direct determination of the timing of sea level change during termination ii an outcrop within the last interglacial terrace on barbados contains corals that grew during the penultimate deglaciation or termination ii we used combined 230th and231pa dating to determine that they grew 135 8 0 8 thousand years ago indicating that sea level was 18 3 meters below present sea level at the time this suggests that sea level had risen to within 20 of its peak last interglacial value by 136 thousand years ago in conflict with milankovitch theory predictions orbital forcing may have played a role in the deglaciation as may have isostatic adjustments due to large ice sheets other corals in the same outcrop grew during oxygen isotope 18o substage 6e indicating that sea level was 38 5 meters below present sea level about 168 0 thousand years ago when compared to the 18o signal in the benthic v19 30 v19 28 record at that time the coral data extend to the previous glacial cycle the conclusion that deep water temperatures were colder during glacial periods

revisiting tectonic corrections applied to pleistocene sea level highstands tectonic displacement contaminates estimates of peak eustatic sea level and equivalently minimum continental ice volumes determined from the elevation of quaternary interglacial highstand markers for sites at which a stratigraphic or geomorphic marker of peak marine isotope stage mis 5e sea level exists the standard approach for estimating local tectonic uplift or subsidence rates takes the difference between the elevation of the local highstand marker and a reference mis 5e eustatic value commonly chosen as 6 m and divides by the age of the marker the resulting rate is then applied to correct the elevation of all other local observed sea level markers for tectonic displacement including peak highstands of different ages e g mis 5a mis 5c and mis 11 under the assumption that the tectonic rate remained constant over those periods this approach introduces two potentially significant errors first the peak eustatic value adopted for mis 5e in most previous studies i e 6 m is likely incorrect second local peak sea level during mis 5e is characterized by significant departures from eustasy due to glacial isostatic adjustment in response to both successive glacial interglacial cycles and excess polar ice sheet melt relative to present day values we use numerical models of glacial isostatic adjustment that incorporate both of these effects to quantify the plausible range of the combined error and show that even at sites far from melting ice sheets local peak sea level during mis 5e may depart from eustasy by 2 4 m or more we also demonstrate that the associated error in the estimated tectonic rates can significantly alter previous estimates of peak eustatic sea level during quaternary highstands notably those associated with earlier interglacials e g mis 11

u th ages obtained by mass spectrometry in corals from barbados sea level during the past 130 000 years the study of the sea level record during the last glacial cycle has primarily proceeded indirectly by means of oxygen isotope measurements on foraminifera from deep sea sediments1 2 the direct approach of dating sea level indicators stagnated during the past decade mainly because the samples required to complete our knowledge of the past glaciations are below the present day sea level3 7 using the 14c ages of acropora palmata samples collected by drilling offshore the island of barbados fairbanks8 presented the first detailed chronology for the last deglaciation this radiocarbon chronology is limited to the past 30 kyr because of the short half life of 14c 5 730 yr we must therefore rely on other dating methods to obtain information for the whole last glacial cycle during the past four years 230th 234u dating of corals by thermal ionization mass spectrometry has been shown to be significantly more precise and accurate than the classical counting method9 14 we have used this technique to measure u th ages in coral samples from the barbados collection and from subaerially exposed outcrops see also ref 15 here we present results bearing on the sea level record for the past 130 000 years we conclude that the last deglaciation started 3 000 years earlier than previously thought and confirm that there were two surges in melt water8 at about 11 kyr and 14 kyr bp before present

aminostratigraphy and faunal correlations of late quaternary marine terraces pacific coast usa recent studies using the extent of racemization of amino acids to date fossil mollusc shells in the arctic1 the british isles2 and on the atlantic3 4 and pacific5 13 coasts of north america have relied mainly on theoretical kinetic models of racemization ages generated in this fashion are highly model dependent and require estimates of integrated long term diagenetic temperatures we present here an alternative empirical approach to aminostratigraphy in which we plot amino acid enantiomeric ratios versus latitude for localities along the pacific coast of the united states and generate isochronal correlations by connecting data points of geographically proximal localities that have similar d l ratios and zoogeographic aspect isochrons are calibrated at a few localities by independent radiometric dates the diagenetic temperature effect on racemization is reflected in the slope of the isochrons but the need to quantify temperature is eliminated

the role of ocean thermal expansion in last interglacial sea level rise 1 a compilation of paleoceanographic data and a coupled atmosphere ocean climate model were used to examine global ocean surface temperatures of the last interglacial lig period and to produce the first quantitative estimate of the role that ocean thermal expansion likely played in driving sea level rise above present day during the lig our analysis of the paleoclimatic data suggests a peak lig global sea surface temperature sst warming of 0 7 0 6 c compared to the late holocene our lig climate model simulation suggests a slight cooling of global average sst relative to preindustrial conditions sst 0 4 c with a reduction in atmospheric water vapor in the southern hemisphere driven by a northward shift of the intertropical convergence zone and substantially reduced seasonality in the southern hemisphere taken together the model and paleoceanographic data imply a minimal contribution of ocean thermal expansion to lig sea level rise above present day uncertainty remains but it seems unlikely that thermosteric sea level rise exceeded 0 4 0 3 m during the lig this constraint along with estimates of the sea level contributions from the greenland ice sheet glaciers and ice caps implies that 4 1 to 5 8 m of sea level rise during the last interglacial period was derived from the antarctic ice sheet these results reemphasize the concern that both the antarctic and greenland ice sheets may be more sensitive to temperature than widely thought

sea level records at 80 ka from tectonically stable platforms florida and bermuda studies from tectonically active coasts on new guinea and barbados have suggested that sea level at 80 ka was significantly lower than present whereas data from the atlantic and pacific coasts of north america indicate an 80 ka sea level close to that of the present we determined ages of corals from a shallow submerged reef off the florida keys and an emergent marine deposit on bermuda both localities are on tectonically stable platforms distant from plate boundaries uranium series ages show that corals at both localities grew during the 80 ka sea level highstand and geologic data show that sea level at that time was no lower than 7 9 m below present florida and may have been 1 2 m above present bermuda the ice volume discrepancy of the 80 ka sea level estimates is greater than the volume of the greenland or west antarctic ice sheets comparison of our ages with high latitude insolation values indicates that the sea level stand near the present at 80 ka could have been orbitally forced

late quaternary uplift and earthquake potential of the san joaquin hills southern los angeles basin california analysis of emergent marine terraces in the san joaquin hills california and 230 th dating of solitary corals from the lowest terraces reveal that the san joaquin hills have risen at a rate of 0 21 0 27 m k y during the past 122 k y movement on a blind thrust fault in the southern los angeles basin has uplifted the san joaquin hills and has the potential to generate an m w 7 3 earthquake within this densely populated area our structural modeling suggests that the fault dips to the southwest and slips at 0 42 0 79 m k y yielding an estimated minimum average recurrence interval of 1650 3100 yr for moderate sized earthquakes recognition of this blind thrust extends the known area of active blind thrusts and fault related folding southward from los angeles into coastal orange county

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

coastal landscape evolution as a function of eustasy and surface uplift rate cascadia margin southern oregon we explore the relative importance of eustatic versus tectonic factors in sculpting preserving and modifying coastal landforms the study area is a 30 km coastal reach in southern oregon using degree of soil development as a means of correlating wave cut platforms along the coast we document that surface uplift rate is variable in a shore parallel sense variability being a function of differential vertical displacement of crustal blocks along faults and flexures in the upper plate of the cascadia subduction zone a consequence of this variability is that in areas of moderate uplift rate 0 7 0 9 m k y flights of up to seven emergent wave cut platforms are preserved along the interfluves of coastal drainages whereas in areas of low uplift rate 0 05 0 2 m k y only one wave cut platform commonly exists within a few meters of present sea level preservation of shore platforms in both areas is the result of the inter action of tectonic uplift and eustatic sea level changes operating on a high energy coast subject to platform planation platform reoccupation can be a consequence of late pleistocene eustatic sea level changes operating on low up lift rate coasts particularly in the cases of the 200 ka and 125 ka high sea stands reoccupation by the later highstand is probable when coastal uplift rates are about 0 2 m k y the same eustatic history operating on a higher uplift rate section of the coast results in multiple emergent platforms and no instances of reoccupation coastal drainage basins in the size range of 5 10 km2 have different hypsometries reflecting whether platforms in coastal basins are preserved over a range of altitudes or only near sea level the hypsometric differences are thus a product of differences in uplift rate the dominant mechanism of base level fall varies between the two areas coastal retreat during sea level highstands drives baselevel fall in lower uplift rate basins whereas tectonic uplift mainly drives base level fall in moderate uplift rate basins even though the magnitude of coastal retreat may be about the same in the two areas where coastal retreat largely provides the mechanism for base level fall steep coastal drainages discharge their debris onto coastal piedmonts benches and the resultant alluvial fans prograde over marine deposits in southern oregon the alluvial fan building episode was relatively short about 2 20 k y in duration fan aggradation ceased as a consequence of fan entrenchment most likely brought on by buildup and steepening of the fan over time

sea level and reef accretion history of marine oxygen isotope stage 7 and late stage 5 based on age and facies of submerged late pleistocene reefs oahu hawaii abstract in situ pleistocene reefs form a gently sloping nearshore terrace around the island of oahu tims th u ages of in situ corals indicate that most of the terrace is composed of reefal limestones correlating to marine oxygen isotope stage 7 mis 7 190 245 ka the position of the in situ mis 7 reef complex indicates that it formed during periods when local sea level was 9 to 20 m below present sea level its extensiveness and geomorphic prominence as well as a paucity of emergent in situ mis 7 reef framework deposits on oahu suggest that much of mis 7 was characterized by regional sea levels below present later accretion along the seaward front of the terrace occurred during the latter part of mis 5 i e mis 5a 5d 76 113 ka the position of the late mis 5 reefal limestones is consistent with formation during a period when local sea level was below present the extensiveness of the submerged pleistocene reefs around oahu compared to the relative dearth of holocene accretion is due to the fact that pleistocene reefs had both more time and more accommodation space available for accretion than their holocene counterparts

quaternary coastal lithofacies sequence development and stratigraphy in a passive margin setting north carolina and virginia usa lithofacies analysis is fundamental to unravelling the succession of depositional environments associated with sea level fluctuations these successions and their timing are often poorly understood this report defines lithofacies encountered within the north eastern north carolina and south eastern virginia quaternary section interprets their depositional environments presents a model for coastal depositional sequence development in a passive margin setting and uses this understanding to develop the stratigraphy and quaternary evolutionary history of the region data were obtained from numerous drill cores and outcrops chronology was based on age estimates acquired using optically stimulated luminescence amino acid racemization uranium series and radiocarbon dating techniques geomorphic patterns were identified and interpreted using light detection and ranging imagery since lithofacies occurrence distribution and stratigraphic patterns are different on interfluves than in palaeo valleys this study focused on interfluves to obtain a record of highstand sea level cycles with minimal alteration by fluvial processes during subsequent lowstands nine primary lithofacies and four diagenetic facies were identified in outcrops and cores the uppermost depositional sequence on interfluves exhibits an upward succession from shelly marine lithofacies to tidal estuarine lithofacies and is bounded below by a marine ravinement surface and above by the modern land surface older depositional sequences in the subsurface are typically bounded above and below by marine ravinement surfaces portions of seven depositional sequences were recognized and interpreted to represent deposition from late middle pleistocene to present erosional processes associated with each successive depositional sequence removed portions of older depositional sequences the stratigraphic record of the most recent sea level highstands marine isotope stage 5a and marine isotope stage 3 is best preserved glacio isostatic adjustment has influenced depositional patterns so that deposits associated with late quaternary sea level highstands marine isotope stages 5c 5a and 3 which did not reach as high as present sea level according to equatorial eustatic records are uplifted and emergent within the study area

active deformation of the pacific northwest continental margin tilted and uplifted marine terraces in southern oregon show progressive landward tilting of the coastal ranges at about 5 16 10 8 rad yr 1 for the last 0 25 m y tide gauges in washington and british columbia and ten resurveyed leveling lines running inland from the coast indicate contemporary landward down to the east tilt rates of about 1 12 10 8 rad yr 1 averaged over periods of from 10 to 50 years the leveling lines traverse and the terraces cut across dipping cenozoic strata pleistocene dips to 3 mio pliocene dips to 30 and eocene dips to 60 southern oregon from cape blanco to the siletz river shows geodetic or terrace tilting in the same direction as the underlying stratal dips hence present day deformation continues past deformation of the coastal ranges and is most likely related to active subduction of the juan de fuca plate the steep stratal dips lack of major active faults and historic earthquakes and presence of very young bedding plane faults suggest that much of the onshore deformation and shortening within the overlying north american plate is taken up by folding rather than thrust faulting present shortening rates across north trending folds near the coast are between 0 02 and 1 9 10 7 yr 1 the rate of shortening decreases rapidly eastwards from the juan de fuca north american plate boundary a total of about 25 mm yr 1 of permanent shortening could be occurring within the north american plate most of it in the westernmost 40 km the landward tilt and shortening rates are similar to those above many other subduction zones that have experienced great thrust earthquakes while a high strain rate measured near seattle washington has been interpreted as elastic strain accumulation before a thrust earthquake the low level of historic seismicity and the similarity of short and long term deformation rates suggest alternatively that the subduction beneath washington is aseismic the issue has considerable implications for seismic hazard evaluation in the pacific northwest and could be resolved by a search for the effects or lack of effects of prehistoric great earthquakes

record of mis 5 sea level highstands based on u th dated coral terraces of haiti abstract new geomorphologic investigations and new u th series dates from haiti northwestern peninsula confirm the age of coral reef terraces assigned to mis 5 5 130 ka mis 5 3 107 ka and mis 5 1 83 ka sea level peaks they also provide evidence for a second high sea level occurring some thousand years before 118 ka and indicate a second mis 5 1 sea level stand at about 76 ka these results are in agreement with the raised terraces of barbados although the staircase of haiti consists of four steps compared to eight the haitian sequence can be compared with the maximal number of distinct mis 5 sea level highstands recorded in the world from coral reef tracts and their relative height above or below present sea level three mis 5 5 sea level changes have been recognized with sea level oscillating above or near the present level until 122 ka only dropping then rising to 11 m below present sea level at 120 ka three high frequency sea level oscillations occurred during mis 5 3 and a fourth during mis 5 3 5 2 two or three events may have occurred during mis 5 l according to whether the 73 ka event is considered to belong to mis 5 1

predicted bounds on peak global mean sea level during marine isotope stages 5a and 5c abstract estimates of marine isotope stage mis 5c and 5a global mean sea level gmsl based on marine terraces and coastal indicators range from 15 37 m and 9 30 m below present respectively tectonic displacement and glacial isostatic adjustment gia complicate efforts to refine this range we revisit this issue using numerical predictions of post glacial sea level change and updated estimates of site specific tectonic signals based upon these predictions laurentide and cordilleran peripheral bulge dynamics and variations in the gravitational effect of these ice masses dominate the gia signal along the east and west coasts of north america published compilations suggest that mis 5 sea level indicators extending from virginia to the caribbean lie on the outer flank of the peripheral bulge while those along a transect from oregon to baja california sit on the inner flank of the bulge our gia modeling reconciles these data by adopting a significantly weaker i e lower viscosity upper mantle in analyzing data on the pacific coast relative to the atlantic an inference supported by seismic tomography we present a sensitivity analysis that compares the observed elevation of globally distributed high stand markers to a suite of gia simulations that vary the earth model and gmsl from the last interglaciation mis 5e 130 115 ka to 70 ka we conclude that gmsl peaked at 8 5 4 6 m 1 during mis 5a and 9 4 5 3 m during mis 5c a more restrictive analysis yields slightly wider bounds corresponding to 10 5 5 5 m and 11 1 6 6 m respectively

elevations and ages of marine terraces and late quaternary rock uplift in southeastern korea 1 from a detailed gps survey of marine terraces and their former shoreline elevations along the southeastern coast of the korean peninsula we determined the pattern of late quaternary uplift in a part of the far eastern intraplate region of the eurasian plate using a paleosea level of 6 m for the 117 132 ka sea level highstand the average long term uplift rates are 0 3 m ka in the weolsung and 0 2 m ka in the daebo gori regions persistent uplift that generated marine terraces is mostly the result of local major faulting reflecting an ene wnw maximum compression stress the differences in uplift rates suggest a local triangular crustal block undergoing structural movement controlled by subregional tectonic processes notable local major faulting in an intraplate region plays an important role in raising the emergent flight of marine terraces generated by earthquakes

accelerating and spatially varying crustal uplift and its geomorphic expression san andreas fault zone north of san francisco california abstract marine terraces that bevel the western flank of the point reyes peninsula were used to measure crustal uplift rates west of the san andreas fault segment north of san francisco field measurements of platform inner edges and luminescence ages from overlying marine sediments suggest the youngest platform was cut by waves during the 80 ka sea level high stand mis 5a since 80 ka the platform has been uplifted slowly throughout most of the peninsula but more rapidly in the southern part where uplift reaches a rate of 1 m ka analyses of the spatial distributions of hillslope gradient and elevation are consistent with the terrace data correlations of older terrace levels to high stand ages suggest that crustal uplift has accelerated in the southern part of the peninsula during the past 300 ky probably as a result of a contractional zone that has been migrating northward this study is the first to quantify the rate and style of crustal uplift west of this san andreas fault segment although the transform motions in this region are well documented the complex nature of interacting fault strands are only beginning to be understood these results imply that other faults with reverse motions are also active and potentially contributing to earthquake hazards

u series dates of pleistocene corals and their implications to the paleo sea levels and the vertical displacement in the central philippines abstract results of high precision alpha spectrometric 230th 234u dating of hermatypic corals in palawan in western philippines and cebu bohol and panglao islands in the central philippines confirm the presence of mis 5e reef terraces at 2 to 13 m above the present mean sea level similar to stable regions this suggests the relative vertical stability of the islands since the last interglacial period in panglao island the elevation of the 5e terrace increases to the northeast indicating tilting of the island to the southwest the continued sense of uplift since at least the last interglacial is indicated by the similarity in the spatial variation of middle holocene tidal notch a 5c terrace though less developed is also recognized in panglao island along the san isidro coast the inner margins of 5c and 5e terraces are at elevations of 5 and 7 1 8 m respectively and the difference in altitude between the terraces is only ca 2 3 m assuming that the sea level during mis 5e was 3 6 m above the present sea level sea level at mis 5c is estimated to be equal to or slightly higher than the present mean sea level

coastal tectonics on the eastern margin of the pacific rim late quaternary sea level history and uplift rates channel islands national park california usa abstract the pacific rim is a region where tectonic processes play a significant role in coastal landscape evolution coastal california on the eastern margin of the pacific rim is very active tectonically and geomorphic expressions of this include uplifted marine terraces there have been however conflicting estimates of the rate of late quaternary uplift of marine terraces in coastal california particularly for the northern channel islands in the present study the terraces on san miguel island and santa rosa island were mapped and new age estimates were generated using uranium series dating of fossil corals and amino acid geochronology of fossil mollusks results indicate that the 2nd terrace on both islands is 120 ka and the 1st terrace on santa rosa island is 80 ka these ages correspond to two global high sea stands of the last interglacial complex marine isotope stages mis 5 5 and 5 1 respectively the age estimates indicate that san miguel island and santa rosa island have been tectonically uplifted at rates of 0 12 0 20 m ka in the late quaternary similar to uplift rates inferred from previous studies on neighboring santa cruz island the newly estimated uplift rates for the northern channel islands are however an order of magnitude lower than a recent study that generated uplift rates from an offshore terrace dating to the last glacial period the differences between the estimated uplift rates in the present study and the offshore study are explained by the magnitude of glacial isostatic adjustment gia effects that were not known at the time of the earlier study set in the larger context of northeastern pacific rim tectonics channel islands uplift rates are higher than those coastal localities on the margin of the east pacific rise spreading center but slightly lower than those of most localities adjacent to the cascadia subduction zone the uplift rates reported here for the northern channel islands are similar to those reported for most other localities where strike slip tectonics are dominant but lower than localities where restraining bends such as the big bend of the san andreas fault result in crustal shortening

post glacial sediment load and subsidence in coastal louisiana 1 sea level rise in the gulf of mexico has occurred at a rate of 1 8 2 2 mm yr during the 20th century or nearly the same as observed globally due to combined steric and water mass changes tide gauges in coastal louisiana however record a substantially larger rate of rise and while a number of causal mechanisms may be responsible their specific contribution is poorly understood using a realistic viscoelastic earth model detailed geologic parameters for south louisiana and new gps data we demonstrate that holocene sedimentary loading in the gulf and mississippi river delta is capable of contributing to 1 8 mm yr of subsidence over areas of 30 0 75 103 km2

sea level rise due to polar ice sheet mass loss during past warm periods background although thermal expansion of seawater and melting of mountain glaciers have dominated global mean sea level gmsl rise over the last century mass loss from the greenland and antarctic ice sheets is expected to exceed other contributions to gmsl rise under future warming to better constrain polarice sheetresponse to warmer temperatures we draw on evidence from in terglacial periods in the geologic record that ex perienced warmer polar temperatures and higher gmsls than present coastal records of sea level from these previous warm periods dem onstrate geographic variability because of the influence of several geophysical processes that operate across a range of magnitudes and time scales inferring gmsl and ice volume changes from these reconstructions is nontrivial and generally requires the use of geophysical models advances interdisciplinary studies of geo logic archives have ushered in a new era of deciphering magnitudes rates and sources of sea level rise advances in our understanding of polar ice sheet response to warmer climates have been made through an increase in the number and geographic distribution of sea level reconstructions better ice sheet constraints and the recognition that several geophysical processes cause spatially complex patterns in sea level in particular accounting for glacial isostatic processes helps to decipher spatial variability in coastal sea level records and has reconciled a number of site specific sea level reconstructions for warm periods that have oc curred within the past several hundred thou sand years this enables us to infer that during recent interglacial periods small increases in

a record of bottom water temperature and seawater δ18o for the southern ocean over the past 440 kyr based on mg ca of benthic foraminiferal uvigerina spp the sensitivity to temperature of mg ca ratios in the shallow infaunal benthic foraminifera uvigerina spp has been assessed core top calibrations over 1 20 c show a range in sensitivity of 0 065 0 084 mmol mol c but few data are available spanning the temperature range anticipated in deep sea records over glacial interglacial cycles in contrast to epibenthic foraminiferal species carbonate ion saturation appears not to affect mg ca significantly a method based on estimating the ratio of the temperature sensitivity of foraminiferal mg ca to that of 18ocalcite shows that sensitivity for mg ca at the high end of the observed core top range 0 1 mmol mol c is required for consistency with lgm holocene differences in each property as constrained by independent proxy data this is supported by a mg ca record for uvigerina spp generated for the southern ocean over the past 440 000 years from ocean drilling program site 1123 chatham rise new zealand the record shows variability that correlates with climate oscillations the lgm deep ocean temperature derived from the mg ca record is 1 1 0 3 c transformation to temperature allows estimates to be made of changes in bottom water temperature and seawater 18o and comparison made with literature records analysis reveals a 2 5 kyr lead in the record of temperature over calcite 18o and a longer lead over seawater 18o this is a reflection of larger phase offsets at eccentricity periods phase offsets at tilt and precession are within error zero

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

isotopic balance of the greenland ice sheet modelled concentrations of water isotopes from 30 000 bp to present abstract polar ice cores contain a complex record of climate and ice flow that can be used to decode climate history interpretation of ice core records requires the flow signature to be either simple or removable when the signature is complex computer modelling can become a powerful aid to interpretation by combining an ice dynamics model with tracer deposition and transport models the stratification of individual tracers can be calculated in this way the time evolving three dimensional chemical stratigraphy can be simulated by linking an ice tracer dynamics model with models of atmosphere and ocean tracer dynamics coupled models of the global geochemical cycling of water isotopes can be developed such models hold promise for an integrated interpretation of the marine and ice core climate records as a first step along this path we apply tracer transport modelling to simulate the temporal and spatial variations of water isotopes in the greenland ice sheet over the past 30 000 years and calculate the influence of greenland ice volume and isotopic chemistry on the isotopic content of the ocean we find that the greenland ice sheet maintained its maximum ice volume from 18 000 to 15 000 bp but was isotopically lightest at 11 000 bp the sea level equivalent of ice volume changes occurring over the past 30 000 years did not exceed 2 1 m and the volume averaged influence on ocean chemistry did not exceed 0 025 for 18 o and 0 20 for d and at the last glacial maximum taken as 21 000 bp these values were respectively 1 9 m for ice volume 0 022 for 18 o and 0 17 for d

submerged late pleistocene reefs on the tectonically stable s e florida margin high precision geochronology stratigraphy resolution of substage 5a sea level elevation and orbital forcing abstract a well preserved submerged in situ fossil reef tract lies offshore of the southeast florida carbonate margin in the florida keys cores in two transects enabled reconstruction of reef stratigraphy and paleoenvironments paleo water depths and paleo sea levels because florida is tectonically stable the elevation data required correction only for the known minor subsidence rate twenty eight pristine aragonitic corals were dated via high precision tims u series methods to produce a comprehensive late pleistocene and early holocene geochronology the pleistocene section of the fossil reef includes a thick section of substage 5a reef growth recorded from 15 to 11 m msl spanning an age range of 86 2 80 9 ka paleoenvironmental reconstruction local water quality constraints and elevations of concurrent bahamian speleothem growth combine to limit sea level to 9 0 m msl at 83 ka this coincides unlagged with the 82 ka 65 n july insolation peak the absence of any lag suggests that the earlier peak in obliquity at 92 ka also controls paleoclimate and sea level a below present sea level estimate for substage 5a from the florida fossil reef data coincides more closely with uplift corrected reef data estimates of 15 to 13 m msl from tectonic margins such as barbados and haiti than with higher than present sea levels derived from detrital corals from bermuda and the u s atlantic coastal plain the best tims dates on corals and speleothem constraining sea level combine to produce a new regional sea level curve for the atlantic caribbean region for late isotope stage 5 and early stage 4

sea level change glacial rebound and mantle viscosity fornorthern europe northwestern europe remains a key region for testing models of glacial isostasy because of the good geological record of crustal response to the glacial unloading since the time of the last glacial maximum models for this rebound and associated sea level change require a detailed knowledge of the ice sheet geometry including the ice thickness through time existing ice sheet reconstructions are strongly model dependent and inversions of sea level data for the mantle response may be a function of the model assumptions thus inverse solutions for the sea level data are sought that include both ice and earth model parameters as unknowns sea level data from fennoscandia the north sea the british isles and the atlantic and english channel coasts have been evaluated and incorporated into the solutions the starting ice sheet for fennoscandia is based on a reconstruction of a model by denton hughes 1981 that is characterized by quasi parabolic cross sections and symmetry about the load centre both global northwestern europe as a whole and regional subsets of the data solutions have been made for earth model parameters and ice height scaling parameters the key results are as follows 1 the response of the upper mantle to the changing ice and water loads is spatially relatively homogenous across scandinavia the north sea and the british isles 2 this response can be adequately modelled by an effective elastic lithosphere of thickness 65 85 km and by an effective upper mantle viscosity from the base of the lithosphere to the 670 km depth seismic discontinuity of about 3 4 1020 pa s the effective lower mantle viscosity is at least an order of magnitude greater 3 the ice thickness over scandinavia at the time of maximum glaciation was only about 2000 m much less than the 3400 m assumed in the denton hughes model 4 the ice profiles are asymmetric about the centre of the ice sheet with those over the western part being consistent with quasi parabolic functions whereas the ice heights over the eastern and southern regions increase much more slowly with distance inwards from the ice margin

new uranium series ages of the waimanalo limestone oahu hawaii implications for sea level during the last interglacial period abstract the waimanalo formation limestone of oahu has been correlated with the last interglacial period based on u series dating of corals by t l ku and colleagues the limestone consists of growth position corals and overlying coral conglomerate an apparent bimodal distribution of ages for the growth position corals mean age 133 ka and the overlying coral conglomerate mean age 119 ka has been interpreted to represent two distinct high stands of sea that occurred within the last interglacial period both growth position corals and overlying conglomerate coral occur in an outcrop east of kaena point and consist mainly of pocillopora and porites u series ages of growth position corals that show closed system conditions are 120 3 ka and 127 4 ka overlying conglomerate corals have u series ages that range from 120 3 ka to 138 4 ka at kahe point conglomerate corals have ages of 120 3 ka and 134 4 ka these data show that the growth position corals are not systematically older than the conglomerate corals thus there is no evidence for two distinct high stands of sea waimanalo deposits at kahe point and mokapu point new u series ages of 134 4 ka and 127 3 ka have beach deposits as high as 12 5 m and at mokapu point growth position corals as high as 8 5 m a last interglacial sea level stand of 8 5 to 12 5 m conflicts with estimates of 6 m from a number of tectonically stable coastlines and islands in the western atlantic ocean we infer therefore that oahu may be undergoing uplift at a low rate this uplift may be due to compensatory lithospheric flexure because the island of hawaii has been subsiding throughout much of the quaternary from volcanic loading because of this possible uplift oahu and islands like it elsewhere in the pacific cannot be used as reference points for sea level during the last interglacial period

pleistocene sea levels from raised coral reefs of haiti the elevations and ages of a sequence of three uplifted pleistocene coral reefs on the northwest peninsula of haiti have been determined with the assignment of a sea level of 6 meters relative to the present day at 130 000 years before present and constant uplift of the reefs the data indicate that sea level stood 10 and 13 meters at 108 000 and 81 000 years before present respectively these results are in substantial agreement with those reported for barbados and new guinea and support the hypothesis of constant uplift for each area sea level data from raised reefs indicate that the interglacial marine oxygen isotope oscillations during oxygen isotope stage 5 are a result of 30 percent ice volume effects and 70 percent temperature effects

age estimates and uplift rates for late pleistocene marine terraces southern oregon portion of the cascadia forearc marine terraces are prominent landforms along the southern oregon coast which forms part of the forearc region of the cascadia subduction zone interest in the cascadia subduction zone has increased because recent investigations have suggested that slip along plates at certain types of convergent margins is characteristically accompanied by large earthquakes in addition other investigations have suggested that convergent margins can be broadly classified by the magnitude of their uplift rates with these hypotheses in mind we generated new uranium series amino acid and stable isotope data for southern oregon marine terrace fossils these data along with terrace elevations and two alternative estimates of sea level at the time of terrace formation allow us to determine terrace ages and uplift rates uranium series analysis of fossil coral yields an age of 83 5 ka for the whisky run terrace at coquille point in bandon oregon a combination of amino acid and oxygen isotope data suggest ages of about 80 and 105 ka for the lowest two terraces at cape blanco these ages indicate uplift rates of 0 45 1 05 and 0 81 1 49 m kyr for coquille point and cape blanco respectively late quaternary uplift rates of marine terraces yield information about deformation in the overriding plate but it is unclear if such data vary systematically with convergent margin type in order to assess the utility of the southern oregon uplift rates for predicting the behavior of the cascadia subduction zone we compared late quaternary uplift rates derived from terrace data from subduction zones around the world on the basis of this comparison the southern oregon rates of vertical deformation are not unusually high or low furthermore late quaternary uplift rates show little relationship to the type of convergent margin these observations suggest that local structures may play a large role in uplift rate variability in addition while the type of convergent margin may place an upper limit on possible uplift rate greater upper limits serve to increase the range of possible uplift rates in the case of the southern oregon coast variability in uplift rate probably reflects local structures in the overriding plate and the rate of uplift cannot be used as a simple index of the potential for great earthquakes along the southern cascadia subduction zone

whole rock aminostratigraphy and quaternary sea level history of the bahamas abstract the surficial geology of the tectonically stable bahamian archipelago preserves one of the most complete records of middle to late quaternary sea level highstand cycles in the world however with the exception of deposits from marine isotope substage mis 5e fossil corals for radiometric dating of this rich stratigraphic sequence are rare this study utilizes the previously published independent lithostratigraphic framework as a testing ground for amino acid racemization in whole rock limestone samples at least six limestone soil couplets provide a relative age sequence of events that encompass as many interglacial glacial cycles d alloisoleucine l isoleucine data fall into six clusters or aminozones on the basis of independent dating and the inferred correlation with global mis the ages of several aminozones are known while the ages of others are calculated from calibrated amino acid geochronology this study demonstrates the utility of the whole rock aminostratigraphy method for dating and correlating widespread emergent marine deposits constitutes the first regional geochronological framework for the bahamas and highlights major sea level events over the past half million years

a cool eastern pacific ocean at the close of the last interglacial complex abstract new high precision thermal ionization mass spectrometric tims u series ages of solitary corals balanophyllia elegans from several marine terrace localities along the california and southern oregon coasts date to the 80 000 yr bp high stand of sea correlative with marine isotope substage 5a late in the last interglacial complex ages of multiple corals from localities north of point ano nuevo central california and san nicolas island southern california suggest that this high sea stand could have lasted at least 8000 yr from 84 000 to 76 000 yr bp these ages overlap with those from marine deposits on tectonically stable bermuda and tectonically emergent barbados higher elevation terraces at two california localities in the palos verdes hills and on san nicolas island have corals with ages that range mostly from 121 000 to 116 000 yr bp correlative with marine isotope substage 5e these ages are similar to those reported for other terraces in southern california but are younger than some ages reported from hawaii barbados and the bahamas marine terrace faunas are excellent proxies for nearshore marine paleotemperatures during past high sea stands terraces on the palos verdes hills and san nicolas island dated to the 120 000 yr bp high sea stand have dominantly zoogeographically neutral species in exposed coastal localities indicating nearshore waters similar to those of today in contrast 80 000 yr bp exposed coastal localities typically have molluscan faunas characterized by numerous extralimital northern species and a lack of extralimital southern species these fossil assemblages are indicative of nearshore water temperatures that were cooler than modern temperatures at 80 000 yr bp waters at least as warm as today s at 120 000 yr bp and cooler than present at 80 000 yr bp are in excellent agreement with marine alkenone records and coastal vegetation records derived from pollen data from both southern and northern california decreased insolation or increased upwelling seem inadequate to explain the cool waters off the pacific coast from southern oregon to southern california at 80 000 yr bp we propose that a stronger california current or at least one with a greater component of subarctic waters may explain cooler than modern coastal waters during the 80 000 yr bp high sea stand

late quaternary tectonic deformation in the cape arago bandon region of coastal oregon as deduced from wave cut platforms the cape arago region of south central oregon sits on the upper plate of the cascadia subduction zone about 80 km east of the base of the continental slope the style of late pleistocene deformation along the cascadia forearc near cape arago is well expressed by the altitudinal variation of a set of five uplifted wave cut platforms these platforms record open folding with a half wavelength of about 6 7 km as well as late quaternary offset on flexural slip reverse faults that parallel bedding in the underlying bedrock the folds have produced both landward and seaward tilts to the uplifted wave cut platforms because the folds cut obliquely across the coastline the magnitude of coastal uplift is variable in the case of the lowest 80 ka wave cut platform this variable uplift has resulted in coastal deformation ranging from subsidence to a maximum uplift of 0 8 m kyr quantitative analysis of the mechanism of flexural slip folding for the south slough syncline near cape arago indicates that the late quaternary strain rate has decreased in the last 200 kyr evidence of past great subduction style earthquakes such as regional uplift and regional landward tilting of wave cut platforms or regional submergence of coastlands is lacking inmore the cape arago region instead the deformational style is controlled by folding though localized folding is dominant the occurrence of great subduction style earthquakes is not precluded because localized folding could occur concurrently with regional coseismic deformation less

uranium series coral ages from the us atlantic coastal plain the 80 ka problem revisited abstract uranium series coral ages for emergent units from the passive continental margin us atlantic coastal plain acp suggest sea level above present levels at the end of marine oxygen isotope stage mis 5 contradicting age elevation relations based on marine isotopic or coral reef models of ice equivalent sea level we have reexamined this problem by obtaining high precision 230th 238u and 231pa 235u thermal ionization mass spectrometric ages for recently collected and carefully cleaned acp corals many in situ we recognize samples that show no evidence for diagenesis on the basis of uranium isotopic composition and age concordance combining new and earlier data among those ages close to or within the age range of mis 5 over 85 cluster between 65 and 85 ka bp of the corals that we have analyzed those that show the least evidence for diagenesis on the basis of uranium isotopic composition and age concordance have ages between 80 and 85 ka bp consistent with a mis 5a correlation the units from which these samples have been collected are all emergent and have elevations within 3 5 m of those few units where early stage 5 125 000 ka bp coral ages have been obtained the acp appears to record an unusual history of relative sea level throughout mis 5 a history that is also apparent in the dated coral record for bermuda we speculate that this history is related to the regional near to intermediate field effects of ancestral laurentide ice sheets on last interglacial shorelines of the western north atlantic

u series and amino acid racemization geochronology of bermuda implications for eustatic sea level fluctuation over the past 250 000 years abstract bermuda is a stable mid oceanic carbonate platform for which a particularly complete record of late pleistocene eustatic sea level fluctuation has been reconstructed from a detailed study of geological field relationships combined with an extensive programme of u series and amino acid racemization geochronology only twice in the past 250 000 yr has sea level in bermuda been above its present level once at approximately 200 k y when it stood at about 2 m and most recently at 125 4 k y when it stood at 5 1 m these times of interglacial high sea level are characterized by the development of patch reefs and marine calcarenites at elevations above present sea level episodes of lower sea stand onto the bermuda platform at elevations higher than 20 m are observed within the two interglacial periods and are characterized by the deposition of eolianites by contrast glacial periods are times of residual soil formation and deposition of speleothems in caves at elevations below present sea level excellent correlation is observed between the bermuda glacio eustatic sea level record and other marine and terrestrial paleoclimate records

interpreting quaternary uplift rates at the mendocino triple junction northern california from uplifted marine terraces analysis of the altitudinal spacing of 14 flights of marine terraces indicates a spatial pattern of varying uplift rates that agrees with that determined from previously dated terraces for the past 3 81 ka and temporal changes in uplift rates from 1 m ka to 3 5 m ka that may reflect response to changes in tectonic regime during passage of the mendocino triple junction mtj a possible mechanism for regional uplift is growth of a slab window south of the mtj the region of most rapid uplift is 25 43 km south of the mtj immediately south of the northern boundary of the slab window the coastline is tilted upward to the south in the region directly above the southern edge of the subducted gorda plate at point delgada 55 km south of the present mtj where the northern edge of the slab window passes approximately 300 ka uplift rates have been 1 2 m ka for at least 330 ka more than 1 4 m y after passage of the southern edge of the subducted slab at the mendocino coast uplift rates have been less than 0 4 m ka for at least 330 ka

barbados based estimate of ice volume at last glacial maximum affected by subducted plate coral records from the barbados have been used to infer that due to ice expansion sea level was 120 m lower than today during the last glacial maximum a 3d simulation of the mantle in this region suggests these estimates were biased by the presence of a subducted slab and indicates the sea level difference was closer to 130 m

ice volume and sea level during the last interglacial during the last interglacial period 125 000 years ago sea level was at least several meters higher than at present with substantial variability observed for peak sea level at geographically diverse sites speculation that the west antarctic ice sheet collapsed during the last interglacial period has drawn particular interest to understanding climate and ice sheet dynamics during this time interval we provide an internally consistent database of coral u th ages to assess last interglacial sea level observations in the context of isostatic modeling and stratigraphic evidence these data indicate that global eustatic sea level peaked 5 5 to 9 meters above present sea level requiring smaller ice sheets in both greenland and antarctica relative to today and indicating strong sea level sensitivity to small changes in radiative forcing

further thermoluminescence dates from the dune sequence in the southeast of south australia abstract our thermoluminescence dating technique has been applied to several new samples from the remarkable sequence of stranded beach dunes in southeast south australia that were formed during the past 800 ka we show that robe iii is probably 100 ka as suggested by schwebel and not 80 ka as we suggested earlier a sample from the west dairy dune is shown to belong to 18 o stage 7 in accordance with schwebel s original suggestion and not stage 5 as he suggested later a new west naracoorte sample yielded acceptable data and an age consistent with formation just after the brunhes matuyama magnetic reversal at 780 ka as required by palaeomagnetic measurements two more samples from the woakwine dune show that our reproducibility is consistent with our derived errors

moment tensor inversion of recent small to moderate sized earthquakes implications for seismic hazard and active tectonics beneath the sea of marmara summary we retrieve the moment tensors of 64 small to moderate sized events that occurred mostly beneath the sea of marmara using near field data recorded at strong motion and broad band seismic stations the near field displacement records are inverted to their sources utilizing kuge s method where the best fit between the synthetic and observed seismograms is achieved through searching a centroid moment tensor cmt point in a grid scheme we also analyse the stress fields acting in the eastern and western parts of the sea of marmara by inverting the p and t axes of the focal mechanisms obtained significant biases in the stress tensors are obtained the nearly horizontal maximum compressive axis 1 in the western part is rotated 16 counter clockwise compared with 1 in the eastern part the 2 axis is close to vertical shear tectonic regime in the east and the plunge of 2 axis in the west is 36 transpressive tectonic regime changes in the 3 axis are also observed that is it is close to horizontal in the east and dips 49 in the west the spatial distribution of the focal mechanisms suggests that the stress field in the eastern part of the sea of marmara is homogenous compared with the western part and we identify five distinct subsidiary faults 1 a wnw ese striking right lateral strike slip fault located a few kilometres sw of the princes islands 2 a wsw ene striking right lateral strike slip fault named the yalova hersek fault 3 an e w striking normal fault located onshore between

quaternary climates and sea levels of the u s atlantic coastal plain uranium series dating of corals from marine deposits of the u s atlantic coastal plain coupled with paleoclimatic reconstructions based on ostracode marine and pollen continent data document at least five relatively warm intervals during the last 500 000 years on the basis of multiple paleoenvironmental criteria we determined relative sea level positions during the warm intervals relative to present mean sea level were 7 5 meters at 188 000 years ago 7 5 1 5 meters at 120 000 years ago 6 5 3 5 meters at 94 000 years ago and 7 3 meters at 72 000 years ago the composite sea level chronology for the atlantic coastal plain is inconsistent with independent estimates of eustatic sea level positions during interglacial intervals of the last 200 000 years hydroisostatic adjustment from glacial interglacial sea level fluctuations lithospheric flexure and isostatic uplift from sediment unloading due to erosion provide possible mechanisms to account for the discrepancies alternatively current eustatic sea level estimates for the middle and late quaternary may require revision

highstands during marine isotope stage 5 evidence from the ironshore formation of grand cayman british west indies abstract the ironshore formation on grand cayman is formed of six unconformity bounded packages units a f units a b c and d known from the subsurface in the northeastern part of grand cayman formed during marine isotope stages mis 11 9 7 and 5e respectively unconformities at the tops of units a b and c are highlighted by terra rossa and or calcrete layers strata in core obtained from wells drilled in george town harbour and exposed on the west part of grand cayman belong to unit d and the newly defined units e and f corals from unit e yielded th u ages of 104 ka whereas conch shells from unit f gave ages of 84 ka unit e equates to mis 5c whereas unit f developed during mis 5a th u dating of corals and conchs from the ironshore formation on the western part of grand cayman shows that unit d formed during the mis 5e highstand whereas units e and f developed in association with highstands at 95 110 ka mis 5c and 73 87 ka mis 5a unit e 5 m thick in the offshore cores is poorly represented in onshore exposures unit f which unconformably overlies unit d at most localities is formed largely of fossil poor cross bedded ooid grainstones the unconformity at the top of unit d a marine erosional surface with up to 2 5 m relief is not characterized by terra rossa or calcrete in the offshore cores or onshore exposures unit d formed with a highstand of 6 m asl whereas units e and f developed when sea level was 2 to 5 asl and 3 to 6 m asl respectively thus the highstands associated with mis 5e 5c and 5a were at similar elevations

rapid fluctuations in sea level recorded at huon peninsula during the penultimate deglaciation about 140 000 years ago the breakup of large continental ice sheets initiated the last interglacial period sea level rose and peaked around 135 000 years ago about 14 meters below present levels a record of last interglacial sea levels between 116 000 years to 136 000 years ago is preserved at reef vii of the uplifted coral terraces of huon peninsula in papua new guinea however corals from a cave situated about 90 meters below the crest of reef vii are 130 000 2000 years old and appear to have grown in conditions that were 6 c cooler than those at present these observations imply a drop in sea level of 60 to 80 meters after 130 000 years sea level began rising again in response to the major insolation maximum at 126 000 to 128 000 years ago the early about 140 000 years ago start of the penultimate deglaciation well before the peak in insolation is consistent with the devils hole chronology

the quaternary marine terraces of santa cruz california evidence for coseismic uplift on two faults the coast parallel elevation pattern of marine terraces along 50 km of coast centered about santa cruz california provides an opportunity to assess the relative roles of candidate uplift mechanisms we assemble 130 existing latitude longitude elevation inner edge locations from three of these marine terraces to constrain elastic dislocation models of coseismic uplift uplift resulting from repeated oblique slip seismic events similar to the loma prieta earthquake m s 6 9 of october 17 1989 appears to explain well the portion of the terrace uplift pattern south of santa cruz depending on whether the lowest terrace is assumed to correspond to isotope stage 5c or 5e the calculated mean repeat time for loma prieta events is either 490 or 820 yr corresponding to either 4 1 or 2 4mm yr slip rates on the loma prieta fault residual uplift not explained by such events increases monotonically to the north toward ano nuevo where the san gregorio fault zone intersects the coastline we assess whether this residual uplift may result from repeated events on the san gregorio fault given only the strike of the san gregorio fault we use an extensive parameter search to determine the geometry of and the style of motion on the implied rupture plane that best explains this residual uplift the fault parameters that minimize the misfit between data and model imply activity of a moderately steep 70 north east dipping san gregorio fault that ruptures in oblique thrust slip from 15 km to the surface the thrust slip component dominates the uplift pattern resulting in uplift of the coastline from santa cruz northward these parameters match available geological geodetic and seismic data on the dip and sense of motion on strictures within the san gregorio fault zone the san gregorio fault has therefore been an active late pleistocene participant in north american pacific plate boundary motion we conclude that the complex pattern of uplift along this 50 km reach of coastline can be explained by coseismic mechanisms tied to san andmas bend related fault structures onshore and to the san gregorio fault zone offshore as both of these mechanisms result locally in considerable shore normal uplift gradients caution is warranted in applying common correlation techniques based solely on uplift rates in the assignment of terrace ages in this and other such settings in addition while it is tempting to use terrace culmination offsets as a means of estimating san andreas fault dextral slip rates we provide a formalism to determine under what conditions such calculations are meaningful we conclude that the terrace offsets along the santa cruz coastline result not from dextral slip on the san andreas but from differential indentation of the loma prieta uplift pattern by the various sea level highstand coastlines

contrasting styles and rates of tectonic uplift of coral reef terraces in the ryukyu and daito islands southwestern japan abstract coral reef terraces on kikai hateruma and yonaguni in the ryukyu islands on the eurasian lithospheric plate and those of kita daito and minami daito islands on the philippine sea plate indicate three distinct patterns of coral reef terrace formation and preservation primarily reflecting different uplift rates the kikai type which includes many terraces from oxygen isotope stages 5e to 1 is a result of high uplift rate of ca 1 8 m kyr on the fore arc rise of a chilean type subduction zone arcward westward tilting and faulting are also characteristic of the kikai type the hateruma type is characterized by two coral reef terraces younger than the stage 5e terrace and they are arranged in a concentric annular pattern slow uplift rate of ca 0 3 m kyr adjacent to a mariana type subduction margin is typical of the hateruma type the emergence of kikai and hateruma islands is recent younger than isotope stage 5e and 7 respectively reflecting the active deformations of the leading edge at the overriding eurasian plate in the daito type atolls surrounded by fringing reefs have been uplifted very slowly less than 0 05 m kyr but over a time period of at least several million years slow uplift and long history of daito type islands is the result of up bulging of the philippine sea plate as it migrates toward the ryukyu trench

maximum sea levels for the last glacial period from u series ages of submerged speleothems pleistocene sea levels reflect changes in the surface distribution of land sea and ice which in turn significantly influence the earth s climate1 the most complete record of sea levels for the last glacial cycle has come from raised coral reef terraces of the huon peninsula papua new guinea2 4 but interpretation of this record is hampered by relatively large age uncertainties and the possibility of variation in the rate of tectonic uplift subaerial speleothems stalagmites stalactites and flowstones from submerged caves in tetonically stable areas provide an alternative source of data5 8 as their growth stops when rising sea levels flood the caves previous studies of speleothems have been limited by dating precision5 6 and sample availability5 7 here we present high precision thermal ionization mass spectrometric 230th ages9 11 for a comprehensive suite of speleothem samples from the bahamas our results provide a record of maximum elevation of sea levels for the period from 80 to 10 kyr before the present for much of which sea levels are poorly known we also find that regional palaeoclimatic change can be an important factor in the termination of speleothem growth

coastal neotectonics in southern central andes uplift and deformation of marine terraces in northern chile 27 s abstract neotectonic observations allow a new interpretation of the recent tectonic behaviour of the outer fore arc in the caldera area northern chile 27 s two periods of deformation are distinguished based on large scale neogene to quaternary features of the westernmost part of the coastal cordillera late miocene to early pliocene deformations characterized by a weak ne sw to e w extension is followed by uppermost pliocene nw se to e w compression the middle pleistocene to recent time is characterized by vertical uplift and nw se extension these deformations provide clear indications of the occurrence of moderate to large earthquakes microseismic observations however indicate a lack of shallow crustal seismicity in coastal zone we propose that both long term brittle deformation and uplift are linked to the subduction seismic cycle

postglacial rebound at the northern cascadia subduction zone postglacial rebound is the response of the earth to the decay of ice sheets a postglacial rebound model explains crustal tilting and rapid uplift at the northern cascadia subduction zone that occurred during retreat of the cordilleran ice sheet observations explained by the model include the shoreline tilts of two proglacial lakes that formed at 13 5 14 ka 14c yr ago and rapid sea level fall land uplift at 12 12 5 ka modelled mantle viscosity values range from 5 1018 to 5 1019 pa s and are consistent with previous viscosity inferences from observations of crustal deformation following subduction zone earthquakes 1018 1019 pa s no lower limit to subduction zone mantle viscosity is apparent from our model but viscosity values equal to or larger than 1020 pa s are de nitely ruled out our modelled subduction zone viscosity values are smaller than most upper mantle viscosity estimates derived from postglacial rebound studies of tectonically less active regions 1020 1021 pa s the rapid observed uplift at 12 ka requires in addition to a low mantle viscosity rapid unloading from a sudden collapse of remaining coastal portions of the southern cordilleran ice sheet the sudden collapse provides 0 18 m of global eustatic sea level rise approximately 0 7 of the sea level rise associated with melt water pulse ia predictions of a global postglacial rebound model ice 3g with a 1021 pa s upper mantle viscosity were previously applied to geodetic data from this region to isolate signals associated with the earthquake cycle owing to the low viscosity values and resulting rapid recovery of glacial deformation our model predicts present day postglacial rebound uplift rates at least 10 times smaller than ice 3g less than about 0 1 mm yr as the ice 3g adjustments were substantial this indicates the need for re evaluation of the geodetic data 2000 elsevier science ltd all rights reserved

the submarine quaternary stratigraphy of northern spencer gulf south australia abstract the seafloor morphology and lithology of northern spencer gulf south australia is related to successive transgressions and regressions accompanying glacial and non glacial periods vibrocoring has revealed a veneer of holocene bioclastics and a sequence of pleistocene marine strata which display varying degrees of pedogenesis oxidation decalcification and clay illuviation the contact between the holocene and pleistocene sediments is marked by either a thin alluvial or aeolian horizon or by a soil horizon of variable development the pleistocene marine strata have been assigned to four formations older pleistocene marine beds mambray fm false bay fm and lowly point fm based on superposition of lithofacies and intervening pedogenic horizons a sequence of slightly altered laminated lagoonal clays lowly point formation and bryozoan rich limestones false bay formation has been encountered in deeper parts of the gulf stratigraphically below these is a widespread weathered marine unit mambray formation which contains abundant remains of the bivalve anadara trapezia and the foraminifer marginopora vertebralis species absent from the present biota this unit in turn is underlain by a sedimentary sequence strongly altered by pedogenesis and clay illuviation older pleistocene marine beds its original marine character has been largely obliterated a dearth of fluvial gravels and sand from the vibrocores as well as evidence from palaeosols indicate that a predominantly semi arid to arid climate has persisted in the northern gulf region since ca 125 000 yrs ago and that there has been little subsequent terrigenous material transported to the gulf

transformation textures in post perovskite understanding mantle flow in the d layer of the earth 1 deformation and texture formation in mg fe sio3 post perovskite ppv is a potential explanation for the strong seismic anisotropy that is found in the d layer of the earth however different experimental approaches have resulted in different lattice preferred orientations lpo in deformed ppv that have led to ambiguity in the interpretation of deformation in the lowermost mantle here we show that deformation of the analogue substance cairo3 during a phase transformation from perovskite to ppv leads to a transformation texture that differs from the cairo3 ppv deformation texture but resembles the results from ppv deformation experiments in diamond anvil cells assuming material spreading parallel to the core mantle boundary our results predict a widespread shear wave splitting with fast horizontal s waves which is compatible with seismic studies downwelling material that undergoes a phase transformation may develop a transformation texture that would locally result in vertically polarized fast s waves