level rise the transgressive phase took place between 136 ka or earlier and ca 128 ka during highstand between ca 127 and 120 ka the floor and seacliff continued to recede landward re gression began at or after ca 120 ka and sea level fell 37 m below the highstand level by ca 115 ka in stage 5c the seaward front of the last interglacial terrace was eroded landward an uncertain distance the sea level record at cave hill has implications for timing and constituent events of the penultimate glacial the last interglacial highstand and the fall in sea level at the transition from stage 5e to stage 5d shoreline angles which are isochronous linear geomorphic features are the most accurate markers of sustained highstand levels highstand levels and uplift rates interpreted from a palmata in barbados are less accurate and lower because the coral grew mainly in transgression the coral derived data therefore include uncertainties of depths of growth and collapse

effects of h2o on the phase behaviour of the forsterite enstatite system at high pressures and temperatures and implications for the earth abstract in addition to many of the naturally occurring hydrous minerals known in the system mgo sio2 h2o various dense hydrous magnesium silicates 10 a phase phases a b c and d have been synthesized by high pressure and high temperature experiments in the past two decades in conjunction with these high pressure hydrous phases the effects of h2o on the observed phase transformations in the forsterite mg2sio4 enstatite mgsio3 system at high pressures and high temperatures are investigated on the basis of both experimental data and theory for forsterite the modified spinel phase may exist up to 7 1 wt h2o along with enstatite phase a up to 9 9 wt h2o along with stishovite phase a and up to only 3 2 wt h2o along with stishovite phase b the spinel phase of mg2sio4 is no longer stable when more than 3 2 wt h2o is present although both stishovite and the ilmenite type mgsio3 do not occur in dry mg2sio4 at high pressures a small amount of h2o would yield assemblages containing stishovite and the ilmenite phase in mg2sio4 at high pressures the post spinel phase assemblage perovskite periclase may be stable along with phase d up to 11 wt h2o in the case of enstatite except for the assemblage modified spinel stishovite which exists along with phase a up to 7 1 wt h2o and for the perovskite type mgsio3 along with periclase and phase d which exists up to 15 wt h 2 o all the high pressure phase transformations observed in dry mgsio3 may not occur at high pressures if 2 3 wt h2o is present based on experimental observations the various high pressure hydrous phases are stable from as low as 40 kbar to more than 280 kbar at various temperatures thus there is no lack of storage phases for h2o in the deeper interior of the earth s mantle according to the impact induced dehydration model advanced recently by shock wave experiments it is estimated that the earth s interior contains probably at least more than five times its present water contents in the near surface geochemical reservoirs hydrosphere crust so long as both forsterite olivine and h2o coexist in the upper mantle even in trace amounts there must exist a water line which is defined by the reaction 5mg 2 sio 4 3h 2 o 3mgsio 3 mg 7 si 2 o 14 h 6 forsterite water enstatite phase a in the upper mantle the equilibrium boundary of the water line has been in fact determined in two different phase assemblages by experiments but was not noticed if the earth s surface was covered by large scale melts during and shortly after its accretion h2o would be stored in phases a b below the water line and would liberate as water above the water line during freezing today s oceans were most likely derived from water released in the mantle when the palaeogeotherm dropped below the solidus of mantle materials stripping the free water above the water line from depths near 350 km thus the oceans were formed rapidly and early in the earth s history and slow degassing is still going on today the low velocity zone observed in today s mantle is interpreted as a region containing free water between the water line and the stability field of amphiboles in the suboceanic mantle and between the water line and the stability field of phlogopite in the subcontinental mantle in other words the low velocity zone is the free water zone and the water line is the base of the low velocity zone in the earth s mantle

age of 360 m reef terrace hawaii and the rate of late pleistocene subsidence of the island observations from a manned submersible vehicle indicate that the 360 m reef terrace northwest of the island of hawaii is a drowned coral reef the preferred uranium series age of coralline algae collected from the reef face is 120 5 ka this age agrees with the notion that the reef was drowned during the sea level rise following the major lowstand of the sea that occurred at 145 ka oxygen isotope stage 6 this drowning pattern is similar to the previously determined radiocarbon age of 13 ka for drowning of the 150 m reef off west hawaii which drowned during the sea level rise following the last major lowstand of the sea at 18 ka oxygen isotope stage 2 estimated average subsidence of the reef site off northwest hawaii is 2 7 mm yr since final drowning of the 360 m reef

soulevement et tectonique de l ile d efate vanuatu arc insulaire des nouvelles hebrides au cours du quaternaire recent datations de terrasses soulevees par la methode abstract the uplift of vanuatu formerly new hebrides is related to the subduction of the australian plate beneath the pacific plate the tropical latitude of these volcanic islands favours important quaternary growth of coral reefs during the periodic uplifts several terraces emerged forming typical features of the landscape when eustatic sea level rise is compensated by the uplift relative sea level is therefore constant and favours development of terraces efate situated near the centre of vanuatu archipelago is related to this series of uplifts and reef crest facies lie discordantly on a volcanic substratum thirty five new u th datings of corals in growth position confirm high eustatic sea levels at about 82 000 103 000 and 125 000 yrs b p and perhaps at 140 000 yrs b p the amplitude of the vertical movements is estimated quantitatively from a geomorphological study of the terraces complemented by the dates and the positions of the corals a calculation of the average uplift rates permits the distinction of four major areas on the western part of efate the numerous faults in these areas also favour minor local uplifts the northwestern area is affected by a differential uplift which at about 180 000 yrs b p formed a broad terrace sloping northward from 80 to 50 m the younger about 103 000 and 125 000 yrs b p and the older 300 000 yrs b p terraces are narrower generally the uplift was not uniform during any particular stage of sea level the average uplift rate here ranges from 0 2 to 0 6 mm yr the western area is the best known and shows four prominent major pleistocene terraces their ages range from 103 000 to 300 000 yrs b p but the latter age is uncertain due to the method used and to the high rate of calcification of the samples most of the faults are radially oriented and perpendicular to the terraces forming samoa point the average uplift rate in the western area is 0 9 1 mm yr more than in the north the southwestern area displays two remarkable series of terraces ranging from 50 to 110 m in altitude and dating from 86 000 to 130 000 yrs b p the average uplift rate is 0 8 mm yr the southern area close to port vila is very low in altitude as low as 50 m and bears three terraces dated at 40 000 85 000 and 125 000 yrs b p the uplift rates were 1 mm yr from 40 000 yrs b p to the present but before this time were 0 3 mm yr altitudes as a function of age display a remarkable clustering the levels given by a frequency diagram confirm the stages of sea level previously defined by other authors these results also coincide with the curve of changes in sea level the different average uplift rates between high stages in sea level are shown and appear to be variable they change from one area to the other comparatively slowly between 103 000 and 10 000 yrs b p and generally faster from 10 000 yrs b p to the present a possible effect of a recent local tectonic uplift these periodic uplifts are less important here than in the northern islands of santo and malekula which are affected by the subduction of d entrecasteaux ridge

a revised morpho and chronostratigraphy of the late and middle pleistocene coral reef terraces on southern barbados west indies the barbados coral reef terraces are one of the few type localities worldwide that provide insights into interglacial sea level change during the late and middle pleistocene several sea level estimates have been established since the late 1960s and each has contributed to the barbados model of sea level change this paper presents new morpho and chonostratigraphic data from the barbados coral reef terraces developed over the last 12 years the work is based on significant advances in electron spin resonance esr dating of fossil coral air photo interpretation and a greatly improved geomorphic map of preserved fossil beach formations and reef terraces above present sea level the need for a revision of past published morpho and chronostratigraphies is best demonstrated on the southern part of the island the morpho and chronostratigraphic sequence in this region is both more complex and diverse than has been assumed so far the revised morphostratigraphy presented here includes a differentiation of coral reef terraces wave cut platforms and other erosive features such as notches and cliffs our study of these geomorphic features combined with new numeric dating results esr u th enable a revised estimate of the spatial and temporal variation in tectonic uplift rate within south barbados these new rates are an essential requirement for more precise glacio eustatic sea level reconstructions during the late and middle pleistocene from this region

coastal uplift west of algiers algeria pre and post messinian sequences of marine terraces and rasas and their associated drainage pattern the north africa passive margin is affected by the ongoing convergence between the african and eurasian plates this convergence is responsible for coastal uplift folding and reverse faulting on new and reactivated faults on the margin the active deformation is diffuse and thus rather difficult to locate precisely we aim to determine how a coastal landscape evolve in this geodynamic setting and gain insights into active tectonics more particularly we evidence and quantify coastal uplift pattern of the chenoua sahel and algiers reliefs algeria using sequences of marine terraces and rasas and computing several morphometric indices from the drainage pattern upper and middle pleistocene uplift rates are obtained by fossil shoreline mapping and preliminary u th dating of associated coastal deposits extrapolation of these rates combined to analyses of sea level referential data and spatial relationships between marine terraces rasas and other geological markers lead us to tentatively propose an age for the highest coastal indicators purported the oldest values of morphometric indices showing correlations with uplift rate allow us to analyze uplift variation on area devoid of coastal sequence geological and geomorphological data suggest that coastal uplift probably occurred since the middle miocene it resulted in the emergence of the algiers massif followed by the sahel ridge massif the sahel ridge has asymmetrically grown by folding from west to east and was affected by temporal variation of uplift compared to previous study the location of the sahel fold axis has been shifted offshore near the coast the chenoua fault vertical motion does not offset significantly the coastal sequence mean apparent uplift rates and corrected uplift rates since 120 ka are globally steady all along the coast with a mean value of 0 055 0 015 mm year apparent and of 0 005 0 045 mm year corrected for eustasy mean apparent coastal uplift rates between 120 and 400 ka increase eastward from 0 045 0 025 to 0 19 0 12 mm year without correction for eustasy or from 0 06 0 06 to 0 2 0 15 mm year with correction for eustasy in addition the combination of structural and geomorphic data suggests a low uplift rate for the southern part of the algiers massif

orbital forcing of the marine isotope stage 9 interglacial milankovitch orbital forcing theory has been used to assign time scales to many paleoclimate records however the validity of this theory remains uncertain and independent sea level chronologies used to test its applicability have been restricted largely to the past approximately 135 000 years here we report u series ages for coral reefs formed on henderson island during sea level high stands occurring at approximately 630 000 and approximately 330 000 years ago these data are consistent with the hypothesis that interglacial climates are forced by northern hemisphere summer solar insolation centered at 65 degrees n latitude as predicted by milankovitch theory

rapid and accurate u th dating of ancient carbonates using inductively coupled plasma quadrupole mass spectrometry here the potential for rapid and accurate u th dating technique of marine aragonite skeletons deep sea corals lophelia pertusa and secondary calcite deposits speleothems and stalagmites has been explored using inductively coupled plasma quadrupole mass spectrometry icp qms the analytical procedure includes a largely simplified chemical separation technique for uranium u and thorium th using uteva resin the developed technique permits simultaneous quantification of uranium 238u and thorium 232th concentrations and their respective isotopic composition required for u series disequilibrium dating up to 50 u th dates per day can be achieved through icp qms with 234u and 230th reproducibility 2 of 3 4 and 1 respectively the high sensitivity 3 0 105 cps ppb together with low background 0 5 cps on each mass between 228 and 236 amu allowed u th dating of ancient deep water corals 15 260 kyr and stalagmites 30 85 kyr at precision levels of less than 2 consequently the combination of simplified chemistry using uteva with state of the art icp qms isotopic measurements that do not require a u th separation step now provides an extremely rapid and low cost u series dating technology the level of precision is most convenient for numerous geochronological applications such as the determination of climatic influences on ecosystem development and carbonate precipitation as a first example application we present icp qms u th dates of north atlantic deep water coral fragments retrieved in the southeastern porcupine seabight md01 2463g mound therese indicating a purely interglacial growth of deep water corals on so called carbonate mounds over several climate cycles

stability of hydrous magnesium silicates in the mantle transition zone phase relations in the mg oh 2 sio2 system have been studied up to 18 gpa a new hydrous phase phase e mg2 3si1 3h2 4o6 was encountered at 13 17 gpa and 1000 c phase f mg1 2si1 8h2 4o6 another new hydrous phase was observed at 15 5 gpa and 800 c the stability field of phase a was also briefly studied these new hydrous phases might be stabilized in the mantle transition zone especially in subducting slabs at those depths

how do sea level curves influence modeled marine terrace sequences abstract sequences of uplifted marine terraces are widespread and reflect the interaction between climatic and tectonic processes at multiple scales yet their analysis is typically biased by the chosen sea level sl curve here we explore the influence of quaternary sl curves on the geometry of marine terrace sequences using landscape evolution models lems first we modeled the young rapidly uplifting sequence at xylokastro corinth rift

timing and duration of the last interglacial evidence for a restricted interval of widespread coral reef growth abstract we report new mass spectrometric u series ages for eight last interglacial fossil reefs along the continental margin of western australia corals were selected in growth position from localities that are characterized by apparently low levels of diagenesis and relative tectonic stability so that the fossil reefs provide critical information on last interglacial sea levels without requiring corrections for tectonic movements in addition we have improved the constraint on the timing of onset of reef growth by recovering drill core coral from the base of the reefs uranium and thorium isotopes were measured with high levels of precision leading to improvements in age resolution and allowing samples which have undergone diagenetic exchange of uranium and thorium to be more easily identified and discarded these data supplement our previous results for rottnest island and leander point leading to more than seventy mass spectrometric u series ages from which constraints can be placed on the timing duration and character of the last interglacial sea level highstand reliable ages show that reef growth started contemporaneously at 128 1 ka along the entire western australian coastline while relative sea levels were at least 3 m above the present level because western australia is located far from the former penultimate glacial maximum ice sheets and are not significantly effected by glacial unloading these data constrain the timing of onset of the last interglacial period to 128 1 ka assuming reef growth started soon after sea level approached interglacial levels a unique regressive reef sequence at mangrove bay constrains the timing of termination of the last interglacial period to 116 1 ka the major episode of reef building however both globally and locally along the western australian coast is restricted to a very narrow interval occurring from 128 ka and 121 ka suggesting that global ocean surface temperatures were warm and or sea levels were stable enough to allow prolific reef growth only during the earlier part of the last interglacial

quaternary shorelines in southern peru a record of global sea level fluctuations and tectonic uplift in chala bay abstract the coastal area bordering the bay of chala 14 50 s 74 15 w southern peru contains one of the most complete sequences of quaternary shorelines in south america remnants of about 27 high seastands have been preserved between present mean sea level and 275 m most remnants consist of staircased marine terraces and associated deposits which are partly covered by alluvial fan and colluvial units deposited during intervening periods of lower sea levels no geochronological data are yet available a tentative chronostratigraphy of the terrace sequence is based on the geometric and stratigraphic relationships between successive landforms and deposits we group most marine terraces into 15 major morphostratigraphic units mmus some of these major units seem to correlate with interglaciations for example isotopic stage 5 or with interstadials stage 3 higher in the chala sequence major morphostratigraphic units mapped during field and air photo studies may represent only parts of middle pleistocene interglaciations we infer that shorelines located at 68 121 168 and 184 or 200 m correlate with the highest seastands of isotopic stages 5 7 9 and 11 respectively the proposed chronostratigraphy suggests an average uplift rate of ca 460 mm kyr for the chala bay area during the last 500 ka this rate is slightly higher than in the surrounding coastal areas ca 270 350 mm kyr but significantly lower than rates in the area where the nazca ridge is being subducted below the south american plate maximum rate ca 740 mm kyr deformed shorelines evidence several fault displacements within the chala basin but such deformation does not seriously disort the record of former sea levels in the basin the chala terrace sequence is the first reliable record of middle and late quaternary sea level fluctuations described from peru

modelling holocene relative sea level observations from the caribbean and south america abstract holocene data from the caribbean and the atlantic coast of south america have been critically assessed and a subset of the best quality data are presented these data cover a large north south geographic extent and display a distinct spatial variation we make the first comparisons of this data set to predictions based on a realistic model of glaciation induced sea level change with the main aims of understanding the cause of the observed spatial trend and estimating a eustatic signal for the holocene the spatial variation is dominated by the influence of the ice and ocean mass redistribution on sea level change with the ice induced effect dominating the observed north south trend a best fitting model is applied to estimate a holocene eustatic signal from the observations we find that the model corrected data are consistent with a relatively rapid rise of 7 8 mm yr in the early holocene with a marked reduction in this rate around 7 cal kyr bp from this time until present the model corrected data suggest that the volume of mass transfer between ice sheets and oceans was no more than 1 m eustatic sea level equivalent

deep focus earthquakes and recycling of water into the earth s mantle for more than 50 years observations of earthquakes to depths of 100 to 650 kilometers inside earth have been enigmatic at these depths rocks are expected to deform by ductile flow rather than brittle fracturing or frictional sliding on fault surfaces laboratory experiments and detailed calculations of the pressures and temperatures in seismically active subduction zones indicate that this deep focus seismicity could originate from dehydration and high pressure structural instabilities occurring in the hydrated part of the lithosphere that sinks into the upper mantle thus seismologists may be mapping the recirculation of water from the oceans back into the deep interior of our planet

paleoshoreline record of relative holocene sea levels on pacific islands abstract understanding the history of relative holocene sea levels on pacific islands is important for constraining fundamental geodynamic theories interpreting the environments of early human occupation sites and forecasting future environmental conditions on the islands an observational paleoshoreline record is provided by emergent paleoshoreline indicators formed at higher relative sea levels hence standing at higher elevations than modern counterparts emergent paleoshoreline notches in limestone seacliffs record paleo high tide levels and emergent paleoreef flats record paleo low tide levels whereas emergent paleobeachrock locally records paleo intertidal levels both paleonotches and paleoreefs occur along the coasts of high standing islands exposing volcanic bedrock and uplifted reef complexes but low lying coralline atolls lack sufficient relief to preserve paleonotches controls on relative holocene sea level include global eustatic and regional hydro isostatic changes in ambient sea level relative to island landmasses and shifts in the elevations of islands relative to sea level caused by thermal subsidence of the oceanic lithosphere or thermally rejuvenated loci of hotspot volcanism by flexure of the lithosphere under the load of growing volcanic edifices hawaii samoa society islands by arching of the lithosphere over trench forebulges loyalty islands niue bellona rennell and by tectonism within forearc belts between active volcanic chains and trenches mariana islands tonga vanuatu the dominant pattern of relative sea level change where not overprinted by local tectonism or lithospheric flexure was a uniform early holocene rise in eustatic sea level followed by a regionally variable late holocene hydro isostatic drawdown in sea level the resultant was a mid holocene highstand in relative sea level that affected the development of shoreline morphology throughout the tropical pacific ocean the earliest human migrations into intra oceanic island groups of both the northwestern and southwestern pacific ocean followed close on the heels of the mid holocene sea level highstand and took advantage of newly attractive coastal environments engendered by sea level drawdown the effects of the mid holocene highstand were modified to varying degrees in different island groups by geodynamic uplift or subsidence

growth of the maritime continent and its possible contribution to recurring ice ages the areal extent of the maritime continent the islands of indonesia and surrounding region has grown larger by 60 since 5 ma we argue that this growth might have altered global climate in two ways that would have contributed to making recurring ice ages possible first because rainfall over the islands of the maritime continent not only is heavier than that over the adjacent ocean but also correlates with the strength of the walker circulation the growth of the maritime continent since 5 ma may have contributed to the cooling of the eastern tropical pacific since that time scaling relationships between the strength of the walker circulation and rainfall over the islands of the maritime continent and between sea surface temperature sst of the eastern tropical pacific and the strength of easterly wind stress suggest that the increase in areal extent of islands would lead to a drop in that sst of 0 75 c although only a fraction of the 3 4 c decrease in ssts between the eastern and western tropical pacific the growth of the maritime continent may have strengthened the walker circulation increased the east west temperature gradient across the pacific and thereby enabled ice sheets to wax and wane over canada since 3 ma second because the weathering of basaltic rock under warm moist conditions extracts co2 from the atmosphere more rapidly than weathering of other rock or of basalt under cooler or drier conditions the increase in weathering due to increasing area of basalt in the maritime continent may have drawn down enough co2 from the atmosphere to affect global temperatures simple calculations suggest that increased weathering of basalt might have lowered global temperatures by 0 25 c possibly important for the overall cooling

antarctic temperature and global sea level closely coupled over the past five glacial cycles sea level has varied by over one hundred metres across glacial interglacial cycles over the past 520 000 years an extended sea level reconstruction shows a strong coupling between these sea level changes and antarctic surface temperatures over the past five glacial cycles

the analysis of last interglacial mis 5e relative sea level indicators reconstructing sea level in a warmer world the last interglacial mis 5e 128 116 ka is among the most studied past periods in earth s history the climate at that time was warmer than today primarily due to different orbital conditions with smaller ice sheets and higher sea level field evidence for mis 5e sea level was reported from thousands of sites but often paleo shorelines were measured with low accuracy techniques and in some cases there are contrasting interpretations about paleo sea level reconstructions for this reason large uncertainties still surround both the maximum sea level attained as well as the pattern of sea level change throughout mis 5e such uncertainties are exacerbated by the lack of a uniform approach to measuring and interpreting the geological evidence of paleo sea levels in this review we discuss the characteristics of mis 5e field observations and we set the basis for a standardized approach to mis 5e paleo sea level reconstructions that is already successfully applied in holocene sea level research application of the standard definitions and methodologies described in this paper will enhance our ability to compare data from different research groups and different areas in order to gain deeper insights into mis 5e sea level changes improving estimates of last interglacial sea level is in turn a key to understanding the behavior of ice sheets in a warmer world

on the long lasting sequences of coral reef terraces from se sulawesi indonesia distribution formation and global significance many islands of the eastern indonesian archipelago exhibit late cenozoic sequences of coral reef terraces in se sulawesi on the tukang besi and buton archipelagos we identified 23 islands bearing such sequences remote sensing imagery and field mapping combined to u th and 14c dating enable to establish a chronologic framework of the reef terrace sequences from wangi wangi buton as well as on the neighbouring smaller islands of ular siumpu and kadatua we identified the terraces from the last interglacial maximum mis 5e at elevations lower than 20 m except on w kadatua where it is raised at 34 5 m such elevations yield low to moderate upper pleistocene uplift rates 0 3 mm yr 1 on se buton island a sequence culminates at 650 m and includes at least 40 undated strandlines next to this exceptional sequence on the sampolawa peninsula 18 strandlines culminate at 430 m dated samples at the base of this sequence 40 m yield mean middle pleistocene uplift rates of 0 14 0 09 mm yr 1 extrapolation of these uplift rates compared to the geological setting suggests that the sequences of the sampolawa peninsula provide a record of sea level high stands for the last 3 8 0 6 ma the sequences on se buton island therefore constitute the best preserved long lasting geomorphic record of plio quaternary sea level stands worldwide

quaternary hinterland evolution of the active banda arc surface uplift and neotectonic deformation recorded by coral terraces at kisar indonesia abstract coral terrace surveys and u series ages of coral yield a surface uplift rate of 0 5 m ka for kisar island which is an emergent island in the hinterland of the active banda arc continent collision based on this rate kisar first emerged from the ocean as recently as 450 ka these uplifted terraces are gently warped in a pattern of east west striking folds these folds are strike parallel to more developed thrust related folds of similar wavelength imaged by a seismic reflection profile just offshore this deformation shows that the emergence of kisar is influenced by forearc closure along the south dipping kisar thrust however the pinnacle shape of kisar and the protrusion of its metamorphic rocks through the forearc basin sediments also suggest a component of extrusion along shear zones or active doming coral encrusts the island coast in many locations over 100 m above sea level terrace morphology and coral ages are best explained by recognizing major surfaces as mostly growth terraces and minor terraces as mostly erosional into older terraces all reliable and referable coral u series ages determined by mc icp ms correlate with marine isotope stage mis 5e 118 128 ka the only unaltered coral samples are found below 6 m elevation however an unaltered tridacna giant clam shell in growth position at 95 m elevation yields a u series age of 195 31 ka which corresponds to mis 7 this age agrees with the best fit uplift model for the island loose deposits of unaltered coral fragments found at elevations between 8 and 20 m yield u series ages of

coral indicators of past sea level change a global repository of u series dated benchmarks fossil corals provide valuable data for reconstructing past sea levels as they are often well preserved in the fossil record and can be dated with u series methods here we present a global and internally consistent database of usingle bondth dated fossil coral sea level indicators including full consideration of all known associated uncertainties both vertical and chronological we include carefully determined taxon specific depth distributions rather than blanket depth uncertainty terms as used in most previous work this is based on a synthesis of extensive modern ecological information on depth ranges these ranges are found to be spatially variable between ocean basins between regions and on sub regional scales because depth itself is not limiting instead depth distributions arise from complex physical chemical and biological interactions with coral reef growth distribution and composition one of the main causes for recognition of the greater depth variability of coral taxa has been the routine inclusion of deep diving and rov surveys in coral ecological studies over the past few decades which has broken through the shallow water bias of early surveys by adding frequent observations on deeper occurrences although more are needed it is also clear from our assessment that coral habitat depth distributions must be determined on the species level to reduce uncertainties in reconstructions of past sea levels and that application to sea level studies then requires these studies also to identify fossil corals to the species level samples identified only to the genus level give rise to wide uncertainties in habitat depth and hence sea level our database contains extensive metadata to assist evaluations of dating quality as well as geomorphic and stratigraphic metadata we demonstrate with examples how such metadata can help to evaluate sea level reconstructions for example by identifying outlier points one example discusses the last interglacial lig where we use the available data with their uncertainties to assess probabilistically the time at which local sea levels exceed that of the present which yields a mean age of 124 6 ka with 95 probability bounds at 118 5 and 129 5 ka we conclude with identification of key outstanding issues relating to i current incomplete understanding of tectonic setting including the current lack of independent verification of uplift subsidence rates and reliance of somewhat unsatisfactory and circular use of the elevation of last interglacial deposits ii the depth distributions of coral taxa and iii the complete documentation of stratigraphic geomorphological and other contextual information with suggestions for strategies to address these issues

origin of the sula platform eastern indonesia the sula platform is a fragment of continental crust that is generally regarded as a piece of new guinea that was detached from western irian jaya in late cenozoic time the assumption is based on the apparent correlation of the stratigraphy of the sula platform with that of western irian jaya new data from the sula platform and western irian jaya show that this correlation is probably not valid the best correlation of the sula platform stratigraphy with that of the former northern margin of the australian craton is found in central papua new guinea between long 141 and 145 e more than 1200 km farther east than any previously proposed site of origin implying a displacement of more than 2500 km

uplift rate of coral reef terraces in the area of kupang west timor preliminary results abstract a th u date of 152 000 years obtained from the prominent fifth step at 44 m elevation of a flight of 7 well defined raised reef terraces at cape namosain 5 km west of kupang allows inference of a preliminary mean uplift rate of 0 3 mm yr since the last interglacial such a slow uplift rate is supported by the observation of numerous large modern reef platforms and of very limited mid holocene emergence if any throughout the region subject to conformation through further dating this suggests the existence of a more rapid uplift zone in central west timor by contrast with the area of kupang to the west and of northern east timor and atauro island to the east possibly in relation with the nw se seismic tear zone which has been recently pointed out within the subducting plate north of west timor one of the main interests in the terraces of cape namosain apart from its neotectonic aspect resides in the fact that there may be an oppurtunity to define the 180 000 year old paleo sea level terrace viii of huon peninsula based on the geomorphological interpretation of the series it could correspond here to the fourth or the sixth terrace field investigation and dating in that regard are currently in progress another th u date of 124 000 years obtained on the lowest emerged terrace 7 m above low tide in the southeast of the nearby island of semau indicates that this second area has been uplifting little during the last 125 000 years this together with the observation of tilts and other structural features leads to the conclusion that the area of the southwest of kupang is affected by differential uplifts and block faulting

sea level and deep water temperature changes derived from benthic foraminifera isotopic records we show that robust regressions can be established between relative sea level rsl data and benthic foraminifera oxygen isotopic ratios from the north atlantic and equatorial pacific ocean over the last climatic cycle we then apply these regressions to long benthic isotopic records retrieved at one north atlantic and one equatorial pacific site to build a composite rsl curve as well as the associated confidence interval over the last four climatic cycles our proposed reconstruction of rsl is in good agreement with the sparse rsl data available prior to the last climatic cycle we compute bottom water temperature changes at the two sites and at one southern indian ocean site taking into account potential variations in north atlantic local deep water 18o our results indicate that a last glacial maximum lgm enrichment of the ocean mean oxygen isotopic ratio of 0 95 is the lowest value compatible with unfrozen deep waters in the southern indian ocean if local deep water 18o did not increase during glacials with respect to present such a value of the lgm mean ocean isotopic enrichment would impose a maximum decrease in local bottom water 18o at the north atlantic site of 0 30 during glacials

holocene land and sea level changes in great britain analysis of more than 1200 radiocarbon dated samples that constrain relative sea levels in great britain over the past 16 000 yr provides estimates of current land level changes negative of relative sea level change maximum relative land uplift occurs in central and western scotland ca 1 6 mm yr 1 and maximum subsidence is in southwest england ca 1 2 mm yr 1 sediment consolidation arising from autocompaction as the sediment accumulates and from land drainage increases the subsidence in areas with thick sequences of holocene sediments with an average effect equivalent to at least an extra ca 0 2 mm yr 1 land subsidence but more in parts of southeast england 0 5 1 1 mm yr 1 modelled changes in tidal range during the mid to late holocene in eastern england suggest that the calculated rate of land subsidence is overestimated unless such changes are quantified the effect is most significant for large coastal lowlands the fenland and humber ca 0 5 and 0 6 mm yr 1 that were tidal embayments during the mid to late holocene

relative sea level fall since the last interglacial stage are coasts uplifting worldwide the growing interest in quantification of vertical ground motion stems from the need to understand in detail how the earth s crust behaves for both scientific and social reasons however only recently has the refinement of dating techniques made possible the use of paleoshorelines as reliable tools for tectonic studies although there are many local studies of quaternary vertical motions of coastlines we know of no comprehensive worldwide synthesis here we provide a compilation of 890 records of paleoshoreline sequences with particular emphasis on the last interglacial stage marine isotopic stage mis 5e 122 ka the quality of dating mis 5e makes it a reliable marker to evaluate vertical ground motion rates during the late quaternary on a global scale the results show that most coastal segments have risen relative to sea level with a mean uplift rate higher than 0 2 mm yr i e more than four times faster than the estimated eustatic drop in sea level the results also reveal that the uplift rate is faster on average for active margins than for passive margins neither dynamic topography nor glacio hydro isostasy may explain sustained uplift of all continental margins as revealed by the wide distribution of uplifted sequences of paleoshorelines instead we suggest that only plate tectonic processes reconcile all observations of quaternary coastal uplift we propose that long term continental accretion has led to compression of continental plates and uplift of their margins therefore this study concludes that plate tectonics processes impact all margins and emphasizes the fact that the notion of a stable platform is unrealistic these results therefore seriously challenge the evaluation of past sea levels from the fossil shoreline record

phasing and amplitude of sea level and climate change during the penultimate interglacial the penultimate interglacial period was punctuated by three sea level highstands uranium thorium ages obtained from speleothems in italian caves show that the relationship between the timing of the peaks in sea level and northern hemisphere insolation is dependent on the previous extent of continental ice sheets