valley scale morphology drives differences in fluvial sediment budgets and incision rates during contrasting flow regimes abstract high resolution topographic surveys using lidar and multibeam sonar can be used to characterize and quantify fluvial change this study used repeat surveys to explore how topographic change fluvial processes sediment budgets and aggradation and incision rates vary across spatial scales and across two contrasting decadal flow regimes in a regulated gravel cobble river a novel method for quantifying digital elevation model uncertainty was developed and applied to a topographic change detection analysis from 2006 2008 to 2014 during this period which had four modest 3 5 year floods most sediment was laterally redistributed through bank erosion and channel migration erosion primarily occurred in the floodplain 97 000 m 3 terraces 80 000 m 3 and lateral bars 58 000 m 3 while deposition occurred in the adjacent pools 73 000 m 3 fast glides 48 000 m 3 and runs 36 000 m 3 in contrast significantly higher magnitude and longer duration floods from 1999 to 2006 2008 caused sediment to be displaced longitudinally with the upstream reaches exporting sediment and the downstream reaches aggrading the river maintained floodplain connectivity during both periods despite different processes dominating the type of connectivity larger floods promoted overbank scour and avulsion while smaller floods promoted bank erosion and lateral migration this study explores and illustrates how the geomorphic response to contrasting flood regimes in a nonuniform river is highly dependent on which landforms are controlling hydraulics

variability of the north atlantic thermohaline circulation during the last interglacial period studies of natural climate variability are essential for evaluating its future evolution greenland ice cores suggest that the modern warm period the holocene has been relatively stable for the past 9 000 years much less is known about other warm interglacial periods which comprise less than 10 of the climate record during the past 2 5 million years here we present high resolution ocean sediment records of surface and deep water variables from the bermuda rise spanning the last interglacial period about 118 000 127 000 years ago in general deep water chemical changes are coincident with transitions in surface climate at this site the records do not show any substantial fluctuations relative to the much higher variability observed during the preceding and subsequent cool climates the relatively stable interglacial period begins and ends with abrupt changes in deep water flow we estimate using 230 th measurements to constrain the chronology that transitions occur in less than 400 years

history of stage 5 sea level in bermuda review with new evidence of a brief rise to present sea level during substage 5a abstract oxygen isotope substage 5e is represented by the devonshire formation in bermuda the occurrence of these coastal marine deposits to about 5 m indicates pleistocene sea level data in bermuda do not need tectonic corrections a few published u series coral dates suggest that a conglomerate spencer s point formation may have formed during substage 5c geologic mapping however indicates that the eolianite beneath the conglomerate is pre rather than post devonshire formation in age as was previously thought and the aminostratigraphy of marine sheels also confirms the correlation of the spencer s point and devonshire formations substages 5c and 5a are represented by the southampton formation large eolianites comprise the bulk of this formation they are onlapped by a few small younger marine 1 m and eolian deposits aminostratigraphy confirms that these late southampton age deposits are significantly younger than the devonshire formation and u series dates indicate a substage 5a age the setting of some of these deposits along a protected shoreline precludes discounting their position as anomalous due to large storms this evidence that sea level in bermuda was at about present datum late in substage 5a agrees with interpretations of neotyrrhenian deposits of mediterranean shorelines but not with inferences from the deep sea oxygen isotope record or with data from uplifted coral reefs

residence of ree y th and u in granites and crustal protoliths implications for the chemistry of crustal melts a systematic study with laser ablation icp ms scanning electron microscopy and electron microprobe revealed that 70 95 wt of ree except eu y th and u in granite rocks and crustal protoliths reside within reeythu rich accessories whose nature composition and associations change with the rock aluminosity the accessory assemblage of peraluminous granites migmatites and high grade rocks is composed of monazite xenotime in low ca varieties apatite zircon thorthosilicate uraninite and betafite pyrochlore metaluminous granites have allanite sphene apatite zircon monazite and thorthosilicaie peralkaline granites have aeschinite fergusonite samarskite bastnaesite fluocerite allanite sphene zircon monazite xenotime and th orthosilicate granulite grade garnets are enriched in nd and sm by no less than one order of magnitude with respect to amphibolite grade garnets granulitegrade feldspars are also enriched in lree with respect to amphibolite grade feldspars accessories cause non henrian behaviour of ree y th and u during melt solid partitioning because elevated fractions of monazite xenotime and zircon in common migmatites are included within major minerals their behaviour during anatexis is controlled by that of their host settling curves calculated for a convecting magma show that accessories are too small to settle appreciably being separated from the melt as inclusions within larger minerals biotite has the greatest tendency to include accessories thereby indirectly controlling the geochemistry of ree y th and u we conclude that ree y th and u are unsuitable for petrogenetical modelling of granitoids through equilibrium based trace element fractionation equations

sea level change and superstorms geologic evidence from the last interglacial mis 5e in the bahamas and bermuda offers ominous prospects for a warming earth abstract geological observations from last interglacial lig mis 5e eemian carbonate landscapes in the bahamas and bermuda reveal a turbulent climate transition at the close of the peak interglacial the interval is associated with rapid multi meter shifts in sea level as major ice sheets melted and or collapsed sedimentary evidence from the eastern bahamas includes wave transported megaboulders lowland chevron storm ridges and hillside runup deposits this trilogy collectively provides direct geological evidence of frequent intense storms generating sustained long period waves from the northeast atlantic ocean penecontemporaneous with wave deposits is the subtidal production and flux of a massive volume of ooid sediments associated with amplified winds and storminess during the latter half of mis 5e that resulted in exponential island growth steeper temperature and pressure gradients were evident in the north atlantic ocean while the southern ocean appears to have had a major role in affecting atmospheric co2 as warming of the southern ocean drives ventilation of the deep ocean co2 in turn acts as a tight control knob on global climate the dramatic oceanographic and island building events of late mis 5e are unique among other interglacial periods of the past half million years the lig record reveals that strong climate forcing is not required to yield major impacts on the ocean and ice caps antarctic ice cores document that lig atmospheric co2 was 275 ppm while global temperature was in terms of lyellian uniformitarian principles the trilogy of coeval deposits of mis 5e described herein do not translate to our modern climate parameters and further cannot be explained by coincidental megatsunami in our industrial world rapidly increasing atmospheric co2 rates 2 ppm yr have surpassed 408 ppm levels not achieved since the pliocene 3 ma ago while global temperature increased 1 c since the 1870s with greatly increased co2 forcing at unmatched rates except perhaps during global extinction events dramatic change is certain in the interest of our future world we must seek to understand the complex set of linked natural events and field observations that are revealed in the geology of past warmer climates

south carolina interglacial sites and stage 5 sea levels abstract amino acid and other studies have been made on the 30 km pleistocene sections of the intracoastal waterway between myrtle beach and little river south carolina our ratios differentiate the long established waccamaw oldest canepatch and socastee formations the ratios from the four laboratories that have worked in this area agree very well and apparent conflicts with u series dates may merely reflect an abundance of reworked corals our amino acid correlations with u series coral dates in south carolina bermuda and the mediterranean all argue that the classical canepatch and its horry clay date from isotope stage 5e and not as has been implied from stage 7 9 11 or 13 excavations and erosion have increased position fixing problems along the waterway and canepatch amino acid ratios and u series dates 460 000 100 000 yr b p at icw5 may be from an older unit the canepatch shows the double marine transgression visible in many stage 5e deposits pollen shows that the second transgression occurred late in the interglaciation and stratigraphic studies show that it reached 14 m it therefore fits very well antarctic ice surge models of stage 5 sea level and climate the socastee adds to the evidence for one or more sea levels above 0 m late in stage 5

influence of oxygen fugacity on mineral compositions in peralkaline melts the katzenbuckel volcano southwest germany the igneous rocks of the katzenbuckel southwest germany represent a unique and unusual alkaline to peralkaline association within the european volcanic province the magmatic activity can be subdivided into two main phases phase i comprises the main rock bodies of phonolite and nepheline syenite which were later intruded by different peralkaline dyke rocks tinguaites and alkali feldspar syenite dykes of phase ii the dyke assemblage was accompanied by magnetite and apatite veins and was followed by a late stage pneumatolytic activity causing autometasomatic alterations as is typical for alkaline to peralkaline igneous rocks early mafic minerals of phase i rocks comprise olivine augite and fe ti oxides which are substituted in the course of fractionation by na amphibole and na pyroxene for the early magmatic stage calculated temperatures range between 880 and 780 8c with low silica activities 0 4 to 0 6 but high relative oxygen fugacities between 0 5 and 1 9 log units above the fmq buffer even higher oxygen fugacities above the hm buffer are indicated for the autometasomatic alteration which occurred at temperatures between 585 and 780 8c and resulted in the formation of pseudobrookite and hematite the unusually high oxygen fugacities even during the early magmatic stage are recorded by the major element compositions of the mafic minerals forsterite content in olivine between 68 and 78 mol up to 6 2 wt zro2 and 8 5 wt tio2 in clinopyroxene the unusual mineral assemblages pseudobrookite freudenbergite and by the enrichment of fe 3 in the felsic

partitioning of sr ba rb y and lree between alkali feldspar and peraluminous silicic magma samples from well known rhyolitic systems in the western usa were analyzed to determine trace element partition coefficients between sanidine and coexisting melt both d sr and d eu correlate positively with an concentration in sanidine barium not surprisingly shows more correlation with or in sanidine all three show negative correlations with whole rock al2o3 partition coefficients for ree show a decreasing trend with strong positive d eu d lree correlate negatively with the whole rock al2o3 in peraluminous rocks al2o3 in magma seems to exert a major influence on partition coefficients of trace elements with increasing al2o3 concentration the melt composition becomes increasingly similar to that of feldspar incompatible trace elements rb y nb and zr in sanidine show positive trends whereas compatible trace elements sr eu and ba show negative correlations when plotted against whole rock al2o3 lrees which are expected to substitute for ca in the sanidine structure behave like sr and eu because trace element partitioning is influenced by both crystal and magma compositions multiple regression analysis has been used to predict trace element partition coefficients the equations will assist workers in the selection of partition coefficients used in petrogenetic models of silicic systems

geology of new providence island bahamas contrary to the popular notion that the bahama islands are built of eolianite deposits at least new providence island consists principally of elevated marine sand flat and protected lagoon deposits narrow eolianite ridges separate such deposits from reef tract deposits capped by prograding beach deposits on the northern bank margin side of the island all exposed depositional phases are quaternary the most extensively exposed deposits we correlate with the 125 000 yr high sea level recognized world wide elevations of keystone vugs in beach deposits of that depositional phase indicate paleo mean sea levels of as high as 10 m deposits of an earlier depositional phase suggest that there was then no island but only a barrier sand shoal and reef tract holocene additions to the island9s area have been minor and in the form of prograding beach deposits classical superpositional stratigraphy has limited value in the elucidation of new providence geology due to the nature of the deposits which are partially overlapping thin facies sheets and lenses therefore we have also used a morphostratigraphic approach and as paleontological markers species of cerion a very rapidly evolving genus of land snail limited radiometric dating is reported islands on bahama type banks of earlier geologic periods were probably built almost entirely of beach deposits rather than the eolianites and elevated marine deposits of which new providence is built

holocene oolitic marine sand complexes of the bahamas abstract although the general factors influencing the occurrence and distribution of oolitic systems are well known details of their landscape scale patterns and formative processes are less systematically explored by reviewing published studies and presenting new data and insights this review systematically examines a suite of holocene systems from the bahamas in which patterns and processes are characterized and explicitly linked with the goal of providing more realistic and accurate models for variability heterogeneity and predictability in these systems and their ancient analogs sedimentological geomorphic and hydrodynamical data document that each ooid shoal is unique in detail yet shoals share common elements within bar forms systematic trends in grain size type and sorting are related to spatial and temporal variability in wave tide and current energy these trends are driven by connections among sedimentology hydrodynamics and geomorphic forms as they shape and concomitantly are shaped by each other similarly due to feedbacks a limited number of bar forms occur among shoals including tidal sand ridges parabolic bars transverse shoulder bars tidal deltas and sand flats the dominant bar form broadly corresponds with flow velocities within and among shoals among bahamian tidal shoals the mean grain size of ooids maximum bar heights and the width of the oolitic facies belts are all positively correlated collectively these results illustrate the mode and magnitude of variability in shapes orientations and sedimentology of holocene oolitic bodies interpreted to be driven by self organization and autogenic processes these perspectives provide testable qualitative and quantitative insights that can be used to understand and predict the character of ancient analogs

revision of the late pleistocene stratigraphy of bermuda the quaternary stratigraphy of bermuda is one of the world s most complete sedimentary records of interglacial highstands representing at least the past million years yet in terms of the last interglacial rocky bay formation marine isotope substage mis 5e only scanty deposits are preserved in contrast mis 7 generally regarded as a diminutive interglaciation exposes widespread emergent subtidal deposits of the belmont formation indicating a prolonged sea level highstand at ca 2 5 0 3 m this belmont paradox has prompted a reexamination of the geology of key sites along the south shore of bermuda this revision of the late quaternary stratigraphy of bermuda is based on geological field observations primarily the questionable origin of red soil like deposits it is concluded here that there is no physical evidence of the exposure of the upper belmont surface for a full glacial cycle 70 100 ka and that interbedded reddish soil like lenticular deposits are the result of colluvial activity during mid mis 5e reexamination of previously published uranium series u th ages indicates that several 3 m notches contain a mix of ca 125 ka and older coral ages contrary to previous works this study favors an early mis 5e interpretation of the coral ages from the 2 5 m belmont shoreline which is further supported by amino acid racemization aar ratios on whole rock poecilozonites glycymeris and brachiodontes samples from shore and notch deposits an updated aar kinetic model demonstrates that the bulk of epimerization occurred during warm interglacial intervals between 130 and 80 ka and the last 10 ka of the holocene this revised stratigraphy of bermuda now falls into accordance with a more general view of middle and late pleistocene sea level history

changes in meridional temperature and salinity gradients in the north atlantic ocean 30 72 n during the last interglacial period eight deep sea sediment cores from the north atlantic ocean ranging from 31 to 72 n are studied to reconstruct the meridional gradients in surface hydrographic conditions during the interval of minimum ice volume within the last interglacial period using benthic foraminiferal 18o measurements and estimates of sea surface temperature sst and sea surface salinity sss we show that summer ssts and ssss decreased gradually during the interval of minimum ice volume at high latitude sites 52 72 n whereas they were stable or increased during the same time period at low latitude sites 31 41 n this increase in meridional gradients of ssts and ssss may have been due to changes in the latitudinal distribution of summer and annual average insolation and associated oceanic and atmospheric feedbacks these trends documented for the eemian ice volume minimum period are similar to corresponding changes observed during the holocene and may have had a similar origin

boulder deposits from large waves during the last interglaciation on north eleuthera island bahamas abstract seven boulders measuring 100 to 1000 m 3 are scattered along the coastal ridge of north eleuthera some are situated on ridge crests up to 20 m above present sea level the boulders were probably deposited during oxygen isotope substage 5e or 5d as shown by their stratigraphic setting and by amino acid racemization ratios d alloisoleucine l isoleucine ratios were determined for land snails and oolite of both marine and eolian origin was associated with the boulders like the boulders the probable source rocks exposed in the adjacent cliffs are composed of marine and eolian limestone of oolitic and peloidal composition the source beds are correlated with stage 9 or 11 the largest boulder is about 10 times the size of the largest holocene ones moved by waves in the area tsunamis are a reasonable possibility as a transporting mechanism of the pleistocene boulders however if deposited instead by storms during the last interglaciation the storms were of much greater intensity than those occurring in the region during the late holocene

chevron ridges and runup deposits in the bahamas from storms late in oxygen isotope substage 5e abstract landward pointing v shaped sand ridges several kilometers long are common along the windward margin of the bahama islands their axes share a northeast southwest trend internally the ridges contain low angle oolitic beds with few erosional truncations commonly interbedded are tabular fenestrae rich beds such as those formed by the sheet flow of water over dry sand defined here as chevron ridges these landforms appear to have originated in the rapid remobilization of bank margin ooid bodies by the action of long period waves from a northeasterly source deposits along adjacent coastlines also preserve evidence of the impact of large waves reworked eolian sand bodies preserve beach fenestrae and hydraulic scour traces up to 40 m on older ridges on cliffed coasts 1000 ton boulders have been thrown well inland recording the impact of large waves amino acid ratios confirm a correlation of the ridges across the archipelago while stratigraphy spacing and cross cutting relationships indicate emplacement as sea level fell rapidly from the substage 5e maximum at or above 6 m

evidence for sea level oscillations by the characteristic thickness of marine deposits from raised terraces of southern calabria italy abstract clastic deposits associated with marine terraces can provide evidence for detecting eustatic oscillations the method is based on the characteristic thickness ct of beach formations which are generally deposited on a wave cut platform between the breakpoint and the swash upper limit on any present day coast ct reflects equilibrium related to current shore processes with a constant sea level it represents a local threshold t cr as when sea level rises ct increases by a value equal to the rise amplitude this amount is reduced in uplifted areas by the magnitude of coeval uplifting the amplitude of sea level variations detected by ct can be calculated knowing ct t cr uplift rate and the duration of an oscillation the method is applied to the clastic deposits of 23 marine terraces stepped between 52 and 172 m and shaped over the mis 5 mis 4 period along the calabria coast of the messina strait not only the great orbital oscillations mis 5 5 mis 5 3 mis 5 1 and mis 3 are recorded but also several rapid and low amplitude events are detected into each substage the most surprising result is the ten small oscillations during mis 5 5 the duration of which ranges between 2 ka and less than 1 ka while sea level oscillates from 0 5 to 12 m in amplitude by calculating initial relative sea level highstands and also lowstands preceding them detailed eustatic oscillations of the curve are drawn

elemental and sr nd isotope geochemistry of two neoproterozoic mangerite suites in se brazil implications for the origin of the mangerite charnockite granite series abstract neoproterozoic 625 ma mangerites are the dominant rock type in a 100 km long belt of deformed tabular bodies in the socorro guaxupe nappe sgn a high grade terrane southwest of the sao francisco craton southeastern brazil the mangerites form two suites sao pedro de caldas shows a wide compositional variation and abundant felsic rocks mangerite hornblende granite leucogranite initial 87 sr 86 sr of 0 707 and initial e nd of 4 to 5 divinol ndia is dominated by more mafic mangerites with minor charnockite granite and diorite and has initial 87 sr 86 sr of 0 710 and initial e nd of 10 to 12 the probable sources of the sao pedro de caldas mangerites were granulites depleted by previous melting events in radiogenic elements and the light rare earth element primary melts of sao pedro de caldas were generated at 950 c p 10 kbar from a biotite free and k feldspar bearing source with plagioclase as an important residual phase the amount of melting was low as required by low mg enrichment in nb and ta relative to potential sources and high nb ta and was probably controlled by exhaustion of k feldspar in the source contribution from infracrustal mafic melts cannot be ruled out and would help explain the weakly negative e nd and high nb but is not essential the divinol ndia rocks depart from typical within plate mangerites towards more mafic rocks with orogenic signatures e g higher mg sr ca lower zr radiogenic isotope data require sources with greater crustal residence time than those envisioned for sao pedro de caldas elemental data require that these sources were more depleted e g higher k rb granulites with these characteristics are exposed in the northern portion of the sgn these were probably melted at slightly higher temperatures than the sao pedro de caldas suite 970 c before a sufficient amount of melt was generated and the magmas could leave their sources in this case k feldspar was exhausted and plagioclase in amounts exceeding those of the granite minimum was dissolved

the mineralogical diversity of alkaline igneous rocks critical factors for the transition from miaskitic to agpaitic phase assemblages geochemically the large family of alkaline plutonic rocks both qtz undersaturated and oversaturated compositions can be subdivided into metaluminous na 2 o k 2 o al 2 o 3 types in this paper we discuss two important aspects of the mineralogical evolution of such rocks with respect to their fe mg phases a major mineralogical transition observed is the precipitation of arfvedsonite or aegirine instead of fayalite or magnetite ilmenite the relative stability of these phases is controlled by oxygen fugacity and na activity in the crystallizing melts if na activity in the melt is high enough arfvedsonite aegirine form a common assemblage in peralkaline rocks under both reduced and oxidized conditions major mineralogical differences within this rock group exist with respect to their high field strength element hfse rich minerals most syenitic rocks known as miaskites contain zircon titanite or ilmenite as hfse rich minerals whereas in agpaites complex na k ca ti zr silicates incorporate the hfse similarly only a small group of peralkaline granites are found to lack zircon titanite or ilmenite but instead contain na k ca ti zr silicates here we present a detailed phase petrological analysis of the chemical parameters na 2 o cao k 2 o that influence the transition from miaskitic to agpaitic rocks based on the occurrence of ti and zr minerals several transitional mineral assemblages are identified and two major evolution trends for agpaites are distinguished a high ca trend which is exemplified by the alkaline rocks of the kola province russia and a ca depletion trend which is displayed by the alkaline rocks of the gardar province south greenland both trends show significant na enrichment during magmatic evolution high ca agpaites evolve from nephelinitic parental melts that did not crystallize large amounts of plagioclase in contrast agpaites showing ca depletion originate by extensive fractionation of plagioclase from basaltic parental melts in some peralkaline granites evolutionary trends are observed that culminate in agpaite like hfse mineral associations in the most evolved rocks

valley formation by fluvial and glacial erosion cross valley profiles from the west slope of the olympic peninsula washington are used to investigate the relative effects of fluvial and glacial erosion on valley formation unlike most ranges where glaciers and rivers sequentially occupied the same valleys neighboring valleys in the olympic mountains developed in similar lithologies but were subject to different degrees of glaciation allowing comparison of the net effect of glacial and fluvial processes integrated over many glacial cycles upslope drainage area was used to normalize comparisons of valley width ridge crest to valley bottom relief and valley cross sectional area as measures of net differences in the mass of rock excavated from below ridgelines for 131 valley spanning transects valley width relief and cross sectional areas are similar for glaciated partly glaciated and unglaciated fluvial valleys with drainage areas of 10 km 2 but diverge downslope glaciated valleys draining 50 km 2 reach two to four times the cross sectional area and have to 500 m greater relief than comparable fluvial valleys partly glaciated valleys have intermediate dimensions at distances of 5 km from valley heads the cumulative upstream volume of rock removed to form valleys is two to four times greater in glacially incised valleys than in fluvial valleys the finding of strong differences in the net result of valley excavation by fluvial and glacial erosion supports the interpretation that alpine glaciers are more effective erosional agents than are rivers and implies that large alpine valleys deepened and enlarged in response to pleistocene glaciation

sedimentary dynamics and high frequency sequence stratigraphy of the southwestern slope of great bahama bank abstract new geophysical data from the leeward slope of great bahama bank show how contour currents shape the slope and induce re sedimentation processes along slope segments with high current control drift migration and current winnowing at the toe of slope form a deep moat here the slope progradation is inhibited by large channel incisions and the accumulation of large mass transport complexes triggered by current winnowing in areas where the slope is bathed by weaker currents the accumulation of mass transport complexes and channel incision is rather controlled by the position of the sea level large slope failures were triggered during the mid pleistocene transition and mid brunhes event both periods characterized by changes in the cyclicity or the amplitude of sea level fluctuations within the seismic stratigraphic framework of third order sequences four sequences of higher order were identified in the succession of the upper pleistocene these higher order sequences also show clear differences in function of the slope exposure to contour currents two stochastic models emphasize the role of the contour currents and slope morphology in the facies distribution in the upper pleistocene sequences in areas of high current influence the interplay of erosional and depositional processes form a complex facies pattern with downslope and along strike facies alterations in zones with lower current influence major facies alternations occur predominately in downslope direction and a layer cake pattern characterizes the along strike direction therefore this study highlights that contour currents are an underestimated driver for the sediment distribution and architecture of carbonate slopes

flood driven topographic changes in a gravel cobble river over segment reach and morphological unit scales regulated rivers generally incise below dams that cut off sediment supply but how that happens and what the consequences are at different spatial scales is poorly understood modern topographic mapping at meter scale resolution now enables investigation of the details of spatial processes in this study spatial segregation was applied to a meter scale raster map of topographic change from 1999 to 2008 on the gravel cobble regulated lower yuba river in california to answer specific scientific questions about how a decadal hydrograph that included a flood peak of 22 times bankfull discharge affected the river at segment reach and morphological unit scales the results show that the river preferentially eroded sediment from floodplains compared to the channel and this not only promoted valley wide sediment evacuation but also facilitated the renewal and differentiation of morphological units especially in the channel at the reach scale area of fill and mean net rate of elevational change were directly correlated with better connectivity between the channel and floodplain while the mean rate of scour in scour areas was influenced by the ratio of slope to bankfull froude number a ratio indicative of lateral migration versus vertical downcutting hierarchical segregation of topographic change rasters proved useful for understanding multiscalar geomorphic dynamics this article is protected by copyright all rights reserved

crystallization conditions and controls on trace element residence in the main minerals from the pedra branca syenite brazil an electron microprobe and la icpms study abstract major and trace element microanalyses of the main minerals from the 610 ma pedra branca syenite southeast brazil allow inferences on intensive parameters of magmatic crystallization and on the partition of trace elements among these minerals with important implications for the petrogenetic evolution of the pluton two main syenite types make up the pluton a quartz free syenite with tabular alkali feldspar laminated silica saturated syenite lss with na rich augite phlogopite hematite magnetite titanite apatite and a quartz bearing syenite laminated silica oversaturated syenite lso with scarce corroded plagioclase plus diopside biotite hornblende ilmenite magnetite titanite apatite both types share a remarkable enrichment in incompatible elements as k ba sr p and lree apatite saturation temperatures of 1060 1090 c are the best estimates of liquidus whereas the pressure of emplacement based on al in hornblende barometry is estimated as 3 3 to 4 8 kbar although both units crystallized under oxidizing conditions oxygen fugacity was probably higher in lss as shown by higher mg of the mafic minerals and higher hematite contents in hem ilmss in contrast with the ca bearing alkali feldspar from lso which hosts most of the whole rock sr and pb virtually ca free alkali feldspar from lss hosts 50 of whole rock sr and 80 of pb the remainder of these elements being shared by apatite pyroxene and titanite this contrast reflects a strong crystal chemical control whereby a higher proportion of an element with similar ratio and charge ca2 enhances the residence of sr and pb in the m site of alkali feldspar the more alkaline character of the lss magma is inferred to have inhibited zircon saturation zr hf remained in solution until late in the crystallization and were mostly accommodated in the structure of ca na pyroxene and titanite which are one order of magnitude richer in these elements compared to the same minerals in lso where most of zr and hf are inferred to reside in zircon the ree th and u reside mostly in titanite and apatite d ree tit ap raises steadily from 1 to 6 from la to tb then remains constant up to lu in the lso sample these values are about half as much in the lss sample where lower contents of incompatible elements in titanite are attributed to its greater modal abundance and earlier crystallization

cliff top megaclast deposits of ireland a record of extreme waves in the north atlantic storms or tsunamis past occurrences of major tsunami in the global record have often been inferred from the presence of megaclast accumulations at significant heights above sea level which sometimes exhibit a pronounced seaward directed imbricate fabric the aran islands off the west coast of ireland exist in a marine environment which is totally unprotected from the most extreme sea states encountered in the north atlantic spectacular megaclast accumulations are found along the tops of vertical cliffs on these islands the elevation of these deposits varies from 0 m to 50 m above mean sea level and they include clasts weighing 250 tonnes at sea level over 117 tonnes at 12 m and 2 9 tonnes at 50 m above sea level imbrication measurements on these megaclasts indicate a well defined and consistent mean direction from the southwest for the emplacing waves one that is consistent with the prevalent storm wind direction for the area the megaclast accumulations are subject to episodic and on going erosion by cliff retreat but the existing accumulations are estimated to record events since at least 1839 recent emplacement and reworking is evidenced by trapped plastic detritus within the deposits and eyewitness accounts of large storms during which clasts have been emplaced similar deposits are found on the exposed coasts of the shetland and orkney islands off scotland there is at present no evidence of any tsunami in recorded history affecting the western irish and scottish coasts other than those generated by the lisbon earthquake of 1755 where the wave effects were slight thus the presence of megaclast accumulations at significant heights above sea level on exposed coasts and exhibiting imbrication should not be used as a definitive criterion for the past occurrence of tsunami these deposits attest to extreme wave conditions occasionally encountered in the north atlantic and act as a record of such events extending back at least 160 years such data on extreme wave conditions are essential for the prediction of the effects of deepwater waves on structures such as offshore drilling platforms

sea level and climate changes during ois 5e in the western mediterranean palaeontological geomorphological and sedimentological data supported by isotopic dating on oxygen isotopic stage ois 5e deposits from the spanish mediterranean coast are interpreted with the aim of reconstructing climatic instability in the northern hemisphere data point to marked climatic instability during the last interglacial ois 5e with a change in meteorological conditions and consequently in the sedimentary environment the oolitic facies generated during the first part of ois 5e ca 135 kyr shift into reddish conglomeratic facies during the second part ca 117 kyr sea surface temperature sst and salinity are interpreted mainly on the basis of warm senegalese fauna which show chronological and spatial differential distribution throughout the western mediterranean present hydrological and meteorological conditions are used also as modern analogues to reconstruct climatic variability throughout the last interglacial and this variability is interpreted within the wider framework of the north atlantic record all the available data indicate an increase in storminess induced by an increase in the influence of northwesterlies a slight drop of sst in the northern western mediterranean and an important change in meteorological conditions at the end of ois 5e 117 kyr these changes correlate well with the decrease in summer insolation and with the climatic instability recorded in north atlantic high latitudes

palaeoclimatic significance of co occurring wind and water induced sedimentary structures in the last interglacial coastal deposits from bermuda and the bahamas abstract the late pleistocene stratigraphic record from the bahamas and bermuda archipelagoes includes peculiar v shaped coastal ridges and wedges of seaward dipping planar beds showing fenestral porosity up to 40 m above present sea level judging from this porosity these landforms were till now interpreted as resulting from the action of giant waves during a period of climatic instability at the end of the last interglacial period the occurrence of widespread mm thick laminae of aeolian origin subcritically climbing translatent stratification throughout these deposits does not agree with this hypothesis it rather suggests that the v shaped ridges and seaward dipping beds represent fossil parabolic and climbing aeolian dunes respectively the occurrence of fenestrae high above the intertidal zone could be related to both wave splashing and rainfall action parabolic dunes are restricted to the nw bahamas they were probably formed during a time interval ca 500 5000 yr when regional climatic conditions were dryer than today and characterized by persistently blowing ne trade winds

osl dating of the aterian levels at dar es soltan i rabat morocco and implications for the dispersal of modern homo sapiens the aterian is a distinctive middle palaeolithic industry which is very widely spread across north africa its dating and significance have been debated for nearly a century renewed interest in the aterian has arisen because of a recent proposal that its development and spread may be linked to the dispersal of anatomically modern humans the industry contains technological innovations such as thin bifacially flaked lithic points and pedunculates as well as evidence for personal ornaments and use of red ochre such markers as shell beads are believed to be indicative of symbolic behaviour dar es soltan i on the atlantic coast of morocco contains a thick sequence of aterian deposits that were thought to represent the later stages of development of this industry new optically stimulated luminescence dates and geomorphological study indicate a much older sequence and so far the earliest yet recorded ages for the aterian they suggest an appearance in the maghreb region during mis marine isotope stage 5

growth and development of notch speleothems from cayman brac british west indies response to variable climatic conditions over the last 125 000 years abstract the spectacular wave cut notch on cayman brac which is 6 m above sea level formed during marine isotope stage 5e highstand 128 000 to 116 000 years ago on cayman brac the notch is commonly decorated with speleothems mostly stalactites that are formed of calcite aragonite and micrite these notch speleothems are characterized by numerous growth zones that are delimited by minor and major hiatal surfaces u th dating indicates that the major growth phases which took place 73 000 to 59 000 years ago 46 000 to 49 000 years ago and 4000 to 1000 years ago were separated by periods when erosion and minimal precipitation were the norm the 18ovpdb values range from 6 5 to 0 3 with a mode between 2 and 4 and an average of 3 1 whereas the 13cvpdb values range from 10 5 to 1 9 with one mode between 2 0 and 3 0 a second mode between 7 0 and 8 0 and an overall average of 6 1 the 18o and 13c values co vary the 18ovpdb and 13cvpdb values are similar to those from the young 125 000 years cave speleothems today with the little evidence of active speleothem growth in the notch or caves cayman brac is characterized by dry sub tropical forest and shrubland with xeric components on the elevated eastern end of the island available data indicate that most of the speleothem growth took place during the transitions from marine isotope stage mis 5a to 4 and mis2 to 1 these transitional periods which define the onset and termination of glaciation in the northern latitudes were probably characterized by higher rainfall and development of tropical rainforests it is evident that notch speleothems like those from cayman brac are valuable archives of the paleoclimate conditions that have existed since the highstand associated with mis5e

discussion of palaeoclimatic significance of co occurring wind and water induced sedimentary structures in the last interglacial coastal deposits from bermuda and the bahamas kindler and strasser 2000 sedimentary geology 131 1 7 kindler and strasser sediment geol 131 2000 1 have identified sedimentary structures of possible aeolian origin within the chevron ridges of north eleuthera thereby proposing that they are migrating parabolic dunes formed by wind rather than the impact of giant waves as postulated by hearty et al quat res 50 1998 309 however the abundance of beach fenestrae and the conspicuous absence of foreset bedding throughout the chevron structures invalidate their conclusions in addition enormous megaboulders situated between the two kindler and strasser 2000 study sites in north eleuthera confirm the occurrence of giant waves at the end of marine isotope substage mis 5e and argue strongly the same genesis for the chevron ridges and runup deposits

the last interglacial shoreline in australia a review abstract marginal marine strata of last interglacial age occur in a range of morphostratigraphic settings around the australian coastline the lithofacies are similar to their holocene equivalents but are partly lithified elevated and laterally displaced inland uranium series ages for corals and molluscs from widely separated localities around the australian coastline are generally in accord with the accepted age for oxygen isotope substage 5e 125 000 10 000 bp the value generally accepted for the last interglacial maximum amino acid racemisation has principally been applied to correlation of sequences with benchmark sites dated by the uranium series method elevations of preserved last interglacial shorelines do not support the notion that australia is a stable continent significant neotectonic anomalies include cape cuvier 10 5 m fleurieu peninsula 6 m the coorong coastal plain 10 m and tasmania 32 m each indicating contrasting degrees of local uplift the tasmanian sequences are the highest occurrence on the australian continent and have been attributed to uplift as a result of mantle hotspot processes with the exception of these tectonically uplifted sites the height of the last interglacial sea surface around the australian coastline is consistently below the 6 m level globally attributed to this high sea level stand in australia the most consistent datum is from western eyre peninsula where a level 2 m above present mean sea level is ubiquitous the more southerly limit of coral growth and wider distribution of subtropical molluscan fauna are in accordance with warmer ocean waters during substage 5e approximately 2 c the extent of racemisation in molluscan fossils from southern australia also excludes the possibility of a more equable latitudinal distribution of mat during substage 5e

irregular fenestrae in bahamian eolianites a rainstorm induced origin abstract fenestrae are primary or penecontemporaneous pores in the sediment framework that are larger than grain supported interstices these features have long been used to characterize peritidal environments and as a sea level indicator in ancient successions we report the occurrence of irregular i e equidimensional fenestrae in pleistocene eolianites on san salvador and eleuthera bahamas as much as 35 m above the coeval sea level a rainstorm induced origin is proposed as the mechanism for production of such voids in eolian deposits we suggest that fenestrae should be used as a sea level indicator only when they are associated with other intertidal or peritidal characteristics

chronostratigraphic confirmation of mis 5 age of a baymouth bar at is arenas cagliari italy in 2005 the national geological survey of italy released the new sheet 557 cagliari 1 50 000 scale a coastal barrier marine formation at is arenas cagliari sardinia italy containing strombus bubonius was reassigned a holocene age in contradiction with extensive literature published over the past century indicating an mis 5 5 age in 2007 spurred by this controversy a short note was published in il quaternario demonstrating the stratigraphic difficulties in attributing the age of this formation to the holocene later another paper signed by numerous italian geologists was published in il quaternario criticizing the holocene attribution the tectonic consequences of assigning a holocene age to these deposits are of great significance as their elevation could only be explained by strong uplift over the past few thousand years such a tectonic setting would imply a radical change in the recent geodynamic history of sardinia which is considered to be among the most stable areas of the mediterranean basin this paper provides further geochronological data for a mis 5 age for the deposits at is arenas electron spin resonance esr analyses were performed on 4 fossil shells sampled along the fossil baymouth bar the results established an mis 5 age the amino acid racemization aar and u series data that first determined a correlation with the last interglacial tyrrhenian age of this ancient shoreline is reviewed with additional documentation provided by the fossil marker s bubonius

geomorphic evidence of major sea level fluctuations during marine isotope substage 5e cape cuvier western australia abstract a detailed geomorphologic and morphostratigraphic investigation of raised marine terraces at cape cuvier western australia reveals two morphologically distinct units a lower well developed accretional reef terrace between 3 and 5 5 m above mlws mean low water springs hereafter denoted as represents an extended interval of stable sea level an upper erosional terrace and incipient coralgal rim between 8 5 to 10 5 m represents a brief sea level stillstand at this higher elevation these features suggest the lower and upper terraces developed during discrete sea level events in an attempt to better define the timing of emplacement of each marine unit 20 coral samples collected along vertical and lateral reef growth axis from both terraces were analysed with u series dating unfortunately all coral samples exhibited elevated 234 u initial values suggesting that pervasive uptake of 234 u enriched uranium and 230 th thorium had occurred despite the shortcomings of absolute dating a succession of events can be resolved though morphostratigraphic relationships comparison of the facies relationships coral growth and morphostratigraphic features between the lower and upper terraces indicates that an early to mid mis 5e stillstand at 3 to 5 m was followed by a late rise to 8 5 to 10 5 m this agrees with an emerging global view of mis 5e sea level history derived from stable carbonate platforms rejecting the hypothesis that these higher sea level benchmarks are an artefact of localized tectonic processes

scalloped bank margins beginning of the end for carbonate platforms bathymetric seismic reflection and satellite data have revealed the common existence of a new type of carbonate bank margin scalloped margin throughout the gulf of mexico and the caribbean region these large up to tens of kilometres across irregular convexbankward embayments are interpreted as predominantly erosional features produced by large scale failure of platform margins in tectonically active areas they may be triggered by earthquake shocks whereas in stable regions they may more likely be the result of undercutting by dissolution and or deep water currents scalloped margins are common in the south eastern bahamas this suggests that these relatively small isolated bahama banks may be erosional remnants of once larger platforms the processes that create scalloped margins may result in erosional deep water carbonate basins and potentially the demise and disintegration of carbonate platforms

geochemical evidence of saharan dust parent material for soils developed on quaternary limestones of caribbean and western atlantic islands abstract most previous workers have regarded the insoluble residues of high purity quaternary limestones coral reefs and oolites as the most important parent material for well developed clay rich soils on caribbean and western atlantic islands but this genetic mechanism requires unreasonable amounts of limestone solution in quaternary time other possible parent materials from external sources are volcanic ash from the lesser antilles island arc and saharan dust carried across the atlantic ocean on the northeast trade winds soils on quaternary coral terraces and carbonate eolianites on barbados jamaica the florida keys united states and new providence island bahamas were studied to determine which if either external source was important caribbean volcanic ashes and saharan dust can be clearly distinguished using ratios of relatively immobile elements al 2 o 3 tio 2 ti y ti zr and ti th comparison of these ratios in 25 soils where estimated ages range from 125 000 to about 870 000 yr shows that saharan dust is the most important parent material for soils on all islands these results indicate that the northeast trade winds have been an important component of the regional climatology for much of the quaterary saharan dust may also be an important parent material for caribbean island bauxites of much greater age

middle pleistocene saalian lake outburst floods in the munsterland embayment nw germany impacts and magnitudes abstract during the late saalian drenthe glaciation ice damming of the upper weser valley led to the formation of glacial lake weser the lake drained catastrophically into the munsterland embayment as the western ice dam failed releasing up to 110 km3 of water with a calculated peak discharge of 2 5 105 m3 s to 1 3 106 m3 s geographic information systems gis and high resolution digital elevation models dem were used to map streamlined landforms and channel systems in front of lake overspills geological maps 2450 boreholes and the dem were integrated into the 3d modeling program gocad to reconstruct the distribution of flood related deposits palaeotopographic surfaces and the internal facies architecture of streamlined hills the drainage pathways are characterized by the occurrence of deep plunge pools channels streamlined hills and 4 km long and 12 m deep v shaped megaflutes plunge pools are deeply incised into mesozoic basement rocks and occur in front of three major overspill channels the plunge pools are up to 780 m long 400 m wide and 35 m deep approximately 1 10 5 km downslope of the overspill channels fan shaped arrays of streamlined hills are developed each covering an area of 60 130 km2 indicating rapid flow expansion the hills commonly have quadrilateral to elongated shapes and formed under submerged to partly submerged flow conditions when the outburst flood entered a shallow lake in the munsterland embayment hills are up to 4300 m long 1200 m wide 11 m high and have characteristic average aspect ratios of 1 3 3 they are separated by shallow anabranching channels in the outer zones and up to 30 m deep channels in the central zones hills partly display v shaped chevron like bedforms that have apices facing upslope are 1 6 2 5 km long 3 10 m high 0 8 1 2 m from limb to limb with limb separation angels of 20 35 these bedforms are interpreted as mixed erosional depositional features it is hypothesized that the post saalian landscape evolution of the munsterland embayment has considerably been influenced by catastrophic floods of glacial lake weser creating large and deep valleys which subsequently became the new site of river systems the outburst floods probably followed the east west trending saalian rhine meuse river system eventually flowing into the north sea the strait of dover and the bay of biscay it is speculated that the hondsrug ice stream may have been enhanced or even triggered by the formation and outburst of glacial lakes in the study area

mineral leucosome trace element partitioning in a peraluminous migmatite a laser ablation icp ms study abstract low pressure peraluminous migmatites from the pena negra complex central spain stayed partially molten for 5 10 ma until the latest hercynian deformations allowed the segregation of melt as discordant leucosome veins due to long residence within its source the melt had time enough to equilibrate with residual phases other than accessories included within major refractory minerals we estimated crystal melt partition coefficients as the concentration ratios between leucosome samples appearing to be pure melts and mesosome minerals which were analyzed for trace elements with a laser probe coupled to an icp mass spectrometer our data reveal that when biotite is stable li rb cs tl sc v cr ni nb and ta become strongly compatible the role of biotite in fractionating y th u and the ree is insignificant cordierite strongly fractionates li and be and also has some effect on the hree and u garnet produces extreme fractionation of sc y and the hree the ree partition coefficients for ferromagnesian silicates increase with the atomic number this effect being progressively more important through biotite cordierite and garnet k feldspar strongly fractionates ba and pb but plays a secondary role to biotite for rb and cs k feldspar fractionation does not change the lree hree ratio but plagioclase fractionation produces a significant decrease in the lree hree ratio both feldspars greatly fractionate sr and eu monazite fractionation produces a dramatic depletion in ree th and u as well as a decrease in the lree hree and th u ratios apatite also fractionates the ree although in contrast with monazite it increases the lree hree ratio and does not affect the th u ratio zircon fractionation like apatite and garnet produces a strong depletion in the hree and a concomitant increase in the lree hree ratio in contrast with monazite zircon fractionation causes the th u ratio to increase

solution conduits as indicators of late quaternary sea level position abstract solution conduits or caves can provide a measure of glacio eustatic sea level position for the quaternary in high latitudes cave deposits contain artifacts fossils and sediments that reflect surface conditions with respect to climate secondary calcite deposits most notably stalagmites record growth episodes during ice minima and non growth during ice maxima they provide an indirect estimate of areal ice cover at high latitudes and are an indirect measure of sea level in low latitudes stable carbonate platforms contain caves that provide a direct measure of past sea level position solution conduits developing in a fresh water lens will record the position of the lens and therefore sea level as sea level fluctuates fresh water lens horizons and conduit development horizons will shift preserving a record of past sea level position cave wall rock and cave deposits can produce a chronology for given conduit positions secondary calcite deposits notably stalagmites record growth periods during sea level low stands or ice maxima and record growth hiatuses during flooding by sea level high stands or ice minima the inverse of high latitude stalagmites lighthouse cave san salvador island bahamas records a sea level high stand at 1 to 6 m for some time period between 85 000 and 70 000 years ago based on position and timing of conduit development and records sea level at present elevation for some time period between 49 000 and 37 000 years ago based on a stalagmite with a marine overgrowth

oxygen isotope record of sea level and climate variations in the sulu sea over the past 150 000 years the sulu sea is located in the warm pool of the western pacific ocean where mean annual temperatures are the highest of anywhere on earth because this large heat source supplies the atmosphere with a significant portion of its water vapour and latent heat understanding the climate history of the region is important for reconstructing global palaeoclimate and for predicting future climate change changes in the oxygen isotope composition of planktonic foraminifera from sulu sea sediments have previously been shown to reflect changes in the planetary ice volume at glacial interglacial and millenial timeseales and such records have been obtained for the late pleistocene epoch and the last deglaciation1 3 here i present results that extend the millenial time resolution record back to 150 000 years before present on timescales of around 10 000 years the sulu sea oxygen isotope record matches changes in sea level deduced from coral terraces on the huon peninsula4 this is particularly the case during isotope stage 3 an interglacial period 23 000 to 58 000 years ago where the sulu sea oxygen isotope record deviates from the specmap deep ocean oxygen isotope record5 thus these results support the idea4 6 that there were higher sea levels and less continental ice during stage 3 than the specmap record implies and that sea level during this interglacial was just 40 50 metres below present levels the subsequent rate of increase in continental ice volume during the return to full glacial conditions was correspondingly faster than previously thought

syn collisional lower continental crust anatexis in the neoproterozoic socorro guaxupe nappe system southern brasilia orogen brazil constraints from zircon u pb dating sr nd hf signatures and whole rock geochemistry abstract the southern brasilia orogen occurs along the southernmost border of the sao francisco craton this orogen is structured as a pile of ediacaran syn metamorphic thicked skinned nappes that diachronically migrate toward the cratonic margin a magmatic arc environment is represented by the socorro guaxupe nappe sgn which is a thick segment of partially molten lower to middle continental crust the sgn comprises three main units a lower granulitic an intermediate diatexitic and an upper metatexitic high temperature metamorphic peak was reached at 625 ma when large volumes of high k diatexitic rocks were formed charnockitic and mangeritic magmatic rocks sao jose do rio pardo suite and in situ leucosomes of mafic composition are inferred to have formed under hornblende dehydration melting conditions i e t 850 c granitic diatexites pinhal type were also formed and zircon thermometry indicates t 850 c elemental and isotopic geochemistry indicate that these diatexites and in situ leucosomes derived from melting of lower to middle continental crust tims zircon u pb ages are presented for the lower and middle units u pb dating coupled to lu hf analysis la mc icp ms was performed on charno enderbitic in situ leucosomes from metatexitic rocks that also resulted from hornblende dehydration melting two different zircon typologies were recognized the first comprises bipyramidal prismatic grains with oscillatory zoning and high luminescence sometimes preserving low luminescence 670 ma cores the high luminescence grains show 19 concordant ages at 621 16 ma the second typology comprises isometric or soccer ball type grains these grains show sector zoning and a concordia age of 608 4 ma th u ratios from soccer ball grains vary from 1 253 to 2 107 whereas prismatic grains vary from 0 118 to 1 774 initial hf signatures between 13 and 21 in both typologies provide evidence of a reworked crustal reservoir the older prismatic grains may be related to the onset of metamorphic peak 625 ma whereas the isometric ones provide evidence of long lived high t conditions until 610 ma

trace element partitioning between alkali feldspar and peralkalic quartz trachyte to rhyolite magma part i systematics of trace element partitioning new alkali feldspar felsic magma trace element partition coefficients d values for rb sr ba eu y zr nb ga zn trivalent ree be cs hf pb th and u for 30 samples of peralkalic quartz trachyte and rhyolite are presented d values of incompatible elements vary systematically with melt polymerization parameters increasing with whole rock silica but decreasing in rocks with higher agpaitic indices a i mol na k al d values for sr and ba evaluated to be accurate vary systematically with crystal chemistry probably substituting for na in the ca poor alkali feldspar phases apparent d values for sr and ba from pre quaternary systems are fraught with contamination and analytical errors respectively and should be used with caution d eu decreases exponentially with a i ranging from compatible in weakly peralkalic a i 1 2 rocks these regular variations strongly suggest that partition coefficients for these elements may be predicted accurately if whole rock and crystal chemical parameters are known

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

channel network extraction from high resolution topography using wavelets 1 the availability of high resolution topography from lidar offers new opportunities for objectively extracting the channels directly from a dem using local topographic information instead of inferring them indirectly based on global criteria such as area or area slope threshold relationships here we introduce the use of wavelet filtering to delineate threshold curvatures for defining valleys and threshold slope direction change for defining probable channeled portions of the valleys this approach exploits the topographic signatures uniquely found in high resolution topography and reveals the fuzzy topographic transition in which local weakly convergent areas lie at the transition between hillslopes and valleys

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

precise chronology of the last interglacial period 234u 230th data from fossil coral reefs in the bahamas a detailed study of 238 u 234 u 230 th ages was made for different coral species from two bahamian reefs to determine the time scale of the sea level high during the last interglacial period using recently developed mass spectrometric techniques for the measurement of u and th isotopes thirty seven coral samples were analyzed in replicate typical errors at 125 ky are 1 5 ky 2 and 3 ky time intervals appear to be well resolved this high precision permits detailed chronologic study with time resolution adequate to define stages of the reef s history these data demonstrate that the time between transgression and regression of the ocean in the last interglacial was about 12 ky after which sea level fell rapidly at more than 2 m ky the high sea level stand began possibly by 132 ky and certainly by 129 ky ago when sea level reached 6 m above present mean low sea level high sea level was sustained until 120 ky and then fell rapidly this time period covers the milankovitch insolation peak at 65 n but is not sharply defined and the sea level high lasted from about 4 ky before the insolation peak to 8 ky after it we find no evidence for a double peak of sea level rise in the last interglacial episode that is high stands at both 125 and 142 ky there appears to be some discrepancy between this precise chronology for a coral reef on a tectonically stable platform and the chronology assigned to deep sea sediments the present results show that the duration of the last interglacial led to a 12 ky period of high sea level stand which is much longer than the insolation peak the study area consists of two sizeable bank barrier coral reefs of sangamon age that crop out along the coast northwest of cockburn town on san salvador island and at devil s point on great inagua island the initial stage of reef development is not revealed at either site but the main parts of both reefs are well preserved at cockburn town the beginning of the reef was marked by colonization of acropora palmata on hardground areas and possibly other corals at 132 ky ago patch reefs at the southeastern flank of the developing reef were growing by 129 to 126 ky ago by 126 to 123 ky ago the crest of the reef was formed by the frame building coral a palmata and associated patch reefs flourished along its flanks a palmata coral heads grew upward to a mean low sea level 6 m above the present one the reef began to decline as sea level dropped at about 123 to 120 ky ago near two measured profiles at devil s point the top of a rubblestone dominated by a cervicornis and patch reef corals preserved in growth position have been beveled off and represent an ancient wave cut surface 230 th ages on corals below and above this surface indicate that it was cut at about 125 1 ky ago

late quaternary deformation history of the volcanic edifice of panarea aeolian arc italy a series of raised palaeoshorelines is documented along the emergent coastal slopes of panarea and surrounding islets at elevations of 115 palaeoshoreline ia and 100 m a s l ib 62 5 m ii 35 m iii 12 m iv 10 12 va and 5 m vb according to stratigraphic constraints and cross cutting relationships these palaeoshorelines are correlated with discrete high sea level stillstands during marine oxygen isotope stages mis 5e 5c 5a and 3 coastal elevation changes suggest the occurrence of a long term sustained uplift trend of the volcanic edifice since the last interglacial last 124 ka the uplift rates are not constant but display a progressive deceleration from maximum values of 1 5 1 58 m ka in the period between 124 and 100 ka down to the lowest values of 0 66 0 69 m ka which tend to be constant starting from 81 ka bp the long term deformation pattern of panarea suggests that a transitory volcano related component of uplift interplayed with the regional tectonic component affecting the sub volcanic basement which has undergone a persistent and widespread uplift since the mid pleistocene the volcano related component of uplift prevailing between 124 and 100 81 ka is interpreted as the result of visco elastic deformation mechanisms which characterize the progressive re equilibration of the shallow magmatic system following the incoming quiescence of the volcanic edifice the long term uplift values at panarea are higher than in the main portion of the western central aeolian arc where a mean uplift rate of 0 34 m ka was estimated since the last interglacial last 124 ka such a pattern of deformation on a regional scale may be a response to active deformation processes connected with the southeastward rollback of the subducting ionian slab which is still active only in correspondence with the eastern sector of the aeolian arc including panarea in the short term a localized submergence trend has been documented at the nearby islet of basiluzzo for the last 2 000 years likely connected to neo tectonic movements along main ne sw trending faults

comment on record of mis 5 sea level highstands based on u th dated coral terraces of haiti by dumas et al quaternary international 2006 106 118 abstract the opening sentence of the introduction dumas b hoang c t raffy j 2006 record of mis 5 sea level highstands based on dated coral terraces of haiti quaternary international 145 146 106 118 quaternary sea level changes are mainly deduced from the study of raised coral terraces involves a flawed premise as two undefined variables operate simultaneously sea level changes and vertical tectonic motion both perhaps having up and down components to produce a succession of terraces it is impossible to solve the equation without supplying real numbers for either variable hence to deduce sea level history either largely unprovable assumption about constant uplift and or featureless sea level histories are required or a model of sea level must be imported from regions that have not experienced tectonic displacement furthermore coral reefs are less than ideal monitors of sea level change rather they might be preferred as monitors of sea level stability as their response time and depositional tempo may be measured in hundreds or thousands of years reefs may grow and flourish during slow rise of sea level once accommodation space is filled vertical growth ceases and only erosion and diagenesis of the reef occurs until sea level changes once more major intervals of sea level change may thus be lost or never recorded in the rocks

stratigraphy and geochronology of pitfall accumulations in caves and fissures bermuda abstract deep fractures fissures and avens skylights in limestone cave roofs create natural traps for sediments and biota fissures fill quickly with surface sediment and organisms soon after opening debris cones are formed as materials fall wash or drift on air through openings in cave skylights such deposits in admiral s and grand canyon cave bermuda contain distinct beds and are composed of mixtures of sediment and charcoal together with fossils of land snails crabs birds reptiles and bats the pitfall accumulations were periodically sealed over by calcite flowstone a stratigraphic record of surface activity and fauna through both glacial and interglacial periods has been preserved the succession also provides an ideal setting in which to compare several geochronological methods calibrated 14 c ages on charcoal and shells provide dated horizons at 1600 12 800 and about 35 000 14 c yr bp thermal ionization mass spectrometric tims ages on several flowstone layers constrain the entire sequence in the admiral s cave sequence between 126 300 900 yr termination ii and historical times a continuous relative age record generated by amino acid epimerization aae geochronology d alloisoleucine l isoleucine or aile ile on the pulmonate land gastropod poecilozonites verifies the biostratigraphy reveals a minimal degree of mixing between stratigraphic units and establishes an independent temporal link between the subterranean and subaerial deposits of bermuda this convergence between stratigraphy and geochronology yields a precisely dated succession from the oceanic island of bermuda and thus presents a unique opportunity to assess the rates and processes of evolutionary and climate change during that interval

new data on the pleistocene of mallorca abstract stratigraphic geomorphologic and isoleucine epimerization studies at 15 sites in mallorca define four aminozones a c e and f g of increasing age that are related to transgressive regressive marine cycles from the holocene to the mid pleistocene calibration of aminozone e glycymeris aile ile mean from all sites 0 41 0 03 n 38 is provided by a 129 7 ka u series coral age on cladocora caespitosa from son grauet of the younger aminozones a relates to the holocene transgression and aminozone c to a mid to late isotopic stage 5 event 90 15 ka revealed only by supralittoral eolianites assigning an age to the older poorly resolved aminozones f and g called f g in this case is uncertain without supporting radiometric data but an age of 180 ka can be assigned to these aminozone s f g based on a kinetic model and other examples in the mediterranean several deposits previously dated u series molluscs between 75 and 300 ka appear to belong to the last interglacial complex stage 5 and aminozone e a proposed revision of the positive sea level history of mallorca shows multiple minor oscillations during the major last interglacial cycle stage 5 and two mid pleistocene sea levels one lower than present and the other at about 14 m a s l

aminostratigraphy and ages of pleistocene limestones of bermuda the pleistocene stratigraphy of bermuda offers important information for sea level history corals are rare in bermuda pleistocene carbonates and so many deposits are not appropriate for u series dating we have extended the geochronological base in bermuda by determining the extent of isoleucine epimerization a i ratios in 1 marine shells glycymeris and others from deposits of sea level high stands 2 land snails poecilozonites from protosols associated with the eolianites that comprise the bulk of bermuda and 3 whole rock samples of bioclastic calcarenites the three distinct types of samples provide independent aminostratigraphies aminozones c e f g h j and k that are mutually consistent and in agreement with the mapped lithostratigraphy correlation of the amino acid ratios with ages based on previously published u series coral dates verifies the utility of the apparent parabolic kinetics model for estimation of amino acid racemization ages extrapolation of ages based on the model to deposits beyond the range of u series dating reveals that a significant middle pleistocene section is present in bermuda

evolving history of the east asian summer monsoon intensity during the mis5 inconsistent records from chinese stalagmites and loess deposits as an important component of the global monsoon system the intensity of east asian summer monsoon easm influences lives and economic development of more than 2 billion people the last interglacial period also known as marine isotope stage 5 mis 5 has been thoroughly investigated due to its similarity to the modern interglacial period mis 1 according to records from chinese stalagmites and loess deposits evolving history of easm intensity during mis5 can be divided into 5 sub stages i e 5a 5e however during the 3 warm sub stages 5a 5c and 5e evolving history of easm intensity recorded by chinese stalagmites and loess deposits is apparently different oxygen isotope 18o records of stalagmites demonstrate that the easm intensity during mis5e 5c and 5a is not obviously different on the other hand easm intensity apparently decreased from mis5e to 5c and 5a based on chinese loess deposits records the discrepancy between chinese stalagmite and loess deposits reveals that 18o records of stalagmites may not be a pure indicator of easm intensity the relationship between 18o and easm intensity is not linear based on 18o data of modern precipitation from 21 weather stations within major monsoon area in china mmac ca 110 e to 122 e 18 n to 41 n we speculate that chinese stalagmite 18o values recorded changes of 18o of summer precipitation as well as adjustment from 18o of winter precipitation inconsistent records from chinese stalagmites and loess deposits indicate that further investigations are needed to study the mechanism and fractionation of 18o in stalagmites collected in china

eastern mediterranean sea levels through the last interglacial from a coastal marine sequence in northern israel a last interglacial marine isotope stage mis5e marine coastal sequence has been identified along the galilee coast of israel with the type section located at rosh hanikra rh the microtidal regime and tectonic stability along with the detailed stratigraphy of the rh shore make the study region ideally suited for determining relative sea level rsl through the mis5e interval in the eastern mediterranean the sequence contains fossilized microtidal subunits at a few meters above the current sea level unfortunately all fossils were found to be altered so that u th datings cannot be considered to represent initial deposition we contend that u th dating of strombus bubonius shells recrystallized to calcite suffices to indicate a lower limit of 110 8 ka for the time sea level dropped below the rh sedimentary sequence the rh section comprises three main subunits of a previously determined member the yasaf member a a gravelly unit containing the diagnostic gastropod strombus bubonius lamarck persististrombus latus which was deposited in the intertidal to super tidal stormy zone b vermetidae reef domes indicating a shallow water depositional environment and c coarse to medium sized bioclastic sandstone probably deposited in the shallow sub tidal zone the sequence overlies three abrasion platforms that are cut by tidal channels at elevations of 0 8 m 2 6 m and 3 4 m and which are filled with mis5e sediments we present a detailed study of the sequence with emphasis on stratigraphic sedimentological and palaeontological characteristics that indicate sea level changes although without precise absolute dating the stratigraphic sequence of rh through mis5e allows us to identify a time series of rsl positions using the elevations of three stratigraphic subunits reconstructed rsl values range from 1 0 m to 7 m with uncertainly 1 m and most fall within a narrow range of 1 0 to 3 3 m toward the end of mis5e rsl exceeded about 7 m glacial isostatic adjustment gia modelling using multiple ice histories suggests that gia corrections range between about 1 8 m and 5 4 m this implies that global mean sea level resided between 0 8 m and 8 7 m during most of mis5e the absolute gia correction would not be constant through the interglacial and reduces to a range of 1 2 m to 2 4 m towards the end of the interglacial

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

u series evidence for widespread reef development in shark bay during the last interglacial field observations and u series ages reveal that shark bay western australia wa has been inundated by the sea on at least three occasions during the late pleistocene holocene resulting in a succession of marine deposits around the bay the exact age of these deposits has until now been problematic due to a lack of reliable and accurate age data this study reports 16 new u series coral dates from emergent reef deposits around shark bay and point to an extended period of coral reef development during the peak of the last interglacial marine isotope stage mis 5e this is attributed to enhancement of marine circulation within the reaches and basins a result of higher sea levels and an absence of major sill and bank structures stromatolites are absent from the geological record within shark bay until the late holocene suggesting that sea levels and marine sedimentary processes that have operated during the present sea level highstand are unique to this period there is little direct evidence of fossil reef development occurring during interglacials of the middle late pleistocene mis 9 11

carbonate petrography as an indicator of climate and sea level changes new data from bahamian quaternary units coeval stratigraphic units of similar petrology occur throughout the northern bahamas islands the petrographic composition of these limestones provides clues about regional sea level and climate changes during the late quaternary at least eight fossil shoreline units which are linked to transgressive episodes between the middle pleistocene and the late holocene are recognized in the bahamas the petrographic composition of these units is either dominated by ooids and peloids or by bioclasts sedimentological observations demonstrate that oolitic peloidal units were formed when sea level was higher than today whereas skeletal units were deposited at or below modern ordnance datum skeletal units may reflect times of partial or modest platform flooding when the bulk of sediments brought to islands originates from bank margin reefs in contrast oolitic peloidal units correspond to major flooding events and active water circulation on the bank top cement fabrics further show that the early diagenesis of oolitic units took place during warm and humid climatic conditions whereas skeletal rock bodies underwent subaerial diagenesis during drier climatic conditions characterized by marked seasonal changes this example from the bahamas suggests that compositional analysis of limestone from fossil carbonate platforms could be used for resolving ancient climate and sea level changes

beach and shoreface ooid deposition on shallow interior banks turks and caicos islands british west indies abstract modern ooids are forming and accumulating as beach dune complexes which face into and prograde across the very shallow broad low energy caicos bank this contrasts with other modern oolite occurrences that are located at shelf margins or at the heads of steep ramps facing deeper water where tidal energy plays an important role in ooid generation ooid quality and distribution coupled with radiocarbon dating indicates that the caicos ooids are forming in the beach and shoreface environment in response to wave and current agitation generated by prevailing southeasterly trade winds the caicos model is a useful analog for many ancient sheetlike oolite accumulations deposited on broad epeiric shelves or gently sloping ramps

spatial discontinuity and temporal evolution of channel morphology along a mixed bedrock alluvial river upper drome river southeast france contingent responses to external and internal controls abstract the rehabilitation of degraded river channels is often guided by assumptions of continuity yet in response to spatial and temporal variations in controlling conditions rivers typically display discontinuous response in space and time this study examines the development of a 5 km reach of the drome river s e france characterised by alternating alluvial and bedrock zones that are separated by abrupt downstream transitions this reach is representative of the drome river as a whole and other rivers in the european alps where braided channel planforms have been replaced by more complex discontinuous morphologies the primary aims are to understand how this spatial complexity has developed on the drome evaluate how temporal channel changes have been affected by local factors particularly bedrock exposures and by long term catchment scale changes in sediment supply and the flood activity and consider the implications of this discontinuous geomorphology for reach management the development of geomorphological zonation is examined by documenting sequential changes in channel planform between seven periods using aerial photography 1948 2006 and by analysing change in bed elevation from profiles surveyed in 1928 2003 and 2005 between 1948 and 2001 bedrock exposed in the channel bed and along the floodplain margins defined discontinuities in sediment connectivity that were largely responsible for the configuration of channel zones the impact of floods on this system was not proportional to flood magnitude a modest flood in 1978 was an important event that by incision and avulsion at key locations defined a pattern of zonation that persisted until the end of the study in 2006 during the final 5 years of the study alluvial zones that previously responded to large floods by widening underwent narrowing despite the occurrence of a large flood and led to an overall reduction in width variance this resulted from progressive incision beneath and disconnection from formerly active channel areas in response to long term catchment scale reductions in sediment supply and flood frequency in 2006 the pattern of zonation remains distinct disguising this recent change in channel response and underlining the need for long term and sequential perspectives of channel development to fully understand the processes in operation contemporary snapshots of channel form may be misleading understanding interactions between inherent channel complexity and prevailing flow and sediment conditions and how this shapes channel response to individual floods is essential when interpreting future trajectories of channel change and likely response to management intervention

floodplain width adjustments in response to rapid base level fall and knickpoint migration abstract geomorphology has long been engaged in characterizing the form and understanding the evolution of floodplains this study primarily examines floodplain width in four tributaries to the minnesota river in southern minnesota namely the maple le sueur and blue earth rivers and seven mile creek the tributary systems are relatively young having formed after retreat of the wisconsinan ice sheet and are rapidly evolving in response to a base level fall of nearly 70 m 13 400 ybp as a result the lower reaches of all four river channels are aggressively incising this study applies a new freely available open code plug in for arcgis to measure floodplain width as a function of elevation above the geomorphic top of bank systematic changes are observed in all four systems above the steep incising knickzone reaches of each of the tributaries relatively wide and mostly unconfined floodplains are observed within the knickzone floodplains progressively narrow to between 25 60 of their width above the knickzone despite the fact that sediment loads increase significantly in the downstream direction a power law relationship is consistently observed between floodplain width and the ratio of local channel slope to contributing drainage area to about the negative one third power in all four rivers this same power law relationship is observed for two other rivers that differ significantly from our study systems in climatic and tectonic environment as well as base level history

the role of xenoliths and flow segregation in the genesis and evolution of the paleoproterozoic itapema granite a crustally derived magma of shoshonitic affinity from southern brazil abstract the paleoproterozoic itapema granite ig is a large granitic body that intrudes orthogneisses and amphibolites altogether representing part of the basement for neoproterozoic granitic magmatism in southern brazil it is composed of fine to medium grained hornblende biotite monzogranites to granodiorites that host abundant country rock xenoliths and irregularly distributed mafic aggregates interaction between magmatic flow and low flow velocity zones related to xenolith rich portions resulted in flow segregation and mineral fractionation as the main mechanisms that led to compositional and textural diversity expressed also in geochemical trends the geometry and distribution of flow foliation suggest that the itapema granite is a subhorizontal sheet like intrusion and that its emplacement was controlled by thrusting under upper amphibolite facies conditions many geochemical characteristics of the itapema granite are similar to those of shoshonitic granitoids however lower alkali contents lack of basic or intermediate associated rocks and intimate temporal association with high grade gneisses and migmatites suggest that it was crustally derived its origin is compatible with melting of amphibolitic orthogneisses derived from continental tholeiitic or shoshonitic sequences under high geothermal gradient conditions where temperatures reached at least 850 c

a sustained 21 m sea level highstand during mis 11 400 ka direct fossil and sedimentary evidence from bermuda abstract a small protected karstic feature exposed in a limestone quarry in bermuda preserved abundant sedimentary and biogenic materials documenting a transgressive phase still stand and regressive phase of a sea level in excess of 21 3 m above present during marine isotope stage mis 11 400 ka as determined by u th dating and amino acid racemization cobbles and marine sediments deposited during the high energy transgressive phase exhibit rim cements indicating a subsequent phreatic environment this was succeeded stratigraphically by a still stand deposition of fine calcareous lagoonal sediments containing bioclasts of red algae and benthic and planktonic foraminifera that was intensely burrowed by marine invertebrates probably upogebiid shrimp that could not be produced under any condition other than sustained marine submergence overlying this were pure carbonate beach sands of a low energy regressive phase containing abundant remains of terrestrial and marine vertebrates and invertebrates the considerable diversity of this fauna along with taphonomic evidence from seabird remains indicates deposition by high run up waves over a minimum duration of months if not years the maximum duration has yet to be determined but probably did not exceed one or two thousand years the most abundant snails in this fauna are two species indicative of brackish water and high tide line showing that a ghyben herzberg lens must have existed at 20 m the nature of these sediments and fossil accumulation is incompatible with tsunami deposition and given the absence of evidence for tectonic uplift of the bermuda pedestal or platform provide proof that sea level during mis 11 exceeded 20 m a fact that has widespread ramifications for geologists biogeographers and human demographics along the world s coastlines

timing and progression of the last interglacial derived from a high alpine stalagmite 1 u th dating and oxygen isotope analysis of a stalagmite from spannagel cave in the austrian alps provides information about the timing and progression of the last interglacial climate we determined two distinct growth intervals warm climate from 130 7 thousand years ka before the present to 130 0 ka and from 125 7 ka to 118 2 ka the latter containing two periods of ceased stalagmite growth colder climate at around 123 8 ka and 120 5 ka high resolution 18o analysis of stalagmite spa 50 reveals a clear regular cyclic pattern with periods of 197 109 and 21 years which are likely to be related to the suess gleissberg and hale cycles respectively indicating that eemian climate in the alps was forced by the sun

rapid sea level and climate change at the close of the last interglaciation mis 5e evidence from the bahama islands the geology of the last interglaciation sensu stricto marine isotope substage mis 5e in the bahamas records the nature of sea level and climate change after a period of quasi stability for most of the interglaciation during which reefs grew to 2 5 m sea level rose rapidly at the end of the period incising notches in older limestone after brief stillstands at 6 and perhaps 8 5 m sea level fell with apparent speed to the mis 5d lowstand and much cooler climatic conditions it was during this regression from the mis 5e highstand that the north atlantic suffered an oceanographic reorganization about 118 3 ka ago during this same interval massive dune building greatly enlarged the bahama islands giant waves reshaped exposed lowlands into chevron shaped beach ridges ran up on older coastal ridges and also broke off and threw megaboulders onto and over 20 m high cliffs the oolitic rocks recording these features yield concordant whole rock amino acid ratios across the archipelago whether or not the last interglaciation serves as an appropriate analog for our greenhouse world it nonetheless reveals the intricate details of climatic transitions between warm interglaciations and near glacial conditions

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

high resolution paleotemperature proxy record for the last interglaciation based on norwegian speleothems two speleothems from a coastal lowland and an alpine cave site in northern norway grew in isotopic equilibrium during termination ii and marine isotope stage 5 150 000 80 000 yr b p as dated by the u series technique the stable isotope record 18o 13c displays a time resolution down to 20 yr the 18oc signal in the two speleothems appears to be mainly dominated by the meteoric signal i e there is a positive relationship between 18oc and temperature 18oc t 0 the fm 2 couplet a younger dryas type two step structure in termination ii at 132 000 5000 and 129 000 5000 yr is prominent in the speleothem record the record correlates well with details and gross features of the grip ice core and confirms the time scale and the unstable climate proposed for substage 5e the isotopic response in termination ii is delayed relative to the devil s hole record and is in accord with the specmap chronology but cooling at the end of substage 5e seems to be synchronous between devil s hole and the norwegian flowstones

synthetic river valleys creating prescribed topography for form process inquiry and river rehabilitation design abstract the synthesis of artificial landforms is complementary to geomorphic analysis because it affords a reflection on both the characteristics and intrinsic formative processes of real world conditions moreover the applied terminus of geomorphic theory is commonly manifested in the engineering and rehabilitation of riverine landforms where the goal is to create specific processes associated with specific morphology to date the synthesis of river topography has been explored outside of geomorphology through artistic renderings computer science applications and river rehabilitation design while within geomorphology it has been explored using morphodynamic modeling such as one dimensional simulation of river reach profiles two dimensional simulation of river networks and three dimensional simulation of subreach scale river morphology to date no approach allows geomorphologists engineers or river rehabilitation practitioners to create landforms of prescribed conditions in this paper a method for creating topography of synthetic river valleys is introduced that utilizes a theoretical framework that draws from fluvial geomorphology computer science and geometric modeling such a method would be valuable to geomorphologists in understanding form process linkages as well as to engineers and river rehabilitation practitioners in developing design surfaces that can be rapidly iterated the method introduced herein relies on the discretization of river valley topography into geometric elements associated with overlapping and orthogonal two dimensional planes such as the planform profile and cross section that are represented by mathematical functions termed geometric element equations topographic surfaces can be parameterized independently or dependently using a geomorphic covariance structure between the spatial series of geometric element equations to illustrate the approach and overall model flexibility examples are provided that are associated with mountain lowland and hybrid synthetic river valleys to conclude recommended advances such as multithread channels are discussed along with potential applications

eemian climate fluctuations observed in a european pollen record recent ice core data from greenland1 2 suggest that the climate during the last interglacial period the eemian was more unstable than that of the holocene about 10 000 years ago to the present being characterized in particular by a series of cold episodes each lasting about 70 to 750 years subsequent analysis of a second greenland ice core3 4 however failed to corroborate the details of these eemian climate fluctuations a result that may be attributable to the effects of ice flow4 to resolve this discrepancy it is imperative to seek alternative sources of information about the eemian climate here we present climate reconstructions from pollen data from the annually laminated eemian lake sediment record at bispingen5 and from the eemian and holocene peat records at la grande pile6 the former record indicates that an initially warm period of 2 900 yr was followed by cooling and a series of colder episodes one of which had winter temperatures comparable to those at the end of the preceding cold stage the latter records show greater climate instability during the eemian than the holocene these results are in broad agreement with those from the grip ice core but contrast both with the gisp2 core3 4 and with recent high resolution marine records from the north atlantic7 8

the geology of eleuthera island bahamas a rosetta stone of quaternary stratigraphy and sea level history abstract a 5 km stretch of coastline in north eleuthera reveals a long and detailed stratigraphy that includes all known surficial limestone units in the bahamas and supplements the record with several previously unrecognized ones eight paleosol bounded limestone parasequences comprise at least six interglacial periods the lithostratigraphy demonstrates cyclicity at several frequencies 10 5 10 4 20 40 ka and 10 3 years and displays a variety of distal to proximal shoreline facies indicative of shifting depocenters associated with changing sea levels stratigraphy petrology pedology and whole rock aminostratigraphy are used to correlate units and subunits among the 12 described sections amino acid ratios are also converted to absolute age estimates which support the lithostratigraphy the parasequences are correlated with marine oxygen isotope stages 1 to 13 or older evidence of middle pleistocene highstands are abundant in the eleutheran stratigraphy including paleo sea levels of decreasing age at 2 m 7 m 20 m associated with stages 11 and or 9 and two near present highstands during stage 7 a complex sea level history is associated with substage 5e while substage 5a is represented by near shore aggradation of coastal dune complexes in eleuthera and throughout the bahamas concordance of sea level deposits between bermuda and the bahamas reinforce their tectonic stability while the abundance of highstand evidence during the middle pleistocene contradicts suggestions that platform subsidence has obscured all evidence of these events below present sea level the high resolution late quaternary stratigraphy of eleuthera is unrivaled among geologic records from stable carbonate coastlines and thereby offers a rosetta stone for interpretation of the quaternary evolution of the bahamas and sea level history over the past 500 ka

neoproterozoic high pressure metamorphism and tectonic constraint from the nappe system south of the sao francisco craton southeast brazil abstract the neoproterozoic giant nappe system exposed south of the sao francisco craton underwent a minimum of 150 km of near horizontal northeastward displacement this nappe system comprises an uppermost unit derived from a plutonic magmatic arc terrane with high pressure high temperature intermediate to mafic granulites at its base socorro guaxupe nappe underlain in sequence by a high pressure kyanite granulite nappe an amphibolite facies metapelite nappe and finally by a quartzite nappe which forms the lowest part of the pile and rests on a parautochthonous unit related to the passive margin of the craton the kyanite granulites crystallized ca 13 kbar 750 c and have only at their top sillimanite related to t increase overprinting t 890 c a consequence of downward heat advection from the overlying socorro guaxupe granulites equilibrated at 900 c pressures of 13 14 kbar are documented in the underlying metapelite nappe with temperatures of 640 670 c in which lenses of eclogite indicate p max of ca 17 5 kbar phyllites of the parautochthonous unit are directly overlain by hp granulites in the north and record p 7 kbar and t 500 c the distribution of metamorphic facies is reminiscent of inverted metamorphism with eclogites from subduction related metamorphism and kyanite granulites from early extrusion of subducted continental crust the metamorphic conditions of the parautochthon may represent a stage achieved during late metamorphic thinning of the nappe pile the overall picture suggests that high pressure units recrystallized in a subduction zone located to the wsw the frontal thrusts of the nappe system show a late north northeastward transported thin skinned pattern

scaling in river corridor widths depicts organization in valley morphology landscapes have been shown to exhibit numerous scaling laws from horton s laws to more sophisticated scaling in topography heights rivernetworktopology andpower lawsinseveralgeomorphicattributes inthispaper weproposeadifferent wayof examining landscape organization by introducing the river corridor width lateral distance from the centerline of the river to the left and right valley walls at a fixed height above the water surface as one moves downstream we establish that the river corridor width series extracted from 1 m lidar topography of a mountainous river exhibit a rich multiscale statistical structure anomalous scaling which varies distinctlyacross physicalboundaries e g bedrockversusalluvialvalleys we postulatethatsuchananalysis inconjunctionwith field observations and physical modeling has the potential to quantitatively relate mechanistic laws of valley formation to the statistical signature that underlying processes leave on the landscape such relations can be useful in guiding field work by identifying physically distinct regimes from statistically distinct regimes and advancing process understanding and hypothesis testing 2007 elsevier b v all rights reserved

quaternary tectonic stability of the bahamian archipelago evidence from fossil coral reefs and flank margin caves abstract throughout the islands of the bahamian archipelago fossil coral reefs are found from current sea level up to a maximum elevation of 4 m 234 u 230 th radiometric dates obtained from in situ corals from these reefs by both alpha count and mass spectrometric techniques indicates that they were all formed during oxygen isotope substage 5e ca 125 000 years ago those data are consistent with a maximum sea level highstand of 6 m during substage 5e and either no vertical motion of the bahamas or possible isostatic subsidence of up to 2 m during the past 120 000 years no older in situ fossil corals or other subtidal deposits have been found subaerially exposed anywhere in the bahamas that finding suggests that late quaternary at least the past 300 000 years isostatic subsidence has occurred at a rate of 1 2 m per hundred thousand years and or no pre 5e highstands were above modern sea level an independent corroboration of the conclusions drawn about sea level amplitude and tectonic stability of the bahamas from the coral reef data is available from examination of abundant flank margin caves horizontal phreatic dissolution caves found above modern sea level throughout the bahamas these horizontally extensive air filled caves have dissolutional ceilings with elevations that are restricted to 1 to 7 m which is consistent with formation at the margin of a thin freshwater lens elevated by a past 6 m sea level highstand the restricted cave elevations and the lack of stalagmites in these caves that are older than 100 000 years are also consistent with cave formation during substage 5e and possible subsequent isostatic subsidence of a few metres the subsurface geology of the southeastern bahamas contains a long term record millions of years that has been attributed to past tectonic activity along the north american caribbean plate boundary while that record suggests differential subsidence across the bahamas in the tertiary period the data from fossil coral reefs and subtidal deposits and flank margin caves indicate that all bahamian banks on which there are islands have been tectonically stable and behaving similarly for at least the past several hundred thousand years

rapid sea level changes at the close of the last interglacial substage 5e recorded in bahamian island geology rapid and abrupt relative sea level changes within the last interglacial substage 5e are recorded in the island geology of the tectonically stable bahamas from 132 to 118 ka reef growth reached a maximum elevation near 2 m as indicated by fossil reef elevation across the platform whereas bioeroded notches are incised in coastal cliffs as high as 6 m the end of the interval is characterized by voluminous eolianites exhibiting palm tree and frond impressions it is inferred that sea level for most of the interval remained near 2 m restraining reef growth and that the notch at 6 m represents a rapid and brief excursion just before the close of the substage the subsequent fall must have been rapid in order to leave the notch profile intact and mobilize windward lagoon ooids into dunes before cementation could anchor them in order to explain the rapid rise to 6 m glacial surging is invoked the subsequent fall also rapid may be a consequence of the surge flooding high latitudes and providing enough moisture to initiate reglaciation and drawdown

pedogenic carbonate crusts calcretes in karstic landscapes as archives for paleoenvironmental reconstructions a case study from yucatan peninsula mexico abstract in the northeastern margin of the yucatan peninsula which is located in southeastern mexico three levels of compact carbonate crusts calcretes interlayered with indurated coastal calcareous sediments calcarenites are discernible since both the calcretes and calcarenites form a continuous carbonate sequence a combined methodology macro and micromorphology geochemistry and mineralogy is used to differentiate them additionally the calcrete layers are dated using the uranium thorium method in order to establish a chronological framework the carbonate differentiation and chronology are then used to establish the paleoenvironmental conditions that prevailed during calcrete formation as well as to reconstruct the coastal landscape evolution and its relation to pleistocene sea level changes during marine isotope stages mis 6 and 5 samples of calcrete layers and calcarenites were taken from two sections in the cancun tulum corridor the lowest level of calcrete underlies a sequence of calcarenites and the two younger levels cap the sequence in calcretes the micromorphology provides evidence of the presence of a relict soil with subangular blocky microstructure root traces and needle fiber calcite associated with soil fungi interactions in contrast the micromorphology of the calcarenites shows ooids and bioclasts typical of a coastal environment geochemically calcretes are depleted in 13c compared to calcarenite with values ranging between 2 and 10 and they have a lower proportion of rare earth elements calcrete mineralogy consists mainly of calcite over aragonite with a low proportion of mg calcite u th dating indicates that the oldest calcrete was formed during the penultimate glacial maximum pgm in mis 6 and the two younger calcretes correspond to the last interglacial period in mis 5c the calcarenite formation occurred earlier also during mis 5 soil formation strong karstification and soil erosion have occurred on younger calcretes this study suggests that these processes developed between mis 4 to mis 1

revisiting scaling laws in river basins new considerations across hillslope and fluvial regimes 1 increasing availability of high resolution 1 m topography data and enhanced computational processing power present new opportunities to study landscape organization at a detail not possible before here we propose the use of directed distance from the divide as the scale parameter instead of horton s stream order or upstream contributing area for performing detailed probabilistic analysis of landscapes over a broad range of scales this scale parameter offers several advantages for applications in hydrology geomorphology and ecology in that it can be directly related to length scale dependent processes it can be applied seamlessly across the hillslope and fluvial regimes and it is a continuous parameter allowing accurate statistical characterization higher order statistical moments across scales application of this scaling formalism to three basins in california demonstrates the emergence of three distinct geomorphic regimes of divergent highly convergent and moderately convergent fluvial pathways with notable differences in their scaling relationships and in the variability or spatial heterogeneity of topographic attributes in each regime we show that topographic attributes such as slopes and curvatures conditional on directed distance from the divide exhibit less variability than those same attributes conditional on upstream contributing area thus affording a sharper identification of regime transitions and increased accuracy in the scaling analysis

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

global sea level fluctuations during the last interglaciation mis 5e the geomorphology and morphostratigraphy of numerous worldwide sites reveal the relative movements of sea level during the peak of the last interglaciation marine isotope stage mis 5e assumed average duration between 13072 and 11972 ka because sea level was higher than present deposits are emergent exposed and widespread on many stable coastlines correlation with mis 5e is facilitated by similar morphostratigraphic relationships a low degree of diagenesis uranium thorium u th ages and a global set of amino acid racemization aar data this study integrates information from a large number of sites from tectonically stable areas including bermuda bahamas and western australia and some that have experienced minor uplift 2 5 m 100 ka including selected sites from the mediterranean and hawaii significant fluctuations during the highstand are evident at many mis 5e sites revealed from morphological stratigraphic and sedimentological evidence rounded and flat topped curves derived only from reef tracts are incomplete and not representative of the entire interglacial story despite predictions of much different sea level histories in bermuda the bahamas and western australia due to glacio and hydro isostatic effects the rocks from these sites reveal a nearly identical record during the last interglaciation the last interglacial highstand is characterized by several defined sea level intervals slis that include sli 1 post glacial mis 6 5e termination ii rise to above present before 130 ka sli 2 stability at 2 to 3 m for the initial several thousand years 130 to 125 ka during which fringing reefs were established and terrace morphology was imprinted along the coastlines sli 3 a brief fall to near or below present around 125 ka sli 4 a secondary rise to and through 3 4 m 124 to 122 ka followed by sli 5 a brief period of instability 120 ka characterized by a rapid rise to between 6 to 9 m during which multiple notches and benches were developed and sli 6 an apparently rapid descent of sea level into mis 5d after 119 ka u th ages are used to confirm the last interglacial age of the deposits but unfortunately in only two cases was it possible to corroborate the highstand subdivisions using radiometric ages sea levels above or at present were relatively stable during much of early mis 5e and the last 6 7 ka of mis 1 encouraging a comparison between them the geological evidence suggests that significant oceanographic and climatic changes occurred thereafter midway through and continuing through the end of mis 5e fluctuating sea levels and a catastrophic termination of mis 5e are linked to the instability of grounded and marine based ice sheets with the greenland gis and west antarctic wais ice sheets being the most likely contributors late mis 5e ice volume changes were accompanied by oceanographic reorganization and global ecological shifts and provide one ominous scenario for a greenhouse world r 2007 elsevier ltd all rights reserved

evidence for nonlinear diffusive sediment transport on hillslopes and implications for landscape morphology steep soil mantled hillslopes evolve through the downslope movement of soil driven largely by slope dependent transport processes most landscape evolution models represent hillslope transport by linear diffusion in which rates of sediment transport are proportional to slope such that equilibrium hillslopes should have constant curvature between divides and channels on many soil mantled hillslopes however curvature appears to vary systematically such that slopes are typically convex near the divide and become increasingly planar downslope this suggests that linear diffusion is not an adequate model to describe the entire morphology of soil mantled hillslopes here we show that the interaction between local disturbances such as rainsplash and biogenic activity and frictional and gravitational forces results in a diffusive transport law that depends nonlinearly on hillslope gradient our proposed transport law 1 approximates linear diffusion at low gradients and 2 indicates that sediment flux increases rapidly as gradient approaches a critical value we calibrated and tested this transport law using high resolution topographic data from the oregon coast range these data obtained by airborne laser altimetry allow us to characterize hillslope morphology at 2 m scale at five small basins in our study area hillslope curvature approaches zero with increasing gradient consistent with our proposed nonlinear diffusive transport law hillslope gradients tend to cluster near values for which sediment flux increases rapidly with slope such that large changes in erosion rate will correspond to small changes in gradient therefore average hillslope gradient is unlikely to be a reliable indicator of rates of tectonic forcing or baselevel lowering where hillslope erosion is dominated by nonlinear diffusion rates of tectonic forcing will be more reliably reflected in hillslope curvature near the divide rather than average hillslope gradient