bryozoans as carbonate sediment producers on the cool water lacepede shelf southern australia abstract modern sediments on the lacepede shelf and adjacent slope are typical mid latitude cool water palimpsest deposits dominated by bryozoan mollusc and quartz particles bryozoan bioclasts form autochthonous and to a lesser extent allochthonous accumulations across the grain size spectrum from mud to boulder size the bryozoan skeletons are grouped on the basis of architecture and style of disarticulation fragmentation into nine morphotypes erect rigid forms comprise 1 fenestrate 2 foliose 3 flat robust branching and 4 delicate branching morphotypes large adeona sp skeletons are recognised as a separate type of fenestrate form because of their distinctive shape mineralogy and restricted environment erect flexible forms are either 5 articulated branching or 6 articulated zooidal other important morphotypes are 7 encrusting 8 nodular arborescent and 9 vagrant differences in skeletal architecture result in distinct particle types encrusting morphotypes on soft organic substrates and the wide variety of erect rigid forms are broken into fragments erect flexible forms disintegrate upon death into definitive sand and silt size grains encrusting morphotypes on hard substrates nodular arborescent and vagrant forms remain whole and when large accumulate in place morphotypes are mineralogically distinct and so bryozoan sediment composition is environmentally controlled shallow water

genesis of palimpsest cool water carbonate sediment on the continental margin of southern australia abstract the continental margin of southern australia is a site of extensive quaternary cool water carbonate sedimentation seafloor sediments are a mixture of holocene biofragments and late pleistocene relict and stranded particles relict sediments produced during marine isotope stages 3 and 4 are generally preserved as iron stained intraclasts such grains in the great australian bight are photozoan in character they include symbiont bearing benthic foraminifers and coralline algal particles and indicate that the wide shelves were bathed in shallow relatively warm oligotrophic waters and floored by marine grasses similar to many modern shallow inboard embayments in the region today in contrast east of the great australian bight relict sediments are more heterozoan in character with coralline algal and molluscan facies on the inner shelf and bryozoan sediments on the outer shelf stranded sediments marooned during the sea level rise associated with marine isotope stage 2 are gray to buff in color and composed of both biofragments and intraclasts these particles are mainly heterozoan in character throughout the region with subtropical photozoan marine grassbank facies localized to portions of the inner great australian bight stranded sediments are interpreted to have accumulated in an areally restricted photic zone and upon an overall narrow shelf covered in cool nutrient rich waters swell driven seafloor sediment disturbance to depths of 100 m along the southern australian margin in conjunction with reduced rates of sedimentation that characterize the cool water carbonate realm have resulted in mixing of sediment currently being produced with exhumed relict and stranded sediments generated during previous sea level stands the composition of these deposits and the nature of their pre burial alteration are a function of sea level history late pleistocene relict sediments originally accumulated in low energy inboard environments but were modified in the surf zone during subsequent sea level fluctuations this resulted in the formation of intraclasts abraded infilled and cemented biofragments of local origin the widespread distribution of intraclasts and of composite grain assemblages derived from multiple sedimentary environments that display highly variable degrees of seafloor alteration may be signatures of modern cool water carbonate assemblages worldwide while such palimpsest sediments may complicate paleoenvironmental interpretation their differentiation in the rock record can be utilized to discern subtleties in paleoceanography and sea level history

distribution of recent benthic foraminifera on the sunda shelf south china sea in this study we investigate the species composition and spatial distribution patterns of rose bengal stained and unstained benthic foraminifera from the central part of the sunda shelf in the south western south china sea in relation to environmental factors the uppermost centimetre of the surface sediments 150 mu m from 45 sites from inner 60 m to outer shelf 226 m water depths revealed 584 species including 443 stained species the univariate analyses of individual species abundances and community parameters and next canonical correspondence analysis were used to relate the faunal data to a set of measured environmental parameters four biofacies recognised on the sunda shelf are most strongly correlated to water depth primary production and sediment type of the habitat the inner shelf biofacies cca cluster a defined by ammomassilina alveoliniformis and asterorotalia pulchella occurs in fine grained sediments classified as modem terrigenous mud in the region with the highest primary production values the high energy inner shelf biofacies cca cluster b defined by heterolepa dutemplei and textularia lythostrota occurs in modem terrigenous sand and silt dominated sediments northeast from the natuna island the high energy outer shelf biofacies cca cluster c defined by cibicidoides pachyderma and textularia bocki is sandwiched between assemblages of biofacies d it occurs in the region characterised by neritic relict sand in the shallow waters on the sunda shelf the relationship of benthic foraminiferal faunal composition to grain size of sediments indirectly signals the prevailing bottom hydrodynamic conditions the dominance of the epibenthic foraminifera attached to bigger particles e g cibicides lobatulus planulina arimiensis and much higher abundances of empty tests suggest greater current velocities northeast of natuna island the outer shelf biofacies cca cluster d is defined by facetocochlea pulchra and bulimina marginata it occurs in an area covered with modem terrigenous silt and mud and is characterised by lower annual primary production but seasonally influenced by weak upwelling c 2006 elsevier b v all rights reserved

benthic foraminifera from the carnarvon ramp reveal variability in leeuwin current activity western australia since the pliocene abstract benthic foraminiferal assemblages from a 300 m deep core from an outer carbonate ramp site off western australia international ocean discovery program core u1460a were examined to reconstruct the paleoceanographic evolution of the carnarvon ramp and the warm surficial leeuwin current lc for the last 3 54 ma of the identified 179 benthic foraminiferal species occurrences of the 15 most abundant taxa were assessed using q mode cluster analysis and non metric dimensional scaling diversity equitability planktonic benthic index microhabitat preference and sedimentary parameters such as lithology and sponge spicule content were analyzed to gather information about past intermediate and surface water circulation relative abundances of infaunal and epifaunal species were applied to indicate changes in organic matter supply and oxygenation at the sea floor influence of upwelling was recognized by a high infaunal species ratio with dominance by uvigerina peregrina lagena annellatrachia and trifarina bradyi epifaunal species such as hanzawaia nipponica and hyalinea florenceae gradually became more abundant around 1 14 ma indicating increased ventilation and establishment of the paleo lc a more substantial change was initiated by 0 91 ma as marked by key species spirorutilus carinatus and rotorbinella sp together with increased faunal diversity benthic foraminiferal accumulation rates and evidence for suspension feeding sponges with the lc flow suppressing upwelling and better ventilated waters entering the shelf the environment favored epifaunal agglutinates rotalids and miliolids while buliminids decreased under high flow conditions of the lc sponge spicules and skeletal carbonate production reached an optimum at 0 6 ma before returning to modern conditions supported by these observations we propose the following paleoceanographic evolution of the carnarvon ramp during the late pliocene to mid pleistocene 3 54 0 91 ma conditions of deep water upwelling from the western australian current and indian ocean gyre indicate the absence of the capping lc on the outer carbonate ramp a transitional phase started in the mid pleistocene 1 14 0 61 ma the paleo lc triggered gradual oxygenation at the sediment water interface which coincided with an increase in carbonate sedimentation rates and waning sea surface productivity during a third phase mid pleistocene to present 0 91 0 ma the lc s intensity and flow rates peaked at 0 6 ma benthic foraminiferal accumulation rates reached a high then decreased to present day rates for short periods sea surface productivity was moderately enhanced likely due to fluctuating lc persistence or landward shift during glacial maxima

origin of late pleistocene bryozoan reef mounds great australian bight bryozoan rich biogenic mounds grew periodically on the prograding carbonate slope of the central great australian bight throughout pliocene pleistocene time cores from three odp leg 182 drill sites provide a record of mound growth during the last 300 000 years over a stratigraphic thickness of similar to 150 m these mounds the first such structures described from the modern ocean grew between paleodepths of 100 and 240 m we infer that the upper limit of growth was established by swell wave base and the lower boundary was fixed by an oligotrophic water mass detailed chronostratigraphy based on radiometric and u series dating benthic foraminifer stable isotope stratigraphy and planktonic foraminifer abundance ratios confirms that buildups flourished during glacial lowstands even numbered marine isotope stages but were largely moribund during interglacial highstands and are not extant today mound floatstones are compositionally a mixture of in situ bryozoans comprising 96 genera and characterized by fenestrate flat robust branching encrusting nodular arborescent and delicate branching growth forms the packstone matrix comprises autochthonous and allochthonous sand size bryozoans benthic and planktonic foraminifers serpulids coralline algae sponge spicules peloids and variable glauconite and quartz grains together with mud size ostracods tunicate spicules bioeroded sponge chips and coccoliths intermound allochthonous packstone and local grainstone contain similar particles but they are conspicuously worn abraded blackened and bioeroded an integrated model of mound accretion during sea level lowstands begins with delicate branching bryozoan floatstone that increases in bryozoan abundance and diversity upward over a thickness of 5 10 m culminating in thin intervals of grainstone characterized by reduced diversity and locally abraded fossils mound accumulation was relatively rapid 30 67 cm ky and locally punctuated by rudstones and firmgrounds intermound highstand deposition was comparatively slow 17 25 cm ky and typified by meter scale fining upward packages of packstone and grainstone or burrowed packstone with local firmgrounds overlain by characteristically abraded particles mound growth during glacial periods is interpreted to have resulted from increased nutrient supply and enhanced primary productivity such elevated trophic resources were both regional and local and thought to be focused in this area by cessation of leeuwin current flow together with northward movement of the subtropical convergence and related dynamic mixing

core and intact polar glycerol dialkyl glycerol tetraethers gdgts in sand pond warwick rhode island usa insights into the origin of lacustrine gdgts branched and isoprenoidal glycerol dialkyl glycerol tetraethers gdgts are abundant in lake sediments and have potential use for determining past changes in climate and limnology however emerging evidence suggests that both classes of gdgts can be associated with both allochthonous soil organic matter and in situ production potentially complicating interpretation of these compounds in lacustrine sedimentary environments here we investigate the dual source issue surrounding lacustrine gdgts with an emphasis on the branched gdgts by studying both core and intact polar gdgts within a pond and its watershed in warwick ri significant differences in both absolute concentrations of branched gdgts and the percent of branched gdgts present as ipls between the soils and shallow lake sediments suggests in situ production of these compounds within the lake environment principal components analysis of gdgt lipid concentrations and environmental parameters in sand pond sediments and soils highlights two prominent trends in the data one related to the absolute concentrations of type i branched gdgts brgdgt i ib ic and the majority of the isoprenoidal gdgts and another related to the concentration of the more methylated type iii branched gdgts brgdgt iii iiib iiic and isoprenoidal gdgt 0 the latter trend exhibits a subsurface maximum in the sediment column potentially indicating in situ production of more highly methylated branched gdgts and gdgt 0 within the lacustrine sediment column trends in the distributions of branched gdgts as reflected by the mbt and cbt indices imply mixing of two distinct sources of branched gdgts soil derived and in situ or alternatively two or more different microbial producers both possibilities present a challenge to the application of brgdgt based paleoenvironmental proxies in lakes this study highlights the importance of determining the sources of gdgts to the lacustrine environment prior to paleoenvironmental application

foraminiferal biofacies on the mid latitude lincoln shelf south australia oceanographic and sedimentological implications foraminiferal assemblages on the southern mid latitude lincoln shelf comprise mixtures more strongly in shallow waters of holocene and relict pleistocene specimens over 200 benthic and 15 planktonic species were recorded and a higher diversity was found in the central and deeper parts of the shelf and slope cluster analysis identified five assemblages or biofacies nearshore assemblage a 50 m and inner mid shelf assemblage b 50 90 m are dominated by relict and recent shallow water species the outer mid shelf assemblage c 90 120 m contains more cibicidids and is transitional between the shallow and deep water assemblages outer shelf assemblage d 120 170 m is characterized by cibicidids and anomalinids and by a higher planktonic and benthic diversity and it can be subdivided into three sub assemblages d1 d3 unlike others assemblage d was not recognized from the most western transect samples the outer shelf to slope assemblage e 170 400 m is typically deep water having forms like hoeglundina elegans pullenia bulloides and melonis affinis the western great australian bight sector has the larger epifaunal benthic sorites marginopora group while the infauna is higher in the eastern neptune sector of the shelf we attribute these contrasts to the influence of the warm leeuwin current and to the mixing between gulf shelf and oceanic waters respectively a former lagoonal environment is largely responsible for the accumulation of relict tests during lower sea level periods of the late pleistocene when climate was more arid the lack of recent sediments preserved on the inner shelf is considered to be due to strong wave abrasion causing sediment starvation richer forarniniferal assemblages from the outer shelf to upper slope parallel an increasingly calcareous sediment faunal evidence indicates a warmer nearly oligotrophic condition on lincoln shelf compared to the mesotrophy on the adjacent lacepede shelf this difference may be due to the separation of these two shelves by kangaroo island acting as a local oceanographic environmental and biogeographic barrier

holocene carbonate sedimentation on the west eucla shelf great australian bight a shaved shelf the southern continental margin of australia is a cool water carbonate sedimentary province located in a high energy swell dominated oceanographic setting a vibrocore transect of 14c dated sediments across the centre of the eucla shelf is the first record of holocene shelf deposition in the great australian bight much of the seafloor shallower than 70 m water depth the base of wave abrasion is bare cenozoic limestone in some places encrusted by late pleistocene coral rich limestone that is cemented by high magnesium calcite 12 mole mgco3 the areally extensive 100 km wide hard bored substrate supports an epibiota of coralline algae minor bryozoans and soft algae or is covered by patches of holocene sediment up to 1 5 m thick generally a basal bivalve lag 3 ka overlain by quartzose bioclastic palimpsest sand this pattern of active carbonate production but little accretion on the wave swept mid to inner shelf is similar to that on other parts of the southern australian continental margin the term shaved shelf is proposed for this style of carbonate platform formed by alternating periods of sediment accretion cementation and erosion the palimpsest sand is typically rich in bivalves coralline algae and locally detrital dolomite outer shelf holocene sediment below the base of wave abrasion but inboard of the shelf edge is a metre thick unit of fine microbioclastic muddy sand with minor delicate bryozoans overlying a 9 13 ka rhodolith gravel some of this outer shelf sediment appears to have been resedimented the shelf edge is a sandy and rocky seafloor with active bryozoan growth and sediment production the holocene sediments are enriched in coralline algal particles and conspicuous large foraminifers cf marginopora and depleted in bryozoans as compared to coeval deposits on the lacepede and otway shelves off southeastern australia these differences are interpreted to reflect warmer waters of the leeuwin current and prevalent downwelling in this area as opposed to the general upwelling and colder waters in the east

early palaeozoic palaeobiogeography of the variscan regions abstract the palaeobiogeographic method appears to be an attractive alternative for reconstruction of the palaeogeography of the variscan regions during the palaeozoic the evolution of faunal assemblages and climatic characteristics from the cambrian up to the end of the devonian demonstrates that baltica and north gondwana represent two major and independent palaeogeographic entities separated by a mid european rheic ocean which opened as early as the cambrian and closed progressively from the devonian the south armorican ocean whose closure generated the so called ligerian orogen is regarded as a branch of the rheic ocean both a tornquist s sea separating baltica from its western extension avalonia during the ordovician and a proto tethys ocean extending between southwestern europe and north africa during the devonian are excluded from our reconstructions

a novel proxy for terrestrial organic matter in sediments based on branched and isoprenoid tetraether lipids we propose a novel tracer for terrestrial organic carbon in sediments based on the analysis of tetraether lipids using high performance liquid chromatography mass spectrometry hplc ms analysis of terrestrial soil and peats shows that branched tetraether lipids are predominant in terrestrial environments in contrast to crenarchaeol the characteristic membrane lipid of non thermophilic crenarchaeota which is especially abundant in the marine and lacustrine environment based on these findings an index was developed the so called branched and isoprenoid tetraether bit index based on the relative abundance of terrestrially derived tetraether lipids versus crenarchaeol this bit index was applied to surface sediments from the angola basin where it was shown to trace the outflow of the congo river furthermore analyses of particulate organic matter from the north sea showed relatively higher bit indices in water column particulate organic matter near large river inputs a survey of globally distributed marine and lacustrine surface sediments shows that the bit index in these environments correlates with the relative fluvial input of terrestrial organic material making this index generally applicable the new proxy allows the rapid assessment of the fluvial input of terrestrial organic material in immature sediments up to 100 ma old

sediments and history of the rottnest shelf southwest australia a swell dominated non tropical carbonate margin abstract the rottnest shelf is a narrow wave dominated open shelf on the passive continental margin of southwest australia adjacent to a hinterland of low relief and sluggish drainage high physical energy low nutrients in cool subtropical waters and rapid postglacial transgression have limited carbonate productivity restricted grain types and reworked the transgressed surface to form only a thin given sufficient time the rottnest shelf could recover from drowning and form blanket like skeletal carbonates thin

surficial cool water carbonate sediments on the otway continental margin southeastern australia abstract the otway continental margin of southern australia is a swell dominated open cool water carbonate platform it is partitioned into a series of depth related zones of biological sediment production and accumulation by three hydrodynamic interfaces 1 abrasion depth 70 m 2 swell wavebase 130 m and 3 storm wavebase 250 m the otway shelf profile drops steeply from the strandline the shallow shelf lies largely between 30 and 70 m and is a high energy zone of carbonate sediment production intensive destructive diagenesis and erosion the seafloor is characterized by widespread exhumed limestone substrates which host dense encrusting assemblages of molluscs sponges bryozoans and red algae loose sediment accumulation is patchy and consists of a thin quartz rich palimpsest gravel veneer the middle shelf 70 to 130 m is a zone of swell wave shoaling and production and accumulation of coarse mega rippled 2 d dunes bryozoan sands deep shelf areas 130 to 180 m accumulate finer bioclastic sands foraminiferal echinoid bryozoan that are intensely bioturbated and episodically reworked by storms grains are variably fragmented and marginally bored at the shelf edge and top of slope 180 to 350 m nutrient rich upwelling currents support laterally extensive aphotic biostromal hermal bryozoan sponge coral communities which generate and accumulate thick successions of muddy skeletal sand sediments of the upper slope 350 to 500 m are a bioturbated mixture of periplatform bioclastic debris and pelleted foraminiferal nannofossil mud turbidites and resedimentation features are common bioturbation and shelf derived skeletal content decrease progressively downslope and pelagic muds dominate below 500 m lower slope areas are cross cut by gullies and have low accumulation rates the base of slope is characterized by sediment apron deposits consisting of interbedded shelf derived coarse grained turbidites and pelagic ooze

early diagenesis of carbonates on a cool water carbonate shelf southern australia abstract the southern australian continental margin is an immense cool water carbonate factory the high energy open shelf is blanketed by heterozoan carbonates of both holocene and late pleistocene age three distinct grain types have been identified and radiocarbon dated these include 1 relict grains highly abraded iron stained intraclasts formed during the intermediate sea level stands of marine isotope stages 3 and 4 2 stranded grains gray and buff colored abraded biofragments and intraclasts marooned during the sea level rise associated with marine isotope stage 2 and 3 holocene grains unaltered biofragments formed during marine isotope stage 1 optical mineralogical and chemical characterization of grains of each age has revealed pathways of early diagenesis in this realm both calcitic and aragonite biogenic grains undergo dissolution while dissolution of calcitic components is minor and incomplete relict sediments are predominantly mg calcite aragonitic skeletons undergo significant dissolution within 30 000 years in contrast to early dissolution of aragonite micritic calcite cement with 12 mol mgco3 is a significant diagenetic phase in these sediments infilling many stranded and most relict skeletons similar cement precipitates between grains forming small numbers of cemented grain aggregates in most samples microprobe and icp ms analysis demonstrates fe oxides mn oxides and associated clay minerals discolor stranded and relict grains by coating grain surfaces and infesting micropores such coatings begin to form on holocene grains during or soon after formation the oxides scavenge trace elements including v ti cr and ree altering the elemental compositions of biogenic carbonate

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

coupled thermal and hydrological evolution of tropical africa over the last deglaciation we analyzed the distribution of branched tetraether membrane lipids derived from soil bacteria in a marine sediment record that was recovered close to the congo river outflow and the results enabled us to reconstruct large scale continental temperature changes in tropical africa that span the past 25 000 years tropical african temperatures gradually increased from 21 to 25 c over the last deglaciation which is a larger warming than estimated for the tropical atlantic ocean a direct comparison with sea surface temperature estimates from the same core revealed that the land sea temperature difference was through the thermal pressure gradient an important control on central african precipitation patterns

silurian and devonian biogeography of china integration of newly available chinese data for the biogeography of the silurian and devonian makes possible a number of globally sigificant advances the early silurian the llandoverian can now be shown to have been moderately provincial rather than cosmopolitan as considered earlier the uralian cordilleran region defined previously for the late silurian can now be shown with chinese information to have been in existence with a co occurring north atlantic region since the beginnings of the silurian and to have been somewhat more provincial than the late silurian the view of late silurian provincialism with two major regions is further substantiated with the help of chinese data for the early devonian it is now possible to define a south china region that includes the bulk of the yangtze platform region of south china plus adjacent tonkin in north vietnam the boundary of the south china region is present in central yunnan and extends in an approximately north south direction the south china region is still prominent during the lower eifelian half of the middle devonian relatively cosmopolitan devonian conditions affect china by the latter givetian half of the middle devonian as is also the case in most other parts of the world except for eastern north america and the southern hemisphere malvinokaffric realm the chinese upper devonian is cosmopolitan in a manner similar to that of the rest of the world it is notable during the lower devonian that the nonmarine vertebrate fauna is unusually provincial and very distinct from faunas known in europe and north america as well as from those present in northern asia it is suggested that previous distinctions between lower devonian uralian and mongolo okhotsk regions are more likely provincial or even subprovincial the presence of the atrypacean genus tuvaella in the silurian of east central asia is shown to represent the restricted occurrence of a single genus rather than being indicative of a major biogeographic unit however it may indicate the presence of a subprovincial unit or of an endemic center

where has all the aragonite gone mineralogy of holocene neritic cool water carbonates southern australia abstract surficial carbonate sediments on the southern continental shelf of australia are cool water in aspect and composed of biogenic particles produced largely during the late quaternary current understanding is that such sediments are calcite dominated as were their older cenozoic counterparts the holocene fraction of these sediments in modern open shelf neritic environments between 30 and 350 meters water depth is however 50 to 80 aragonite scant evidence of significant former aragonite in many cool water carbonate sedimentary rocks implies that most aragonite is lost before such sediments exit the marine diagenetic environment although marine dissolution must be taking place in such settings the conundrum is exacerbated because seawater over the shelf in southern australia is saturated with respect to aragonite it is proposed that the aragonite from skeletons of gastropods infaunal bivalves and certain bryozoans is dissolved in the shallow subsurface probably as the byproduct of bacterial degradation of sedimentary organic matter as a consequence the geological and paleontological record of many cool water carbonates is strongly biased and the inferred original calcitic composition of such sediments is the product of early diagenetic taphonomic loss not selective biogenic productivity the net result is not only dissolution of aragonite but also neomorphism of mg calcite to calcite with a marine geochemical signature synsedimentary aragonite loss by removing caco3 that is usually available for calcite cementation during meteoric diagenesis leads to retarded lithification of these cool water carbonates until deeply buried such removal of a significant carbonate fraction during deposition likely contributes to the low rates of cool water sediment accumulation

heinrich event imprints in the okinawa trough evidence from oxygen isotope and planktonic foraminifera planktonic foraminiferal faunas oxygen isotope and modern analog technique sea surface temperature records were obtained in piston core dgks9603 28degrees08 869 n 127degrees16 238 e water depth 1100 in collected from the middle okinawa trough during the last glaciation four cold events were identified and correlate heinrich events he h2 5 of the last 45 ka during the last deglaciation core dgks9603 has begun to be influenced by the kuroshio since about 16 cal ka bp three weakenings of this warm current occurred at about 2 8 5 3 11 4 and 15 5 cal ka bp respectively among the three fluctuations the oldest one is synchronous with he1 and could be a response to the strong cooling observed in the north atlantic ocean the fluctuation occurring at about 11 4 cal ka ago corresponds to the younger dryas within the age error bars our observations provide new evidence that the hes documented from greenland and the northern north atlantic had a global climatic impact changes in the intensity of the east asian monsoon could be the main mechanism responsible for the paleoccanographic variations observed in the okinawa trough c 2001 elsevier science b v all rights reserved

polar wander and paleomagnetic reference pole controversies the purpose of this paper is to review the progress made over the past four years in studies of phanerozoic and precambrian polar wander with an emphasis on the contributions made by u s scientists we perceive a general theme embracing the notion that the accuracy of cratonic reference poles and therefore of apparent polar wander apw paths is not as good as was generally believed four years ago a renewed interest in research concerning cratonic reference poles is largely the result of paleomagnetic studies in orogenic belts namely the western cordillera and appalachians of north america the andes of south america and elsewhere which seek to document the existence or non existence of displacements of suspect terranes i e rotation and or translation with respect to their presently associated cratons some of the results of this research are reviewed in this volume by hillhouse and mcwilliams an important realization of which paleomagnetists have long been aware but which was demonstrated recently by a number of sobering examples for both the paleozoic and mesozoic apw paths for north america is that the reliability of concordance discordance parameters that define terrane displacement is dependent not only on the precision and accuracy of the individual paleomagnetic study but also on the precision and accuracy of the appropriate cratonic reference pole

major changes in glacial and holocene terrestrial temperatures and sources of organic carbon recorded in the amazon fan by tetraether lipids the amazon basin is a major component of the global carbon and hydrological cycles a significant natural source of methane and home to remarkable biodiversity and endemism reconstructing past climate changes in the amazon basin is important for a better understanding of the effect of such changes on these critical functions of the basin using a novel biomarker proxy based on the membrane lipids of soil bacteria with a new regional calibration we present a reconstruction of changes in mean annual air temperatures for the amazon catchment during the last 37 kyr b p biomarkers were extracted from ocean drilling program sediment core odp942 recovered from the amazon fan the amazon fan is a major depository for terrestrial sediments with the advantage that the terrestrial material captured reflects a regional integration of the whole river catchment the reconstructed tropical amazonian temperatures were similar to 5 degrees c cooler at the last glacial maximum similar to 21 degrees c compared to modern values similar to 26 degrees c this is in agreement with previous estimates of tropical continental temperatures in the tropical amazon basin and tropical africa during the last glacial maximum moreover we also illustrate how the soil bacterial membrane lipid record reveals major changes in basin dynamics and sediment provenance during the glacial holocene transition impacting the biomarker reconstructions from similar to 11 kyr onward

palaeozoic strike slip rift pulses and palaeogeography in the circum mediterranean tethyan realm abstract five main rifting cycles supported by different types of field evidence including magmatism sedimentation and tectonics have been recognized in the circum mediterranean area western tethys realm before the opening of the jurassic tethys proper they occurred roughly in the late cambrian early ordovician early silurian late devonian dinantian early mid permian and mid triassic times each of these rifting cycles began with intracontinental mainly shallow marine conditions evolving usually to basinal environments of quite different bathymetry the palaeozoic ccd has been proved to be much less deep than the post liassic one minor suboceanic seaways cut across and fragmented the gondwana south european plate following the early palaeozoic rifting cycles the long mid palaeozoic devono dinantian rifting cycle migh possibly have resulted in a wider system of suboceanic sea ways connecting a palaeo tethys ocean to the east of gondwana with the rheic ocean to the west of it the birth of palaeo tethys or of its westward extension would have been directly linked with the gradual death of the devono mississippian rheic ocean a complex large scale dextral transform system is inferred to have connected the two respectively expanding and contracting oceans fragmentation and mutual displacement of microblocks in the connection area the circum mediterranea area and southern europe resulted from strike slip oblique rift pulses with coeval local contractional and extensional processes a major change of the gondwana rotational vector is believed to have produced the mid late carboniferous transpressional strike slip hercynian orogen this is a good explanation of the peculiar thermal regime of the hercynian diastrophism all over europe there is no support for the hypothesis of a very wide more than 3000 km palaeozoic ocean separating northern europe from southern europe or gondwanaland this idea was mainly based on poor palaeomagnetic data and is heavily contradicted by palaeobiogeographical and geological data furthermore it ignores the dramatic shortening of the hercynian orogen all over europe the early palaeozoic to early mesozoic history of the circum mediterranean area involves the cyclic recurrence of oblique rifts culminating in the early jurassic strike slip rift and subsequent limited opening of the tethys proper to avoid confusion in terminology one should use prefixes referring to age bathymetry physiography and geotectonic setting to qualifying the general term tethys e g shallow cretaceous tethys basinal intracontinental devonian tethys oceanic jurassic tethys etc

a paleozoic pangaea paleozoic paleogeographies should be consistent with all available reliable data however comparison of three different devonian paleogeographies that are based largely or wholly on the data of remanent magnetism show them to be inconsistent in many regards when these three paleogeographies are provided with possible ocean surface current circulation patterns and have added to them lithofacies and biogeographic data they also are shown to be inconsistent with such data a pangaeic reconstruction positioned in the southern hemisphere permits the lithofacies and biogeographical data to be reconciled in a plausible manner

decoupled warming and monsoon precipitation in east asia over the last deglaciation our understanding of the continental climate development in east asia is mainly based on loess paleosol sequences and summer monsoon precipitation reconstructions based on oxygen isotopes delta o 18 of stalagmites from several chinese caves based on these records it is thought that east asian summer monsoon easm precipitation generally follows northern hemisphere nh summer insolation however not much is known about the magnitude and timing of deglacial warming on the east asian continent in this study we reconstruct continental air temperatures for central china covering the last 34 000 yr based on the distribution of fossil branched tetraether membrane lipids of soil bacteria in a loess paleosol sequence from the mangshan loess plateau the results indicate that air temperature varied in phase with nh summer insolation and that the onset of deglacial warming at similar to 19 kyr bp is parallel in timing with other continental records from e g antarctica southern africa and south america the air temperature increased from is c at the onset of the warming to a maximum of 27 degrees c in the early holocene similar to 12 kyr bp in agreement with the temperature increase inferred from e g pollen and phytolith data and permafrost limits in central china comparison of the tetraether membrane lipid derived temperature record with loess paleosol proxy records and stalagmite 5180 records shows that the strengthening of easm precipitation lagged that of deglacial warming by ca 3 kyr moreover intense soil formation in the loess deposits caused by substantial increases in summer monsoon precipitation only started around 12 kyr bp ca 7 kyr lag our results thus show that the intensification of easm precipitation unambiguously lagged deglacial warming and nh summer insolation and may contribute to a better understanding of the mechanisms controlling ice age terminations

an interlaboratory study of tex86 and bit analysis using high performance liquid chromatography mass spectrometry recently two new proxies based on the distribution of glycerol dialkyl glycerol tetraethers gdgts were proposed i e the tex86 proxy for sea surface temperature reconstructions and the bit index for reconstructing soil organic matter input to the ocean in this study fifteen laboratories participated in a round robin study of two sediment extracts with a range of tex86 and bit values to test the analytical reproducibility and repeatability in analyzing these proxies for tex86 the repeatability indicating intralaboratory variation was 0 028 and 0 017 for the two sediment extracts or 1 2 c when translated to temperature the reproducibility indicating among laboratory variation of tex86 measurements was substantially higher i e 0 050 and 0 067 or 3 4 c when translated to temperature the latter values are higher than those obtained in round robin studies of mg ca and u37 k paleothermometers suggesting the need to primarily improve compatibility between labs the repeatability of bit measurements for the sediment with substantial amounts of soil organic matter input was relatively small 0 029 but reproducibility was large 0 410 this large variance could not be attributed to specific equipment used or a particular data treatment we suggest that this may be caused by the large difference in the molecular weight in the gdgts used in the bit index i e crenarchaeol versus the branched gdgts potentially this difference gives rise to variable responses in the different mass spectrometers used calibration using authentic standards is needed to establish compatibility between labs performing bit measurements

bathymetry and paleoecology of silurian bethic assemblages late llandoverian new york state late llandoverian marine shales in new york state are highly fossiliferous and provide and opportunity to examine gradients of biofacies the williamson and willowvale formations llandoverian c6 were deposited during a major transgressive episodes in and adjacent to the axis of a narrow ne sw trending central appalachian foreland basin the williamson shale is a black to dark green graptolite bearing unit of the upper clinton group of western new york state it grades eastward into gray fossiliferous shales and coquinoidlimestones of the willowvale formation orientation analysis of graptolites monograptus clintonensis indicates paleoccurents dominantly from the northeast to east the presence of rippled cross laminated sandstone beds tempestites within dark gray graptolitic facies of the lower williamson indicates that the darl shale facies was deposited in dysaerobic to marginally aerobic water slightly below storm wave base poorly fossiliferous green shales higher in the willimason appear to slow deposition in dysaerobic water and suggest a gradual deepening graded brachipod coquinoid limestones interpreted as storm layers occur near the middle and top of the williamson and in the willovale shale and indicate deposition of these sediments above maximum storm wave base the faunas of the williamson and willowvale shales are subdivisible into five vertically and laterally adjacent associations as follows a ichnofossil chondrites b monograptid chonetes cornutus c eopletodonta atrypta d palaeocyclus bryozoan and e eocoelia chonetes cornutus associations this spectrum of fossil associations appears to parallel the increasing frequency of bottom disturbance by waves and currents from deeper basinal areas to higher energy outer and low energy inner shallow shelf settings the fossil associations of the williamson a c probably belong to the deeper benthic assemblages 4 5 but developed in environments within to slightly below storm wave base about 50 80 m deep the willowvale fauna c d representing benthic assemblages 3 4 inhabited somewhat shallower better oxygenated environments of the photic zone probably at depths of approximately 20 50 m the easternmost to slightly southeastward equivalent of williamson willowvale fauna e evidently represents shallow water benthic assemblage 2 these conclusions indicate the need for a critical reevaluation of the bathymetric relations of benthic assemblages 3 5 a new interpretations of approximate depths for this range is presented herein

geology of the early devonian oolitic iron ore of the gara djebilet field saharan platform algeria abstract the oolitic iron ore of the gara djebilet field occurs within the early devonian sediments of the tindouf basin algerian sahara particularly in the upper djebilet formation of pragian age three large lenses form three individual deposits extending e w for about 60 km namely gara west gara center and gara east the mineralization is interbedded with argillaceous to sandy sediments and it can be related to a barrier island palaeoenvironment bordered by an inner lagoon or shallow embayment and an epicontinental sea trapped by palaeozoic shoals the oolitic sediments show a mineralogy marked mainly by magnetite hematite goethite maghemite chamosite bavalite siderite apatite and quartz three paragenetic associations present a vertical distribution with a lower non magnetitic ore a magnetitic ore and an upper non magnetitic ore three petrographical facies types have been defined a cemented facies foc a detrital facies fod and a non detrital facies fond chemical data for the whole field show a difference between the lower non magnetitic ore fe 54 6 the magnetitic ore fe 57 8 and the upper non magnetitic ore fe 53 the magnetitic ore which corresponds mainly to the workable ore cutoff grade at 57 has the following composition sio2 4 9 al2o3 4 2 fe2o3 61 43 feo 19 2 and p2o5 1 8 the corresponding calculated economical ore reserves are 985 106t with 57 8 fe regarding the genesis of the oolitic iron ore a southern source is suggested for the iron with deposition taking place in a quiet environment there the ooids developed by an intrasedimentary accretion mechanism around detrital grain within an iron rich mud the gara djebilet field is an important occurrence of the north african palaeozoic ironstone belt extending from the zemmour to libya which also includes ironstones of ordovician silurian and devonian age

biogeographic impact of the leeuwin current in southern australia since the late middle eocene abstract the leeuwin current can be tracked from the western margin of the australian continent to the southern margin by the record of fossilized organisms typical of warm water marine environments this transport smudges the normal latitudinal asymmetry in the biotas of opposing oceanic and continental margins in which the eastern margins of oceans are cooler than the western margins and warmer biotas are restricted to lower latitudes in the east the most comprehensive record is in the large benthic foraminifera although fossils of benthic invertebrates nektonic nautiloids and planktonic protists are also informative in addition organic biomarker hydrocarbons in stranded bitumens and resins demonstrate that they have travelled the same route from their ultimate sources in cenozoic sedimentary basins and modern tropical rainforests of the indonesian archipelago the earliest spoor of the current is in the later middle eocene at which time the part deflection of counter gyral circulation in the indian ocean to the southeast was stimulated by the accelerated opening of the oceanic gap between australia and antarctica thus the origin of the leeuwin current is twice the age of the previously suggested origin in the miocene the current turns on and turns off in the great australian bight during the late quaternary in concert with the interglacials and the glacials at scales of 10 5 yr the switch can be seen in the faunal succession of planktonic foraminifera which are consistent with the neritic benthic faunas of the central gulfs both communities show that at the warm peak of the last interglacial the current transported biota across the bight more strongly than it has during the holocene the cenozoic record of the past 40 ma is in the same mode at 10 6 yr scales the relevant fossils are found concurrently at major marine transgressions and warming reversals of the overall fall in global temperature however the fossil pattern is due to transport on the activated leeuwin current not merely to general warming and the spread of friendly environments to higher latitudes

root associated branched tetraether source microorganisms may reduce estimated paleotemperatures in subsoil abstract branched glycerol dialkyl glycerol tetraethers gdgts are complex lipids of high molecular weight recently discovered in soils and suggested to be produced by still unknown bacteria the relative distribution of these compounds was shown to depend on environmental parameters mainly temperature and ph over the last years an increasing number of studies have focused on the application of branched gdgts as paleoclimate proxies but only a few were performed in terrestrial archives in this study branched gdgts were analyzed in calcified and non calcified living and dead roots in surrounding soil and sediment and in reference material distant from the roots samples were mainly collected from subsoil of two forest sites near sopron hungary where soils developed on fluvial sand and loess deposits respectively branched gdgts were more abundant in root samples and or surrounding rhizosphere compared to reference material suggesting that branched gdgt source microorganisms are closely associated with the root surface in subsoil the gdgt based temperature estimates from former roots and surrounding sediments were mainly lower than those from reference material in both loess and sand profiles this is likely due to the post sedimentary incorporation of branched gdgts deriving from microorganisms that fed on root organic matter in terrestrial sediments in contrast branched gdgt derived temperatures do not seem to be influenced by the presence of roots in topsoil which may be related to the much higher density of recent roots in topsoil than in subsoil this argues for a more homogeneous distribution of root associated microorganisms especially in densely rooted topsoils in addition we show that sample pre treatment may have an effect on the abundance and distribution of branched gdgts indeed washing root samples with ultrapure water might lead to a decrease in gdgt abundance and an increase in temperature estimates likely due to the removal of particles adhering to the root surface decarbonatization of root and surrounding sediment had only a limited effect on gdgt derived parameters taken together these results suggest that paleoenvironmental data obtained from branched gdgts in terrestrial archives might depend on the way the samples were collected and prepared and should be interpreted with caution especially in loess paleosol sequences where the frequency of calcified roots can be locally very high

branched gdgt signals in fluvial sediments of the danube river basin method comparison and longitudinal evolution abundances and distributional changes of branched glycerol dialkyl glycerol tetraethers brgdgts in fluvially influenced sediments are used in various paleoclimate studies to reconstruct variations in soil export continental air temperature and soil ph in corresponding river basins for accurate interpretation of these records it is important to understand the provenance and the evolution of biomarker signals as they move through the river system here we investigate the brgdgt composition of modern river sediments of the danube river the second largest river in europe brgdgt based mean annual air temperature and soil ph parallel the actual values of air temperature and soil ph from the upper to the lower basin showing that signals predominantly reflect local as opposed to basin wide environmental conditions furthermore data generated using the recently developed method with improved chromatography separating the 6 methyl isomers from the 5 methyl isomers was compared with that resulting from the conventional method we show that the temperatures and ph values reconstructed using the data obtained by improved chromatography best resemble the local environmental conditions throughout the danube river basin our results highlight the importance of in depth studies within river systems to better understand the provenance of biomarker signals in fluvially derived sedimentary archives

modern carbonate and terrigenous clastic sediments on a cool water high energy mid latitude shelf lacepede southern australia the wide lacepede shelf and narrow bonney shelf are contiguous parts of the south eastern passive continental margin of australia the shelves are open generally deeper than 40 m covered by waters cooler than 18 c and swept by oceanic swells that move sediments to depths of 140 m the lacepede shelf is proximal to the delta of the river murray and the coorong lagoon shelf and upper slope sediments are a variable mixture of holocene and late pleistocene quartzose terrigenous clastic and bryozoa dominated carbonate particles bryozoa grow in abundance to depths of 250 m and are conspicuous to depths of 350 m they can be grouped into four depth related assemblages coralline algae the only calcareous phototrophs are important sediment producers to depths of 70 m active benthic carbonate sediment production occurs to depths of 350 m but carbonate sediment accumulation is reduced on the open shelf by continuous high energy conditions the shelf is separated into five zones the strandline is typified by accretionary sequences of steep shoreface beach and dune carbonate siliciclastic sediments similar shoreline facies of relict bivalve limestone cobble ridges are stranded on the open shelf the shallow shelf c 40 70 m deep is a wide extremely flat plain with only subtle local relief it is a mosaic of grainy quartzose palimpsest facies which reflect the complex interaction of modern bioclastic sediment production dominated by bryozoa and molluscs numerous highstands of sea level over the last 80 000 years modern mixing of sediments from relatively recent highstands and local introduction of quartz rich sediments during lowstands the middle shelf c 70 140 m deep is a gentle incline with subtle relief where holocene carbonates veneer seaward dipping bedrock clinoforms and local lowstand beach complexes carbonates are mostly modern uniform clean coarse grained sands dominated by a diverse suite of robust to delicate bryozoa particles produced primarily in situ but swept into subaqueous dunes the deep shelf edge c 140 250 m deep is a site of diverse and active bryozoa growth resulting accumulations are characteristically muddy and distinguished by large numbers of delicate branching bryozoa the upper slope between 250 and 350 m depth contains the deepest platform related sediments which are very muddy and contain a low diversity suite of delicate branching cyclostome bryozoa this study provides fundamental environmental information critical for the interpretation of cenozoic cool water carbonates and the region is a good model for older mixed carbonate terrigenous clastic successions which were deposited on unrimmed shelves

the influence of shelf vicinity on the distribution of planktic foraminifera south of puerto rico abstract the effects of water masses and depth on the distribution of planktic foraminifera across the island slope of southwestern puerto rico were studied in holocene surface sediments samples from the depth range of 432 4700 m covered 0 5 95 km distance from the shelfbreak shallower samples in this region are altered by winnowing plankton net tows through the upper 120 m of the water column sampled the living planktic foraminiferal population in the same area they contained shallow water benthic foraminifera that were probably brought into suspension on the shelf and transported seawards with the shelf outflow water illustrating the exchange of water and suspended particles from the shelf to the slope the grain size spectrum of the sediment samples shows no depth related trend the sand fraction 63 m consists of foraminifera pteropoda and on the upper slope of reef detritus the bulk carbonate content varies from 51 to 73 the abundance of planktic foraminifera per gram sediment increases with depth while the number of benthic foraminifera decreases with water depth the composition of the benthic assemblage shows an increase of the ratio of agglutinated versus calcareous perforate forms the planktic foraminiferal assemblage 150 m is dominated by globigerinoides ruber and shows no obvious trend over the sampled depth range the plankton benthos ratio increases with depth from 0 63 to 0 99 as a result of opposite trends in accumulation rates of benthic and planktic foraminifera accumulation rates of planktic foraminifera increase with distance from the shelfbreak and with water depth from 10 000 to 30 000 specimens cm 2 ka indicating the influence of ecological and or depositional processes on their distribution it is suggested that the tests of planktic foraminifera are displaced in a seaward direction by lateral advection therefore their place of deposition does not lie directly underneath the place of production

late miocene intensification of continentality in the black sea region the black sea basin is the sink for some of the largest european rivers and has acted as such since it was part of the eastern paratethys the late miocene to pliocene sedimentary record of the black sea documents several phases of strongly evaporitic conditions associated with extreme changes in regional hydrology here we present the first combined record of continental temperature soil type and biomass burning in the circum black sea region from the late miocene to the transition into pliocene 10 0 to 5 0 ma we use branched glycerol dialkyl glycerol tetraethers brgdgt to reconstruct mean annual air temperature mat and soil ph within the catchment of the black sea basin and complement these data with evidence from charcoal morphology as a proxy for burned biomass the brgdgt data reveal generally decreasing temperatures and acidic soils between 10 and 8 5 ma overlapping with increase in herbaceous cover in the black sea region the pontian flooding at 6 12 ma is characterized by large quantities of organic debris and charcoal fragments in the basin and is followed by cooling starting at 5 97 ma event that is superimposed on the tg 20 and tg 22 glacial peaks at 5 8 ma between 5 8 and 5 0 ma the brgdgts seem to be primarily derived from a cold steppe environment enhanced fire activity coinciding with generally cooler temperatures and a higher proportion of herbaceous plants are indicative of increased continentality between 5 8 and 5 0 ma in the black sea region

sources of organic matter in changjiang yangtze river bed sediments preliminary insights from organic geochemical proxies insight into the content and composition of organic carbon oc in river systems contributes to our understanding of the global carbon cycle the changjiang yangtze river plays a significant role in global carbon and hydrological cycles as it is an important supplier of sediment nutrients and oc to the east china sea to provide a preliminary insight into the source of oc transported by the changjiang we analyzed bulk grain size organic carbon content 13c and molecular lignin phenols branched and isoprenoid gdgts characteristics of organic matter in bed sediments at eight locations along the river the 13c values and lignin phenol composition indicate that the oc originates from a mixture of primarily soils and plants comparison between branched gdgt br gdgt distributions in riverbed sediments and those in the different soil types in the drainage basin indicate that the br gdgt signal in the upper reaches is largely derived from soils from the qinghai tibet plateau downstream changes in br gdgt distributions can be linked to subsequent input of local soil material the observed variation in br gdgt composition along the river implies that a portion of the oc may be oxidized or replaced by the local input during transit although the relationship between 13c and lignin phenol composition indicates that the contribution of phytoplankton is limited comparison of gdgt ratios gdgt 0 crenarchaeol iso gdgts br gdgts bit index for the sediments and surrounding soils indicates that at least part of the iso gdgts has an aquatic origin overall the downstream evolution of br gdgts in the changjiang implies that their use as paleoclimate proxy in downcore applications will likely yield a local rather than a basin integrated continental climate record

southern ocean deglacial record supports global younger dryas abstract in northern hemisphere deglaciation records the transition from the last glacial to the holocene indicates a rapid return to near glacial conditions during the younger dryas whereas their southern hemisphere ice core counterparts record two separate cooling events the antarctic cold reversal and the oceanic cold reversal spatial distribution and relative timing of these events in both hemispheres are central for our understanding of causes and mechanisms of abrupt climate change to date no marine record from the southern mid latitudes conclusively demonstrates that the younger dryas was a significant event in the southern ocean here we present high resolution oxygen isotope and iron content records of a radiocarbon dated sedimentary sequence from the great australian bight which constrains oceanic and atmospheric changes during the last deglaciation oxygen isotopes from planktonic foraminifera indicate two rapid cold reversals between 13 1 and 11 1 kyr bp separated by a brief warming the sedimentary iron content interpreted as a proxy for wind strength indicates a simultaneous change in atmospheric circulation pattern both records demonstrate the existence of cooling events in the southern hemisphere which are synchronous with the northern hemisphere younger dryas cold reversal between 12 9 and 11 5 kyr bp such evidence for the spatial distribution and timing of abrupt climatic fluctuations is essential data for groundtruthing results derived from global climate models

distribution of glycerol dialkyl glycerol tetraether gdgt lipids in a hypersaline lake system isoprenoid glycerol dialkyl glycerol tetraethers isogdgts of archaeal origin and branched br gdgts of bacterial origin occur in a diverse range of lacustrine sedimentary environments they have attracted attention as potential temperature proxies providing high resolution palaeo environmental reconstruction from continental interiors for this study the distribution of gdgts in and application of gdgt based proxies to surface samples from chaka salt lake china as well as soils and in flow river sediments were investigated to assess whether gdgt based proxies were applicable to this hypersaline lake system we show that iso and brgdgts were present in all sediments and soils from the chaka salt lake system gdgt 0 and crenarchaeol were generally the two most abundant isogdgts suggesting thaumarchaeota as a major biological source of isogdgts the low ratio of crenarchaeol crenarchaeol regioisomer suggests that thaumarchaeota of the lake sediments is likely thaumarchaeota group i 1b derived from the surrounding alkaline soils arguing against the use of the tex86 proxy in this system because alkaline soils generally have high isogdgt concentrations it is likely that a large allochthonous input of isogdgts would be a pervasive challenge to palaeoclimate applications in such settings on the other hand the brgdgt distributions in the lake and river sediments differed markedly from those in the surrounding soils suggesting that instead of deriving from the surrounding soils at least part of the brgdgts is synthesized in situ or delivered from more distal upland soils taken together our results indicate that the mixed sources of gdgts in chaka salt lake complicate the application of gdgt based proxies and it will be challenging to use such proxies in this system

distribution of tetraether lipids in the 25 ka sedimentary record of lake challa extracting reliable tex86 and mbt cbt palaeotemperatures from an equatorial african lake the distribution of isoprenoid and branched glycerol dialkyl glycerol tetraether gdgt lipids was studied in the sedimentary record of lake challa a permanently stratified partly anoxic crater lake on the southeastern slope of mt kilimanjaro kenya tanzania to examine if the gdgts could be used to reconstruct past variation in regional temperature the study material comprised 230 samples from a continuous sediment sequence spanning the last 25 ka with excellent age control based on high resolution ams c 14 dating the distribution of gdgts showed large variation through time in some time intervals i e from 20 4 to 15 9 ka bp and during the younger dryas 12 9 11 7 ka bp crenarchaeol was the most abundant gdgt whereas at other times i e during the early holocene branched gdgts and gdgt 0 were the major gdgt constituents in some intervals of the sequence the relative abundance of gdgt 0 and gdgt 2 was too high to be derived exclusively from lacustrine thaumarchaeota suggesting a sizable contribution from methanogens and other archaea this severely complicated application of tex86 palaeothermometry in this lake and limited reliable reconstruction of lake water temperature to the time interval 25 13 ka bp i e the last glacial maximum and the period of post glacial warming the tex86 inferred timing of this warming is similar to that recorded previously in two of the large african rift lakes while its magnitude is slightly or much higher than that recorded at these other sites depending on which lake based tex86 calibration is used application of calibration models based on distributions of branched gdgts developed for lakes inferred temperatures of 15 18 degrees c for the last glacial maximum and 19 22 degrees c for the holocene however the mbt cbt palaeothermometer reconstructs temperatures as low as 12 degrees c for a lateglacial period centred on 15 ka bp variation in down core values of the bit index are mainly determined by the varying production rate of crenarchaeol relative to in situ produced branched gdgts the apparent relationship of the bit index with climatic moisture balance can be explained either by the direct influence of lake level and wind strength on nutrient recycling or by influx of soil nutrients promoting aquatic productivity and nitrification this study shows that gdgts can aid in obtaining climatic information from lake records but that the obtained data should be interpreted with care

distributions of branched gdgts in a tropical lake system implications for lacustrine application of the mbt cbt paleoproxy branched glycerol dialkyl glycerol tetraether gdgt lipids are abundant and ubiquitous in lake sediments potentially allowing for a paleolimnological application of the so called mbt cbt proxy methylation index of branched tetraethers cyclization ratio of branched tetraethers to investigate the origin and characteristics of these compounds in lacustrine environments we examined the distributions of gdgts in soils river sediments and lake sediments from lake towuti on the island of sulawesi indonesia we found significant differences in the degree of methylation and cyclization expressed by way of the mbt and cbt indices between the soil samples and the aquatic samples suggesting that there may be in situ production of gdgts in the aquatic environment based on these findings we urge caution in the application of the mbt cbt paleoproxy to lake sediments and encourage more rigorous study of these compounds in freshwater environments

environmental controls on paleo ph at mid latitudes a case study from central and eastern europe abstract here we present the first reconstruction of the black sea catchment soil ph evolution during the last glacial period and insights into its environmental controls the ph reconstruction is derived from the cbt index cyclization ratio of branched tetraethers brgdgts weijers et al 2007a a proxy based on the relative abundance of branched tetraethers applied in this study to a northwestern black sea sediment core since branched tetraethers are produced primarily in soils but also in aquatic environments we first evaluate the potential of the cbt proxy to reconstruct soil ph regarding the possible origins of brgdgts based on a previous study we propose a correction of the reconstruction to account for the increase in brgdgts derived from in situ production in the black sea paleo lake we also use the cbt ph record to track the soil signal of the black sea catchment as well as to investigate the internal i e soil parent material and external i e climatic controls on long term soil ph change at mid latitudes given that cbt ph was first proposed as a qualitative proxy of paleoprecipitation at lower latitudes we investigate in particular the influence of precipitation on our setting we show that in central and eastern europe soil ph evolution during the last glacial interglacial transition cannot be explained by precipitation amounts only but can be explained by i variations in the spatial source of brgdgts associated with that of soil parent material ii soil water balance and iii soil vegetation litter notably the cbt ph is significantly influenced by a spatial change of brgdgt sources during heinrich stadial 1 moreover the cbt ph record suggests a strong decrease in the soil moisture budget from the lgm towards the early holocene interrupted by an abrupt increase during the younger dryas our study stresses the importance of considering evapotranspiration in addition to precipitation shifts in order to better understand chemical changes of mid latitude soil under major climate change furthermore we suggest that mid latitude soil chemistry during the last glacial interglacial climate transition was more prone to and or more sensitive to vegetation cover changes through i the role of vegetation cover in evapotranspiration and thus in soil leaching and ii the different quality of vegetation litters whatever the latitude the cbt proxy appears useful as one of the only soil chemistry proxies to provide insights into the past hydrology of soil

in situ produced branched glycerol dialkyl glycerol tetraethers in suspended particulate matter from the yenisei river eastern siberia abstract soil derived branched glycerol dialkyl glycerol tetraethers brgdgts in marine river fan sediments have a potential use for determining changes in the mean annual temperature mat and ph of the river watershed soils prior to their incorporation in marine sediments the compounds are transported to the marine system by rivers however emerging evidence suggests that the brgdgts in freshwater systems can be derived from both soil run off and in situ production the production of brgdgts in the river system can complicate the interpretation of the brgdgt signal delivered to the marine system therefore we studied the distribution of brgdgt lipids in suspended particulate matter spm of the yenisei river chromatographic improvements allowed quantification of the recently described hexamethylated brgdgt isomer characterized by having two methyl groups at the 6 6 instead of the 5 5 positions in an environmental dataset for the first time this novel compound was the most abundant brgdgt in spm from the yenisei its fractional abundance correlated well with that of the 6 methyl isomer of the hexamethylated brgdgt that contains one cyclopentane moiety the yenisei river watershed is characterized by large differences in mat 11 c as it spans a large latitudinal range 46 73 n which would be expected to be reflected in brgdgt distributions of its soils however the brgdgt distributions in its spm show little variation furthermore the reconstructed ph values are high compared to the watershed soil ph we therefore hypothesize that the brgdgts in the yenisei river spm are predominantly produced in situ and not primarily derived from erosion of soil this accounts for the absence of a change in the temperature signal as the river water temperature is more stable using a lake calibration the reconstructed temperature values agree with the mean summer temperatures mst recorded the brgdgts delivered to the sea by the yenisei river during this season are thus not soil derived possibly complicating the use of brgdgts in marine sediments for palaeoclimate reconstructions

geochemistry of iron rich sediments on the outer continental shelf off northern new south wales abstract iron rich sediments on the outer continental shelf off northern new south wales have formed as a result of authigenesis mainly within skeletal chambers these sediments are significantly enriched in fe and marginally enriched in p as and mn when compared to other shelf sediments from the same region mineralogical data and microprobe analyses of the authigenic phases indicate that berthierine chamosite rather than glauconite was the primary mineral but this has subsequently broken down to poorly crystalline phases that are intermediate between berthierine and goethite during this breakdown the foraminiferal infillings and pellets have become enriched in fe and both p and as have been incorporated by anionic adsorption the geochemical data for the sediments and associated phosphatic nodules suggest that the source of phosphorus for the nodules may be the surrounding iron rich sediments the phosphatic nodules are relatively enriched in fe and as and low in p2o5 compared to modern phosphorites associated with upwelling regions it is postulated that reduction of the iron rich sediments produces significant quantities of inorganic phosphate within the interstitial waters that are ultimately precipitated as carbonate fluorapatite this could explain the formation of modern an ancient phosphorites in east coast situations that are not related to upwelling

sources and distributions of branched and isoprenoid tetraether lipids on the amazon shelf and fan implications for the use of gdgt based proxies in marine sediments branched glycerol dialkyl glycerol tetraethers brgdgts in river fan sediments have been used successfully to reconstruct mean annual air temperature maat and soil ph of the congo river drainage basin however in a previous study of amazon deep sea fan sediments the reconstructed maats were ca 10 c colder than the actual maat of the amazon basin in this study we investigated this apparent offset by comparing the concentrations and distributions of brgdgts in amazon river suspended particulate matter spm and sediments to those in marine spm and surface sediments the riverine brgdgt input was evident from the elevated brgdgt concentrations in marine spm and surface sediments close to the river mouth the distributions of brgdgts in marine spm and sediments varied widely but generally showed a higher relative abundance of methylated and cyclic brgdgts than those in the river since this difference in brgdgt distribution was also found in intact polar lipid ipl derived brgdgts which were more recently produced the change in the marine brgdgt distribution was most likely due to marine in situ production consequently the maats calculated based on the methylation of branched tetraethers mbt and the cyclisation of branched tetraethers cbt were lower and the cbt derived ph values were higher than those of the amazon basin however spm and sediments from stations close to the river mouth still showed mbt cbt values that were similar to those of the river therefore we recommend caution when applying the mbt cbt proxy it should only be used in sediment cores that were under high river influence the influence of riverine derived isoprenoid gdgt isogdgt on the isogdgt based tex86 temperature proxy was also examined in marine spm and sediments an input of riverine isogdgts from the amazon river was apparent but its influence on the marine tex86 was minor since the tex86 of spm in the amazon river was similar to that in the marine spm and sediments

drastic changes in the distribution of branched tetraether lipids in suspended matter and sediments from the yenisei river and kara sea siberia implications for the use of brgdgt based proxies in coastal marine sediments abstract the distribution of branched glycerol dialkyl glycerol tetraethers brgdgts in soils has been shown to correlate with ph and mean annual air temperature because of this dependence brgdgts have found an application as palaeoclimate proxies in coastal marine sediments based on the assumption that their distribution is not altered during the transport from soils to marine systems by rivers to study the processes acting on the brgdgt distributions we analysed the full suite of brgdgts including the recently described 6 me brgdgts in both the suspended particulate matter spm of the siberian yenisei river and the spm and sediments of its outflow in the kara sea the brgdgt distribution in the spm of the yenisei river was fairly constant and characterized by high abundances of the 6 me brgdgts reflecting their production at the neutral ph of the river water however the brgdgt distribution showed marked shifts in the marine system firstly in the yenisei river mouth the fractional abundance of the 6 me brgdgts decreases sharply the brgdgt signature in the yenisei river mouth possibly reflects brgdgts delivered during the spring floods that may carry a different distribution also coastal cliffs were shown to contain brgdgts and to influence especially those sites without major river inputs e g khalmyer bay further removed from the river mouth in situ production of brgdgts in the marine system influences the distribution however also the fractional abundance of the tetramethylated brgdgt ia increases resulting in a distribution that is distinct from in situ produced signals at similar latitudes svalbard we suggest that this shift may be caused by preferential degradation of labile riverine in situ produced brgdgts and the subsequent enrichment in less labile soil material the offshore distribution indeed agrees with the brgdgt distribution encountered in a lowland peat this implies that the offshore kara sea sediments possibly carry a soil dominated signal indicating potential for palaeoclimate reconstructions at this site both in the river system and coastal cliffs brgdgts were much more abundant than crenarchaeol an archaeal isoprenoid gdgt resulting in high 0 93 branched and isoprenoid tetraether bit index values moving downstream in the marine sediments a decrease in brgdgt concentrations coeval with an increase in crenarchaeol resulted in decreasing bit index values this decrease correlates with changes in bulk proxies for terrigenous input 13corg c n confirming the use of the bit index to trace the delivery of river transported and coastal cliff derived terrigenous organic matter

insights into continental temperatures in the northwestern black sea area during the last glacial period using branched tetraether lipids abstract in the continental realm continuous quantitative temperature reconstructions spanning the last glacial are rare especially in central and eastern europe here we provide a reconstruction from the northwestern black sea catchment spanning 40 to 9 ka bp from a study of the relative distribution of branched glycerol dialkyl glycerol tetraethers brgdgts in black sea lacustrine sediments first the origins of brgdgts are discussed the comparison of geochemical proxies from the same core supports a dominant terrestrial origin for brgdgts during the last glacial and a strong decrease in the soil derived brgdgt proportion toward the holocene since the lowering of soil vs lacustrine derived brgdgts is prone to bias the temperature signal that is reconstructed using a soil calibration a correction for in situ production is applied the corrected signal is compared to independent discrete temperature records from the study area the brgdgt temperature relative evolution reconstructed in this work provides additional insight regarding millennial scale climate variability in central and eastern europe notably the imprints of heinrich event cold spells and lateglacial climatic oscillations are consistent with other regional paleorecords from the northern hemisphere

neogene history of the west pacific warm pool kuroshio and leeuwin currents 1 foraminiferal analysis of miocene to recent strata of the northwest shelf of australia is used to chart west pacific warm pool wpwp influence the assemblage is typified by larger foraminifera with ingressions of the indo pacific smaller taxa asterorotalia and pseudorotalia at around 4 ma and from 1 6 to 0 8 ma a review of recent and fossil biogeography of these taxa suggests their stratigraphic distribution can be used to document wpwp evolution from 10 to 4 4 ma a lack of biogeographic connectivity between the pacific and indian ocean suggests indonesian throughflow itf restriction during this period the collision of australia and asia trapped warmer waters in the pacific creating a central wpwp biogeographic province from the equator to 26 n by 3 ma indo pacific species migrated to japan with the initiation of the modern kuroshio current coinciding with the intensification of the north pacific gyre and northern hemisphere ice sheet expansion indo pacific taxa migrated to the northwest australia from 4 4 to 4 ma possibly because of limited itf the absence of indo pacific taxa in northwest australia indicates possible itf restriction from 4 to 1 6 ma full northwest australian biogeographic connectivity with the wpwp from 1 6 to 0 8 ma suggests an unrestricted stronger itf compared to today and the initiation of the modern leeuwin current the extinction of some indo pacific species in northwest australia after 0 8 ma may be related to the effects of large glacial interglacial oscillations and uplift of the indonesian archipelago causing indonesian seaway restriction

identification and carbon isotope composition of a novel branched gdgt isomer in lake sediments evidence for lacustrine branched gdgt production branched glycerol dialkyl glycerol tetraethers brgdgts are bacterial membrane lipids that occur ubiquitously in soils and lacustrine sediments and have great potential as proxy indicators for paleotemperature and ph reconstructions initially brgdgts in lakes were thought to originate from soils of the watershed the composition of the lacustrine brgdgt pool however often differs substantially from that in catchment soils complicating the application of the brgdgt paleothermometer to lake sediments this suggests that terrigenous brgdgt signals in lacustrine sedimentary archives may be affected by aquatic in situ production in sediments of a swiss mountain lake we detected a novel hexamethylated brgdgt which elutes between the known 5 and 6 methyl brgdgt isomers during hplc ms analysis this novel isomer accounted for 8 5 of the total brgdgts most remarkably this brgdgt was not detected in soils collected from the catchment of the lake providing circumstantial evidence for an in situ brgdgt source in the lake s water column or sediments isolation of the compound by preparative hplc and subsequent gc ms analysis of the alkyl chains revealed that the novel brgdgt comprises two structural isomers one possesses a 5 13 16 and a 6 13 16 trimethyloctacosanyl moiety and constitutes 84 of the new brgdgt the second contains a 13 16 dimethyloctacosanyl and a 5 13 16 23 tetramethyloctacosanyl moiety the 13c values of both the alkyl chains derived from the novel brgdgt 46 and all other major brgdgts 43 to 44 were significantly lower than those of brgdgt derived alkanes in catchment soils 27 to 28 further attesting to in situ production of brgdgts in the studied lake

benthic foraminiferal response to late glacial and holocene sea level rise and rainfall variability off east africa analogous to west and north africa east africa experienced more humid conditions between approximately 12 and 5 kyr bp relative to today while timing and extension of wet phases in the north and west are well constrained this is not the case for the east african humid period here we present a record of benthic foraminiferal assemblages and sediment elemental compositions of a sediment core from the east african continental slope in order to provide insight into the regional shallow indian ocean paleoceanography and east african climate history of the last 40 kyr during glacial times the dominance of a benthic foraminiferal assemblage characterized by bulimina aculeata suggests enhanced surface productivity and sustained flux of organic carbon to the sea floor during heinrich stadial 1 h1 the nuttallides rugosus assemblage indicates oligotrophic bottom water conditions and therefore implies a stronger flow of southern sourced aaiw to the study site during the east african humid period the saidovina karreriana assemblage in combination with sedimentary c n and fe ca ratios suggest higher river runoff to the indian ocean and hence more humid conditions in east africa between 8 5 and 8 1 kyr contemporaneous to the globally documented 8 2 kyr event a severe reduction in river deposits implies more arid conditions on the continent comparison of our marine data with terrestrial studies suggests that additional moisture from the atlantic ocean delivered by an eastward migration of the congo air boundary during that time period could have contributed to east african rainfall since approximately 9 kyr the gaining influence of the millettiana millettii assemblage indicates a redevelopment of the east african fringe reefs

the holocene non tropical coastal and shelf carbonate province of southern australia abstract carbonate dominant sediments are currently forming and accumulating over the extensive marine shelf of the passive margin of southern australia a dearth of continental detritus results from both a very low relief and a predominantly arid climate the wide continental shelf is bathed by cold upwelling ocean waters that support luxuriant growths of bryozoans and coralline algae together with sponges molluscs asteroids benthic and some planktonic foraminifera the open ocean coast is battered by a persistent southwest swell resulting in erosion of calcrete encrusted pleistocene eolianites much sediment is reworked and overall shelf sedimentation rates are low high energy microtidal beach dune systems occur between headlands and along the very long ocean beach in the coorong region the northern more arid coastal areas also contain saline lakes that precipitate gypsum from infiltrated sea water and display marginal facies of aragonite boxwork to fenestral carbonate crusts with stromatolites and tepee structures in contrast the southern seasonally humid coorong region has a predominantly continental groundwater regime where sulphate is rare and the high summer evaporation precipitates dolomite magnesite and aragonite muds fenestral crusts breccias tepees and some stromatolites are also present st vincent and spencer gulfs both afford some protection from ocean swell but tidal amplitude and currents increase and a depth and inundation related zonation of plants and animals is established muddy carbonate sand accumulates on the sea floor below 30 m where filter feeding bryozoans bivalves and sponges dominate in shallower regions seagrass meadows contain a rich fauna that results in rapid accumulation of an unsorted muddy bioclastic sand mangrove woodlands backed by saline marsh with cyanobacterial mats are common and accumulate mud rich and gastropod bearing sediment as tidal amplitude and desiccation increase northward into both gulfs a supratidal zone bare of vegetation sabkha becomes the site for deposition of gypsum rich and fenestral calcitic mud

branched glycerol dialkyl glycerol tetraethers in pleistocene loess paleosol sequences three case studies abstract branched glycerol dialkyl glycerol tetraethers branched gdgts are membrane lipids presumably derived from anaerobic heterotrophic soil bacteria empirical studies have shown that the composition of branched gdgts in topsoils varies in degree of cyclization and methylation expressed as cbt and mbt i e cyclization and methylation index of branched tetraethers depending on soil ph and mean annual air temperature mat here we present results from three case studies namely three well studied loess paleosol sequences lpss in which we measured the branched gdgts in order to test the applicability of these biomarkers for paleoclimate reconstruction the results show that major disagreements exist between expectations based on available stratigraphic pedological and geochemical data on the one hand and gdgt derived reconstructions on the other hand caution is therefore advised when interpreting the respective indices in lps studies we discuss several potential directions for future research i some of the target peaks in the hplc chromatograms consist of multiple unidentified compounds this needs to be addressed by way of improved component separation identification and new calibration studies ii factors other than mat and soil ph that could affect membrane composition should be further investigated e g nutrient availability and redox conditions as well as seasonality and changes in bacterial communities iii gdgts may be produced in non negligible amounts at depth and thus overprint the original in situ signal a concern that could be termed growth depth effect iv gdgts should also be analyzed in dust source regions and contemporaneous eolian sediments in order to address a potential redeposition effect

palaeoceanographic significance of recent foraminiferal biofacies on the southern shelf of western australia a preliminary study the southern shelf of western australia lies close to the subtropical convergence in a region strongly influenced by the warm leeuwin current from the north and the cold more massive western australian current from the south fresh holocene and relict pleistocene foraminiferal specimens are mixed in dredged sediment samples similar in composition to those from other parts of the southern australian margin the holocene planktonic assemblages are dominated in the west by subtropical forms globigerinoides trilobus s l globorotalia menardii and neogloboquadrina dutertrei and in the east by the temperate species globorotalia inflata three holocene benthic assemblages are distributed from the inner shelf to the upper slope also showing a strong longitudinal gradation from west to the east the change from warm water assemblages to temperate assemblages is progressive and continuous but the southwest corner is marked by the southerly limit of some larger benthic taxa including heterostegina and the area off esperance is the furthermost extent of an abundant though patchy living amphisorus marginopora association this w e gradation indicates that the leeuwin current has played a key role in influencing the distribution of foraminifera as from at least the last interglacial because this pattern exists not only in the holocene but also in the relict foraminiferal biofacies 1999 elsevier science b v all rights reserved

response of deep sea benthic foraminifera to late quaternary climate changes southeast indian ocean offshore western australia the late quaternary benthic foraminifera of four deep sea cores off western australia odp 122 760a odp122 762b bmr96gc21 and rc9 150 have been examined for evidence of increased surface productivity to explain the anomalously low sea surface paleotemperatures inferred by planktic foraminifera for the last and penultimate glaciations the 13c trends ofcibicidoides wuellerstorfi and differences between the 13c trends of planktics globigerinoides sacculifer and benthicsc wuellerstorfi in the four cores indicate that during stage 6 bottom waters were significantly depleted in 13c and strong 13c gradients were established in the water column while during stage 2 and the last glacial maximum 13c trends did not differ greatly from that of the holocene two main assemblages of benthic foraminifera were identified by principal component analyses one dominated byuvigerina peregrina another dominated byu proboscidea abundance of these uvigerinids and of taxa preferring an infaunal microhabitat and ofepistominella exigua andbulimina aculeata indicate that episodes of high influx of particulate organic matter were established in most sites during glacial episodes and particularly so during stage 6 while evidence for upwelling during the last glacial maximum is less strong the penultimate glaciation upwellings were established within the areas of low sea surface paleotemperature indicated by planktic foraminifera during the last interglacial climax upwelling appears to have been established in an isolated region offshore from a strengthened leeuwin current off north west cape last glacial maximum 13c values ofc wuellerstorfi at waterdepths of less than 2000 m show smaller than global mean glacial interglacial changes suggesting the development of a deep hydrological front a similar vertical stratification bathyal front was also established during the penultimate glaciation

linking danube river activity to alpine ice sheet fluctuations during the last glacial ca 33 17 ka bp insights into the continental signature of heinrich stadials abstract offshore archives retrieved from marine lacustrine environments receiving sediment from large river systems are valuable quaternary continental records in the present study we reconstruct the danube river activity at the end of the last glacial period based on sedimentological mineralogical and geochemical analyses performed on long piston cores from the north west black sea margin our data suggest that the danube river produced hyperpycnal floods throughout the ca 33 17 ka period four main periods of enhanced danube flood frequency each of 1 5 3 kyr duration are recorded at ca 32 5 30 5 ka equivalent to the first part of heinrich stadial hs 3 at ca 29 27 5 ka equivalent to greenland stadial 4 at ca 25 3 23 8 ka equivalent to hs 2 and at ca 22 3 19 ka based on mineralogical and geochemical data we relate these events to enhanced surface melting of the alpine ice sheet ais that covered 50 000 km2 of the danube watershed at the last glacial maximum lgm our results suggest that i the ais growth from the inner alps to its lgm position in the northern alpine foreland started from ca 30 5 ka ended no later than ca 25 3 ka and was interrupted by a melting episode ca 29 27 5 ka ii the ais volume drastically decreased from ca 22 3 to 19 ka as soon as summer insolation energy at the ais latitude increased and iii hss strongly impacted the ais mass balance through enhanced summer surface melt this together with evidence of severely cool winters and the rapid expansion of sea ice in the north atlantic implies strong seasonality in continental europe during stadials

formation morphology and preservation of high energy carbonate lithofacies evolution of the cool water recherche archipelago inner shelf south western australia cool water carbonate environments are responsible for up to one third of the carbonate sediment produced on continental shelves and are useful modern analogues for many geologically ancient carbonate deposits on modern and ancient high wave energy carbonate ramps it has been suggested that wave abrasion generally limits sediment accumulation to the outer shelf sediment are produced on the modern inner shelf although few studies have investigated processes of sedimentation in these energetic environments the recherche archipelago in the west of the great australian bight gab was examined to better identify processes of carbonate sedimentation and preservation on extremely high energy shelves surficial sediments video traverses multibeam sonar data cores and shallow seismics were analysed these data reveal that the topographically varied environment of the recherche archipelago experienced gradual episodic accumulation of a prograding sediment wedge with substantially thicker deposits located on the lee side of topographic highs modern sediment accumulation is largely restricted to the shoreface and inner shelf where the highly discontinuous storm influenced blanket of holocene sediment comprises a shore attached quartzose sediment prism leeward accretionary wedges and rhodolith beds above a laterally continuous pecten dominated basal transgressive lag storm events play an important role in these environments resulting in a mostly bare shaved middle and outer shelf onshore sediment transport reworking of particles and periodic removal of sediment the modern recherche archipelago is a high energy end member of cool water carbonate environments in which calcareous algae dominate sediment production modern esperance bay provides a useful analogue for the interpretation of high energy palaeoenvironments and demonstrates that in addition to sea level change wave energy and local geomorphology are important considerations for carbonate facies reconstructions this study has presented new information for carbonate inner shelves that differs from classic carbonate ramp models showing that ancient rhodolith bearing carbonate deposits have the potential to form and be preserved in very high energy settings

surficial sediments of the great australian bight facies dynamics and oceanography on a vast cool water carbonate shelf abstract the great australian bight gab the largest sector of the southern australia continental margin is a site of cool water carbonate sedimentation throughout ranging from locally warm temperate inboard to cool temperate outboard surficial sediments are a mixture of calcareous pleistocene skeletal and lithic intraclasts relict grains and holocene biofragments with minor amounts of quartz inboard the inner shelf is an area of abundant macrophytes and seagrasses active carbonate sediment production and accumulation and little relict sediment the huge middle portion is a shaved shelf with active sediment winnowing and mostly relict sediment the outer shelf and upper slope is a variably productive sediment factory characterized by prolific calcareous epibenthic growth on hard substrate subaqueous islands shedding particles into surrounding sands and muds patterns of holocene sedimentation are linked to modern oceanographic parameters in this high energy setting characterized by overall downwelling prolific rhodoliths occur on the nw inner shelf where shallow summer waters are the warmest in the gab these warm saline nutrient depleted waters then drift eastward across the shelf suppressing heterozoan carbonate production on the central and eastern mid shelf this arrested production in the eastern gab is countered locally by summer coastal upwelling along western eyre peninsula with bryozoan rich sediment extending well inboard onto the mid shelf the outer shelf and upper slope is an area of prolific bryozoan growth likely linked to upwelling except in the central gab a region of year round downwelling where the area is one of off shelf fine sediment transport and carbonate mud deposition these patterns in the central gab at least are present in the underlying holocene and pleistocene suggesting that the general modern oceanographic dynamics and resultant carbonate sedimentation have persisted throughout the quaternary

the significance of marginopora vertebralis foraminifera in surficial sediments at esperance western australia and in last interglacial sediments in northern spencer gulf south australia abstract surficial sediments at esperance on the southern coast of western australia are predominantly bioclastic carbonates in which tests of foraminifera are a major constituent the megascopic species marginopora vertebralis is prolific occupying relatively protected areas of algal turf and seagrasses the abundance of this normally tropical foraminifer at southern latitudes can be attributed to the leeuwin current which brings warm waters from the tropics to southwestern australia and then eastwards past esperance into the great australian bight the leeuwin current is significantly warmer than the cool interfacing waters of the southern ocean that otherwise characterise the southern australian continental shelf last interglacial sediments of the glanville formation in northern spencer gulf of south australia host an assemblage of fossil foraminifera which is similar to that of the modern environment at esperance especially the presence of m vertebralis two bivalve molluscs anadara trapezia and pinctada carchariarium both characteristic of warm waters are also present in the glanville formation marginopora vertebralis and other faunal elements migrated to south australia by means of the last interglacial equivalent of the leeuwin current which apparently had greater definition at that time it may therefore be inferred that during other times of global warming and corresponding higher sea levels the palaeo leeuwin current had greater ecological influence across the continental shelf of southern australia thus warm water marine fossils in the glanville formation do not necessarily signify last interglacial water temperatures for the open southern ocean beyond the continental shelf similarly it cannot be assumed that these fossils necessarily indicate a last interglacial climate for terrestrial southern australian that was warmer than presently prevails

global tectonics since the breakup of pangea 180 million years ago evolution maps and lithospheric budget abstract pangea the earth s youngest single supercontinent broke up 180 million years ago tectonic plates were subsequently formed by dispersal of the continental fragments and accretion of new oceanic lithosphere the configurations of all the major lithospheric plates at 0 20 65 95 140 180 ma bp are reconstructed on six globes of the earth each with a radius of 10 cm it appears that plate boundaries maintain a remarkably close fit on model globes of constant radii if the reconstructions include the recovery of subducted spreading patterns this is illustrated with maps in equatorial orthographic oblique orthographic and transverse hammer aitoff projections the snug fit of the tectonic plates at every tested time since the breakup of pangea 180 ma bp is consistent with the theory of plate tectonics on a non expanding earth and contradicts rapidly expanding earth models the areas of oceanic lithosphere produced and consumed during the past 180 ma bp are estimated from surface measurements of the globes reconstructed on the basis of particular assumptions these measurements suggest a consistent increase in the production rate of oceanic lithosphere during the past 140 ma it was decided to revise the assumptions and see if alternative reconstructions of the ancient spreading patterns on the floors of the tethys and eo pacific oceans could avoid implying an increase of lithospheric production rates with time this appeared to be possible the revised maps suggest that ophiolites older than 180 ma bp may have been obducted in cenozoic collision zones of the himalayas andes rockies and the western part of the banda arc timor new guinea estimates of the ocean floor production and consumption budget appear to be quite similar for both map series and only the possible ranges are summarized here time averaged for the past 180 ma world wide production and consumption of oceanic lithosphere appears to have varied between 2 6 and 3 5 km2 a 1 at most the mean of world wide spreading velocities ranges between 2 4 and 3 5 cm a 1 and world wide means of subduction velocities lie between 4 2 and 6 3 cm a 1 more accurate estimates are possible on the basis of particular assumptions and have been specified for the various time intervals distinguished i e the neogene 0 20 ma bp palaeogene 20 65 ma bp upper cretaceous 65 95 ma bp lower cretaceous 95 140 ma bp and middle and upper jurassic 140 180 ma bp

molecular records of continental air temperature and monsoon precipitation variability in east asia spanning the past 130 000 years our current understanding of past changes in east asian summer monsoon easm precipitation intensity derives from several loess paleosol sequences and oxygen isotope 18o records of well dated stalagmites although temperature is generally presumed to have had minimal impact on easm records past air temperature dynamics over east asia are so far relatively poorly understood mainly due to the lack of tools to reconstruct continental paleotemperatures here we report a high resolution record of east asian air temperature over the past 130 000 years based on soil bacterial lipid signatures preserved in a loess paleosol sequence from the mangshan loess plateau in china we find that maximum local insolation is the main driver of air temperature although greenhouse gas concentrations and southern hemisphere climate may influence temperature at times when insolation is weak causing a decoupling with easm precipitation intensity direct comparison of our temperature record with precipitation induced changes in past soil ph derived from the same suite of lipids confirms this decoupling subsequent cross spectral analysis of the two molecular proxy records reveals that variations in monsoon precipitation consistently lag those in air temperature throughout the whole record at the dominant precession band the length of this lag is variable however and increases as glaciation develops this observation is consistent with an increasing influence of northern hemisphere ice sheets on the modulation of easm response to insolation forcing during ice ages

the influence of geomorphology and sedimentary processes on shallow water benthic habitat distribution esperance bay western australia the mapping of seabed environments is fundamental to successful fisheries management and environmental monitoring however there is an emerging need to better characterise habitats based upon appropriate physical parameters in this study relationships between seabed geomorphology and the distribution of benthic habitats were examined using multibeam sonar underwater video predicted wave energy and sediment data for esperance bay part of the recherche archipelago this shallow 50 m high energy biogenic sediment dominated environment is located in temperate southwestern australia exposure to wave energy appears to determine the distribution of unconsolidated substrate and is the most useful regional scale predictor of rhodolith and seagrass habitats although they are intermittently smothered by mobile sediments limestone reefs provide habitat for a wide range of sessile organisms even in very high wave exposure environments the distribution of rhodolith beds is related to poorly sorted sediments that contain high gravel mud and caco3 percentages our results reveal that in the recherche archipelago wave abrasion coupled with localised sediment transport and accumulation play a major role in increasing the diversity of inner shelf benthic habitats this highlights the value of assessing geomorphic processes in order to better understand the distribution and structure of benthic habitats

isotopic composition of a large photosymbiotic foraminifer evidence for hypersaline environments across the great australian bight during the late pleistocene abstract analysis of carbon and oxygen isotopic compositions of large benthic foraminifera tests marginopora vertebralis that lived in the great australian bight during the late pleistocene reveal that the tests are enriched by 1 to 3 in both 18o and 13c relative to modern specimens from the same region the intolerance of m vertebralis for cool waters negates lower ocean water temperature as an explanation for such high 18o values the oxygen isotopic compositions are thus interpreted to reflect tests secreted in hypersaline waters of up to 56 ppt salinity concentrated from seawater by evaporation m vertebralis thrives today in waters of similar salinity at shark bay western australia the pleistocene sedimentary assemblage supports an interpretation that environments broadly similar to those in outer modern day shark bay were wide spread across the great australian bight during portions of marine isotope stages 2 3 and 4 the high 13c values of the pleistocene m vertebralis are interpreted to reflect enhanced photosynthetic activity that depletes dissolved carbonate in 12c in such shallow saline settings these hypersaline environments formed during periods of lower sea level when shallow waters