abundant sr rich aragonite in eastern mediterranean sapropel s1 diagenetic vs detrital biogenic origin caco3 contents in eastern mediterranean sapropels are generally lower than in the enclosing marl sediments in sediments of a transect from 650 to 2100 m water depth at the sirte continental slope the opposite feature was observed although the increased sr ca ratios observed in these sediments agree with such feature observed in other eastern mediterranean s1 sediments their absolute magnitude is much higher the enhanced sr ca ratio in these sediments is associated with their aragonite content which for the sirte transect reaches levels of up to 40 wt the aragonite content and sr ca ratios in the s1 sediments of this transect decrease with increasing water depth and decrease with distance to the african coast for all eastern mediterranean cores in view of the lack of a coherent relationship with sedimentary reduced sulphur contents and porosity and considering the major amount of aragonite found specifically in the sediments of the sirte transect authigenic precipitation can contribute only a limited fraction at most sem observation and electron microprobe analyses showed that the needles and needle clusters are morphologically aragonite contain the highest sr ca ratio and are similar to skeleton fragments of the green alga halimeda consequently a detrital biogenic source is the likely mechanism for the major part of the aragonite enrichments found in s1 sediments possibly offshore directed surface water flows related to wind stress and or enhanced run off consistent with enhanced precipitation during sapropel s1 may have assisted in the transport of near coastal aragonitic organisms to more coast remote areas

geochemical and petrographical characterization of fine grained carbonate particles along proximal to distal transects the origin of carbonate ooze particles is often poorly understood this is due to their polygenic origin and potential post depositional alteration here the outcome of a physical separation study with regard to different component classes of micritic carbonates is shown the focus is on grain size and morphology mineralogy and isotope signatures two contrasting proximal to distal transects were investigated 1 the miocene leeward margin of great bahama bank odp leg 166 and 2 the transition between the maiella platform and the umbria marche basin in central italy near the cenomanian turonian boundary in both case settings carbonate particles of biogenic origin include at least three groups of organisms i planktonic foraminifera ii calcareous nannofossils and iii fragments of unspecified neritic skeletal material two further particle types lack diagnostic structures and based on particle size and mineralogy are here referred to as iv macroparticles 5 20 m mainly xenomorphic and v microparticles 12 m mainly automorphic to sub automorphic macro and microparticles represent 50 to 80 of the carbonate phase in slope and toe of slope domains and share characteristic carbon and oxygen isotope signatures macro and microparticles are considered shallow water precipitation products subsequently exported into the slope and toe of slope domains macroparticles are probably related to the fragmentation of neritic skeletal components while microparticles point to inorganic and or bioinduced precipitation in the water column in some cases macro and microparticles may have an early diagenetic origin the identification of the origin of fine grained particles allows for a quantitative assessment of exported in situ and diagenetic carbonate materials in periplatform environments the data shown here represent an important step towards a more complete characterization of carbonate ooze and micrite

globorotalia truncatulinoides growth and chemistry as probes of the past thermocline 1 shell size this work identifies features of the life history of the deep living planktonic foraminifer globorotalia truncatulinoides that offer possibilities for reconstructing characteristics of the past ocean s main thermocline part 1 considers two aspects of variation in shell size the predictability of growth related size changes which we need to calculate changes in shell chemistry and a model for environmentally forced changes in shell size frequency which suggests how shell size may be a direct source of paleoceanographic information even though size variation among shells of g truncatulinoides at the same stage of growth same number of chambers exceeds the size difference between successive growth stages growth related size changes are predictable because shells tend to grow at the same rate variation in initial shell size is sufficient to account for the large size variation found among shells at the same stage of growth several lines of evidence suggest that g truncatulinoides reproduces at 600 m in the water column and it appears that vertical mixing to that depth is required to return juvenile shells to the surface anything that prevents this such as shallowing of the thermocline can interfere with g truncatulinoides life history in such a way that its shell size frequency distributions are altered among shells falling to the seafloor from a reproducing population are large numbers of both juvenile and adult sizes and if reproduction is inhibited the frequencies of those sizes are reduced and the relative frequency of intermediate sized shells increases a paleoceanographically useful result of this is that the topography of the main thermocline tends to be reflected in the size frequency distribution of g truncatulinoides shells from the underlying sediments in areas where the top of the main thermocline is shallower than 600 m production of juveniles 125 177 m and reproductive adults 425 m is reduced leaving predominantly intermediate sized 212 355 m shells

production and off bank transport of carbonate sediment black rock southwest little bahama bank abstract surficial sediments between the intertidal zone and 600 m were studied with the objectives of characterizing their source dispersal pathways and sites of accumulation bioerosion is a major source of sediment in the intertidal and shallow subtidal environments in situ enclosure experiments showed that the urchin echinometra lucunter produced 667 mg sediment cm 2 yr 1 and an associated diverse rock infauna produced an additional 183 mg cm 2 yr 1 microborers caused erosion of 25 mg cm 2 yr 1 and feeding activity by the chiton acanthopleura granulata caused additional erosion of 10 mg cm 2 yr 1 sequential weighing of tethered limestone plates showed an abrasion rate of 5 5 mg cm 2 yr 1 due chiefly to impacts on the plate edges surficial sediments between the intertidal zone and the top of the bank margin wall at 30 m are gravel sand mixtures containing 0 2 mud molluscs and halimeda plates are the main constituents of gravel fractions sand fractions are composed of bioerosion produced carbonate rock fragments 1 70 skeletal material from halimeda 3 63 forams 1 33 molluscs 6 15 and coral 0 6 gravel and sand are transported as bedload in chutes across the narrow rocky shelf chutes end at 45 m and sediment traps indicate an average flux of 5 4 kg chute 1 yr 1 equivalent to 945 kg km 1 yr 1 moving to deep water a dense population of halimeda living on the wall between 30 70 m contributes gravel and sand to sediment on wall ledges at the base of the steep wall 65 a ramp slopes into the northwest providence channel between 120 300 m the ramp 30 slope is a zone by passed by coarse and fine sediment at 300 m the slope decreases to an average of 13 and an apron shaped body of mud is accumulating the apron extends parallel to the bank margin and wall and reaches depths 600 m traps showed that sediment flux to the ramp is 0 12 kg m 2 yr 1 which is 2 of the particle flux overtopping the bank margin surficial sediment of the ramp is mostly mud 70 which is primarily of shallow water origin some form of bottom current transporting gravel and sand mostly halimeda and abraded coral heads has cut gullies into the ramp this bottom flow is probably episodic and turbulent enough to suspend and supply halimeda sand to sediment traps on the ramp at 463 m

contribution of oxygen minimum zone waters to the coastal upwelling off mauritania the coastal upwelling off mauritania and its connection with the oxygen minimum zone omz in the tropical atlantic is investigated in an eddy resolving general circulation model two main supply routes for the upwelling are identified first a southern eastward pathway crossing 23 degrees w between 3 degrees n and 10 degrees n related to the equatorial zonal current system supplies up to 50 of the water upwelled in winter and about 30 in summer second another eastward pathway crossing 23 degrees w further north between 28 degrees n and 38 degrees n supplies 35 of the upwelled water in spring compared to 25 during the rest of the year most of the water of the northern pathway is entrained into the mixed layer already before reaching the upwelling region only the southern pathway contributes not recently ventilated waters to the upwelling the connection with the omz is very weak only about 1 of the upwelling waters originate here on the other hand if water from the omz reaches the surface mixed layer within 6 years this mostly 71 happens in the upwelling region

palaeoenvironmental control on sponge microbialite reefs and contemporaneous deep shelf marl limestone deposition late oxfordian southern germany abstract the late oxfordian bimammatum zone deep shelf deposits of southern germany are characterised by abundant reefs that laterally pass into marl limestone alternations the bioconstructions are made from three main components sponges microbialites and allochthonous sediment a detailed morphological analysis of sponge microbialite reefs in the plettenberg section swabian alb southern germany is combined with investigation of calcareous nannofossil assemblages in laterally correspondent marl limestone alternations in order to trace the evolution of palaeoenvironmental conditions during reef development fluctuations of caco3 content in deep shelf deposits provides evidence of a succession of small scale lithological units generally formed by five to six marl limestone couplets within a small scale lithological unit a close link is observed between growth patterns of sponge microbialite reefs and the changes in the nannofossil assemblage composition phases of expansion of the build ups correspond to carbonate deposits characterised by a relative dominance of large oligotrophic nannoplankton species large watznaueria britannica watznaueria manivitiae and schizosphaerella spp marly intervals reveal a high relative abundance of small sized taxa mainly lotharingius hauffii small w britannica and subordinated biscutum dorsetensis and bioconstructions show a net reduction in size or a total demise this suggests that the same palaeoenvironmental parameters controlled at the same time marl versus limestone deposition reef growth phases and calcareous nannofossil assemblage composition successive reef growth phases recognized within a bioherm are correlated to the limestone hemi couplets each reef growth phase is composed of several stacked elementary sequences comprising the following succession i sponge ii microbialites and iii carbonate mud in turn the microbialitic crust is formed of three successive microbial layers 1 a fine crust of dense to clotted micrite 2 a centimetre scale to multicentimetric columnar layer of clotted to peloidal micrite 3 a centimetre scale stromatolitic crust the passage from an initial dense microbial layer with numerous microencrusters to a final stromatolitic crust is interpreted as resulting from an increase of the microbial growth rate mainly driven by changes in the accumulation rate deep shelf deposits resulted from changes in platform carbonate production and export basinwards controlled both by sea level and climate changes climate controlled the intensity of carbonate production in shallow platform environments and export towards the deep shelf as well as the trophic conditions of the deep shelf marine waters low trophic conditions favoured platform carbonate production and export basinwards and a large development of the sponge microbialite reefs in the deep shelf however a high carbonate accumulation rate in the deep shelf was also commonly responsible for the demise of sponge microbialite reefs during unfavourable and higher trophic conditions during marl deposition reduced development and frequent demise of the sponge microbialite reefs is observed

carbonate apron models alternatives to the submarine fan model for paleoenvironmental analysis and hydrocarbon exploration sediment gravity flow deposition along the deep water flanks of carbonate platforms typically does not produce submarine fans rather wedge shaped carbonate aprons develop parallel to the adjacent shelf slope break the major difference between submarine fans and carbonate aprons is a point source with channelized sedimentation on fans versus a line source with sheet flow sedimentation on aprons two types of carbonate aprons may develop along relatively gentle 4 platform margin slopes aprons form immediately adjacent to the shallow water platform and are referred to as carbonate slope aprons along relatively steep 4 15 platform margin slopes redeposited limestones accumulate in a base of slope setting by passing an upper slope via a multitude of small submarine canyons and are referred to as carbonate base of slope aprons both apron types are further subdivided into inner and outer facies belts inner apron sediments consist of thick mud supported conglomerates and megabreccias facies f as well as thick coarse grained turbidites facies a interbedded with subordinate amounts of fine grained peri platform ooze facies g outer apron sediments consist of thinner grain supported conglomerates and turbidites facies a as well as classical turbidites facies c with recognizable bouma divisions interbedded with approximately equal proportions of peri platform ooze facies g seaward aprons grade laterally into basinal facies of thin base cut out carbonate turbidites facies d that are subordinate to peri platform oozes facies g carbonate base of slope aprons grade shelfward into an upper slope facies of fine grained peri platform ooze facies g cut by numerous small canyons that are filled with coarse debris as well as intraformational truncation surfaces which result from submarine sliding in contrast slope aprons grade shelfward immediately into shoal water platform margin facies without an intervening by pass slope the two carbonate apron models presented here offer alternatives to the submarine fan model for paleoenvironmental analysis and hydrocarbon exploration for mass transported carbonate facies

geomorphology of carbonate platform marginal uppermost slopes insights from a holocene analogue little bahama bank bahamas as the product of a variety of sediment sources and sedimentation and re sedimentation and erosion processes the geomorphology and sedimentology of carbonate slopes are highly variable the purpose of this study is to describe sub bottom profiles and side scan sonar multibeam and optical data acquired by an autonomous underwater vehicle to explore variability in geomorphological and sedimentological character of the present day platform marginal uppermost slope environments 240 m water depth on the north open ocean facing flank of little bahama bank bahamas although at time scales of greater than 100 ka this margin is progradational the data illustrate a complex juxtaposition of erosional and depositional processes and features erosion is evidenced by two prominent escarpments 70 m and 120 m that expose eroded bedded rocky outcrops these escarpments are interpreted to represent relict features related to past sea level positions although they still may be shedding debris aside from erosional remnants sedimentation and active transport is indicated by several features including active bedforms especially above the 70 m escarpment but ripples occur to depths of ca 200 m several mass transport complexes that overlie and cover the lower escarpment gravity flow deposits and rare slump features similarly a thick up to 20 m onlapping sediment wedge interpreted to be holocene in age suggests lateral accretion of the slope by more than 75 m in this period data illustrate that this open ocean margin is distinct from windward margins in the bahamas which typically include near vertical walls of erosion or bypass flanked downdip by rubble and talus and leeward margins which have onlapping muddy wedges but that lack marked terraces or escarpments collectively the results provide perspectives into the nature and controls on complex geomorphological patterns of erosion and deposition in holocene uppermost slope systems concepts potentially applicable to ancient analogues

a multi method luminescence dating of the palaeolithic sequence of la ferrassie based on new excavations adjacent to the la ferrassie 1 and 2 skeletons abstract a new interdisciplinary project was initiated to excavate a portion of the palaeolithic site of la ferrassie left intact by earlier excavations one of the aims of this project was to provide chronological information on the succession of middle and upper palaeolithic layers as well as on the skeletons unearthed by capitan and peyrony in the early 1900 s we report here preliminary results on the lithics faunal remains site formation processes and on the stratigraphic context of the la ferrassie 1 and 2 skeletons that were found adjacent to our excavations finally results from luminescence dating of the sediments and a preliminary set of radiocarbon ages are presented quartz osl both at the multi grain and single grain levels of analysis and post ir irsl of feldspar at various stimulation temperatures are compared the quartz feldspar comparison revealed a bleaching problem for the quartz osl and the feldspar pirir signals from layer 2 as a consequence the age of this layer was determined using a minimum age model a mousterian industry with bifaces at the base of the sequence has been dated between 91 9 and 44 3 ka the ferrassie mousterian layers are attributed to mis 3 between 54 3 and 40 2 ka and thus appear very late in the final middle palaeolithic of the region furthermore these ages constrain the chronology of the la ferrassie 1 and 2 skeletons which have been attributed to one of these ferrassie mousterian layers the ch telperronian layer is dated to 42 3 ka and the aurignacian to 37 2 ka implications of the ages for the la ferrassie 1 and 2 skeletons and for the variability of late mousterian are discussed

dynamics of the carbonate system in a large continental shelf system under the influence of both a river plume and coastal upwelling national basic research program of china 973 program 2009cb421201 national science foundation of china nsfc 90711005 40821063 nsfc rgc 40731160624 n hkust623 07 scope project

controls on grain size patterns in periplatform carbonates marginal setting versus glacio eustacy the importance of grain size as a fundamental property controlling other physically derived properties is well known recent grain size studies on periplatform sediments of the caribbean and western north atlantic have shown that grain size variability is coupled with changes in carbonate platform productivity and export in response to pleistocene holocene glacio eustacy these findings showed that periplatform sediments are dominated by fine grained material during sea level highstands and coarser material during sea level lowstands this paper addresses the question of grain size patterns in periplatform settings and their relationship to glacio eustacy furthermore it considers whether these patterns are applicable to different types of margin settings accretionary erosional here existing data pleistocene holocene from the accretionary western leeward margin of great bahama bank odp leg 166 and new data from the erosional eastern windward margin odp leg 101 are used the results show that the grain size patterns of both margins are controlled by late neogene sea level fluctuations the accretionary leeward margin sediments indicate the same grain size pattern as previously described in the literature however the erosional windward margin shows a reverse pattern with coarser sediments in interglacials and finer deposits in glacials this proposes that the leeward margin grain size pattern is controlled by the productivity export mode of the platform this is indicated by the platform top derived fine muds transported off bank to form a thick sediment wedge on the low angled slope during interglacials in contrast on the windward margin the sediment flux pattern is controlled by the impact of mass transport processes this is indicated by the increased occurrence of turbidites during interglacials that might be more frequent at this time because the steep angled erosional slope is less apt for the deposition of excess fine material this material is eroded and or bypasses the slopes and is redeposited in the periplatform basin setting

pelagic sedimentation of aragonite its geochemical significance the relative importance of the pelagic flux of aragonite as compared to calcite to the deep sea floor has been evaluated by means of a quantitative x ray diffraction study of samples collected from sediment traps and from an unusually shallow portion of the open atlantic ocean the rio grande rise the results suggest that the aragonite flux constitutes at least 12 percent of the total flux of calcium carbonate on a worldwide basis the presence of high magnesium calcite in several samples suggests that some of the calcareous material falling to the deep sea floor may be derived from the long distance transport of debris from shallow water beenthic organisms as well as from the settling of planktonic remains this observation supports the contention that 12 percent represents a minimum value aragonite and high magnesium calcite transported laterally from shallow water regions upon dissolution during settling into deeper water may contribute to the neutralization of excess anthropogenic carbon dioxide added to the oceans

effects of upwelling tides and biological processes on the inorganic carbon system of a coastal lagoon in baja california abstract the role of coastal lagoons and estuaries as sources or sinks of inorganic carbon in upwelling areas has not been fully understood during the months of may july 2005 we studied the dissolved inorganic carbon system in a coastal lagoon of northwestern mexico during the strongest period of upwelling events along the bay different scenarios were observed for the distributions of ph dissolved inorganic carbon dic and apparent oxygen utilization aou as a result of different combinations of upwelling intensity and tidal amplitude dic concentrations in the outer part of the bay were controlled by mixing processes at the inner part of the bay dic was as low as 1800 mol kg 1 most likely due to high water residence times and seagrass co 2 uptake it is estimated that 85 of san quintin bay at the oceanic end acted as a source of co 2 to the atmosphere due to the inflow of co 2 rich upwelled waters from the neighboring ocean with high positive fluxes higher than 30 mmol c m 2 d 1 in contrast there was a net uptake of co 2 and hco 3 by the seagrass bed zostera marina in the inner part of the bay so the p co 2 in this zone was below the equilibrium value and slightly negative co 2 fluxes of 6 mmol c m 2 d 1 our positive nep and dic values indicate that bahia san quintin was a net autotrophic system during the upwelling season during 2005

thermoluminescence dating of le moustier dordogne france the chronology of the neanderthal cultures commonly called mousterian which flourished between 100 000 and 40 000 yr ago has not been well established the lower rock shelter of le moustier provides one of the most important stratigraphic sequences incorporating ten main mousterian layers originally identified by peyrony1 and two early upper palaeolithic layers the stratigraphy of which is mainly defined in terms of the regional climatic chronostratigraphy derived from the alpine glacial sequence1 4 a correlation has recently been proposed between the chronostratigraphy of dordogne and the past 125 000 yr of the well established stratigraphy based on oceanic oxygen isotope ratios5 6 but the lack of absolute datings of mousterian settlements makes this correlation uncertain between 100 000 and 40 000 yr bp we now report dates obtained by thermoluminescence measurements of 34 specimens of burnt flint recovered from the upper 3 m of the mousterian deposits and from the superimposed upper palaeolithic layer the dates which range from 56 000 to 40 000 yr bp allow us to correlate the cold sediment deposits of le moustier with cold intervals of the oxygen isotopic record of the mediterranean sea during isotopic stage 3

oxygen minimum zone in the north atlantic south and east of the cape verde islands the open ocean oxygen minimum zone omz south and east of the cape verde islands is studied from ctd hydrography adcp velocities argo float trajectories and historical data with a focus on the zonal supply and drainage paths the strongest oxygen minimum is located north of the north equatorial countercurrent necc at about 400 to 500 m depth just above the boundary between central water and antarctic intermediate water aaiw it is shown that the necc the north equatorial undercurrent at 4 to 6 n and a northern branch of the necc at 8 to 10 n are the sources for oxygen rich water supplied to the omz in summer and fall a weak eastward necc at 200 m depth also exists in winter and spring as derived from argo floats drifting at shallow levels historical oxygen data from 200 m depth confirm this seasonality showing high low oxygen content in summer and fall spring within the supply paths compared to the strong oxygen supply at 150 to 300 m depth the ventilation of the omz at 300 to 600 m depth is weaker westward drainage of oxygen poor water takes place north of the guinea dome i e north of 10 n most pronounced at 400 to 600 m depth in july 2006 the total eastward transport of both necc bands above 27 1 kg m 3 at 23 w was about 13 sv 1 sv 106 m3 s 1 about half of this water volume circulates within the guinea dome or recirculates westward north of the guinea dome

ocean acidification and biologically induced seasonality of carbonate mineral saturation states in the western arctic ocean calcium carbonate caco3 mineral saturation states for aragonite aragonite and calcite calcite are calculated for waters of the chukchi sea shelf and canada basin of the western arctic ocean during the shelf basin interactions project from 2002 to 2004 on the chukchi sea shelf a strong seasonality and vertical differentiation of aragonite and calcite saturation states was observed during the summertime sea ice retreat period high rates of phytoplankton primary production and net community production act to increase the aragonite and calcite of surface waters while subsurface waters become undersaturated with respect to aragonite due primarily to remineralization of organic matter to co2 this seasonal phytoplankton carbonate saturation state interaction induces strong undersaturation of aragonite aragonite 10 the seasonal aragonite undersaturation of waters observed on the chukchi sea shelf is likely a recent phenomenon that results from the uptake of anthropogenic co2 and subsequent ocean acidification with seasonality of saturation states superimposed by biological processes these undersaturated waters are potentially highly corrosive to calcifying benthic fauna e g bivalves and echinoderms found on the shelf with implications for the food sources of large benthic feeding mammals e g walrus gray whales and bearded seals the benthic ecosystem of the chukchi sea and other arctic ocean shelves is thus potentially vulnerable to future ocean acidification and suppression of caco3 saturation states

whiting related sediment export along the middle miocene carbonate ramp of great bahama bank modern aragonite needles are present all along the modern leeward margin of great bahama bank odp leg 166 while middle miocene sediments contain needles only in more distal areas sites 1006 and 1007 in contrast to the rimmed flat topped platform topography during the plio pleistocene the miocene great bahama bank morphology is a carbonate ramp profile this might imply a different location and precipitation type for miocene aragonite needles in this study aragonite needles in miocene sediments were isolated using a granulometric separation method furthermore the isolation of the various carbonate components enables the identification of primary versus diagenetic components the miocene aragonite needles are concentrated in the finest granulometric sediment fractions 12 m the fraction specific geochemical analyses 13c 18o and sr elemental abundance represent useful tools to assess the possible sources of the aragonite mud the geochemical variation of the fractions rich in pristine aragonite needles and the characteristics of the needle morphology point to whiting phenomena as the main sediment source and algal fragmentation as a minor component both components indicate shallow water environments as the main sediment source area ramp top related fine grained particles now present at distal sites were likely exported as suspended material similar to present day transport mechanisms the scarcity of needles at proximal sites is probably linked to hydrodynamic processes but dissolution and recrystallization processes cannot be excluded the granulometric separation approach applied here enables a better characterization of the finest carbonate particles representing an important step towards the discrimination between primary and diagenetic fine grained components

ubiquity of anomalous fading in k feldspars and the measurement and correction for it in optical dating anomalous fading rates were measured in k feldspars separated from 49 sediment samples mainly from north america the intensity of the optically stimulated luminescence was found to decrease linea

in situ evaluation of air sea gas exchange parameterizations using novel conservative and volatile tracers measurements of air sea gas exchange rates are reported from two deliberate tracer experiments in the southern north sea during february 1992 and 1993 a conservative tracer spores of the bacterium bacillus globigii var niger was used for the first time in an in situ air sea gas exchange experiment this nonvolatile tracer is used to correct for dispersive dilution of the volatile tracers and allows three estimations of the transfer velocity for the same time period the first estimation of the power dependence of gas transfer on molecular diffusivity in the marine environment is reported this allows the impact of bubbles on estimates of the transfer velocity derived from changes in the helium sulphur hexafluoride ratio to be assessed data from earlier dual tracer experiments are reinterpreted and findings suggest that results from all dual tracer experiments are mutually consistent the complete data set is used to test published parameterizations of gas transfer with wind speed a gas ex change relationship that shows a dependence on wind speed intermediate between those ofliss and merlivat 1986 and wanninkhof 1992 is found to be optimal the dual tracer data are shown to be reasonably consistent with global estimates of gas exchange based on the uptake of natural and bomb derived radiocarbon the degree of scatter in the data when plotted against wind speed suggests that parameters not scaling with wind speed are also influencing gas exchange rates

depositional mechanisms for upper miocene sediments in the south china sea central basin evidence from calcareous nannofossils abstract in 2014 the international ocean discovery program iodp expedition exp 349 discovered carbonate layers at sites located in the south china sea scs central basin preliminary results from shipboard investigation showed that most of these carbonate layers are calcareous nannofossil ooze and interpreted them as turbidites however more detailed studies are required to determine their depositional mechanisms and paleoenvironmental implications in this study we have analyzed caco3 content calcareous nannofossil abundance assemblage composition and preservation in carbonate and clay samples from the upper miocene sections of site u1433 in the scs central basin we confirm that these carbonate layers are of turbidity current genesis but are not typical nannofossil ooze while the clays represent regular in situ deep sea sediments the study interval spanned approximately from 10 to 5 million years before present ma calcareous nannofossil abundance and assemblage are used to reconstruct the evolution of the upper seawater structure in the scs central basin our results indicate that the seawater shifted from strongly stratified to well mixed due to enhanced monsoon this shift was accompanied by an increase in pelagic productivity at 8 ma this environmental change is critical for component variations of the carbonate turbidites since we suggest that these turbidites mainly sourced from periplatform ooze in the southern scs composed by of mixed neritic and pelagic particles the neritic and pelagic caco3 production have inversed responses to the change of seawater environment in the scs and thus cause the component variations in the carbonate turbidites of site u1433

morphometric analysis of plunge pools and sediment wave fields along western great bahama bank abstract a systematic assessment of morphometric parameters of over 200 plunge pools along the steep escarpment base of western great bahama bank and 2000km2 of sediment wave fields of upslope migrating cyclic steps documents the importance of cascading density currents for sedimentation on the slope the abrupt downslope termination of the holocene mud wedge with the cyclic steps shows that strike parallel bottom currents interacting with the off bank currents are responsible for slope sediment distribution the plunge pools and sediment waves were generated by density cascading and both are related to a hydraulic jump caused by two gradient changes along the slope profile the bedforms highlight both the erosional and depositional nature of this current regime which is controlled by slope gradient and the directional confinement by either grooves on the steep escarpment or gullies on the middle to lower slope the 20 m deep plunge pools are ellipsoidal with an average width of 211 m and length of 283 m but variations between 80 360 m and 100 650 m for width and length occur they are caused by an average gradient break of 16 on the cemented upper slope gradient breaks of as low as 2 are reported to be sufficient to scour a plunge pool like the ones in the study area but higher gradient breaks between 10 and 20 are quite common for consistent plunge pool development a second gradient break further down slope changes flow conditions for the generation of cyclic steps with asymmetric waveforms of 4 m high average in large wave fields in the entire the study area orientation is mainly orthogonal to the main slope direction but wave lengths and sinuosity vary depending on the morphologic location of the wave field the comparison with sediment wave fields with similar geometries or in similar environments shows that flow reconstruction based on the wave height and wave length alone along with a characterization of sediment grain size however yields non unique results and is site specific

new experimental evidence on the relation between percussion flaking and flake variation abstract controlled experiments in percussion flaking allowed for objective analysis of relationships between variables of flake production and those variables which are attributes of the final result the independent variables those controlled by the flintknapper in the production of stone tools include force and angle of blow platform thickness and exterior platform angle the dependent variables are those attributes of the flakes which are often used in current lithic analyses and include interior platform angle length thickness and flake termination the results clearly show that exterior platform angle is highly significant for understanding many aspects of flake production these and other relationships between the independent and dependent variables are also discussed

chronology and formation processes of the middle to upper palaeolithic deposits of ifri n ammar using multi method luminescence dating and micromorphology abstract the existence of an early upper palaeolithic culture at the transition from the middle palaeolithic to the upper palaeolithic in north african cave sites is currently under debate we studied ifri n ammar in north east morocco which is one of the oldest settlement sites of anatomically modern humans amh in the maghreb and contains several sediment layers which are attributed to middle and upper palaeolithic occupations in order to investigate processes of sediment accumulation and postdepositional alteration we studied thin sections from these levels according to micromorphological analysis aeolian input considerably contributed to sediment accumulation and postdepositional mixing by bioturbation occurred we compared multiple and single grain quartz and multiple grain feldspar luminescence dating of three samples from corresponding sediment layers to achieve a comprehensive chronology the single grain dose distributions scatter strongly and the source of the scatter is unclear we used an arithmetic mean to calculate the equivalent doses archaeological evidence and age control from radiocarbon dating was essential to interpret the data quartz and feldspar multiple grain luminescence ages are between 15 and 80 ka the central part of the profile shows an intermediate accumulation which lacks specified lithic artefacts this supports the idea of an occupational gap between middle and upper palaeolithic layers

thermoluminescence dates for the middle palaeolithic site of chez pinaud jonzac france thermoluminescence dating of heated flint artefacts from the middle palaeolithic sequence of chez pinaud jonzac france places an assemblage of quina type mousterian into mis 4 while the overlying assemblage of denticulate mousterian which is followed by two layers with mousterian of acheulean tradition are all assigned to mis 3 tl dating is used to verify the mixed nature of deposits from which diagnostic middle as well as upper palaeolithic tools were recovered the tl ages are significantly different for samples from this layer and broadly agree with the archaeological attributions while the study is generally limited by the low number of heated samples available a correlation with a generalized chronostratigraphic sequence is possible by including proxy data from the faunal remains associated with the lithic assemblages in question the quina mousterian in southwestern france therefore can be placed by chronometric dating methods in mis 4 to mis 3

the contribution of lithic production systems to the interpretation of mousterian industrial variability in south western france the example of combe grenal dordogne france disentangling the relative contribution of the various factors underlying middle palaeolithic industrial variability remains one of the foremost problems for researchers interested in neandertal technological and behavioural adaptations the site of combe grenal dordogne has figured prominently in these discussions given its long stratigraphic sequence and rich archaeological record that extends from mis 6 to mis 3 and contains all of f bordes mousterian facies departing from a strict typological approach we provide a revised vision of the site s sequence focused on individualising lithic production systems we investigate to what extent typologically different industries beyond their separation imposed by the very idea of discrete mousterian facies nevertheless portray comparable production systems by eschewing a chronology of the traditional mousterian facies our technological approach to the combe grenal assemblages succeeded in identifying a clear stratigraphic succession where strictly typological approaches had previously failed moreover comparison with other regional sequences shows the succession of mousterian technological systems identified at combe grenal not to be an exception in south western france we propose a revised chronology for the site s sequence based on a correlation of changes in the structure of regional faunal communities with independent palaeo environmental data finally comparing technological data with raw material provisioning strategies and elements of faunal exploitation such as prey availability provides insights concerning the interpretation of mousterian variability and the investigation of changing patterns of neandertal landscape use

luminescence dating of the stratzing loess profile austria testing the potential of an elevated temperature post ir irsl protocol abstract feldspar infrared stimulated luminescence irsl signals saturate at 2000 gy i e 500 700 ka assuming a dose rate of 3 4 gy ka typical for loess and it is therefore theoretically possible to date middle pleistocene loess however the accuracy of age estimates is hampered by anomalous fading which leads to significant age underestimation fading corrections have been proposed but these corrections are reliant on inherent assumptions and in any case are inapplicable at large doses as the growth curve approaches saturation recent studies have identified a post ir irsl signal that shows less fading and is thus less dependent on accurate fading corrections this study builds upon these investigations and applies a post ir irsl sar dating protocol to polymineral fine grain samples of the loess palaeosol sequence in stratzing lower austria after a preheat at 320 c 60 s and an ir bleach at 50 c 200 s irsl was measured at 290 c for 200 s the same set of conditions were used to measure the response to a test dose recycling ratios recuperation and dose recovery tests show that this protocol is suitable for the loess under investigation although finite residual doses of up to 20 gy are observed for the oldest samples the natural signal is in or close to saturation indicating that fading is negligible in nature this observation is inconsistent with the measured laboratory fading rates of 1 1 5 decade and needs further investigation

late middle palaeolithic lithic technocomplexes mis 5 3 in the northeastern aquitaine basin advances and challenges abstract establishing and interpreting patterns of lithic assemblage variability is of great interest to archaeologists as they shed light on cultural adaptations in the deep past nowhere has this topic provoked more interest and debate than in the middle palaeolithic of southwestern france the region s rich archaeological record has produced numerous sites many of which have been recently excavated and thus provide a reliable dataset for better structuring mousterian lithic variability researchers working with these types of datasets frequently employ the chaine operatoire concept to approach lithic assemblage variability however the validity of such analyses has recently been questioned here we present results of a combined quantitative and qualitative technological analysis of a large sample of assemblages from numerous well contextualised sites in the northeastern aquitaine basin we selected clearly identifiable diagnostic elements typical of different flake production systems that can be quantified by different analysts in a replicable fashion our results show strong differences in assemblage composition in terms of dominant production systems as well as a smaller number of mixed assemblages that combine two or more flake production methods when considered together these results provide not only a means for defining lithic technocomplexes and subsequently comparing assemblages but also for investigating elements of neanderthal material culture variability

heterozoan carbonates from the equatorial rocky reefs of the galapagos archipelago strongly influenced by seasonal and interannual i e el nino southern oscillation upwelling the equatorial setting of the galapagos archipelago is divided into well defined temperature nutrient and calcium carbonate saturation aragonite regions to understand the relationship between oceanographic properties and sediment grain associations grain size carbonate content and components from sea floor surface samples were analysed representing the main geographical regions of the galapagos archipelago the shallow water rocky reefs of the galapagos archipelago are characterized by mixed carbonate siliciclastic slightly gravelly sands despite minor differences in carbonate content major differences exist in the distribution and composition of key carbonate producing biota halimeda is absent and benthic foraminifera occur in extremely low abundance the western side of the galapagos archipelago is strongly influenced by nutrient rich low aragonite subtropical water which generates a heterozoan carbonate biofacies in a tropical realm resembling cold water counterparts i e serpulid echinoderm gastropod barnacle and bryozoan rich facies the central east region is composed of a transitional heterozoan biofacies biofacies observed in the northern region have an increased occurrence of tropical corals albeit with a minor overall contribution to the carbonate components although the temperature gradient would allow for a broader distribution of photozoan biofacies the increased nutrient concentration and related reduced light penetration from the upwelled waters favour heterozoan carbonate factories mimicking cool water deeper or higher latitude environments the recent sedimentary record of the galapagos archipelago presents a range of tropical heterozoan carbonate communities responding to more than simply latitude or temperature but a much more complex mixture of physical evolutionary and geological processes

modern deep water coral mounds north of little bahama bank criteria for recognition of deep water coral bioherms in the rock record abstract deep water ahermatypic coral mounds are present at water depths of 1 000 1 300 m on the lower slope north of little bahama bank the mounds are patchily distributed over a minimum area of 2 500 km2 and typically display 5 40 m of relief above the surrounding sea bottom a diverse benthic community exists on these apparently unlithified mounds including l 1 genera and 16 species of ahermatypic coral bathypsammia caryophyllia deltocyathus desmophyllum enallopsammia javania madrepora polymyces solenosmilia stephanocyathus and a previously undescribed genus alcyonaceans gorgonians antipatharians hydroids ophiuroids crinoids barnacles galatheid crabs polychaetes gastropods bivalves and sponges conspicuously absent from the coral fauna are lop elia and dendrophyllia common deep water corals in other parts of the atlantic radiocarbon dates on fresh coral and gorgonian fragments of 940 40 and 860 50 years indicate the mounds are at least in part recent and are probably actively forming today bored and stained corals date at around 22 10314c years b p which establishes a minimum age for these mounds we speculate that the mounds develop on sea floor perturbations in areas where strong bottom currents provide needed oxygen and nutrients to the fauna the mounds may have undergone multi stage evolution from colony to thicket to coppice to bank this evolution may be accomplished through the in situ contribution of skeletal material along with the baffling and trapping of fine grained carbonate sediment winnowed from adjacent areas by bottom currents if found in the rock record the coral mounds north of little bahama bank would probably be considered bioherms geologists should thus be aware that scleractinian bioherms are not uniquely shallow water in origin the distinction between ancient deep and shallow water coral buildups involves using multiple recognition criteria including 1 presence or absence of algae 2 diversity of corals 3 coral morphology and microstructure 4 abundance of planktonic benthonic components 5 microborings 6 surrounding litho and biofacies 7 stable isotopes of carbon and oxygen and 8 trace element geochemistry particularly sr and u concentrations the distinction between deep and shallow water bioherms is crucial to regional paleoenvironmental and stratigraphic interpretations

component specific petrographic and geochemical characterization of fine grained carbonates along carboniferous and jurassic platform to basin transects abstract fine grained carbonates are present throughout much of the geological record and are widely used as geochemical archives even though their origin and diagenetic pathways remain poorly understood here petrographical and geochemical properties of granulometrically separated component spectra of marine mudstones sampled along two proximal to distal transects carboniferous of spain and jurassic of morocco are documented these settings represent end members in terms of platform geometry steep flanked versus gentle ramp and the aragonite versus calcite sea mode the data from spain reveal a bimodal organization of microcrystalline carbonate isotope values from platform top and slope and toe of slope settings the data from morocco lack a clear spatial and bathymetrical pattern the significance of the complex site specific biological and physico chemical parameters is emphasized mudstones have been separated in granulometric fractions of 8 5 5 3 and

optical dating studies of quartz and feldspar sediment extracts abstract continuing developmental work into optical dating has led to some clarification of the optical behaviour of quartz and feldspar sediment extracts we have verified the key assumption intrinsic to the method that the optical signal is zeroed completely upon exposure to daylight we also show that the rate of zeroing in optical dating is much more rapid than it is in tl dating studies concerned with the extraction of the thermally stable signal from laboratory irradiated samples showed that problems may arise from medium to high temperature preheating of young samples optical alternatives to thermal stabilization were tested using dye and krypton lasers using a krypton laser we have succeeded in obtaining an equivalent dose of 0 0 0 7 gy for the quartz from a modern intertidal sand and an average dose of 120 22 gy for the feldspar extract of a 70 ka sand unit both were obtained using six wavelengths from the infrared to the violet and no dependence on wavelength was found we found that the photon energies of infrared and deep red light can stimulate luminescence in unirradiated quartz and feldspar extracts of sediments this was not expected and suggests that the process of trap emptying is more complex than we had envisioned but implies a far greater than expected degree of technical flexibility for the optical dating method

fluvial landscape development in the southwestern kalahari during the holocene chronology and provenance of fluvial deposits in the molopo canyon the southern kalahari drainage network is in a key position to analyze spatiotemporal changes in the tropical easterly and the temperate westerly circulation over the southern african subcontinent however due to the prevailing aridity paleoenvironmental archives within the southwestern kalahari are sparse and often discontinuous hence little is known about holocene environmental change in this region this study focuses on reconstructing paleoenvironmental change from the timing and provenance of fluvial deposits located within the molopo canyon which connects the southern kalahari drainage to the perennial flow regime of the orange river to gain insight into temporal aspects of fluvial morphodynamics within the molopo canyon the entire variety of fluvial landforms consisting mainly of slope sediments alluvial fans and alluvial fills were dated using optically stimulated luminescence osl we additionally applied a provenance analysis on alluvial fill deposits to estimate potential sediment source areas source areas were identified by analyzing the elemental and mineralogical composition of tributaries and eolian deposits throughout the course of the lower molopo the results allow the first general classification of fluvial landscape development into three temporally distinct deposition phases in the southern kalahari 1 a phase of canyon aggradation associated with short lived and spatially restricted flash floods during the early to mid holocene 2 a phase of fan aggradation indicating a decrease in flood intensities during the mid to late holocene and 3 a phase of canyon aggradation caused by the occurrence of supra regional flood events during the little ice age we interpret the observed spatiotemporal deposition patterns to latitudinal shifts of the tropical easterly circulation in the early to mid holocene and the temperate westerly circulation in the late holocene however despite marked changes in the provenance and timing of fluvial deposits in the molopo canyon throughout the holocene our analysis did not detect a contribution of sediments originating from the kalahari interior to the deposition of alluvial fills these results suggest that the southern kalahari drainage remained endorheic and therefore disconnected from the orange river throughout the holocene

rapidity of freshwater calcite cementation implications for carbonate diagenesis and sequence stratigraphy abstract in less than 10 years subaerially exposed holocene oolitic sand on eleuthera island bahamas was completely case hardened by freshwater vadose calcite cementation this phenomenon demonstrates the rapidity of freshwater carbonate diagenesis and explains in part why carbonate platforms preferentially shed unconsolidated sediment during highstands and not during lowstands when they are subaerially exposed it further proves contrary to what the exxon conceptual sequence stratigraphic models imply that carbonate deposits do in fact respond differently to subaerial exposure than siliciclastic deposits case hardening of unconsolidated carbonate sediment in response to subaerial exposure and early near surface freshwater diagenesis helps explain why shallow water platform sediments are preferentially shed into adjacent basins during highstands of sea level and not during lowstands during lowstands rapid subaerial lithification of carbonate sediments retards their reworking by wind or water once lithified these deposits are further stabilized by vegetation and karstification inhibiting their transport as unconsolidated sediment into adjacent deeper water basins observations from eleuthera island also document the reciprocal processes associated with freshwater carbonate diagenesis calcium carbonate released by partial dissolution of aragonitic ooids was locally reprecipitated as pore filling low magnesian calcite cement this reciprocity is confirmed by the confinement of freshwater dissolution and cementation to the upper 10 20 cm of the subaerially exposed body of oolitic sand below this case hardened surface oolitic sands remained unconsolidated only very minor amounts of calcite cement were required for effective casae hardening

surface sediment carbonate mineralogy and water column chemistry nicaragua rise versus the bahamas abstract periplatform surface sediments were studied for carbonate mineralogy in conjunction with analyses of the water column for carbonate chemistry on the eastern northern nicaragua rise nnr in the caribbean sea the results show a strong correspondence between variations and disappearance with increasing water depth of metastable carbonate minerals fine aragonite and magnesian calcite and their respective saturation levels in the overlying waters similar correspondence between variations in sediment proportions of fine aragonite and magnesian calcite and their respective saturation levels has previously been established in the bahamas there are however significant differences between the two areas the sharp decrease in aragonite content and the measured aragonite saturation level occur at 4000 m in the bahamas compared to 1800 m on the eastern nnr in both areas magnesian calcite minima correspond to the in situ pco 2 maxima in the water column the magnesian calcite minimum however is at 950 m in the bahamas and 750 m on the eastern nnr magnesian calcite disappears in the bahamas at 3800 m and at 2000 m on the eastern nnr these results demonstrate the importance of the influence of overlying water chemistry on the preservation of metastable carbonate minerals in off bank periplatform sediments and they clearly demonstrate the difference in terms of carbonate preservation between the poorly ventilated waters of the caribbean sea and the well oxygenated waters of the adjacent atlantic ocean they also open the possibility of obtaining paleoceanographic information on the depth of the co 2 maximum o 2 minimum and its separation from the aragonite saturation depth in at least some areas

new radiometric ages for the early upper palaeolithic type locality of brno bohunice czech republic comparison of osl irsl tl and 14c dating results new radiometric data are reported from the recent excavation of the type locality of the early upper palaeolithic entity of the bohunician recently obtained radiocarbon 14c data on charcoal are compared with new optically stimulated luminescence osl dating of sediment osl ages were determined on sediment from the archaeological occupation at brno bohunice as well as from the over and underlying loessic sediments multiple techniques were applied which all gave congruent results while a dual protocol post ir osl failed the quality criteria tests ages were obtained by multiple aliquot additive dose maad on polymineral material and single aliquot regeneration sar on fine grain quartz extract as well as on polymineral material fading tests show significant loss of infrared stimulated luminescence irsl after storage for 3 and 12 months for one sample but little or no fading for others the resulting uncorrected age estimates are smaller than those on quartz by osl methods the latter are considered to be more reliable estimates of the sedimentation age of these deposits the measured osl doses do not show a simple distribution and the lowest 5 was used for age calculation to represent the most likely sedimentation age the quartz from the loess overlying the archaeological layer is osl dated to 30 9 3 1 ka while the sediment for the paleosol which contains the archaeological layer gave an age of 58 7 5 8 ka the attribution of this paleosol to the hengelo interstadial is therefore questionable however if the hengelo interstadial is correlated with the dansgaard oeschger d o event 12 statistical agreement within 2 is achieved the osl result for the archaeological layer is in accordance with a weighted average tl date on heated flint artifacts of 48 2 1 9 ka from this layer as well as calibrated radiocarbon data calpal hulu 2007 from nearby locations however radiocarbon data on charcoal samples obtained during excavation at brno bohunice 2002 provide age estimates between 30 and 40 ka 14c years which translate to approximately 33 35 44 ka on the calendric time scale according to the hulu 2007 model for the underlying loess a depositional age of 104 3 10 6 ka was obtained by osl the presented osl ages indicate that a simple correlation of soil sequences between sites within a region has to be verified by chronometric dating

carbonate shedding and sedimentary cyclicities of a distally steepened carbonate ramp miocene great bahama bank depositional geometries as imaged in seis mic lines logging data and quantitative petrographic data were used to analyse the slope and toe of slope deposits of the miocene distally steepened carbonate ramp of great bahama bank the shedding pattern along the slope of this ramp is more complex than it is along the slope of the pliocene pleistocene flat topped carbonate platform compositional changes and compositional trends of periplatform sediments correlate with the positions of geophysically defined sequence boundaries two types of depositional sequences occur the first sequence is characterised by laterally traceable sequence internal reflections whereas the second type contains major intrasequen tial incisions erosional incisions and sedimentary infills of these canyons by turbidites formed during sea level lowstands as is indicated by the composition of the turbidites having a mixture of shallow water and pelagic particles highstand turbidites are charac terised by more extensive laterally traceable geome tries and by the occurrence of abundant shallow water particles in contrast to highstand turbidites shed from the pliocene pleistocene flat topped platform shal low water components in highstand turbidites of the miocene ramp are of skeletal origin the stacking pat tern of the periplatform deposits is controlled by sea level fluctuations four orders of sea level changes are distinguished third order cycles are delimited by sequence boundaries and fourth 100 000 a order cycles govern the bundling of turbidites into packages fifth 40 000 a and sixth 23 000 a order cycles are recorded in the background sediments and resolvable with spectral analysis

building models of neanderthal territories from raw material transports in the aquitaine basin southwestern france abstract the middle palaeolithic of southwestern france has long been a testing ground for models of neanderthal lithic assemblage variability and mobility strategies advances in our understanding of the lithological structure of the northern aquitaine basin combined with numerous raw material studies allows connections between different areas of the region to be revealed based on the movement of particular tracer materials by comparing technological data with raw material transport patterns elements of late neanderthal techno economic behaviour emerge raw materials were transferred over longer distances in both the levallois and quina techno complexes compared to the discoid techno complexes where evidence for similar movements are almost entirely absent comparing these patterns of raw material provisioning and transfer against the distribution of key middle palaeolithic sites forms the basis of a new model for the territorial organisation of late neandertal groups in the aquitaine basin to be built

the use of biface manufacturing flakes functional analysis of three middle palaeolithic assemblages from southwestern and northern france abstract this paper presents a use wear analysis of biface manufacturing flakes from three french middle palaeolithic sites jonzac fonseigner and saint amand les eaux low and high power approaches combined with a morphometric analysis demonstrate these flakes whether retouched or not to have primarily been used to cut soft and soft to medium hard materials whereas numerous pieces exhibit typical scar patterns referable to butchery activities clear meat polishes are only evident on a handful of flakes from jonzac together with less definitive examples from saint amand several differences between these two sites can be seen in the morphology of prehensile areas on biface manufacturing flakes finally factors such as flake morphology assemblage composition site function and cultural traditions that may have influenced the way these artefacts were used are also discussed

site formation and chronology of the new paleolithic site sima de las palomas de teba southern spain abstract the newly identified paleolithic site sima de las palomas de teba hosts an almost seven m thick sediment profile investigated here to elucidate the rock shelter s chronostratigraphy and formation processes at its base the sediment sequence contains rich archeological deposits recording intensive occupation by neanderthals luminescence provides a terminus ante quem of 39 4 2 6 ka or 44 9 4 1 ka osl and 51 4 8 4 ka tl this occupation ended with a rockfall event followed by accumulation of archeologically sterile sediments these were covered by sediments containing few middle paleolithic artifacts which either indicate ephemeral occupation by neanderthals or reworking as suggested by micromorphological features above this unit scattered lithic artifacts of undiagnostic character may represent undefined paleolithic occupations sediment burial ages between about 23 0 1 5 ka osl and 40 5 3 4 ka pirir provide an upper paleolithic chronology for sediments deposited above the rockfall finally a dung bearing holocene layer in the uppermost part of the sequence contains a fragment of a human mandible dated to 4032 39 14 c yr bp overall the sequence represents an important new site for studying the end of neanderthal occupation in southern spain

the complementarity of luminescence dating methods illustrated on the mousterian sequence of the roc de marsal a series of reindeer dominated quina mousterian layers dated to mis 3 abstract located in southwest france roc de marsal is a cave with a rich mousterian stratigraphic sequence the lower part of the sequence layers 9 5 are characterized by assemblages dominated by levallois lithic technology associated with composite faunal spectra including red deer roe deer and reindeer that shows a gradual increase in the frequency of reindeer the top of the sequence layers 4 2 are characterised instead by quina lithic technology both in terms of technology and typology with the faunal remains dominated by reindeer roc de marsal thus provides a very interesting case study to place behavioural changes in a context of changing climates and environments in western europe during the late pleistocene to link the occupations at roc de marsal with global and regional climatic conditions known independently a robust chronology is needed with this aim in mind we applied three luminescence dating methods tl osl and irsl on different minerals flint quartz and k feldspar extracts here the results of two of these methods are presented in detail tl and osl and compared with preliminary irsl data at roc de marsal a comparison of methods was necessary to overcome a complex sedimentary history with very heterogeneous dose rate distributions both at the beta mm and gamma dm dose rate scales the results indicate that the lower levallois layers are dated to 65 70 ka while overlying quina layers are dated to 49 ka these ages for the lower layers fit well with some models that place mixed faunal assemblages in the initial mis 4 however while the quina ages overlap with several other quina assemblages from the region they place the reindeer dominated fauna well after the peak cold of mis 4 and suggest a more extended and complex period of contemporaneous lithic techno complexes than posited by some current models

surface ocean carbon dioxide during the atlantic meridional transect 1995 2013 evidence of ocean acidification abstract here we present more than 21 000 observations of carbon dioxide fugacity in air and seawater fco 2 along the atlantic meridional transect amt programme for the period 1995 2013 our dataset consists of 11 southbound and 2 northbound cruises in boreal autumn and spring respectively our paper is primarily focused on change in the surface ocean carbonate system during southbound cruises we used observed fco 2 and total alkalinity ta derived from salinity and temperature to estimate dissolved inorganic carbon dic and ph total scale using this approach estimated ph was consistent with spectrophotometric measurements carried out on 3 of our cruises the amt cruises transect a range of biogeographic provinces where surface chlorophyll spans two orders of magnitude mesotrophic high latitudes to oligotrophic subtropical gyres we found that surface chlorophyll was negatively correlated with fco 2 but that the deep chlorophyll maximum was not a controlling variable for fco 2 our data show clear evidence of ocean acidification across 100 of latitude in the atlantic ocean over the period 1995 2013 we estimated annual rates of change in a sea surface temperature of 0 01 0 05 c b seawater fco 2 of 1 44 0 84 atm c dic of 0 87 1 02 mol per kg and d ph of 0 0013 0 0009 units monte carlo simulations propagating the respective analytical uncertainties showed that the latter were 2 increased at the same rate as atmospheric co 2

bypass margins basin restricted wedges and platform to basin correlation upper devonian canadian rocky mountains implications for sequence stratigraphy of carbonate platform systems abstract carbonate platforms can commonly keep up with relative sea level rise because of high rates of sediment accumulation and platform aggradation surrounding basinal environments are commonly starved but can receive variable extrabasinal siliciclastic input and episodically deposited carbonate sediment if accumulation rates in basinal settings lag behind those of the platform a bypass or erosional margin can develop under these circumstances platform and basin depositional sequences become physically detached and direct correlation of basinal and platform sequences is hindered we report here the results of high resolution stratigraphic analyses of two upper devonian isolated carbonate platforms in western alberta that provide insight into the sequence stratigraphy of bypass margins and criteria for accurate correlation of platform and basinal sequences the slope and basin sequences surrounding the miette and ancient wall platforms consist of basin restricted onlapping wedges of fine grained background sediment deposited dominantly from suspension and coarse grained platform derived sediment redeposited by a variety of gravity flow mechanisms sequence boundaries are identified within the redeposited carbonate intervals identification of sequence boundaries and differentiation of highstand and lowstand slope and basinal facies was based on the geometry mineralogy and clast content of redeposited carbonate units highstand carbonates contain sheet like debris flows and turbidites with abundant slope derived clasts and background facies with high total carbonate content lowstand carbonates contain sheet like and channelized debris flows and turbidites with abundant platform derived clasts and background facies with low carbonate content and locally high amounts of organic carbon transgressive facies are dominated by initially carbonate poor and organic rich background sediments that display a progressive increase in carbonate content and decrease in organic carbon content these patterns are interpreted to record abundant background carbonate sedimentation during late transgression and highstand when the carbonate factory was robust highstand redeposited carbonates record slope erosion due to oversteepening and slope readjustment processes lowstand redeposited carbonates indicate platform and platform margin erosion and low background carbonate sedimentation when the platform was either exposed or under very shallow peritidal conditions high siliciclastic and organic contents during lowstand and early transgression may partly be the result of reciprocal sedimentation but alternatively may represent continuous siliciclastic supply during times with little dilution by fine grained carbonate sediment successive stages of platform development at miette and ancient wall were controlled by accommodation changes driven by relative sea level fluctuations backstripping analyses of strata from both platforms confirm that significant differential subsidence was a major control on variations in platform thickness and patterns of slope development greater subsidence at ancient wall fostered the development of a steeper bypass margin and different slope evolution compared to miette slope oversteepening also initiated a process of slope readjustment that eventually reduced the platform to basin gradient and facilitated regressive platform progradation in conventional siliciclastic sequence stratigraphy basin restricted wedges are interpreted as lowstand deposits on the basis of their geometry and position relative to an updip margin wedge shaped basinal units along the miette and ancient wall bypass margins contain both highstand and lowstand facies that straddle sequence boundaries the results of this study provide objective criteria for differentiating systems tracts in carbonate slope and basin environments through mineralogic and compositional analyses providing more accurate correlation of detached platform and basin sequences interpretation of carbonate basin restricted wedges as purely highstand or lowstand deposits may lead to erroneous conclusions regarding sequence stratigraphy platform to basin correlation and the volumetric partitioning of sediments deposited in different systems tracts

biological and physical forcing of carbonate chemistry in an upwelling filament off northwest africa results from a lagrangian study the mauritanian upwelling system is one of the most biologically productive regions of the world s oceans coastal upwelling transfers nutrients to the sun lit surface ocean thereby stimulating phytoplankton growth upwelling of deep waters also supplies dissolved inorganic carbon dic high levels of which lead to low calcium carbonate saturation states in surface waters with potentially adverse effects on marine calcifiers in this study an upwelled filament off the coast of northwest africa was followed using drifting buoys and sulphur hexafluoride to determine how the carbonate chemistry changed over time as a result of biological physical and chemical processes the initial phtot in the mixed layer of the upwelled plume was 7 94 and the saturation states of calcite and aragonite were 3 4 and 2 2 respectively as the plume moved offshore over a period of 9 days biological uptake of dic 37 mol kg 1 reduced pco2 concentrations from 540 to 410 atm thereby increasing phtot to 8 05 and calcite and aragonite saturation states to 4 0 and 2 7 respectively the increase 25 mol kg 1 in total alkalinity over the 9 day study period can be accounted for solely by the combined effects of nitrate uptake and processes that alter salinity i e evaporation and mixing with other water masses we found no evidence of significant alkalinity accumulation as a result of exudation of organic bases by primary producers the ongoing expansion of oxygen minimum zones through global warming will likely further reduce the caco3 saturation of upwelled waters amplifying any adverse consequences of ocean acidification on the ecosystem of the mauritanian upwelling system

multi method tl and osl multi material quartz and flint dating of the mousterian site of roc de marsal dordogne france correlating neanderthal occupations with the climatic variability of mis 5 3 abstract roc de marsal has yielded numerous remains of mousterian occupations including lithics fauna and combustion features it was made famous by the discovery of the skeleton of a neanderthal child given the need to date the sequence tl and osl were applied on heated flints and quartz and osl on unheated quartz chronological results combined with palaeoenvironmental data faunal remains and micromorphological features in the sediments from the cave pollen proxies and faunal remains from the region allowed us to place climate variations in southwest france on a numerical time scale denticulate mousterian occupations were dated to the middle of mis 4 65 70 ka and quina layers either to the very end of mis 4 or to mis 3 interestingly a faunal pattern showing a mix of red deer roe deer and reindeer was found to have occurred during mis 4 which was shown to be consistent with data from other similar sites in southwest france

air sea co2 fluxes along the coast of chile from co2 outgassing in central northern upwelling waters to co2 uptake in southern patagonian fjords 1 carbon system parameters measured during several expeditions along the coast of chile 23 s 56 s have been used to show the main spatial and temporal trends of air sea co2 fluxes in the coastal waters of the eastern south pacific chilean coastal waters are characterized by strong pco2 gradients between the atmosphere and the surface water with high spatial and temporal variability on average the direction of the carbon flux changes from co2 outgassing at the coastal upwelling region to co2 sequestering at the nonupwelling fjord region in chilean patagonia estimations of surface water pco2 along the patagonian fjord region showed that while minimum pco2 levels strong co2 undersaturation occurs during the spring and summer period maximum levels including co2 supersaturation occur during the austral winter co2 uptake in the patagonia fjord region during spring summer is within the order of 5 mol c m 2 yr 1 indicating a significant regional sink of atmospheric co2 during that season we suggest that the co2 sink at patagonia most probably exceeds the co2 source exerted by the coastal upwelling system off central northern chile

anatomy of a modern open ocean carbonate slope northern little bahama bank the open ocean carbonate slope north of little bahama bank consists of a relatively steep 4 upper slope between water depths of 200 and 900 m and a more gentle 1 2 lower slope between depths of 900 and 1300 m the upper slope is dissected by numerous small submarine canyons 50 150 m in relief that act as a line source for the downslope transport of coarse grained carbonate debris the lower slope is devoid of any well defined canyons but does contain numerous small 1 5 m hummocks of uncertain origin and numerous larger 5 40 m patchily distributed ahermatypic coral mounds sediments along the upper slope have prograded seaward during the cenozoic as a slope front fill seismic facies of fine grained peri platform ooze surface sediments show lateral gradation of both grain size and carbonate mineralogy with the fine fraction derived largely from the adjacent shallow water platform near surface sedimentary facies along the upper slope display a gradual downslope decrease in the degree of submarine cementation from well lithified hardgrounds to patchily cemented nodular ooze to unlithified peri platform ooze controlled by lateral variations in diagenetic potential and or winnowing by bottom currents submarine cementation stabilizes the upper part of the slope allowing upbuilding of the platform margin and controls the distribution of submarine slides as well as the headward extent of submarine canyons where unlithified sediments are heavily bioturbated and are locally undergoing dolomitization upper slope sediments are also conditioned eustatically resulting in vertical cyclic sequences of diagenetically unstable aragonite and magnesian calcite rich and stable calcite rich carbonates that may explain the well bedded nature of ancient peri platform ooze sequences lower slope sediments have prograded seaward during the cenozoic as a chaotic fill seismic facies of coarse grained carbonate turbidites and debris flow deposits with subordinate amounts of peri platform ooze coarse clasts are internally derived from fine grained upper slope sediments via incipient cementation submarine sliding and the generation of sediment gravity flows gravity flows bypass the upper slope via a multitude of canyons and are deposited along the lower slope as a wedge shaped apron of debris parallel to the adjacent shelf edge consisting of a complex spatial arrangement of localized turbidites and debris flow deposits a proximal apron facies of thick mud supported debris flow deposits plus thick coarse grained ta turbidites grades seaward into a distal apron facies of thinner grain supported debris flow deposits and thinner finer grained ta b turbidites with increasing proportions of peri platform ooze both the geomorphology and sedimentary facies relationships of the carbonate apron north of little bahama bank differ significantly from the classic submarine fan model as such a carbonate apron model offers an alternative to the fan model for palaeoenvironmental analysis of ancient open ocean carbonate slope sequences

late quaternary hemipelagic carbonate oozes on the southwestern balearic slope western mediterranean abstract carbonate sediments on continental slopes in temperate areas have not received as much attention as their tropical counterparts this study documents the sedimentology and main early diagenetic features of hemipelagic carbonate oozes from two piston cores from the continental slope of the south balearic margin western mediterranean between 38 and 39 n the two cores contain hemipelagic carbonate oozes consisting of a mixture of clay minerals and several carbonate phases which settled on the flanks of the balearic carbonate platform during the last full quaternary glacial interglacial cycle textural faunal and mineralogical data suggest that the balearic sedimentary record is closely related to changes in productivity dissolution and dilution all of which are related to 18o and 13c signals during the late quaternary the dominant carbonate phase is low magnesian calcite whereas aragonite and high magnesian calcite are present as minor components the incorporation of low magnesian calcite in the sediment is due to planktonic pelagic rain the high magnesian calcite is incorporated via resuspension of particles originating from the degradation of molluscan and red algal carbonate skeletons from the adjacent carbonate rich balearic shelves aragonite derives from pteropods and presumably shallow water aragonite organisms as the red algae peyssonelia the main differences between tropical carbonate slope sediments and balearic temperate hemipelagic oozes are the lesser amounts of carbonate minerals mainly aragonite and high magnesian calcite and the greater quantity of quartz and clay minerals our results suggest that the hemipelagic carbonate oozes of the balearic slope are an intermediate type of carbonate oozes between the low magnesian calcite deep pelagic oozes with low diagenetic potential and the multiphasal carbonate tropical periplatform sediments with high diagenetic potential

controls on modern carbonate preservation in the southern florida straits abstract the water masses in the florida straits and bahamas region are important sources for the northern atlantic surface ocean circulation in this study we analyse carbonate preservation in surface sediments located above the chemical lysocline in the florida straits and bahamas region and discuss possible reasons for supralysoclinal dissolution calcite dissolution proxies such as the variation of the foraminiferal assemblage fragmentation index benthic foraminifera index and resistance index displayed a good preservation in both areas the pteropod species limacina inflata showed very good preservation in sediments of inter platform channels from the great bahama bank providence channel exuma sound above the aragonite lysocline supralysoclinal aragonite dissolution however was observed at two water depth levels 800 1000 m and below 1500 m in the florida straits our observations suggest that the supralysoclinal dissolution in the florida straits is due to the degradation of organic material the presence of antarctic intermediate water aaiw may be a contributing factor for the significant aragonite dissolution in 800 1000 m the comparison of modern preservation patterns of the surface sediments with hydrographical measurements shows that the l inflata dissolution index ldx might be an adequate proxy to reconstruct paleo water mass conditions in an area which is highly saturated with respect to calcium carbonate

the use of canonical variates for determination of biface manufacturing technology at boxgrove lower palaeolithic site and the behavioural implications of this technology abstract the application of canonical variates analysis to experimentally produced biface reduction sequences and subsequent analysis of archaeological flint debitage indicate that most of the archaeological debitage was knapped with a bone or an antler percussor this soft percussor was used after minimal nodule preparation the use of bone or antler as a percussor suggests both planning in the activities of the people at boxgrove and a degree of curative behaviour two new statistics for the analysis of debitage are introduced and the results suggest that debitage struck by a soft stone hammer can be distinguished from debitage struck by a bone or antler hammer

deposition of upper jurassic fine grained limestones in the western subalpine basin france abstract the fine grained carbonate sequence on the western margin of the french subalpine basin provides information about the depositional conditions of the late jurassic nodular lithofacies which closely resemble the age equivalent ammonitico rosso of the mediterranean and central atlantic domains a variety of rock textures can be distinguished including lumpy nodular restricted sense and conglomeratic the formation of these textures is referred to different sedimentological processes cyclic marl limestone deposition bioturbation winnowing early lithification gravity displacement etc in addition the development of deep water cryptalgal carbonate constructions which include stromatolites and small mud mounds is noted outer shelf deep marine palaeoenvironments 100 s m are inferred from the sedimentary structures biotic associations and facies distributions the callovian oxfordian discontinuity is believed to have resulted from a sediment starved environment part of the overlying fine grained carbonate material was then presumably derived from an adjacent platform oscillations in nature and quantity of carbonate and clay input onto the margin probably reflect cyclic climatic and sea level changes

alternation of ecologic regimes in a deep marine carbonate basin calciturbidite trace fossils from the cretaceous scaglia rossa northeastern italy abstract the mostly pelagic scaglia rossa limestone exposed in the vich quarry near belluno contains numerous light colored turbidites consisting of calcareous sandstone and mudstone derived from the adjacent friuli platform the turbidites contain an ichnofauna that records short lived departures from background conditions in this part of the belluno basin in the late cretaceous at least seven distinctive ichnotaxa were recognized some of which could be the parts or extensions of more complex burrow systems of deposit feeders that exploited the disturbances earliest exploitation of the individual turbidites is indicated by nondescript burrow mottling in the lowest sandstone divisions this is followed by an ensemble of comparatively well preserved sand filled and typically mud lined mantled burrows produced as the mud fraction began to accumulate gradually from suspension all of these structures are crosscut by a latest series of mud filled tunnels this is not exactly the pattern of siliciclastic turbidites of flysch successions having post event ichnoassociations consisting of traces that are more nearly contemporaneous and record either depth of penetration or post depositional movement of the redox boundary because the mud component in the vich turbidites may have required several months to settle out of suspension the patterns of bioturbation were extended over months to years but as in the case of siliciclastic turbidites emplacement of the calciturbidites suppressed the background fauna and supported a post event association of different endobenthic animals by changing temporarily the physical properties of the substrate providing a windfall of organic particles and by ventilating the near bottom water

stratigraphic simulation of sedimentary basins concepts and calibration a two dimensional stratigraphic simulation program based on semiempirical algorithms has been successfully applied to clastic carbonate and mixed clastic carbonate depositional regimes the program may be used to predict reservoir distribution to constrain interpretations of well and seismic data to test exploration scenarios in frontier basins and to evaluate the fundamental controls on basin stratigraphy applications to seismic and well log data sets from main pass u s gulf coast offshore sarawak malaysia and the baltimore canyon u s east coast demonstrate that the program simulates stratigraphy on a basin wide scale as well as on the scale of individual prospects the main pass section is an offlapping sequence of neogene clastics the model simulates 17 m y of geologic history at a 200 000 yr resolution and reproduces gross basin geometry major sequence boundaries depth and location of nearshore marine sands intervals of sediment bypass into deep water shelf margin positions and paleobathymetry three neogene carbonate buildups of central luconia offshore sarawak malaysia were simulated using a sea level history optimized to reproduce the carbonate growth anatomy the model reproduced observed seismic reflection geometries and transgressive aggradational progradational retrogradational and subaerial exposure phases the program has also simulated jurassic pleistocene basin and stratigraphic sequence geometries and mixed clastic carbonate facies distribution along a 300 km regional dip line of the baltimore canyon trough modeled features of interest include a progradational middle jurassic carbonate margin punctuated by clastic deposition during sea level lowstands and a late jurassic early cretaceous aggradational carbonate margin culminating in the development and subsequent drowning of isolated carbonate buildups simulated bathymetries facies relations and subaerial exposure surfaces for the early cretaceous aggradation margin are consistent with detailed petrographic paleontologic and seismic stratigraphic interpretations

intra level technological change and its implications for mousterian assemblage variability the example of le moustier layer g revealing the multiple factors underlying variability observed in middle palaeolithic lithic assemblages of southwestern france continues to be of great interest dividing scholars both in terms of their interpretation and the approaches applied building sound interpretive models whether in terms of chronology or techno economy is however often hindered by the nature of recovery strategies employed during many early excavations in this important region the site of le moustier lower shelter has played a fundamental role in the definition of the well known and controversial mousterian facies as well as the perception of their chronological patterning based on a technological and taphonomic analysis of material recovered from a small test pit it has recently been shown that the original lithic collections recovered from le moustier by peyrony before the first world war are unrepresentative and that clear technological variations exist that were otherwise undetectable in this brief contribution we present additional data concerning newly discovered material from layer g assigned by bordes to his mta type a variant this material further supports the previously documented separation of a lower levallois dominated assemblage from the overlying one with a heavy emphasis on bifacial shaping faconnage finally these results are discussed in terms of broader definitional issues of middle palaeolithic techno complexes focussing specific attention on assemblages with bifacial tools

water masses and currents in the upper tropical northeast atlantic off northwest africa recent current measurements in the tropical eastern north atlantic reproduce the components of the large scale flow field however the observations as well as the 1 12 flame model computations indicate that a lot of eddy scale variability is superimposed on the mean flow field despite of the disturbance by variability the signature of the guinea dome is well present in november 2002 the guinea dome transport from direct observations was about 2 8 sv above 25 8 kg m3 and 4 sv between 25 8 and 27 1 kg m3 the oxygen minimum in the shadow zone comprises the central water and the antarctic intermediate water aaiw layers and is located between the equatorial current system and the north equatorial current the north equatorial counter and undercurrents at 3 to 6 n are major oxygen sources for the central water layer of the low oxygen regions in the northeastern tropical atlantic a second northern north equatorial countercurrent nnecc band exists at 8 to 10 n the nnecc carries oxygen rich water from the southern hemisphere eastward but with an admixture of water from the northern hemisphere a float at 200 m depth was spreading eastward in the north equatorial undercurrent neuc at 28 w it shifted northward into the nnecc and then was trapped in the guinea dome region for more than 3 years the model indicates the region 22 to 32 w as the area of exchange between the necc neuc and the nnecc bands in the aaiw layer the northern intermediate countercurrent acts as oxygen source for the oxygen minimum zone

the late middle palaeolithic in southwest france new tl dates for the sequence of pech de l aze iv the relative and numerical chronological position of the technological and typological variants of the mousterian in southwest france has been the subject of debate for over fifty years since the advent of both esr and tl dating methods in the 1980s a database of chronometric dates for a growing number of sites has been steadily accumulating a recent summary by guibert et al appears to show a complex pattern of broadly overlapping mousterian variants in the late middle palaeolithic and has led some to conclude that bordes initial interpretation of these variants as distinct cultural groups was essentially correct this paper adds to this database with new thermoluminescence dates from pech de l aze iv this site originally excavated by bordes in the 1970s contains a deep sequence of mousterian assemblages which express considerable technological and typological variability and which are associated with well preserved faunal remains excavations were undertaken from 2000 to 2003 in part to gain a better understanding of the geological context of the assemblages and also to obtain chronometric data in this paper new tl dates for the levels 3b 4c 5a and 8 are presented the deepest of these the typical mousterian of layer 8 is placed in marine isotope stage mis 5c another typical mousterian industry from level 5a dates to the transition from mis 5 to mis 4 level 4c which is rich in scrapers is placed in mis 4 while the mousterian of acheulian tradition is attributed to mis 3 at a local scale these new dates allow for the integration of the pech de l aze iv sequence with chronometric dates available for the nearby sites of pech de l aze i and ii and at a more regional scale they provide additional data points from the more poorly dated late interglacial and early mis 4 period these dates are in line with the emerging pattern suggesting that the mousterian variants as they are defined overlap considerably in time and call into question their interpretation as a succession of chronological units while a correlation with climate change of the technological units is not clear either