shell mounds as environmental proxies on the southern coast of brazil despite the multiple constraints of using shell mounds for building relative sea level rsl curves one of the premises behind this use is still valid in modern archaeological research this refers to the sites being continuously built near bodies of water rich in fish species and mollusk beds studies that combine the evolution of settlement patterns with the geological evolution of coastal areas in brazil reach analogous results the distribution of shell mounds in time and space follows the landscape transformations induced by rsl variations through the holocene although shell mounds are not precise indicators of rsl they provide evidences of the paleo geographical changes during the holocene of which rsl is one of the many control variables by collecting and transporting mollusks to the shell mounds humans inevitably carry sediments from the substrate where mollusks live for example the beaches and lagoons near the sites in this work the geoarchaeological study of three shell mounds located in the southern coast of santa catarina state combined with mollusk taxa identification show the direct association of shell mound content with the changing landscape the predominance of ostrea sp versus anomalocardia brasiliana the presence of colluvial versus lagoonal sediments and the occurrence of echinoid spines versus muddy aggregates with diatoms gastropods and glauconitic clay characterize the distinction between sites built before and after the maximum holocene transgression respectively this attests the potential of geoarchaeological analyses in shell mounds as a complementary proxy for paleo environmental reconstructions

lower cambrian paleosols from the cantabrian mountains northern spain a comparison with neogene quaternary estuarine analogues abstract the lower cambrian barrios beds cantabrian mountains consist of a siliciclastic succession deposited in deltaic environments punctuated by intertidal and fluvial systems in the barrios de luna area this succession displays a progradational depositional systems tract that contains linkages between upper offshore tidal sand bars fluvial channels and floodplain environments the uppermost fluvial channels are encased within floodplain or interfluvial deposits some of which develop muddy paleosols the detailed micromorphological scanning electron microscopy sem geochemical and mineralogical studies of their pedogenic profiles indicate the presence of three well differentiated horizons fragmentation and shrinking of the upper horizons originated a network of channel like to vuggy porosity occluded by microlaminated clays cyclically emplaced by tidal floods and seasonal oxidation the middle horizons have concretionary to vermicular textures associated with microbioturbation and bacterial colonization and the lower ones are mottled containing numerous preserved lithorelics the barrios sulfidic ustifluvent paleosols represent short time pedogenic events under semiarid subtropical conditions and support previous studies of cambrian microbial life on subaerially exposed microenvironments

burning peat and reworking loess contribute to the formation and evolution of a large carolina bay basin abstract carolina bays are nearly ubiquitous along 1300 km of the north american atlantic coastal plain but relatively few bays have been examined in detail making their formation and evolution a topic of controversy the lake mattamuskeet basin eastern north carolina usa is a conglomeration of multiple carolina bays that form a 162 km2 lake the eastern shoreline of the lake is made up of a 2 9 km wide plain of parabolic ridges that recorded rapid shoreface progradation the lower shoreface deposit contains abundant charcoal beds and laminae dated 6465 6863 cal yr bp corresponding with initiation of a lacustrine environment in the eastern part of the lake a core from the western part of the lake sampled a 1541 1633 cal yr bp charcoal bed at the base of the lacustrine unit indicating formation of this part of the basin postdates the eastern basin lake mattamuskeet has no relationship to the younger dryas or a linked impact event because rim accretion significantly postdates 12 000 cal yr bp the shoreline progradation and association of charcoal beds with the oldest lake sediment in both main parts of the basin suggest that fire and subsequent hydrodynamic processes were associated with initial formation of these carolina bays

integrated seismic tomography and ground penetrating radar gpr for the high resolution study of burial mounds tumuli the study primarily aims at providing adequate imaging resolution of large and prominent targets of archaeological interest such as pyramids and tumuli at all depth levels we implemented an integrated seismic tomography and georadar stg technique to perform high resolution imaging and characterization of tumuli burial mounds we tested the proposed technique on a preserved late bronze age burial mound in northern italy for which stg succeeded in performing an accurate 3 d reconstruction of the structure and stratigraphy as proved by later archaeological excavations we completed two transmission seismic tomography measurements at present ground level and at 1 5 m elevation with a 24 channel seismograph and 15 angular separation between geophones the ground penetrating radar gpr dataset encompasses 12 250 mhz radial profiles and 12 common mid point gathers for velocity analysis shallow layers of the mound are successfully imaged by gpr whilst the structure of the deep central part of the tomb is reconstructed from seismic traveltime inversion in particular gpr images lenses and layers of sediments forming the external part of the tumulus evidences of a looting attempt peripheral structures associated with later exploitation of the mound furnaces and in the external sector of the tumulus the top of the deep layer of silty sediments covering the funeral chamber tomographic results reveal seismic velocity anomalies of potential archaeological interest at ground level which were successively validated by archaeological excavations the integration of gpr and tomographic datasets is an effective strategy to overcome the imaging and interpretation problems related to the structure of such peculiar funeral monuments stg can be applied to a virtually unlimited dimensional range and requires a limited data acquisition processing and inversion effort the results of the study allowed the identification of the funeral chamber and a detailed imaging of layering and structural details

radarfacies and sedimentological analysis study of sedimentary substrate from an archaeological site shell mound southern brazil integrated results of gpr ground penetrating radar and sedimentological analysis are presented for the jabuticabeira ii archaeological site shell mound santa catarina brazil by means of rada

repeated century scale droughts over the past 13 000 yr near the hudson river watershed usa abstract long term sediment and ground penetrating radar data from davis pond a small lake near the hudson river valley reveal past droughts in a historically humid region that presently supplies water to millions of people in and around new york city a minimum of eleven sandy paleoshoreline deposits in the lake date from 13 4 to 0 6 cal ka bp the deposits span 1500 to 200 yr between bracketing radiocarbon ages and intrude into lacustrine silts up to 9 0 m below the modern lake surface in a transect of six sediment cores three low stands ca 13 4 10 9 9 2 and 8 2 cal ka bp indicate low regional moisture balance when low temperatures affected the north atlantic region consistent with insolation trends water levels rose from ca 8 0 cal ka bp to present but five low stands interrupted the rise and are likely associated with ocean atmosphere interactions similar to evidence from other studies the data from davis pond indicate repeated multi century periods of prolonged or frequent droughts super imposed on long term regional trends toward high water levels the patterns indicate that water supplies in this heavily populated region have continuously varied at multiple time scales and confirm that humid regions such as the northeastern united states are more prone to severe drought than historically expected

ground penetrating radar and its use in sedimentology principles problems and progress abstract ground penetrating radar gpr also referred to as ground probing radar surface penetrating radar subsurface radar georadar or impulse radar is a noninvasive geophysical technique that detects electrical discontinuities in the shallow subsurface

rare earth geochemistry of old phosphorites and probability of syngenetic precipitation and accumulation of phosphate1in memory of richard p sheldon1 abstract old vendian early cambrian phosphorites of the world demonstrate seawater like patterns in their rare earth element ree distributions but are depleted in heavy ree they also show a broad range of variation in total and elemental abundances primary bedded structureless phosphorites contain only 15 ppm total ree ree while granular pelletal varieties contain up to 650 ppm ree were incorporated into phosphate grains diagenetically during prolonged periods of transport and redeposition a higher surface mass ratio in pelletal phosphorites contributed to their enrichment in the ree s in primary bedded structureless phosphorites immediate burial of phosphate syngenetically precipitated and accumulated in situ at the sediment water interface prevented the later incorporation of the ree large deposits of vendian early cambrian phosphorites have originated by both processes primary bedded varieties occur in deeper water facies and granular phosphorites accumulated closer to the shore in terms of their ree geochemistry old granular phosphorites are almost indistinguishable from their phanerozoic counterparts indicating that both were deposited by the same mechanisms primary bedded structureless phosphorites were only deposited on a large scale at the beginning of the phanerozoic

colour banding in a latest neoproterozoic cambrian microbially variegated sabkha of the taoudeni basin adrar of mauritania abstract the taoudeni basin is a large intracratonic trough located in the west african craton with more than 2 km of neoproterozoic lower palaeozoic sedimentary thickness the occurrence of late ediacaran cambrian sabkha deposits in which playa lake evaporites are bounded by proximal braided fluvial and distal shoal complexes is easily distinguishable in the field by their variegated colour banding the diagenetic processes recorded in the sabkha substrates were largely facies controlled associated with microbial development and mat decay mineralization due to anaerobic decay of mat microorganisms chemical conditions beneath mats and biofilms tended to be strongly reducing as a result precipitation of authigenic indicators of anoxic conditions such as pyritic crusts led to variegated colours parallel to stratification reworking of microbial mats and structures by ephemeral streams also generated isolated reduction spots around their microbial clasts leading to the formation of pyritic haloes the subsequent alteration of pyrite to amorphous reddish hematite and subsequent recrystallization to brownish to yellow goethite contributed to the variegated aspect of the unit final reddening of the sediment took place irregularly as a result of dehydration of ferric hydroxides a process relatively common in desert environments

coated phosphate grains proxy for physical chemical and ecological changes in seawater irrespective of geologic age phanerozoic coated phosphate grains deposited beneath productive surface waters in organic rich paleoenvironments are of only two types unconformity bounded grains contain internal discordances and erosional surfaces attributable to multiple episodes of phosphogenesis and sedimentary reworking during periods of stratigraphic condensation redox aggraded grains consist of concordant concentric phosphate laminae that are intimately interlayered with circumgranular layers containing pyrite chamosite or barite recording in situ diagenetic mineralization driven by changes in pore water redox potential such changes can be attributed to variations in biological oxygen demand within suboxic pore water environments resulting from fluctuations in sedimentation rate of organic carbon redox aggraded grains are thus sensitive indicators of variations in organic carbon export and record changes in primary productivity and or ecological dynamics of the surface ocean this concept of coated grain formation necessitates a long residence time just below the sediment water interface if sedimentation rate is too high grains are rapidly buried and so removed from the zone of active phosphate precipitation coated phosphate grains can therefore be considered the granular equivalents of condensed beds these concepts are equally applicable to the interpretation of other types of coated grains and concretions that contain eh sensitive minerals such as iron bearing ooids and polymineralic concretions

cratonic and foreland early cambrian phosphorites of west africa palaeoceanographical and climatical contexts abstract in western gondwana two types of pan african brasiliano fold belts have been distinguished the first type is characterized by an old long lived tectonic cycle 1000 600 ma and is generally oceanic the closure of these oceans resulted in the aggregation of western gondwana in late neoproterozoic time the second type is characterized by a young short lived cycle about 600 520 ma and is mostly intracontinental fold belts of the second type have various geodynamic significances and represent folded foreland intermontane or impactogen type basins formed during or slightly after the deformational closure of the old long lived cycle phosphorites of west africa are associated with the young short lived tectonic cycle they occur together with the upper member of a distinctive formation known all over west africa this formation is made up of three members and consists from base to top of diamictites generally tillites with detrital intercalations carbonate rocks with barite and bedded cherts with local shale or siltstone intercalations in eastern senegal in the cratonic taoudeni basin the carbonate member is palaeontologically dated as early cambrian deposited during a glacio eustatic transgression it can be considered as a chronostratigraphic marker for the entire west africa phosphorites associated with or immediately following the eustatic transgression are also possibly of early cambrian age they are located either in the lower part of the chert member in the upper part of the carbonate member or sandwiched between these two units in fersiga and namel in the taoudeni basin phosphorites are associated with stromatolites characterizing the initial stage of the transgression they are overlain by evaporites which can be related to an isostatic rebound in the volta foreland basin phosphorites are associated with the chert member there they were deposited on a shelf ramp either on its proximal portion where they are strongly reworked kodjari and arli occurrences or in its distal part where they are interbedded with sediments deposited under anoxic conditions tapoa mekrou and aloub djouana occurrences the depth of marine sedimentation as indicated by the sedimentological characteristics of phosphorites and associated sediments was controlled by the combined effect of glacio eustatic sea level rise subsidence rate and isostatic rebound numerous textural features are similar in the phosphorites from the two basins phosphatic grains occurring as oncolites and stromatolitic fragments together with intraclasts show a noticeable biogenic contribution of microbial origin microbial build ups were formed in submergent emergent environments in the taoudeni basin and in the outer shelf of the volta basin apatites from these basins have similar ree contents which suggest a continental origin for the phosphorus early cambrian phosphorites of west africa were deposited soon after glacially derived sediments according to the available palaeocontinental maps both were laid down at palaeolatitudes of about 40 s west african early cambrian phosphorites thus formed at higher latitudes than their modern analogues which are confined within the inter tropical zone

rare earth elements in sedimentary phosphate deposits solution to the global ree crisis abstract the critical role of rare earth elements rees particularly heavy rees hrees in high tech industries has created a surge in demand that is quickly outstripping known global supply and has triggered a worldwide scramble to discover new sources the chemical analysis of 23 sedimentary phosphate deposits phosphorites in the united states demonstrates that they are significantly enriched in rees leaching experiments using dilute h2so4 and hcl extracted nearly 100 of their total ree content and show that the extraction of rees from phosphorites is not subject to the many technological and environmental challenges that vex the exploitation of many identified ree deposits our data suggest that phosphate rock currently mined in the united states has the potential to produce a significant proportion of the world s ree demand as a byproduct importantly the size and concentration of hrees in some unmined phosphorites dwarf the world s richest ree deposits secular variation in phosphate ree contents identifies geologic time periods favorable for the formation of currently unrecognized high ree phosphates the extraordinary endowment combined with the ease of ree extraction indicates that such phosphorites might be considered as a primary source of rees with the potential to resolve the global ree particularly for hree supply shortage

upper neoproterozoic lower cambrian sedimentary successions in the central iberian zone spain sequence stratigraphy petrology and chemostratigraphy implications for other european zones o3 tio2 zr and nb abundances in shales from all the units strongly suggest a gradual compositional change within this sedimentary succession together with the petrological data the chemical results do not reveal any obvious coeval volcanic contribution to the sediments on the basis of the chemical data a comparison is made with other european zones containing detrital sediments composed of reworked crustal components

pin stripe lamination a distinctive feature of modern and ancient eolian sediments abstract pin stripe laminations are a distinctive feature of modern and ancient eolian sediments in sets of eolian ripple or translatent strata they represent deposition of silt and very fine sand in the troughs of the advancing wind ripples in sets of avalanche strata they probably result from the downward settling of fine sand and silt within the moving avalanche to the interface of moving and unmoving sands wind tunnel experiments suggest that pin stripe laminations can also form in grainfall deposits the textural segregation associated with deposition of the fine layers in most cases leads to early cementation along and near the finest sand and silt comprising the pin stripe lamination the pin stripe effect seen in outcrops is usually due to resistance to weathering along such cemented zones the cementation of the pin stripe laminations can occur early in the history of diagenesis and thus may provide clues to the post depositional history of the rock pin stripe laminations in many instances represent the sequestering of the small population of ultrafine sediment present in most eolian depositional systems they may prove useful in the recognition of ancient eolian sediments

eolian depositional episodes controlled by late quaternary relative sea level changes on the imbituba laguna coast southern brazil the late quaternary coastal eolian deposits of the imbituba laguna region santa catarina state southern brazil comprise two eolian depositional sequences separated by an unconformity the older eolian sequence a is correlated to the relative sea level rise of the last interglacial period the eolian sequence b was initiated during the relative sea level rise in the post glacial period and extends up to active dunefields the correspondence between the two eolian depositional episodes represented by these sequences and the relative sea level highstand phases is confirmed by thermoluminescence and optically stimulated luminescence dating this correspondence is explained by a conceptual model that links the availability of coastal sediments for eolian transport with relative sea level changes the link between relative sea level changes and coastal eolian sedimentation can be used to integrate coastal eolian systems to the sequence stratigraphy model

a critical review of mid to late holocene sea level fluctuations on the eastern brazilian coastline abstract the eastern coast of brazil is 7000 km long and has been the subject of systematic paleo sea level investigations for more than 35 years more than 1000 samples have been radiocarbon dated and paleo sea level trends have been determined for 14 coastal sectors these trends have in common a mid holocene sea level maximum pmt above present sea level and a subsequent fall to the present time the time and elevation of the pmt the time when relative sea level rose above present mean sea level and the nature of late holocene sea level fall can however differ significantly discrepancies are observed not only between neighboring coastal sectors but also between different studies in a same coastal sector this paper discusses all the key radiocarbon dated samples used to establish regional trends in relative sea level on the eastern coast of brazil it is concluded that although many of the key sea level indicators are imprecise in time and space there is widespread evidence 30 of the data set for a progressive decline possibly with uneven rates of relative sea level since the end of the pmt

rare earth elements and stable isotope geochemistry of early cambrian chert phosphorite assemblages from the lower tal formation of the krol belt lesser himalaya india abstract the neoproterozoic cambrian transitional sequence in the mussoorie and garhwal hills of the lesser himalaya is represented by dolomites of the upper krol formation and chert phosphorite assemblages of the lowermost tal formation these rocks provide valuable information regarding the assumed existence of a stratified ocean during the terminal neoproterozoic and beginning of earliest cambrian nemakit daldynian the isotopic compositions of carbonate and organic carbon in the transition profile can be best interpreted as reflecting an oceanic anoxic event oae prior to the phase of early cambrian phosphate formation the chert phosphorite beds record negative ce and positive eu anomalies while ce is an important paleooceanic redox indicator eu is rather immobile under normal diagenetic conditions the observed eu anomaly is linked to the high ba content in these phosphorites and is indicative of an anoxic or sulfate reducing diagenetic environment the suggested stratification of the ocean during the late neoproterozoic and nemakit daldynian times would have been linked to the reduction of oxygen supply to the zone below the redoxcline causing 12 c and p rich organic matter previously produced in the photic zone to be trapped in large quantities within the deeper anoxic zone this would in turn increase the 13 c content of the water in the photic zone moreover in the deeper anoxic waters reduction of ce4 to ce3 would result in an enrichment of dissolved ce as ce3 upwelling of this anoxic bottom stratum would bring the 12 c and ce enriched waters back to the oxic marine realm however on entering the highly oxic productive zone the excess ce is expected to be removed from the water by oxidation to insoluble ce4 followed by precipitation or preferential scavenging due to these oxidation reactions the waters of the shallow oxic zone would tend to become rapidly depleted in ce in other words ocean mixing and upwelling during the early cambrian were ultimately responsible for the transport of 12 c p and ce to the oxic shelves sharp drops in both 13 c carb and 13 c org support the existence of oceanic anoxia followed by oceanic mixing at this juncture of earth history the large spread of the 34 s values of early diagenetic pyrites within the phosphorite bearing sequence in contrast to the limited spread of 13 c carb values suggests that phosphatisation took place under exclusively suboxic diagenetic non sulfate reducing condition and pyritisation began only when phosphate layers entered the zone of sulfate reduction

geological characteristics and spatial distribution of paleo inlet channels beneath the outer banks barrier islands north carolina usa abstract nearly 200 km of high resolution ground penetrating radar gpr data were acquired along the outer banks barrier island system of north carolina usa gpr data combined with lithofacies and biofacies data reveal multiple depositional facies including inlet channel flood tide delta overwash peat and inner shelf previously undocumented paleo inlet channels constitute a significant portion of the shallow geologic framework between oregon inlet and cape hatteras gpr data reveal the complex stratigraphy associated with multiple sequences of cut and fill within inlet channels two types of paleochannels non migrating and migrating were classified based on geometry and fill patterns sediments and foraminifera collected from vibracores were correlated to gpr data to define the regional shallow stratigraphic framework channel fill facies are characterized by clinoform packages sometimes bounded by erosional surfaces indicating variable sediment transport directions from the ocean and sound sides channels are incised into older flood tide delta deposits corresponding to older inlet activity when barriers existed further seaward flood tide delta deposits are capped with marsh peat and overwash units migrating inlet facies occur under the widest portions of the island whereas narrow portions of the island are underlain by the non migrating inlet facies or flood tide delta overwash facies this geologic geomorphic relationship is attributed to the successional stage of island evolution during transgression and sediment transport processes associated with the different inlet types the radar facies lithofacies and biofacies provide a comprehensive dataset that will permit more precise identification of barrier island facies in the geologic record

phosphorites of the russian craton abstract phosphorites of various types occur in the phanerozoic sedimentary cover of the russian craton they were deposited in six phosphorite basins all of which contain economic deposits these basins are grouped into peri and epicontinental categories examples of the former are 1 podolian basin where vendian spherical radially built concretionary phosphorites occur embedded in black shales 2 baltic basin where phosphorites composed of phosphatic shells of inarticulate brachiopods were deposited at the cambrian ordovician transition 3 west ural basin with laminated phosphorites occurring in a permian carbonate succession 4 volyn basin with upper cretaceous cenomanian granular phosphorites deposited on the northern tethyan shelf epicontinental phosphorites were more widespread on the russian craton than anywhere else they accumulated in the late jurassic early cretaceous volga ural and late cretaceous trans european seaways in both cases the phosphorites are nodular epicontinental phosphorites differ in composition and geochemistry particularly rare earth element distributions to those of the pericontinental basins the latter are believed to have formed in association with upwelling systems with the world ocean providing a phosphorus source whereas the former had a local supply with phosphorus being introduced largely by river input

lagoa da apulia a residual lagoon from the late holocene nw coastal zone of portugal the lagoa da apulia is a unique feature in the nw coastal zone of portugal a remaining form from a lagoon complex system that during the late holocene was dominant in the region this system was mainly neotectonically controlled occupying a depressed area bounded by faults on a palaeozoic rocky lower platform today observable on beaches at low tide with the intention of knowing the main architecture of the palaeo lagoon geophysical prospecting with gpr and resistivity was carried out accordingly six cores were taken and the sedimentary and mineralogical facies and diatom and foraminifer contents were analysed and five rich organic layers were dated by radiocarbon analysis with the data an evolutionary environment reconstruction model was created for this palaeo lagoon and the main structural features of the neighbouring area

diagenetic constraints on the use of cerium anomalies as palaeoseawater redox proxies an isotopic and ree study of cambrian phosphorites seawater rare earth element ree distributions show heavy ree enrichment and cerium depletion but these characteristics are only rarely found in ancient marine authigenic minerals such as carbonate fluorapatite and calcite this enigma may be due to changing ree distributions in seawater through time or to post depositional redistribution of ree differentiating between these two factors is however far from straightforward as their relative importance is likely to vary and evidence is often ambiguous in this article we present ree as well as strontium and sulphur isotope data for basal cambrian phosphorites of south china which confirm the emerging rule of thumb that granular phosphorites seldom reveal extreme departures from the seawater norm and tend to undergo therefore less diagenetic alteration of ree spectra than skeletal apatites and other phosphate types this study reveals stratigraphic trends in ce anomalies ce ce that could be taken to imply the preservation of a palaeoenvironmental signal however further investigation of our data shows that such trends in phosphorites can also be caused by post depositional alteration which tends to 1 increase ree contents 2 reverse ce depletion 3 alter eu anomalies and 4 concentrate preferentially the middle ree mree further alteration which may be due to weathering has led to hree depletion and positive la and y anomalies tetrad effect this is the first study where ceanom and phosphate bound sulphate s isotope values could be compared for one particular stratigraphic section which provides us with an additional tool for the interpretation of diagenetic redox conditions least altered phosphorites from meishucun that yield a strongly negative ceanom constrain early cambrian seawater 34s to about 33 we conclude that phosphorite ceanom primarily records variations in the local conditions of diagenesis while outlining some special cases in which diagenetic redox conditions may broadly reflect local bottom water redox conditions

barrier island response to late holocene climate events north carolina usa the outer banks barrier islands of north carolina usa contain a geologic record of inlet activity that extends from ca 2200 cal yr bp to the present and can be used as a proxy for storm activity optically stimulated luminescence osl dating 26 samples of inlet fill and flood tide delta deposits recognized in cores and geophysical data provides the basis for understanding the chronology of storm impacts and comparison to other paleoclimate proxy data osl ages of historical inlet fill compare favorably to historical documentation of inlet activity providing confidence in the technique comparison suggests that the medieval warm period mwp and little ice age lia were both characterized by elevated storm conditions as indicated by much greater inlet activity relative to today given present understanding of atmospheric circulation patterns and sea surface temperatures during the mwp and lia we suggest that increased inlet activity during the mwp responded to intensified hurricane impacts while elevated inlet activity during the lia was in response to increased nor easter activity a general decrease in storminess at mid latitudes in the north atlantic over the last 300 yr has allowed the system to evolve into a more continuous barrier with few inlets

the holocene sedimentary history of the kangerlussuaq fjord valley fill west greenland abstract west greenland has been intensively studied to reconstruct and better understand past relative sea level changes and deglacial history this study extends these efforts by linking sea level and deglacial history to the sedimentary infill successions of kangerlussuaq fjord and associated landward valleys based on published and new land and sea based geophysical data radiocarbon dates and geological observations we have characterized the infill and reconstructed the sedimentation history during the holocene based on a revised sea level curve and data presented in this paper we defined three depositional phases phase i 7000 yr bp is represented by dominant glaciomarine deposition associated with a tide water glacier system as the greenland ice sheet gis continued to retreat it became land based during phase ii 7000 1500 yr bp two separate depocenters formed keglen delta depocenter arose from a temporary stabilization phase of the gis and prograded rapidly over the glaciomarine deposits of phase i further inland proglacial lake formation and subsequent sedimentary infill associated with the ongoing gis retreat is represents the second depocenter the watson river connected both depocenters by a flood plain which transferred sediment from the gis to the keglen delta ongoing sea level fall due to glacio isostastic uplift combined with a gradually cooler and dryer climate resulted in terrace formation along the watson river flood plain around 4000 yr bp the gis margin reached its most landward location and began to advance to its present location the final phase phase iii

gpr and inductive electromagnetic surveys applied in three coastal sambaqui shell mounds archaeological sites in santa catarina state south brazil abstract in this article gpr ground penetrating radar and inductive electromagnetic em38 equipment results are presented for three archaeological sites of shell mounds located between laguna and jaguaruna cities mid southern coast of santa catarina state brazil the jabuticabeira ii santa marta iv and encantada iii sites were studied these sites consist of carbonate shell mounds built by societies that inhabited this region during the pre colonial period 7 5 1 3 ky bp geophysical responses obtained in these archaeological sites had allowed the identification of anomalous regions related to archaeological point targets as well as continuous targets correlated to the shell mound s structure and buried geologic features gpr numerical modelling studies were done in order to evaluate the performance of the gpr method in relation to materials found in that environment besides helping interpretations of real results the synthetic gpr model was a good match with real data obtained in the field so the real and synthetic results serve as a reference guide to direct excavation activities in these archaeological and geological structures in the jabuticabeira ii shell mound lithic materials and burials were found amidst archaeological layers characterized by sediment rich in organic material ferruginous concretions and loose shells in the santa marta iv archaeological site a concentration of ceramic materials burials and fireplaces were found in the encantada iii site a strong anomaly characterized by a hyperbolic reflection was related to the presence of a silicified tree root a great example of ambiguity in shallow geophysics interpretation in archaeological applications results functioned as a guide to archaeological excavations allowing cost and time reduction as well as contributing to improve the knowledge of these archaeological sites situated in southern brazil

sedimentary architecture of a spit end salisbury beach massachusetts the imprints of sea level rise and inlet dynamics abstract in the vicinity of tidal inlets the facies architecture of barrier islands is largely controlled by inlet channel shifting and the transfer of sand between the ebb tidal delta and the adjacent shore including processes of inlet sediment bypas sing merrimack river inlet is situated in a mixed energy setting and is characterized by episodic shifting of the ebb channel prior to being stabilized in 1881 here we delineate the internal structure and evolution of the updrift barrier spit terminus by integrating data obtained from ground penetrating radar transects and sediment cores to document the effects of inlet associated sedimentation processes our results document complex radar and sedimentological facies which define two distinctive associations of facies the inlet distal and proximal within the core of the present barrier these facies are associated with three phases of barrier terminus evolution i barrier retrogradation characterized by the preservation of washover and backbarrier marsh facies deposited during sea level rise ii downdrift barrier progradation characterized by channel fill and swash platform deposits overlain by foreshore deposits generated by long shore currents and swash bars migrating to the foreshore from the swash platform and iii foreshore seaward progradation characterized by cross beds this study illustrates the highly complex nature of inlet associated spit ends of barriers likewise our results shed light on the mechanisms of spit elongation and recurving in a setting where the estuary opening is narrowing

ediacaran cambrian phosphorites from the western margins of gondwana and baltica the late ediacaran mid cambrian occurrence s of phosphorites in the wes tern mediterranean region west gondwana and southern sweden north west baltica are related to the poleward drift of west gondwana and thenorthern drift of baltica as a result these regions crossed subtropical andtemperate palaeolatitudes of the southern hemisphere in which oceanicupwelling and high organic productivity were the probable sources of phos phorus along their western margins a parallel south west north east migra tion trend of evaporites and delayed time transgressive phosphorites pointto distal upwelling environments associated with shallower arid conditions concentration of hardground derived phosphate accumulations took placeby repeated alternations of low sedimentation rates and condensation in situ early diagenetic and microbially mediated precipitation of amorphousand cryptocrystalline carbonate bearing francolite winnowing and poly phase reworking of previously phosphatized skeletons and hardground derived clasts thicker phosphorites of economic importance display aspiculate sponge thromboid consortium that points to a distinct benthiccommunity developed on suboxic slope to basinal substrates for mostphosphorite samples an up to ten fold enrichment in rare earth elementconcentration relative to post archaean average australian shale re ects sig ni cant incorporation of rare earth elements and yttrium after deposition considerable scavenging took place from anoxic pore waters followingreductive dissolution of iron oxides as evidenced from the medium rareearth element enrichment in most samples this contrasts with the rare pre servation of primary sea water features such as cerium depletion andyttrium enrichment in phosphatized thrombolites from the shallower realms for example montagne noire the data are consistent with phosphogenesisafter upwelling and transgression of nutrient rich suboxic anoxic ferrugi nous waters over more oxygenated rifting settings and inland portions of anevolving passive margin

crystal chemical controls on rare earth element concentrations in fossil biogenic apatites and implications for paleoenvironmental reconstructions abstract fossil biogenic apatites display rare earth element ree patterns which have been proposed to reflect environmental and biological controls on past seawater composition these patterns can be separated in two groups 1 patterns that are similar to those of open ocean and epicontinental waters and 2 patterns that exhibit a strong enrichment in intermediate ree bell shaped patterns because ree trapping in biogenic apatites occurs mostly post mortem it is essential to understand the crystal chemical inorganic factors that can influence the fractionation of ree between apatite and water a model is proposed by which partition coefficients of ree between apatite and water for a substitution mechanism can be extrapolated from mineral melt partition data to seawater or sedimentary basin conditions these are compared with available experimental partition coefficients for ree adsorption mechanism and used to discuss ree patterns in fossil biogenic apatites calculations of ree patterns for apatites at equilibrium with water show that the bell shaped patterns in fossil apatites can be explained by fractionation with seawater or continental fluids at low temperature under crystal chemical control involving a substitution mechanism and in the context of extensive or late diagenesis in that case the equilibrium composition of the fluid cannot be unequivocally determined from observed ree concentrations in fossil apatites this type of sample is inappropriate to discuss the past environmental or biological controls on ree concentrations in the ocean other sample compositions suggest little to moderate alteration of the original oceanic to freshwater pattern through the adsorption mechanism in the context of weak or early diagenesis and may be used with caution for that purpose

late holocene intensification of colds fronts in southern brazil as indicated by dune development and provenance changes in the sao francisco do sul coastal barrier abstract holocene coastal barriers from southern brazil present great geomorphological changes during their late stages of development in this study we investigate the holocene evolution of the sao francisco do sul sfs barrier through geomorphological heavy minerals and grain size analyses constrained by optically stimulated luminescence osl dating the sfs barrier stands out among the southern brazilian barriers due to its well preserved morphology with a parabolic dune belt in the seaward portion the progradation of the sfs barrier started at least 4914 478 years ago and had a pronounced morphodynamic shift around 1891 155 years ago this shift is characterized by episodic development of parabolic dunes migrating to nnw associated with sand coarsening and a marked variation in sediment provenance represented by the input of sands derived from local coastal watersheds southward from the sfs barrier this morphodynamic provenance shift resulted from the strengthening of sse winds and associated wave systems responsible for the northward alongshore drift implying intensification of cold fronts coupled with higher precipitation since 1891 155 years ago osl dating combined with grain size heavy minerals and geomorphological analyses allowed assessing the response of coastal barriers to the impacts of centennial to millenial climate events occurred during the late holocene reconstruction of the late holocene climate variability and associated impacts on coastal sedimentation is a key issue to evaluate the sensitivity of coastal barriers to future climate changes

redox sensitivity of p cycling during marine black shale formation dynamics of sulfidic and anoxic non sulfidic bottom waters abstract a high resolution geochemical record of a 120 cm black shale interval deposited during the coniacian santonian oceanic anoxic event 3 odp leg 207 site 1261 demerara rise has been constructed to provide detailed insight into rapid changes in deep ocean and sediment paleo redox conditions high contents of organic matter sulfur and redox sensitive trace metals cd mo v zn as well as continuous lamination point to deposition under consistently oxygen free and largely sulfidic bottom water conditions however rapid and cyclic changes in deep ocean redox are documented by short term 15 20 ka intervals with decreased total organic carbon toc s and redox sensitive trace metal contents and in particular pronounced phosphorus peaks up to 2 5 wt p associated with elevated fe oxide contents sequential iron and phosphate extractions confirm that p is dominantly bound to iron oxides and incorporated into authigenic apatite preservation of this fe p coupling in an otherwise sulfidic depositional environment as indicated by fe speciation and high amounts of sulfurized organic matter may be unexpected and provides evidence for temporarily non sulfidic bottom waters however there is no evidence for deposition under oxic conditions instead sulfidic conditions were punctuated by periods of anoxic non sulfidic bottom waters during these periods phosphate was effectively scavenged during precipitation of iron oxyhydr oxides in the upper water column and was subsequently deposited and largely preserved at the sea floor after 15 25 ka sulfidic bottom water conditions were re established leading to the initial precipitation of cds zns and pyrite subsequently increasing concentrations of h2s in the water column led to extensive formation of sulfurized organic matter which effectively scavenged particle reactive mo complexes thiomolybdates at site 1261 sulfidic bottom waters lasted for 90 100 ka followed by another period of anoxic non sulfidic conditions lasting for 15 20 ka the observed cyclicity at the lower end of the redox scale may have been triggered by repeated incursions of more oxygenated surface to mid waters from the south atlantic resulting in a lowering of the oxic anoxic chemocline in the water column alternatively sea water sulfate might have been stripped by long lasting high rates of sulfate reduction removing the ultimate source for hs production

upper pleistocene to holocene peatland evolution in southern brazilian highlands as depicted by radar stratigraphy sedimentology and palynology paleoenvironmental interpretation of proxy data derived from peatlands is largely based upon an evolutionary model for ombrotrophic bogs in which peat accumulates in still environments reports on proxies obtained from minerotrophic fens where hydrologic inputs are variable are less common in this study a highland peatland in southern brazil is presented through ground penetrating radar gpr and sedimentological palynological and geochronologic data the radar stratigraphic interpretation suggests a relatively complex history of erosion and deposition at the site since the beginning of marine isotope stage 3 mis 3 interstadial period in spite of this radar stratigraphic and palynologic interpretations converge electromagnetic reflections tend to group in clusters that show lateral coherence and correlate with different sediment types while pollen grains abound and are well preserved as a result the study of minerotrophic fens provides a source of proxies suggesting that ombrotrophic bogs are not the only reliable source of data in wetlands for palynological analysis

rare earth elements in old biogenic apatites abstract the ree distributions in individual upper devonian conodonts have been measured by ion probe the patterns of all analyzed conodonts are enriched in middle ree eu gd and have a weak or no ce anomaly concentrations and la yb or la sm ratios vary very little within or among individuals from the same zone which suggests that uptake of labile ree from sediments was essentially quantitative therefore the ree signature of the primary carriers probably organic and oxyhydroxides particulates from marine suspensions was efficiently transferred to biogenic apatites and survived late diagenetic processes ree patterns of conodonts do not resemble those of present day seawater and post cretaceous biogenic phosphates which are typically depleted in nd and sm with a negative ce anomaly since ree distributions in the modern water column mimic those of nutrients we assume that in pre cretaceous seawater they were not controlled by surface biological activity we assume instead that ree in pre cretaceous seawater can be explained by mechanism of desorption adsorption on particle surfaces progressive extraction of lree from river water by oxyhydroxides leads to precipitates enriched in middle ree a simple quantitative model was calculated in order to illustrate the proposed mechanism

subseasonal to interannual variability of rainfall over new caledonia sw pacific daily rainfall occurrence and amount at 55 stations over new caledonia nc 20 s 166 e are examined throughout the calendar year during 1980 2010 using a hidden markov model hmm daily rainfall variability is described in terms of six discrete rainfall states identified by the hmm three states are interpreted as trade wind regimes associated with persistent low level anticyclonic conditions and weak to strong easterlies the most prevalent state state 1 36 of days is dry everywhere and is characterized by an elongated anticyclone centered around australia nc is located on the eastern edge of this anticyclone this state is predominant from mid may to mid december and peaks in september the second most prevalent state state 2 27 of days and the last trade regime state 4 12 of days are most frequent in austral summer states 2 and 4 are associated with the subtropical anticyclone centered south of nc close to its climatological location in austral summer and light state 2 to moderate state 4 rainfall mostly along the windward coast a distinct state state 3 11 of days is mostly associated with wintertime extratropical eastward traveling troughs between new caledonia and new zealand inducing light rainfall over the sw of the main island of new caledonia the two last states 5 and 6 are infrequent 15 of days but account for almost 70 of total rainfall across the archipelago they occur mostly in austral summer with their frequency of occurrence peaking in late february early march these states are associated with synoptic wave traveling eastward from eastern australia leading to a strong influx of moisture from the equatorial latitudes when the associated cyclonic centre is located west of new caledonia the wettest state is also strongly modulated by intra seasonal 15 80 days variability these events contribute to intermittent southwestward shifts of the south pacific convergence zone from its mean location northeast of new caledonia on interannual timescales the occurrence of the rainfall states is modulated by el nino southern oscillation enso events the enso impact is strongest from mid august to march with more less frequent trade regimes 1 2 and less more frequent unstable trade regime 4 and states 5 6 during central pacific warm cold enso events stochastic simulations of daily rainfall occurrence and amount at the 55 stations are generated by using predictors based on nino 4 sea surface temperature index and a local intra seasonal 15 80 days olr index superimposed on a climatological annual cycle the cross validated skill peaks in september november

effects of magnetite on high frequency ground penetrating radar large concentrations of magnetite in sedimentary deposits and soils with igneous parent material have been reported to affect geophysical sensor performance we have undertaken the first systematic experimental effort to understand the effects of magnetite for ground penetrating radar gpr characterization of the shallow subsurface laboratory experiments were conducted to study how homogeneous magnetite sand mixtures and magnetite concentrated in layers affect the propagation behavior velocity attenuation of high frequency gpr waves and the reflection characteristics of a buried target important observations were that magnetite had a strong effect on signal velocity and reflection at magnitudes comparable to what has been observed in small scale laboratory experiments that measured electromagnetic properties of magnetite silica mixtures magnetite also altered signal attenuation and affected the reflection characteristics of buried targets our results indicated important implications for several fields including land mine detection martian exploration engineering and moisture mapping using satellite remote sensing and radiometers

facies associations and controls on the evolution from a coastal bay to a lagoon system santa catarina coast brazil abstract the diverse holocene morphological features along the south coast of the state of santa catarina include lagoons and residual lakes a barrier a delta constructed by the tubarao river and pre existing incised valleys that have flooded and filled this scenario contains the sedimentary record of the transition from a bay to a lagoon system which occurred during the rise and subsequent semi stabilisation of the relative sea level during the holocene the geomorphological evolution of this area was investigated using a combination of morphology stratigraphic analysis of rotary push cores vibracores and trenches with radiocarbon dating taxonomic determination and taphonomic characterisation of holocene fossil molluscs palaeogeographic maps were constructed to illustrate how the bay evolved over the last 8000 years the relative sea level rise and local sedimentary processes were the prime forcing factors determining the depositional history and palaeogeographic changes the holocene sedimentary succession began between 8000 and 5700 cal bp with the deposits of transgressive sandsheets these deposits correspond to the initial marine flooding surface that was formed while the relative sea level rose at a higher rate than the input of sediments prior to the formation of the coastal barrier the change from a bay to a lagoon system occurred around 5700 and 2500 cal bp during the mid holocene highstand with the formation of the barrier and with the achievement of a balance between sea level rise and sedimentary supply until 2500 cal bp the presence of this barrier the following gentle decline in sea level and the initial emergence of back barrier features restricted the hydro dynamic circulation inside the bay and favoured an increase in the tubarao river delta progradation rate the final stage during the last 2500 years was marked by the increasing back barrier width with the establishment of salt marshes the arrival of the delta in the back barrier and the advance of aeolian dunes along the outer lagoon margins this study shed light on the mechanisms of coastal bay evolution in a setting existed prior to the beginning of barrier lagoon sedimentation

paleoenvironmental reconstruction of a late quaternary lagoon system in southern brazil jaguaruna region santa catarina state based on multi proxy analysis this paper provides a paleoenvironmental reconstruction of a late quaternary lagoon system in the jaguaruna region of santa catarina state southern brazil integrated results of bulk sedimentary organic matter characterization d 13 c d 15 n and c n microfossil pollen and diatom and grain size analysis from three shallow cores 2 5 m depth allowed us to propose an evolving paleogeographic scenario in this coastal region for the last ca 5500 cal a bp the lagoonal system in this area was more extensive during the mid holocene than today with a gradual and continuous lagoon sea disconnection until the present we add to the debate regarding relative sea level rsl variations for the brazilian coast during the holocene and discuss the importance of sedimentary dynamics for interpreting changes in coastal ecosystems the multi proxy analysis suggests that changes in coastal ecosystems could be directly related to local sedimentary processes which are not necessarily linked to rsl fluctuations and or to climatic variations copyright 2011 john wiley sons ltd

relative sea level changes in the last 5500 years in southern brazil laguna imbituba region santa catarina state based on vermetid ages abstract twenty six new radiocarbon dates from vermetid shells collected in the southernmost sector of the brazilian rocky coast presented dates ranging from 5410 80 to 190 65 years b p with associated paleosea levels varying from 2 10 m to 0 20 m above present sea level the overall suggested trend of the relative sea level rsl declining until at least 190 years b p is somewhat contradictory to a proposed rsl rise in the last 1000 years in southern brazil the data also seem to undermine a more widely accepted rsl trend that suggests that at least two negative rsl oscillations occurred between 4100 and 3800 years b p and between 3000 and 2700 years b p the maximum elevation of the rsl in the holocene in southern brazil was possibly lower than that observed in most of the brazilian eastern coast discrepancies between ancient sea levels of similar ages are attributed to coincidental methodological problems to imprecisions in determining past relative sea levels and to possible changes in the geomorphology and wave climate close to shore during the last 5000 years a general trend of increasing 18 o with a reduction in age in the studied samples may suggest a gradual reduction of water temperature in the region during the same period

parabolic dune reactivation and migration at napeague ny usa insights from aerial and gpr imagery abstract observations from mapping since the 19th century and aerial imagery since 1930 have been used to study changes in the aeolian geomorphology of coastal parabolic dunes over the last 170 years in the walking dune field napeague ny the five large parabolic dunes of the walking dune field have all migrated across or are presently interacting with a variably forested area that has affected their migration stabilization and morphology this study has concentrated on a dune with a particularly complex history of stabilization reactivation and migration we have correlated that dune s surface evolution as revealed by aerial imagery with its internal structures imaged using 200 mhz and 500 mhz ground penetrating radar gpr surveys both 2d transect and high resolution 3d gpr imagery image downwind dipping bedding planes which can be grouped by apparent dip angle into several discrete packages of beds that reflect distinct decadal scale episodes of dune reactivation and growth from aerial and high resolution gpr imagery we document a unique mode of reactivation and migration linked to upwind dune formation and parabolic dune interactions with forest trees this study documents how dune dune and dune vegetation interactions have influenced a unique mode of blowout deposition that has alternated on a decadal scale between opposite sides of a parabolic dune during reactivation and migration the pattern of recent parabolic dune reactivation and migration in the walking dune field appears to be somewhat more complex and perhaps more sensitive to subtle environmental pressures than an idealized growth model with uniform deposition and purely on axis migration this pattern believed to be prevalent among other parabolic dunes in the walking dune field may occur also in many other places where similar observational constraints are unavailable

trace and rare earth element geochemistry of phosphate nodules from the lower cambrian black shale sequence in the mufu mountain of nanjing jiangsu province china abstract phosphate nodules are abundant in the lowermost section of the lower cambrian black shale sequence along a ne trend belt in the yangtze platform south china in this study we examined the neoproterozoic cambrian mufu mountain section near nanjing of jiangsu province and conducted a detailed trace and rare earth element ree study on the phosphate nodules we employed a step leaching acid dissolution protocol of 1 m hac and 1 m hcl respectively to separate carbonate from phosphate mineral contributions in the nodules both the hac leached and hcl leached fractions of the phosphate nodules show similar symmetrical variations in trace and ree concentrations and ratios the total rees and a number of redox sensitive trace metals such as v cr mo ni abundances show a systematic increase from the core to rim whereas the u and mn abundances decrease from the core to rim in most of the nodules similar trends are also observed for the rb sr u th co ni and v ni ratios but these trends in the hac leached fractions are less pronounced than the hcl leached fractions all of the hcl leached fractions for the nodule cores show seawater like shale normalized ree patterns but the rims of the nodules display slightly mree enriched and hree depleted patterns we suggest that the phosphate nodules may have formed in a basinal setting beneath a stratified water column during early cambrian and the compositional variations of rees and redox sensitive trace elements from the core to rim may record a changing redox condition and fluid mixing during different stages of nodule growth the cores of the nodules preserve more pronounced negative ce anomalies and progressively hree enriched patterns which may retain primary early cambrian seawater chemistry whereas the nodule rims record chemistry consistent with changed redox conditions and or influences from pore fluids such as generated from degradation of organic matter

internal architecture of a raised beach ridge system anholt denmark resolved by ground penetrating radar investigations abstract the internal architecture of raised beach ridge and associated swale deposits on anholt records an ancient sea level the holocene beach ridges form part of a progradational beach ridge plain which has been interpreted to have formed during an isostatic uplift and a relative fall in the sea level over the past 7700 years the ridges are covered by pebbles and cobbles and commonly show evidence of deflation material presumably removed from the beach ridges and adjacent swales form the present dune forms on anholt ground penetrating radar gpr reflection lines have been collected with 250 mhz shielded antennae across the fossil ridge and swale structures the signals penetrate the subsurface to a maximum depth of 10 m below the fossil features the gpr data resolve the internal architecture of the beach ridges and swales with a vertical resolution of about 0 1 m gpr mapping indicates that the holocene beach ridges are composed of seaward dipping beachface deposits as well as minor amounts of inland dipping deposits of wash over origin the beachface deposits downlap on underlying shoreface deposits and we use these surfaces as markers of a relative palaeo sea level the new data indicate that the highest relative sea level at about 8 5 m was reached 6500 years ago 700 years later the relative sea level had dropped 0 7 m indicating a change in the relative sea level around 1 mm year this fall in the relative sea level most likely records the influence of an isostatic rebound causing younger beach ridge deposits to indicate lower sea levels

geochemical changes across the proterozoic cambrian transition in the durmala phosphorite mine section mussoorie hills garhwal himalaya india abstract the transition from the neoproterozoic nemakit daldynian 1 krol e dolomite to the tommotian lower tal phosphorite chert black shale sequence denotes a period of drastic change in the depositional environment and the chemical milieu of the sedimentation basin these changes are reflected by a marked negative excursion of carbon isotopes phosphorus enrichment trace metal content high organic carbon burial and notably the first appearance of prolific small shelly fauna and burrowing organisms recent studies have documented these changes along several stratigraphic profiles in the mussoorie hills of the garhwal himalaya for which a single profile from the durmala phosphorite mine provides a key section discussed here

distinctions and uses of stratification types in the interpretation of eolian sand abstract eolian and subaqueous cross strata cannot be distinguished reliably by many commonly cited criteria they can however generally be distinguished by the characteristics of their component types of stratification which represent processes of sorting and transport of the grain population on dunes eolian dune stratification types consist of grainflow cross strata grainfall laminae and wind ripple generated climbing translatent strata some of these types especially translatent strata have characteristics unique to the eolian realm these same stratification types are found to compose some ancient cross strata and their occurrence confirms the eolian interpretations of pans of the entrada jurassic navajo triassic jurassic and galesville cambrian formations a well as revealing emergent islands in the curtis formation jurassic previously considered to be totally marine in origin stratification types show a characteristic distribution on modern eolian dunes and differ in their relative abundances and structure on dunes of differing size and kind these same relations allow some estimates of the type shape and original height of ancient dune deposits as well as influencing the occurrences of surface features such as tracks and tipple forms the geological record of stratification types and other dune features is greatly affected however by the extent of the post depositional truncation of dunes