early pleistocene climate changes in the central mediterranean region as inferred from integrated pollen and planktonic foraminiferal stable isotope analyses vegetation inherited from a pliocene subtropical climate evolved through obliquity oscillations and global cooling leading to modern conditions an integrated highly time resolved record of pollen and stable isotopes 18o and 13c of globigerina bulloides was obtained to understand vegetation responses to early pleistocene climate changes continental and marine responses are compared in the central mediterranean region with a particular consideration of environmental changes during anoxic events pollen data illustrate vegetation dynamics as follows 1 development of mesothermic elements warm and humid conditions 2 expansion of mid and high altitude elements cooler but still humid conditions and 3 strengthening of steppe and herb elements cooler and dry conditions these successions correlate with precession 18o variations recorded by globigerina bulloides define two cycles mis 43 40 related to obliquity at northern low to mid latitudes the pollen signal records temperature and wetness changes related to precession even during global climate changes induced by obliquity this may result in unexpected increasing wetness during glacial periods which has to be considered specific to the central and eastern mediterranean region lastly an analysis of anoxic events reveals that enhanced runoff is indicated by increasing frequency of the riparian trees liquidambar and zelkova

early carboniferous carbonate systems an alternative to the cainozoic paradigm abstract an alternative model for carbonate deposition is offered for the early carboniferous the major features of this interval are not explained using late cainozoic analogues early carboniferous low latitude shallow seas were apparently strongly influenced by upwelling and high nutrient levels these conditions favoured highly carbonate productive offshore systems but also resulted in the formation of extensive abiogenic carbonates as muds and ooids if correct the carboniferous serves to illustrate the dangers in extrapolating from present day systems to the geological record

waulsortian type buildups and resedimented carbonate turbidite facies early mississippian burlington shelf central missouri abstract the crinoidal carbonates of the lower mississippian osagean burlington limestone in central missouri consist of individual and multiple interconnected waulsortian type buildups and associated resedimented debris carbonate turbidite facies this association of waulsortian type buildups and turbidity current sedimentation developed on the foreslope toe of slope and basinal near toe of slope areas of the prograding burlington shelf the waulsortian type buildups contain a core facies of dolomitized bryozoan crinoid lime mudstone and a flank facies of symmetrically disposed thin bedded crinoidal packstone and grainstone the core developed where bryozoan crinoid thickets trapped carbonate fines of upslope turbidity current origin lime mud hardgrounds in the cores developed during prolonged breaks in the influx of lime mud the flank beds developed by in situ disarticulation of indigenous crinoids and minor gravity slide processes the resedimented debris facies are laterally continuous and normally graded grainstone and packstone the beds show 1 a subdivision of bouma intervals a and b 2 coarse tail grading 3 scours flutes and load casts 4 a generally random fabric except for crinoid ossicle alignment in bouma interval b and 5 no articulation of crinoid stems or calyxes these features combined with the absence of infiltration textures escape burrows shell imbrication and hummocky cross stratification are useful in distinguishing these resedimented beds from lag suspension deposits of storm origin the lower part of the burlington 5 15 m thick consists exclusively of waulsortian type buildup core and flank facies these buildups rest on a thin laminated dolomitic shale bed starved basin sediment and represent basinal near toe of slope deposition the upper and middle parts of the burlington limestone corresponding to foreslope and toe of slope depositional settings consist of waulsortian type buildups and resedimented debris facies considering approximate modern analogues the resedimented debris probably came from various linear near shelf margin sources the resedimented debris contains algal bored grains from the shelf margin and foreslope biogenic grains and clasts

stromatolitic framework of carbonate mud mounds abstract mud mounds are an important phanerozoic reef type generally formed in deeper water on carbonate shelf to basin slopes they commonly contain radiaxial calcite spar filled depositional cavities stromatactis but lack abundant metazoan framebuilders mud mounds are often flanked by steeply dipping bioclastic grainstones and sometimes attained widths and depositional reliefs of over a hundred meters they occasionally occur as basal cores on which developed shallow water metazoan constructed reefs stromatactoid mud mounds are composed of a framework of submarine cemented crudely reticulate masses or a succession of laminar crusts surrounded by cement filled cavities these cavities developed when unconsolidated sediment around the framework was removed by winnowing mud mound frameworks of all ages show strong geometric and petrographic similarities to shallow water cryptalgal structures especially thrombolites unlaminated stromatolites which occur in many phanerozoic shallow water reefs both thrombolites and mud mound frameworks are largely composed of lime mudstone cemented on the sea floor and contain fenestral fabric and diagnostic cryptalgal microstructure their depositional surfaces were irregular not bored or burrowed and rarely encrusted stromatolitic lamina ion although commonly not well developed in the subtidal zone anyway occasionally occurs in mud mounds it is proposed that mud mounds accumulated from organic probably blue green algal binding of locally derived lime mud and bioclasts deposited relatively slowly from suspension patchy distribution of algal mats resulted in areas of both bound and unbound sediment sporadic floodlike episodes of rapid sedimentation however temporarily smothered the living algal mat and also left layers of unbound sediment periods of winnowing washed out unconsolidated unbound sediment and promoted synsedimentary cementation of resulting stromatactoid cavities and algal bound framework

foreslope stromatoporoid renalcid bioherm with evidence of early cementation devonian ancient wall reef complex rocky mountains a small mound 4 x 23 m in size on the fore reef slope of the ancient wall reef complex at mouni haultain alberta consists of fenestral renalcid micrite and wac kestone stroniatoporoids are the most abundant skeletal component but do not form an organic framework renalcids together with early micrite cementation performed a supporting and stabilizing role but only rarely directly encrusted skeletal material many of the primary shelter voids interparticle voids and fenestrae were filled with internal sediments and submarine micrite cements a considerable proportion of the micrite matrix appears to be cement the location and development of the bioherm was controlled by a local hard substrate and suitable environmental conditions the mound developed on and around a large block within an underlying megabreccia bed soon after it was deposited in a debris flow on the fore reef slope it formed near wave base in about 30 50 m water depth and was subject to gentle current action laminar stromatoporoids grew on the flanks and top of the mound and fenestral renalcid micrite and wackestone accumulated in the central part deepening water and increased rates of mud accumulation terminated further build up of the bioherm and it was buried by basin mud fenestral renalcid micrite occurs in a number of devonian and lower palaeozoic organic mounds this study suggests that early submarine cementation was a significant factor in the developmen and preservation of this distinctive lithotype

mississippian early carboniferous stromatolite mounds in a fore reef slope setting laibin guangxi south china the mississippian early carboniferous is generally a period of scarce carbonate buildups in south china this study documents outcrops of stromatolite mounds at mengcun and helv villages in laibin city guangxi province south china the stromatolite mounds contain various stromatolite morphologies including laminar wavy laminar domal or hemispheroidal bulbous and flabellate growth columns intramound rocks are brachiopod floatstone and dark thin bedded laminated micrite limestone individual stromatolites at mengcun village are generally 3 6 cm thick and morphologically represent relatively shallow water laminar planar and wavy undulated stromatolites and deeper water domal bulbous and columnar forms where mounds were formed the stromatolites continued growing upward up to 60 cm thick thrombolitic fabrics also occur but are not common stromatolite microscopic structure shows the bulk of the lamination to consist of wavy microbialite and discrete thin micritic laminae these mounds are intercalated in deep water fore reef talus breccia packstone formed as a bioclastic debris flow and thin bedded limestone containing common chert layers of the tatang formation late visean further evidence supporting the deep water setting of the stromatolite mounds are 1 a laterally thinning horizon of brachiopod floatstone containing deep water small thin shelled brachiopods peloidal micritic sediments and low diversity mixed fauna e g thin shelled brachiopods tube like worms and algae that have been interpreted as storm deposits 2 common fore reef talus breccias 3 lack of sedimentary structures indicating current action 4 preservation of lamination with sponge spicules and 5 lack of bioturbation suggesting that the stromatolites grew in a relatively low energy deep water setting the stromatolite mounds are the first described stromatolite mounds in mississippian strata of south china and contain evidence that supports interpretations of 1 growth history of mississippian microbial buildups and 2 environmental controls on stromatolite growth and lithification

comment and reply on probable influence of early carboniferous tournaisian early visean geography on the development of waulsortian and waulsortian like mounds

a centennial scale record of vegetation and climate variability from 312 to 240 ka marine isotope stages 9c a 8 and 7e from tenaghi philippon ne greece abstract based on a new centennial scale resolution pollen record from the terrestrial site of tenaghi philippon ne greece we report a series of high amplitude millennial scale forest expansion events during the interval from 312 to 240 ka equivalent to isotopic substages c a of marine isotope stage mis 9 mis 8 and the onset of mis 7e pollen based indices support the climatic interpretation of the forest expansion events as indicators of abrupt increases in temperature and moisture availability in the mediterranean region long term changes in vegetation cover and composition during the studied interval permit the definition of glacial substages early middle and late analogous to the glacial substages of the last climatic cycle within this framework forest expansion events occurred during the early glacial equivalent to mis 9c a and the later part of the middle glacial mid to late mis 8 but are absent from the early part of the middle glacial early mis 8 forest expansion events are also detected during the lateglacial and onset of mis 7 associated with a millennial scale climate oscillation across the glacial interglacial transition i e termination iii t iii a peak for peak match between forest expansion events and antarctic temperature maxima suggests interhemispheric coupling of millennial scale climate variability via global oceanic circulation change and synergistic variability in atmospheric circulation consistent with the bipolar see saw the resolution of our record mean 290 yr also permits the characterisation of climate evolution over the course of interstadial episodes following forest expansion events and highlights differences in the characteristics of early and middle glacial interstadials saw tooth vs plateau profile these differences point to an influence of long term boundary conditions especially global ice volume on the characteristics of millennial scale events

an upper ocean moored current and density profiler applied to winter conditions near bermuda a new moored instrument which makes repeated high vertical resolution profiles of current temperature and salinity in the upper ocean over extended periods was used to observe midwinter conditions near bermuda the operation and performance of the instrument called the profiling current meter pcm in the surface wave environment of winter storms is reported here the pcm profiles along the upper portion of a slightly subsurface mooring by adjusting its buoyancy under computer control this design decouples the instrument from vertical motions of the mooring induced by surface waves so that its electromagnetic current sensor operates in a favorable mean to fluctuating flow regime current temperature and electrical conductivity are vector averaged into contiguous preselected bins several meters wide over the possible profile range of 20 to 250 m depth the pcm is capable of collecting 1000 4000 profiles in a 6 to 12 month period depending on depth range and ambient currents a variety of baroclinic motions are evident in the bermuda observations upper ocean manifestations of both kelvin and superinertial island trapped waves dominate longshore currents vertical coherences of onshore current and temperature suggest that internal wave vertical wave number energy distribution is independent of frequency but modified by island bathymetry kinetic energy in shear integrated over a 115 6 m thick layer in the upper ocean is limited to values less than or equal to the potential energy required to mix the existing stratification mixing events occur when kinetic energy associated with shear drives the bulk richardson number defined by the ratio of energy integrals over the range profiled to unity where it remains while shear and stratification disappear together

interplay between biotic and environmental conditions in pre salt messinian microbialites of the western mediterranean upper miocene mallorca spain microbial buildups that predate the messinian salinity crisis including one of the few phanerozoic examples of giant microbialites crop out upon the island of mallorca w mediterranean sedimentological and geochemical data from microbialites and associated deposits both essentially dolomitic indicate that they grew in shallow marine conditions but relatively restricted from the open marine realm two microbialite bearing sequences occur both consisting of subtidal to supratidal deposits periods of restriction led to evaporative and hypersaline conditions that favored the development of microbialites and local precipitation of sulfates by contrast ephemeral periods marked by more open conditions were devoid of microbialites and allowed production of bioclastic deposits microbialites range from decameter to decimeter scale reflecting differences in accommodation space despite contrasting sizes all microbialite bodies record similar mesostructure evolution through time from thrombolites to stromatolites with a sharp transition between these endmembers the change from subtidal to shallower more restricted and saline intertidal environments triggered biotic substitution of thrombolite generating microbial communities to stromatolite generating ones furthermore a wide variety of microstructures from agglutinated to micritic with fossilized microbes indicates that two main accretion processes occurred microbially influenced primary dolomite precipitation and grain trapping and binding which were controlled by the interaction between microbes and changes in environmental conditions e g grain supply hydrodynamics and hydrochemistry therefore the diversity of macro meso and microstructures of these microbialites was caused by a complex interplay between depositional biotic and hydrological parameters which offers useful insights for the palaeoecological interpretation of other examples at any scale and throughout geological time

changes in vegetation and marine environments in the eastern mediterranean rhodes greece during the early and middle pleistocene pollen records marine faunal associations and stable isotope compositions of sediments from rhodes greece have been determined to track environmental changes in the eastern mediterranean during the early and middle pleistocene a detailed chronostratigraphic curve based on magnetostratigraphic data was obtained by correlating pollen spectra with the mediterranean oxygen isotopic curve of ocean drilling program site 975 five sedimentary sequences that correspond to marine oxygen isotope stage mis 31 27 and to mis 20 17 have been investigated in the confined tsampika microbasin high amplitude pinus variations confirm glacio eustatic changes deduced from changes in marine faunal associations and sedimentary depositional environments reflecting climatic cycles identified in the marine carbonate oxygen isotope record eight vegetation successions characterized by the dominance first of mesothermic elements then of mid and high altitude elements with pinus and ending with maxima in herb and steppe elements have been documented most of them were probably driven by changes in insolation occurring in high northern latitudes obliquity impact during the late early pleistocene and early middle pleistocene

late mississippian bryozoan microbial build ups on a drowned karst terrain port au port peninsula western newfoundland bryozoan and microbial carbonate build ups occur within the late mississippian mid visean codroy group on the port au port peninsula western newfoundland build ups formed only adjacent to a rocky cliffed shoreline filling narrow submerged palaeovalleys of a well developed late devonian early mississippian karst terrain the nearshore setting was a stressed environment as indicated by 1 the absence of normal marine biota such as corals echinoderms and calcareous algae 2 high numbers and low species diversity of dominant taxa bryozoans brachiopods and microbial communities and 3 abundant plant bearing siliciclastics deposited by the episodic influx of fresh water from adjacent uplands build up development was terminated by meramec time due to falling sea level and seaward progradation of terrestrial sediments preserved structural and constructional fabrics within the build ups include 1 thickets of bryozoans and microbial microthrombolites structurally enhanced by probable marine mg calcite and aragonite cements 2 multigeneration internal sediment and 3 small colonies of serpulid worms and terebratulid brachiopods submarine cementation within the build ups appears to have been abundant during arrested sedimentation whereas intermound sediments carbonates and siliciclastics were lithified only during burial diagenesis shallow burial fracturing stylolitization sulphide and sulphate mineralization and precipitation of phreatic iron poor calcite cement occurred during burial diagenesis codroy build ups are distinct from the more common mississippian mud mounds their internal characteristics and the geologic setting are more like other late palaeozoic and holocene bryozoan rich build ups

sedimentologic role of microproblematica donezella in a lower pennsylvania donezella siliceous sponge dominated carbonate buildup frontal ouachita thrust belt oklahoma u s a abstract the problematic organism donezella emerged worldwide as one of the main carbonate mound builders in the middle carboniferous donezella is composed of thin 70 160 m in diameter bifurcating 45 to 90 degrees tubes microfacies analysis of a donezella buildup from the wapanucka formation frontal ouachita thrust belt oklahoma u s a was undertaken to examine the role of donezella in a carbonate buildup donezella is the predominant biotic component of the wapanucka buildup and the buildup is composed of irregular pockets of boundstone dominated by donezella worm tubes peloids and micritic crusts siliceous sponge spicules less common siliceous sponge boundstone and peloidal wackestone with other bioclasts in the lower part of the buildup donezella colonies are robust convex upward and up to several centimeters in diameter these colonies are composed of delicately branching donezella with an enclosed constructional pore system these robust upward growing donezella structures formed a substrate for other binders therefore it appears that on a microscale donezella together with siliceous sponges and worm tubes played the role of a constructor donezella occurs as a long semicontinuous row of thalli when encrusting other framework grains and encrusts siliceous sponges donezella colonies corals and worm tubes thus it also acted as a member of the binder guild deciphering these various roles of donezella is a crucial first step toward documenting a possible spectrum of donezella dominated lithologies that constitute key elements in carbonate buildups in the early to middle pennsylvanian

new architectures of deep water carbonate buildups evolution of mud mounds into mud ridges middle devonian algerian sahara spectacular totally exhumed carbonate mud buildups of givetian age can be found in the southern ahnet basin of the central sahara their geometries range from isolated mud mounds to mud ridges up to 8 km long the latter are the result of lateral coalescence of closely spaced individual mounds mounds up to 40 m high and ridges up to 85 m high show original slopes of 25 to 65 frame builders in the massive core of the buildups are restricted to scattered small tabulate and solitary rugose corals the total absence of stromatoporoids colonial rugose corals and algae as well as the lack of debris at the toes of the buildups shows that they were constructed in deep water below the photic zone and storm wave base the arrangement of the buildups in north to northwest trending clusters and ridges suggests that their distribution was controlled by early variscan extensional movements inherited from precambrian patterns

microbiological effects on slope stability an experimental analysis a natural pure quartz sand has been seeded with the bacterium pseudomonas atlantica and the fungus penicillium chrysogenum and angles of avalanche and repose have been measured under water using a laboratory clinometer the lowest angles of avalanche occur in freshly packed clean sediment control with the seeded sediments having higher values among the latter the lowest angles of repose occur in the bacterial seeded sediments and the highest in the fungal seeded sediments the largest differences between the angle of avalanche and angle of repose occur in the bacterial seeded and media control sediments the smallest differences occur in the fungal seeded sediment in most cases the second angle of avalanche is lower than the first angle of avalanche whilst the second angle of repose is higher than the first angle of repose the bacteria bind particles together with their extracellular polymeric material while the fungus binds particles by holding them together with a network of hyphal filaments in the bacterial seeded sediment growth is uniform over the sediment surface in the fungal seeded sediment growth occurs as discrete colonies separated by bare sediment and the fungal hyphae penetrate the sediment to a significant depth on avalanching the fungal colonies move down the slope with the hyphal filaments trailing behind them in the sediment overall both the bacterium and the fungus increase slope stability however the fungal colonies maintain slope stability after avalanching more effectively than does the uniform bacterial growth the results are discussed in relation to the wide range of biological effects that stabilize flat sediments and to laboratory and field studies on the stability of sediment slopes

late devonian early carboniferous deep water coral assemblages and sedimentation on a devonian seamount iberg reef harz mts germany abstract growth of the middle late devonian iberg reef a small atoll in the variscan geosyncline of central europe ceased towards the end of the frasnian during the famennian and dinantian the reef continuously subsided relative to sea level in the latest dinantian the reef was covered by clastics five deep water organism assemblages colonized the famennian dinantian seamount successively they are well comparable to recent organism communities on deep water coral banks in the famennian abundant crinoids and ancillary rugose corals and brachiopods colonized the reef top during the late tournaisian a coral crinoid assemblage established on the reef it developed into a varied fauna of corals crinoids trilobites brachiopods bivalves gastropods and goniatites in the early and middle visean the late visean assemblage was dominated by goniatites and pseudoplanktonic bivalves in the latest visean a monospecific brachiopod fauna and small microbial buildups thrived in extreme environmental conditions on the reef top the skeletal debris of the organisms was eroded post mortem and only accumulated in current protected depressions of the reef surface along with carbonate mud local depressions include hollows on the reef top neptunian dikes and pore space of a breccia that formed due to intensive shattering of the reef top during nearby volcanic activity during most of the famennian and tournaisian there is a hiatus caused by non deposition only reworked famennian and tournaisian conodonts recovered from upper tournaisian middle visean limestones give evidence of marine conditions on top of the reef the sedimentary environment on the drowned atoll compares well to that on recent guyots including hiatuses slow and patchy sedimentation erosion and redeposition both the aftermath of the frasnian famennian extinction that drastically reduced metazoan reef builders and a trend towards lower temperatures in the famennian and dinantian are believed to have prevented the reestablishment of a shallow water reef on the drowning devonian atoll

sedimentation during carbonate ramp to slope evolution in a tectonically active area bowland basin dinantian northern england the bowland basin northern england contains a series of carbonates and terrigenous mudstones deposited during the ivorian to early brigantian two regional depositional environments are indicated by facies and facies associations wackestone packstone and calcarenite facies indicate deposition in a carbonate ramp environment while lime mudstone wackestone calcarenite and limestone breccia conglomerate facies often extensively slumped represent a carbonate slope environment stratigraphic relations suggest that the depositional environment evolved from a ramp into a slope through the dinantian two main sediment sources are indicated by the sequence an extra basinal terrigenous mud source and a supply of carbonate from the margins of the basin deposition from suspension and from sediment gravity flows in situ production and remobilization of sediment during sedimentary sliding were important processes operating within the basin periods of enhanced tectonic activity in the late chadian to early arundian and late asbian to early brigantian are indicated by basin wide horizons of sedimentary slide and mass flow deposits both intervals were marked by a decline in carbonate production resulting from inundation and uplift emergence the first of these intervals separates deposition on a seafloor with gentle topography carbonate ramp from a situation where major lateral thickness and facies variations were present and deposition took place in a carbonate slope environment the second interval marks the end of major carbonate deposition within the bowland basin and the onset of regional terrigenous sedimentation

magnesian calcite cements and their diagenesis dissolution and dolomitization mururoa atoll the most ubiquitous syn sedimentary cements affecting mururoa atoll are composed of magnesian calcite three main types are distinguished fibrous bladed and sparitic on the basis of petrography morphology and mgco3 concentration of the constituting crystals while peloid infills a particular form of hmc chemical precipitation also exist petrographic evidence and isotopic signatures are compatible with marine precipitation mururoa atoll was exposed several times to meteoric diagenesis resulting in varied diagenetic alterations including selective dissolution and partial dolomitization of mg calcite cements these alterations are responsible for substantial modifications of the initial cement fabrics and may introduce unconformities in the diagenetic chronology the first stage of the partial dissolution of mg calcite induces the development of chalky white friable zones within the initially crystalline hard cement layers at ultrascale this is due to the creation of micro voids along the elongate cement fibres advanced dissolution includes total disappearance of cement portions as attested to by large voids within the cement crust and or between superposed cement layers mg calcite dissolution is related to meteoric diagenesis during periods of quaternary exposure the creation of voids within mg calcite layers is due to the mechanical removal of previously altered calcium carbonate a process suggesting marine or non marine water flow probably in the vadose environment selective dolomitization of mururoa cements involves alternations of calcite and dolomite which form successive cement like rinds within primary cavities at mururoa these alternations are the result of selective dolomitization of the pre existing mg calcite cements rather than successive precipitation of calcite and dolomite selective dolomitization of mg calcite cements at mururoa indicates that a given cement succession is not necessarily a simple chronological sequence oxygen isotope values of dolomites are enriched in 186 by about 3 pdb within calcite dolomite pseudo alternations the dolomitizing fluid at mururoa seems similar to present marine water although some mixture with meteoric water is probable to favour dissolution associated with dolomitization

vegetation and climate across the early middle pleistocene transition at montalbano jonico southern italy abstract pollen analysis of the montalbano jonico marine succession mjs southern italy provides a continuous vegetational record between 858 ka and 745 13 ka which includes marine isotope stage mis 19 now considered the closest orbital analogue to the holocene a comparison between paleoclimate proxies and global signals of past climate change allows the pollen record to be interpreted in terms of major environmental and climate modifications through mis 21 18 at the orbital and sub orbital scale this is also central to understanding migration patterns of the genus homo interglacials are expressed by the dominance of a mesophilic vegetation typical of a warm temperate and relatively humid climate deciduous quercus dominated fully temperate arboreal forest already devoid of subtropical taxa wooded steppes to steppes expanded during glacials when cold and dry conditions prevailed at mjs the main expansion of temperate forest dominated by broad leaved trees correlates to mis 19 3 whereas the expansion of steppe vegetation during drier conditions marks mis 19 2 directly above the volcaniclastic layer v4 dated at 773 9 1 3 ka more intensively arid conditions developed during mis 20 and mis 18 the pollen temperature index reaches its minimum in uppermost mis 20 in agreement with a significant cold and arid climate phase of wide significance in the north hemisphere as documented by prominent peaks in north atlantic ice rafted debris ird and mediterranean aeolian dust records on the other hand artemisia a significant component of steppes shows its maximum expansion during earlier phases of mis 18 millennial to sub millenial scale climate variability is evidenced by two abrupt short term pollen events within mis 19 3 which show a dominant increase of the cosmopolitan herbaceous component at around 783 54 ka and 774 84 ka respectively the vegetational and inferred climate changes for mis 19 offer two possibilities 1 to investigate the interglacial climate variability and discuss the linkage between climate and changes in geomagnetic field intensity close to the matuyama brunhes paleomagnetic boundary mbb and 2 to help evaluate the role of the mbb in defining the middle pleistocene global boundary stratotype section and point gssp with respect to point 2 a comparison of data at mjs with the pollen record at the nearby and coeval valle di manche section is relevant and evidences the complex response of vegetation to climate events possibly under the effects of both astronomical and local factors

mediterranean climate and oceanography and the periodic development of anoxic events sapropels mediterranean sapropels are layers with elevated organic carbon concentrations that contrast with surrounding sediments which are organic poor sapropels occur quasi periodically in sedimentary sequences of the last 13 5 million years and exist both in the eastern and western mediterranean sub basins they have been the subject of extensive study based on records from both short conventional and long ocean drilling program sediment cores and from a wide variety of uplifted marine sediment sequences on the basin margins and islands previous syntheses in the 1990s and 2000s have discussed how the formation of sapropels is commonly ascribed to deep sea anoxia enhanced export productivity or a combination of these effects however a wealth of new evidence and insights has emerged during the past 1 2 decades based on traditional and novel proxy data as well as modelling which has revealed intriguing new aspects and nuances to the reconstructed conditions hence it is timely to present a new synthesis of current understanding of the processes behind the formation of sapropels which have over the past decade also become a matter of commercial interest in sub salt hydrocarbon exploration in this review we present a context of modern mediterranean climate and oceanography followed by an integrated assessment of the growing understanding of climatological and ocean circulation changes that were associated with sapropel deposition we find that sapropels predominantly formed during astronomically timed episodes when climatic and oceanographic conditions and ecological responses broadly preconditioned the basin for sapropel deposition there is strong correspondence with times of monsoon intensification fuelling runoff from north africa into the mediterranean sea while preconditioning due to sea level rise and regional precipitation and runoff may have contributed as well within these broad episodes of surface buoyancy gain and resultant decline in deep water ventilation specific deposition under dysoxic anoxic or even euxinic conditions occurred within a clearly dynamic system that was characterised by complex spatial and depth dependent patterns gradients with distinct temporal variability on at least decadal to centennial millennial timescales in the final section we evaluate the implications of different modes of deep water removal from silled basins to investigate why sapropels are more frequently and often more intensely developed in the eastern mediterranean than in the western mediterranean

environmental gradients in carbonate sediments and rocks detected by correspondence analysis examples from the recent of norway and the dinantian of southwest england continuous sedimentary gradients are only crudely expressed by standard facies and microfacies methods which are more appropriate to situations where changes occur in relatively discrete steps in carbonate sediments and rocks continuous gradients are often represented by the arrangement of component grain types in a relay that is a systematic shifting of the relative importance of the components subdivision of such relays into micro facies can only be arbitrary correspondence analysis is shown to be useful for detecting isolating and describing relays particular use is made of the arch effect in which samples and components from data sets with a strong unidimensional structure a relay plot in the form of an arch in the plane of the first two factor axes a relay index indicating the position of samples in the relay can be extracted from the analysis and plotted on maps and stratigraphic logs to reveal details of the sedimentary gradient in areal and or stratigraphic context examples are given from i recent shallow marine carbonate sediments from northern norway illustrating a relatively simple depositional setting where surface sediments are viewed in plan and ii lower carboniferous carbonates of southwest england representing a more complex regional study of a particular stratigraphic interval viewed in cross section in both examples the relays can be related to identifiable environmental gradients

the erosion of a thermocline abstract measurements of winds currents and temperature are used to describe the response of the baltic sea to the passage of a sequence of severe storms during the bosex experiment in september 1977 before the onset of the storms the thermocline was at a depth of 25 m the storms deepened the mixed surface layer and redistributed the heat content the storms generated strong inertial waves and vertical current shears which reduced the richardson number within the thermocline to values of 0 25 the non linearity of the inertial waves in this area of variable depth is demonstrated the response of the baltic sea to the meteorological conditions has been modeled numerically by means of a semispectral model the theoretical results are compared to the observations and lead to the same conclusion that the erosion of the thermocline is due to the strong shears of the inertial waves

nonskeletal peloidal precipitates in upper triassic reefs yukon territory canada abstract peloidal sediments and crusts form up to 75 percent of framework limestones in upper triassic reefs in the yukon territory the peloids are spherical to irregular in shape 20 250 m in size and are commonly surrounded by one or more rims of sparry calcite the peloidal sediments occur in confined cavities and in open spaces between reef framebuilders the peloidal crusts generally coat calcareous sponges and tabulozoans internal evidence suggests that the peloids are not detrital grains or fecal pellets and comparisons with mg calcite peloids and peloidal crusts in modern environments suggest that they are precipitates possibly resulting from bacterial activity

a late dinantian peloid cementstone palaeoberesellid buildup from north lancashire england abstract early lithified peloid cementstone palaeoberesellid buildups of a previously undescribed type of late asbian late dinantian age occur near carnforth in north lancashire one of these buildups formed a 1 2 m topographic feature and accreted a total thickness of 11 m before growth stopped the buildup occurs near to a windward shelf margin which is grainstone shoal dominated the buildup and associated sediments comprise three main facies 1 core facies of the palaeoberesellid kamaenella and marine peloidal cements 2 flanking crinoidal bryozoan facies comprising grainstone packstone and conglomeratic textures in which reworked core facies intraclasts are present and 3 shoal lagoonal facies typical of the shelf margin during the asbian kamaenella was a successful coloniser of shallow moderate to low energy shelf environments subject to frequent and rapid sea level changes but it appears to have been only an opportunistic bioherm builder the presence of rounded core facies clasts in the flanking facies indicates that peloidal cementation lithified the buildup these cements probably developed in response to microbial activity in low to moderate energy settings where framebuilder growth and sedimentation rates were low vertical growth of the buildup suggests that deposition kept pace with a rise in relative sea level

aragonite laminae in hot water travertine crusts rapolano terme italy small 5 30 m aggregates of aragonite needles occur in calcite crystal crusts of present day hot water slope travertines at rapolano terme in tuscany italy the aggregates are mainly concentrated in irregular wispy and dark laminae which cross cut calcite crystal feathers to create a pervasive millimetre scale banded appearance in the deposit they also occur less commonly scattered irregularly through the calcite layers the aragonite needle aggregates are in the form of crosses fascicles sheaf shaped bundles or dumbbell shaped rosettes and spherulites locally irregular masses of needles also occur the fascicles rosettes and spherulites have hollow centres which resemble microbial components fungal spores bacterial colonies and pollen suggesting that the aragonite crystals are biotically nucleated the lamination is interpreted to reflect diurnal control stimulation of microbial activity during daylight concentrates cells in laminae and promotes aragonite calcification calcite feather crystals although traversed by the aragonite aggregate laminae have a clear appearance under the light microscope they form more or less continuously through the diurnal cycle by abiotic precipitation the constant association of aragonite with organic nuclei irrespective of whether the latter are in laminae or scattered through the calcite layers supports a biotic control on aragonite formation lamination in pleistocene travertines is superficially similar to that in the present day deposits but is diagenetically altered in the pleistocene deposits the calcite feathers appear dark under the light microscope and the aragonite aggregates where they are not altered to dark calcite are dissolved together with parts of the adjacent spar calcite and therefore appear light coloured

climate variability in se europe since 1450 ad based on a varved sediment record from etoliko lagoon western greece to achieve deeper understanding of climate variability during the last millennium in se europe we report new sedimentological and paleoecological data from etoliko lagoon western greece the record represents the southernmost annually laminated i e varved archive from the balkan peninsula spanning the little ice age allowing insights into critical time intervals of climate instability such as during the maunder and dalton solar minima after developing a continuous ca 500 year long varve chronology high resolution xrf counts stable isotope data measured on ostracod shells palynological including pollen and dinoflagellate cysts and diatom data are used to decipher the season specific climate and ecosystem evolution at etoliko lagoon since 1450 ad our results show that the etoliko varve record became more sensitive to climate change from 1740 ad onwards we attribute this shift to the enhancement of primary productivity within the lagoon which is documented by an up to threefold increase in varve thickness this marked change in the lagoon s ecosystem was caused by i increased terrestrial input of nutrients ii a closer connection to the sea and human eutrophication particularly from 1850 ad onwards and iii increasing summer temperatures integration of our data with those of previously published paleolake sediment records tree ring based precipitation reconstructions simulations of atmospheric circulation and instrumental precipitation data suggests that wet conditions in winter prevailed during 1740 1790 ad whereas dry winters marked the periods 1790 1830 ad dalton minimum and 1830 1930 ad the latter being sporadically interrupted by wet winters this variability in precipitation can be explained by shifts in the large scale atmospheric circulation patterns over the european continent that affected the balkan peninsula e g north atlantic oscillation the transition between dry and wet phases at etoliko points to longitudinal shifts of the precipitation pattern in the balkan peninsula during the little ice age

origin and diagenesis of quaternary travertine shrub fabrics rapolano terme central italy millimetre to centimetre sized arborescent shrub like calcite precipitates are common constituents of hot water travertine shallow pool deposits of quaternary age at rapolano terme tuscany italy in the presently forming travertines the shrubs consist of apparently random associations of i micrite aggregates and ii subhedral to euhedral rhombic spar crystal aggregates in thin section the micrite aggregates appear dark and the spar rhomb aggregates light giving the shrubs a mottled appearance travertines are basically produced by caco3 precipitation due to degassing and evaporation of the spring waters although biological influence may also stimulate precipitation the formation of masses of erect shrubs rather than dense crystal crusts that form on slopes is probably due to limited water flow in the pool environments microbes including bacteria and diatoms are important influences on shrub microfabric and external shape the micrite aggregates are associated with bacteriform bodies seen as tiny rods and spheres the micrite precipitates around these bodies and in adjacent biofilm spar rhomb precipitation appears to be external to the biofilm and may be related to the presence of diatoms which are locally closely associated with the spar rhombs although an essentially inorganic origin particularly for the more euhedral rhombs cannot be ruled out in the older quaternary travertines the original microfabric of the shrubs has been diagenetically altered the original mottled appearance of the shrubs has become uniformly dark and micritic and the evidence for the dual micritic and spar rhomb origin of the shrubs is obscured or destroyed spar micritization of the shrubs is probably due to abiotic and locally biotic dissolution previous studies did not recognize the diagenetic micritization and attributed shrub formation entirely to bacterial activity

microbial micritic carbonates in uppermost permian reefs sichuan basin southern china some similarities with recent travertines the uppermost permian chuenmuping reef formed on the western side of a carbonate platform situated in the eastern sichuan basin southern china contrasts exist between this western patch reef and the better known jiantianba barrier reef complex on the eastern platform margin in western hubei province 250 km to the east microbial micritic carbonates form significant components of the chuenmuping reef limestones three types of fabric can be identified irregular clotted and scalloped laminated an additional cuneiform fabric has been found only in fore reef facies at jiantianba irregular fabric is comparable with the surface of presently forming travertines at rapolano terme central italy which are produced by calcification of cyanobacteria clotted fabric shows indistinct peloids which tend to lack rims and are amalgamated into irregular masses some of which exhibit bush like arrangements where traces of filaments can be seen traces of filaments are observed in both dark and light layers in the scalloped laminated fabric again suggesting a microbial origin cuneiform fabric consists of peloids and filaments and closely resembles deposits in quaternary travertines which may have been caused by bacterial action chuenmuping reef shows a shallowing sequence in normal marine conditions the micritic fabrics interpreted here as microbial occur more commonly in the upper part of the reef this indicates that microbial micrites with a cementing role formed coevally with reef growth within the upper part of the photic zone

was phanerozoic reef history controlled by the distribution of non enzymatically secreted reef carbonates microbial carbonate and biologically induced cement throughout most of the phanerozoic reef rigidity resulted as much or more from early lithification by microbial carbonates and biologically induced cements non enzymatic carbonates than from biological encrustation of or by large enzymatically secreted metazoan skeletons reef framework is divided into four categories 1 skeletal metazoan 2 non skeletal microbialite stromatolite and thrombolite 3 calcimicrobe and 4 biocementstone in which small or delicate organisms serve as scaffolds for rigid cement crusts the last three categories are dominated by non enzymatic carbonates skeletal framework and non skeletal microbialite framework were the most abundant framework types through the phanerozoic the composition and abundance of skeletal framework was controlled largely by mass extinction events but most reefs consisted of both microbialite and skeletal organisms in a mutually beneficial relationship microbialite framework was abundant throughout the palaeozoic and early mesozoic but declined after the jurassic calcimicrobe framework was important during the cambrian early ordovician and devonian and biocementstone framework was important from the late mississippian to the late triassic the phanerozoic history of reefs does not correlate well with the stratigraphic distribution of large skeletal reef builders or with a variety of physicochemical parameters including sea level history wilson cycle or global climate cycles because non enzymatic carbonates result from induction by non obligate calcifiers and not enzymatic precipitation by obligate calcifiers the distribution of these carbonates was controlled to a larger extent by temporal changes in physicochemical parameters affecting the saturation state of sea water with respect to carbonate minerals changes in pco ca mg ratios cation concentrations and temperature may have affected the abundance of non enzymatic carbonates and hence reefs independently from the effects of these same parameters and mass extinction events on skeletal reef biota the decline in abundance of reefal microbialite and absence of calcimicrobe and biocementstone reef framework after the jurassic may be a result of relatively low saturation states of sea water owing to increased removal and sequestration of finite marine carbonate resources by calcareous plankton since the jurassic reef history is difficult to correlate with temporal changes in specific global parameters because these parameters affect skeletal biota and biologically induced carbonate precipitation independently hence reef history was regulated not just by skeletal reef biota but by parameters governing non enzymatic carbonates

the iron isotope composition of microbial carbonate abstract in a comparative study of fossil and recent stromatolites and microbialites we have investigated whether reefal stromatolitic limestones are able to preserve fe isotope compositions that potentially serve as proxies of seawater chemistry at the time of their formation it was found that 56 fe values of archean stromatolites vary between 2 1 and 0 5 devonian and carboniferous microbiallites vary between 0 and 1 and modern microbialites from the great barrier reef show a range from 0 12 to 0 15 five lines of evidence support the possibility that these compositions are potentially pristine 1 fe concentrations and fe isotope ratios are not correlated 2 the concentrations of other elements that are potentially mobile during carbonate diagenesis mg sr do not correlate with 56 fe 3 mn concentrations are inversely correlated with 56 fe which might hint at meteoric alteration however if mn concentrations and fe isotope signatures were pristine features they might serve as a record of the reduction of these two metals in seawater 4 dolomitisation of two devonian limestones does not shift their fe isotope compositions 5 rare earth element and yttrium rey patterns in all limestones are similar to seawater rey sources this suggests that the bulk of the fe in the samples occurs in hydrogenous carbonates not in primary or secondary fe and mn hydroxides because the latter have different rey patterns the modern microbialites are unfractionated in fe relative to crustal rocks thus these hydrogenous precipitates either incorporated unfractionated fe of the ambient seawater composition or they modified the fe composition upon incorporation from a fractionated ocean fe reservoir in either case provided diagenetic alteration has not modified the fe isotope composition in a major way a potential open ocean fe isotope proxy may exist that may allow reconstruction of secular variations in seawater fe isotope compositions our preliminary results suggest that neoarchean microbial carbonate fe may have been lighter than today s microbialite fe and that the carbonates fe isotopes potentially record the efficiency of transition metal reduction in ocean basins through geologic time

depositional controls on lower carboniferous microbial buildups eastern midland valley of scotland in the eastern midland valley of scotland non skeletal carbonate buildup complexes are present in the charlestown main limestone brigantian a thin marine carbonate unit within a lower carboniferous basin fill otherwise dominated by fluvio deltaic sediments and volcanics the buildups are restricted geographically to west lothian and central fife and correspond to an area of reduced subsidence the burntisland high buildup geometry and local facies mosaics reflect the relative water depth and position on the burntisland high that because of its slight topographical relief and more distal position with respect to the location of fluvio deltaic systems became an area of increased carbonate productivity and hence a locus for buildup development away from the burntisland high in the fife midlothian low more monotonous argillaceous limestone facies of low energy and somewhat deeper water aspect accumulated buildup facies contain a diverse marine fauna and are characterized by peloidal clotted and homogeneous micrites interpreted as predominantly microbial in origin two types of buildup complex occur at charlestown vertically stacked tabular banks up to 2 m thick and 100 m wide form the western margin of an asymmetric buildup accumulation east of this margin a complex mosaic of isolated low relief buildups and inter buildup sediments was deposited skeletal sand shoals present within these inter buildup sediments indicate that high energy conditions prevailed during buildup growth in contrast at roscobie inter buildup sediments are of low energy aspect and buildup geometry is domical rather than tabular initiated in slightly deeper and calmer water on the flank of the burntisland high the roscobie buildups up to 15 m thick and 46 m wide accreted vertically rather than laterally as at charlestown and coalesced to form an elongate ridge shaped buildup complex

eemian and holocene sea surface conditions in the southern black sea organic walled dinoflagellate cyst record from core 22 gc3 in order to compare the sea surface conditions in the black sea during the holocene and eemian sapropelic parts of marine core 22 gc3 42 13 53 n 36 29 55 e 838 m water depth were studied for organic walled dinoflagellate cyst content the record shows a change from freshwater brackish assemblages pyxidinopsis psilata spiniferites cruciformis and caspidinium rugosum to more marine assemblages lingulodinium machaerophorum and spiniferites ramosus complex during each interglacial due to the inflow of saline mediterranean water the lacustrine marine transitions in 22 gc3 occurred at 8 3 cal kyr bp during the early holocene and 128 kyr bp during the early eemian slightly later compared to the onset of interglacial conditions on the adjacent land dinoflagellate cyst assemblages reveal higher sea surface salinity 28 30 e g spiniferites pachydermus bitectatodinium tepikiense and spiniferites mirabilis around 126 5 121 kyr bp in comparison to the holocene 15 20 as well as relatively high sea surface temperature e g tuberculodinium vancampoae s pachydermus and s mirabilis especially at 127 6 125 3 kyr bp establishment of high sea surface salinity during the eemian correlates very well with reconstructed relatively high global sea level and is explained as a combined effect of increased mediterranean supply and high temperatures at the beginning of the last interglacial the observed changes in the dinocyst record highlight the importance of nutrients for the composition of the eemian and holocene dinocyst assemblages

mid dinantian waulsortian buildups in the dublin basin ireland abstract the sedimentary history and biostratigraphic setting of waulsortian carbonate buildups of the feltrim limestone formation late courceyan to early chadian within the dublin basin are described there is no unique precursor or successor facies to this formation and the massive waulsortian banks are composed predominantly of peloidal skeletal wackestones and lime mudstones with packstones near the tops of banks these banks form tabular bodies of moderate relief and are interbedded with thin shales and argillaceous crinoidal limestones of inter bank facies in the southwest of the basin inter bank facies are rare and the bank facies have abundant stromatactis cavities and uniquely at roselawn a fauna of rugose corals all buildups in the dublin basin have phase c and or d component assemblages of lees and miller 1985 and are interpreted as accumulating in moderately shallow water depths near or within the photic zone isopachs for the feltrim limestone formation show a ne sw trending axial depocentre where the waulsortian facies is in excess of 400 m thickness deposition appears to have taken place on this double sided ramp in a manner similar to the model of lees 1982 for belgium and southern britain soft sediment deformation such as large scale slumping shale injections and water escape structures not previously recorded from these rocks is widespread the upper surface of the feltrim limestone formation is fissured and displays a prominent erosion surface termination of waulsortian facies deposition and influx of terrigenous sediment was caused by rapid uplift attributed to chadian tectonism however eustatic sea level fall cannot be ruled out as a partial cause of the demise of the waulsortian

pliocene and lower pleistocene vegetation and climate changes at the european scale long pollen records and climatostratigraphy the biostratigraphically calibrated long pollen record at dsdp site 380 southwestern black sea displays a high resolution continuous and contrasted evolution of the vegetation in the region for the entire pliocene and lower pleistocene an accurate correlation is established with the reference global oxygen isotopic curve and with the northwestern european climatostratigraphy climatostratigraphic relationships are evident at the latitudinal and longitudinal scale of europe confirming the extensive strength of pollen analysis as a tool for correlations over large distances

controls of mud mound formation the early devonian kess kess carbonates of the hamar laghdad antiatlas morocco the origin and development of early devonian late pragian to late zlichovian predominantly uppermost zlichovian as indicated by conodont faunas mud mounds of the hamar laghdad area in the eastern antiatlas morocco are controlled by extrinsic and intrinsic factors extrinsic factors include the existence of a paleohigh lochkovian volcaniclastics unidirectional currents and repeated storm events as well as sea level fluctuations intrinsic biologically induced factors are the preferred growth of organisms on the top and the flanks of the mounds because of more favourable ecological conditions and a rapid synsedimentary lithification of the steep mound flanks by interskeletal cementation of auloporid tabulate corals the mounds developed in an epicontinental basin below the wave base but within the range of storms the formation of the mounds started within the uppermost part of the bedded crinoid facies of the kess kess formation with the hydrological accumulation of a bioclastic pile this elevation became settled by crinoids and high diverse tabulate corals producing bioclastic sediment binding activities of the organisms were missing calcareous algae and stromatoporoids are completely absent baffling by thamnoporid tabulate corals might have occurred locally but was not important for the development of the mounds steep slopes to the north and less steep slopes to the south may be the result of north northwest to south southeast trending currents derived from orientation patterns of orthocone nautiloids in the uppermost beds of the kess kess formation a synsedimentary cementation of the flanks possibly triggered by submarine interskeletal cementation of patchily distributed auloporid colonies protected the bioclastic sediment against redistribution by frequent storms indicated by densely spaced eventstone intervals and partly also by the common stromatactis like structures within the mound facies accumulation of more parautochthonous bioclastic sediment within the mounds as compared to the intermound area therefore is caused by a self sustaining system of hydrologic piling of sediment triggered by storms preferred settlement of organisms upon these piles producing bioclastic sediment and coeval biocementation of the growing mound flanks this model differs from existing mud mound models in the lack or only minor significance of binding and baffling in the lack of mound facies sequences and in the greater importance of extrinsic control factors

late mississippian thrombolite bioherms from the pitkin formation of northern arkansas two types of bioherms occur in the pitkin formation chesterian of northern arkansas they are composed of a complex series of ovoid thrombolite heads intergrown with various other algal and bryozoan biolithites and are distinguished from each other on the basis of geometry and faunal and floral content type i mounds have sharp lateral margins and interfinger with horizontally bedded contemporaneous flanking strata owing to having expanded and contracted in size during upward accretion they are interpreted as having had synoptic relief of 3 m or less during growth type ii mounds occur slightly higher stratigraphically to the east of type i mounds and formed in deeper water farther out on the ozark shelf they are interpreted as having had synoptic relief of 6 m or more during growth their margins are similar to those in type i mounds but owing to higher synoptic relief they interfinger with sediments derived from erosion higher on the mound

do carbonate reefs form due to fluid seepage buried carbonate reefs are favoured hydrocarbon prospecting targets mainly due to their high porosity and potential for containing large quantities of petroleum the question of the true relationship between reef structure and the internally trapped fluids hydrocarbons is here raised as one of cause and effect in other words which came first the hydrocarbons or the carbonate reef itself modern bioherms and seabed carbonate reefs in amongst other locations the north sea and the gulf of mexico are shown to form in close association with active hydrocarbon seepages mainly based on results from ecological studies at deep ocean vent communities a new model for carbonate reef formation is promoted that such reefs form at locations containing high concentrations of bacteria and other microorganisms suspended in the water column as a result of seeping fluids solutions and gases that provide some of the energy basis and carbon source for ecosystems independently of photosynthesis therefore on burial and effective sealing capping these carbonate reefs become hydrocarbon reservoirs trapping and accumulating the very minerals on which they in the first place were dependent

facies geometry and geological significance of late ordovician early caradocian coral bioherms lourdes formation western newfoundland late ordovician coral bioherms in the lourdes formation of western newfoundland exhibit a complex mixing of architectural elements including framework boundstone and suspension deposits the bioherms occur within a narrow 16 m stratigraphic interval and a prominent unconformity truncates the interval of bioherm growth and tops of many of the bioherms the buildups developed along a carbonate ramp they occur isolated and in groups individuals in groups are aligned in parallel orientation the sizes of the bioherms range from small 50 100 cm coral piles to columnar and dome shaped masses 1 15 m however topographic relief was never more than 1 m bioherm construction reflects i stacking of the tabulate coral labyrinthites chidlensis and less common stromatoporoids ii accumulation of microbial stromatoporoid boundstone and suspension deposits within shelter cavities between corals and iii detrital bioherm flank skeletal grainstone beds trypanites borings are common in the tops of coral heads the bioherms exhibit three growth development stages i seafloor stabilization wherein rare abraded coral colonies lie scattered within pelmatozoan skeletal grainstone lenses ii colonization wherein corals l chidlensis rare stromatoporoids labechia sp and other biota bryozoans produced a bioherm overlying the basal sediment base and iii diversification which is marked by a more diverse range of fauna and flora as well as occurrence of shelter cavity deposits the diversification stage usually makes up more than 70 of a bioherm structure and in some defines multiple periods of start up and shut down of bioherm growth the latter is defined by bored omission surfaces and or deposition of inter bioherm sediment the lourdes bioherms have a similar ecological structure biotic diversity and depositional environment to patch reefs in the equivalent carters limestone in tennessee the mixture of coral stacking and boundstone as architectural elements identify an early palaeozoic transition of reef design development along shallow water platforms that began to displace the muddy boundstone bafflestone carbonate buildups more typical of the early and middle ordovician time

probable influence of early carboniferous tournaisian early visean geography on the development of waulsortian and waulsortian like mounds all of the known tournaisian early visean ca 360 348 ma age carbonate mud mounds waulsortian and waulsortian like mounds developed in low paleolatitudes on the southern shelf margin of laurussia and in the laurussian interior seaway the tournaisian early visean geography probably prevented hurricanes tropical storms and winter storms from crossing the shelf margin or interior seaway where these mounds developed implications of the lack of storm energy on mound development are discussed

the anatomy of a deep water mud mound complex to the southwest of the dinantian platform in derbyshire uk an elongate waulsortian mud mound complex developed at dovedale on a ramp to the southwest of a developing carbonate platform in derbyshire during chadian early visean times the complex occupied an area of approximately 6 km2 and grew to a maximum relief of 80 m with longitudinal and transverse valleys developed near the southern margin five mound associated facies have been identified mound core mound flank fine mound flank coarse intermound fine and intermound coarse the mound core facies is a massive skeletal wackestone with comminuted sponge debris foraminifera ostracodes and crinoid debris set in a matrix of clotted micrite the mound flank sediments display moderately inclined bedding surfaces while the mound flank fine contains sponge debris the mound flank coarse is dominated by articulated crinoid columnals and includes algal encrusted micritized intraclasts and coarse peloids the well bedded intermound fine facies is bituminous and micritic while the intermound coarse facies is composed of skeletal peloidal intraclast grainstones which locally contain calcified algae although the fauna is diverse the density of colonization by metazoans was low and the supply of macrofossil debris modest the clotted micrite texture is interpreted as the product of micro organisms which precipitated and trapped fine grained sediment the mud mound complex is dominated by the bathymetric assemblages b and c proposed by lees hallet hibo which on their model of the belgian waulsortian indicate depths of between 220 and 280 m intercalation of assemblages b c and c d on the northern margin of the complex is interpreted as the result of local storm disturbance a deep water drift is postulated to explain the nw se alignment of the complex which probably fitted the export model of bosence rowlands quine beneath the sediment surface phreatic flow eroded unlithified sediments and developed interconnected cavities which were filled by cement and sediment relatively eariy mound instability triggered the opening of fissures which filled with crinoid debris peloids indurated lithoclasts and micrite

late holocene evolution of the east eliki fault gulf of corinth central greece abstract trench stratigraphy and morphotectonic analysis was used to examine the recent evolution of the helike eliki plain and eliki fault the entire alluvial plain of the kerynites and vouraikos rivers which cross the eliki fault has subsided at rate of 1 4 mm yr resulting in the burial of the late hellenistic roman occupation horizons under 3 m of fluvial and colluvial sediments along the eastern segment of the eliki fault five trenches have been excavated and their 5000 yr old fluvial and colluvial deposits have been studied in association with the fault strand imprinted on them the kerynites river crosses at high angle the eliki fault and appears to be sensitive in tectonic movements related with the eliki fault sedimentation in the alluvial plain and the fluvial geomorphology of the kerynites river is important for understanding the fault evolution and the burial of the ancient 4th century bc helike city the kerynites river course highlights breaching deformation is the more likely to connect east and west eliki fault segments and that postseismic deformation is a significant mechanism for stress accommodation for part of the west end of the gulf of corinth

pollen evidence for late pliocene early pleistocene vegetation and climate change in the north caucasus north western caspian region abstract pollen and spores have been analysed in deposits of the akchagylian apsheronian in the north western caspian sea region providing a picture of past vegetation and climate change for the late pliocene to early pleistocene on the basis of pollen assemblages in sediment cores and outcrops from the north caucasus the caucasus mineral nyye vody region the tersko sunzhensky area and the foothills of dagestan climatic fluctuations and related changes in vegetation can be recognized for the time from 3 6 to 0 8 ma the lower akchagylian is characterized at first by an open landscape dominated by steppe vegetation in the middle of the lower akchagylian the transgression of the palaeo caspian spread and the treeless landscapes of the earliest akchagylian were replaced by forests with thermophilic relicts during the middle upper akchagylian and apsheronian periods the vegetation cover of the north caucasus gradually changed forests were replaced with steppe and semi desert vegetation in response to episodes of aridification and changes were evident in the structure of the dendroflora the vegetation of the north caucasus shows changes consistent with climatic warming at around 3 2 ma which coincides with a period of warming in the mediterranean and probable represents the mid pliocene warm period

response of the deep ocean internal wave field to traveling midlatitude storms as observed in long term current measurements it has been demonstrated in a recent numerical experiment that double inertial frequency internal waves may play a crucial role in diapycnal mixing processes in the deep ocean with the energy effectively transferred across the internal wave spectrum down to small dissipation scales by nonlinear wave wave interactions hibiya et al 1998 to examine whether or not such double inertial frequency waves are actually generated in the real deep ocean current meter data from long term moorings in the northwest pacific basin are analyzed together with global sea surface wind data by incorporating the wind data into a simple damped slab model predominant inertial currents are shown to be excited in the mixed layer in the northwest pacific basin by traveling midlatitude storms during fall and winter the multiple filter analysis demonstrates that double inertial frequency waves as well as near inertial frequency waves are significantly amplified in the deep ocean internal wave field during the periods strong inertial currents are excited in the mixed layer this suggests that in addition to near inertial frequency waves double inertial frequency waves are actually excited by strong atmospheric disturbances through nonlinear effects as demonstrated in the numerical experiment by niwa and hibiya 1997 double inertial frequency waves thus excited seem to propagate over horizontal distances of the order of 1000 km from their source region while feeding their energy to the local internal wave field consistent with the theoretical prediction based on the magnitudes of group velocity and nonlinear interaction time olbers 1983

alternating diatomaceous and volcaniclastic deposits in milos island greece a contribution to the upper pliocene lower pleistocene stratigraphy of the aegean sea abstract in the northern part of milos island south aegean volcanic arc a stratigraphic succession spanning the late pliocene and early pleistocene exceeds 300 m in thickness and records an alternation of products from submarine volcanic explosive events and fossiliferous both siliceous and carbonate marine sedimentary rocks the accumulation of volcaniclastic deposits took place under subaqueous marine conditions as evidenced by sedimentary features scarce fossil remains and the local presence of burrow traces each major volcanic event was represented by the accumulation of thick bedded pumice and glassy tuffs succeeded by the deposition of marine sediments composed mainly of laminated diatomaceous marlstone and sandy limestone the silica content of the diatomaceous sediments varies from 39 to 70 mostly in the form of biogenic opal a sio 2 al 2 o 3 ratios ranging from 5 to 21 indicate a varied contribution of reworked volcanic grains the sequential arrangement of basinal diatomaceous marlstone and shoreface sandy limestone deposits suggests that the depth of water was not great which is also consistent with features observed in the volcaniclastic deposits calcareous nannofossils from the upper part of the succession of northern milos allow biostratigraphic correlation with nannofossil biozones mnn19a mnn19b across the gelasian calabrian boundary within the early pleistocene a late pliocene piacenzian age has been estimated for the lower part of the section where biozone mnn16a has been documented diatoms planktonic foraminifera and calcareous nannofossil assemblages in the diatomaceous beds point to deposition in a partially closed relatively shallow marine environment in this setting warm and stratified water conditions can be concluded for the piacenzian diatomaceous beds whereas highly productive cool waters are inferred from the gelasian calabrian diatomite

kinematics and ophiolite obduction in the gerania and helicon mountains central greece abstract new structural petrofabric and palaeostress data from the beotia area central greece were used to investigate the tectonic evolution of the suture zone between the external parnassus microplate and internal hellenides pelagonian microplate petrofabric studies of ultramafic rocks were done using conventional u stage analysis and the electron backscatter diffraction ebsd technique detailed structural analysis enabled us to distinguish three main deformation phases that took place from the triassic to the eocene triassic jurassic deformation is related to continental rifting and the progressive formation of an ocean basin ophiolites formed above a westward dipping supra subduction zone ssz in the early late jurassic trench margin collision resulted in the southeastward emplacement of the ophiolite nappe over the pelagonian margin there is also evidence for a north westward thrusting of ophiolitic rocks over the gerania and helicon units during berriasian time this latter tectonic process is closely related to the deposition of beotian flysch into a foreland basin an extensional phase of deformation accompanied by shallow water carbonate sedimentation is documented in the upper cretaceous later during paleocene the area was subjected to a compressional deformation phase characterised by sw directed thrusting and folding as well as ne verging backthrusts and backfolds our proposed geotectonic model suggests the consumption of the ocean between the parnassus and pelagonian microplates this model includes late jurassic eastward ophiolite obduction followed by early cretaceous west directed ophiolite thrusting

freshwater phytoherm reefs the role of biofilms and their bearing on marine reef cementation abstract bioconstructions in carbonate rich freshwater environments generally lead to the development of thick autochthonous tufa deposits in rivers systems these large plant dominated freshwater reef frameworks phytoherms are capable of damming the water courses to produce chains of lakes the resulting phytoherms profoundly modify both local environment and sedimentation patterns in their vicinity and provide a wide range of niches for biota subaqueous fringe cements coat all exposed surfaces they bind the ephemeral plant frameworks providing a cement framework and give rigidity to the bioconstructions peloids are intimately associated with the development of these cements and frequently infil intra reef and framework cavities evidence is presented to suggest that both micritic fringe cements and peloids are the product of biological mediation associated with a procaryote microphyte biofilm and the presence of organic detritus the bladed low magnesium calcite fringes which develop subsequently on the micrite fringes and peloids are possibly slower formed inorganic precipitates the close morphological similarities between phytoherm fringe cements and peloids and their marine reef counterparts are considered to be more than coincidental it is argued that procaryote microphyte biofilms are also responsible for micritic precipitates in the shallow photic marine realm with bacterial films possibly carrying the process deep into unlit reef cavities and conduits and deep water lithoherms

resonant wind driven mixing in the ocean boundary layer abstract the role of resonant wind forcing in the ocean boundary layer was examined using an ocean large eddy simulation les model the model simulates turbulent flow in a box measuring 100 300 m on a side whose top coincides with the ocean surface horizontal boundary conditions are periodic and time dependent wind forcing is applied at the surface two wind forcing scenarios were studied one with resonant winds that is winds that rotated at exactly the inertial frequency at 45 n and a second with off resonance winds from a constant direction the evolution of momentum and temperature for both cases showed that resonant wind forcing produces much stronger surface currents and vertical mixing in comparison to the off resonance case surface wave effects were also examined and found to be of secondary importance relative to the wind forcing the main goal was to quantify the main processes via which kinetic energy input by the wind is converted to potential energy in the form of changes in the

the role of internal erosion and sedimentation in the formation of stromatactis mudstones and associated lithologies abstract a distinctive suite of lithologies occurs in the lower devonian rocky camp mound of eastern victoria lime mudstones contain abundant stromatactis cavities and wackestones contain shelter cavities beneath skeletal constituents together with unsheltered stromatactis cavities irregularly distributed muddy masses occur in grain supported lithologies together with abundant shelter cavities and perched internal sediment these lithologies are completely intergradational and clast content is the principal variant controlling the fabric developed it is proposed that the fabrics in this lithological suite resulted from a process of internal erosion and sedimentation internal reworking which occurred directly below the sediment water interface each stromatactis cavity was subject to erosion of carbonate mud from the roof and redeposition of this material on the floor either directly below the point of erosion or downstream from it in this way cavities migrated upwards leaving a trail of internal sediment beneath in wackestones the migrating cavities were trapped beneath skeletal constituents forming diagenetic shelter cavities the fabrics of grain supported lithologies can be similarly explained a precursor cavity system of organic or inorganic origin is required to initiate the process of internal erosion there is no evidence relating to the origin of this cavity system in the rocky camp mound

late glacial holocene climate variability at the south eastern margin of the aegean sea abstract new micropaleontological palynological and geochemical results from a relatively shallow 500 m sediment core ns 14 in the south eastern aegean sea provide a detailed picture of the regional expression of sapropel s1 formation in this sub basin of the eastern mediterranean sea specifically freshwater input during 10 6 10 0 ka bp has preceded the deposition of s1 further decrease in surface water salinity is evidenced between 10 0 and 8 5 ka bp at the lower part of s1a which in respect to s1b is featured by warmer 19 5 c and more productive surface waters associated with dysoxic bottom conditions a series of coolings detected within the s1 depositional interval may be linked to outbursts of cold northerly air masses and relevant pulses in the deep intermediate water ventilation that caused the s1 interruption between 7 9 and 7 3 ka bp and culminated during the deposition of s1b with the decline of deep chlorophyll maximum dcm at 6 5 ka bp the climate instability and the relevant absence of anoxia weakened the organic matter preservation in the shallow south eastern aegean margin during the s1 times ns 14 record provides evidence for a distinct mid holocene warm up to 25 c and wet phase associated with the deposition of the sapropel like layer smh sapropel mid holocene between 5 4 and 4 3 ka bp the smh layer could represent evidence of on going albeit weak african monsoon forcing only expressed at the south eastern edge of the aegean sea its end is associated with the 4 2 ka bp northern hemisphere mega drought event and the termination of the african humid period at 3 8 ka bp

diversity and factors controlling widespread occurrence of syn rift ladinian microbialites in the western tethys triassic catalan basin ne spain abstract the fault block carbonate ramps of the ladinian middle triassic catalan basin hosted a wide variety of microbial deposits which formed during a syn rift stage stratigraphical and sedimentological analyses of these microbialites allow us to reconstruct two depositional models for such microbial deposits moreover new insights into the interplay between the intrinsic and extrinsic factors that controlled the widespread development of these microbialites are provided stromatolites ooidal muddy microbial laminites and thrombolites were analyzed on the basis of their geometry lamination and textural attributes these microbialites are distributed over two transgressive regressive sequences and coexisted during the fassanian early ladinian regressive stage later stromatolites and ooidal muddy microbial laminites developed during the longobardian late ladinian transgressive stage three types of lamina couplets reflect distinct accretion processes linked to water chemistry sediment supply and hydrodynamic conditions thrombolite textures were produced by accretionary binding and encrusting processes microbially mediated and pervasive cementation the widespread occurrence of microbial deposits is explained as a consequence of a biogeochemical cascade of events e g anoxic dysoxic seawater conditions volcanic activity upwelling of alkaline waters nutrient concentrations and microbial blooms which promoted favorable conditions for microbial growth in the tethys during the ladinian furthermore in the catalan basin syn rift fault induced subsidence and local water energy gradients exerted an essential role in the distribution of the three types of microbialites through space and time thrombolites were prone to grow in the hanging wall block of a half graben subtidal conditions whereas stromatolites and ooidal muddy microbial laminites flourished preferably in a foot wall block setting intertidal shallow subtidal conditions however the fact that thrombolites exhibit abundant botryoidal and isopachous fibrous marine cements corrosion and significant microbial evidence allow us to hypothesize about the relationship between thrombolite occurrence and hydrothermal fault controlled fluid circulation during the triassic rifting the two depositional models here proposed constitute a step forward the understanding of the platform to basin microbialite heterogeneity during the ladinian furthermore this work sheds new light on the mechanisms that likely promoted microbialite development during a period of major ecological restructuration and complex oceanographic conditions

orbital signatures and long term vegetation patterns in the mediterranean abstract an attempt is made to explore the relation between vegetation phases and orbital configurations by comparing long pollen sequences from the mediterranean region and astronomical curves on the basis of their independent chronologies three recurring patterns emerge from this comparison i all intervals with perihelion passage occurring during northern winter were associated with significant contractions of tree populations ii all temperate stage expansions of certain mediterranean vegetation elements occurred when perihelion passage was in summer and iii temperate stage forests reached maximum extent at times of autumn perihelion of these patterns the first corresponds to extreme dry cold episodes culminating at times of march perihelion and the second to maximum summer temperature and evaporation regimes following june perihelion the third associated with the occurrence of september perihelion appears to be more diffuse both in time and space possibly reflecting local variations in hydrological regimes the consistency of at least the first two cases provides some support for the notion that certain recurring vegetation patterns appear to be a result of climate changes linked to specific orbital signatures this could eventually lead to the development of improved terrestrial chronologies through astronomical tuning

mid to late holocene climate evolution of the lake telmen basin north central mongolia based on palynological data abstract palynological and sedimentological data from lake telmen in north central mongolia permit qualitative reconstruction of relative changes in moisture balance throughout the mid to late holocene the climate of the atlantic period 7500 4500 yr ago was relatively arid indicating that lake telmen lay beyond the region of enhanced precipitation delivered by the expanded asian monsoon maximum humidity is recorded between 4500 and 1600 cal yr b p during the subboreal 4500 2500 yr ago and early subatlantic 2500 yr present periods additional humid intervals during the medieval warm epoch 1000 1300 a d or 950 650 ago and the little ice age 1500 1900 a d or 450 50 yr b p demonstrate the lack of long term correlation between temperature and moisture availability in this region a brief aridification centered around 1410 cal yr b p encompasses a decade of cold temperatures and summer frost between a d 536 and 545 1414 1405 yr b p inferred from records of mongolian tree ring widths these data suggest that steppe vegetation of the lake telmen region is sensitive to centennial and decadal scale climatic perturbations

submarine cementation of subsurface pliocene carbonates from the interior of great bahama bank abstract thick intervals of early pliocene subtidal carbonate sediments in the subsurface of northwestern great bahama bank were lithified by submarine cement this cementation subsequently altered by meteoric diagenesis occurred over a broad expanse of the platform interior it shows that submarine cements can lithify thick packstone and grainstone intervals in the interior of large shallow water carbonate shelves and platforms given open circulation moderate to slow sedimentation rates and minimal accumulation of fine sediments a submarine origin for these cements is inferred from direct and circumstantial evidence including 1 regional depositional and diagenetic setting 2 fabric and habit similar to modern submarine cements 3 alteration of cements from mineralogically unstable precursors indicated by a abundant inclusions b relict precursor fabric and commonly e yellowish coloration d undulose crystal extinction and d selective leaching of specific generations of cement or cement types 4 sutured mid pore crystal contacts 5 precipitation coeval with accumulation of internal marine sediment and 6 association with organisms requiring a firm substrate for attachment these considerations may help other workers recognize submarine cements in ancient carbonate rocks

deriving inertial wave characteristics from surface drifter velocities frequency variability in the tropical pacific two techniques have been developed for estimating statistics of inertial oscillations from satellite tracked drifters these techniques overcome the difficulties inherent in estimating such statistics from data dependent upon space coordinates that are a function of time application of these techniques to tropical surface drifter data collected during the norpax epocs and toga programs reveals a latitude dependent statistically significant blue shift of inertial wave frequency the latitudinal dependence of the blue shift is similar to predictions based on global internal wave spectral models with a superposition of frequency shifting due to modification of the effective local inertial frequency by the presence of strongly sheared zonal mean currents within 12 of the equator

palynomorph evidence for tropical climate stability in the gulf of papua papua new guinea over the latest marine transgression and highstand 14 500 years bp to today abstract three sediment cores mv 41 mv 46 and md 50 from the gulf of papua gop papua new guinea were analyzed to assess changes in climatic oceanographic and sedimentological conditions over the last 14 5 kyr palynomorphs which were isolated from sediment core samples were collected at approximately 0 5 m intervals using a strong acid and oxidant md 50 non oxidant mv 41 mv 46 procedure radiocarbon 14c stable isotope geochronology magnetic susceptibility stable isotope analysis md 50 only oxygen 18 18o and carbon 13 13c and clay mineral maturity analysis were also completed for each core palynological data indicate that climatic conditions at sea level have remained warm wet and stable for the past 14 5 kyr with sea surface temperatures in the gop above 14 c potential decreases in vegetative cover marked the younger dryas interval 12 5 11 5 kyr bp as indicated by reduced pollen and spore recovery the end of the latest marine transgression and the subsequent return to eustatic sea level highstand is clearly delineated by increases in marine palynomorph recovery and decreases in mangrove pollen at approximately 5 kyr bp an increase in seasonality and potential el nino southern oscillation variability is observed in md 50 s oxygen isotope results at 5 kyr bp this is not supported by the palynomorph record likely because of the sampling interval and dilution by tropical pollen flora which indicates stable climatic conditions throughout the last 14 5 kyr sediment transport pathways in the gop remained fairly constant throughout the time interval which is supported by the lack of major changes in palynomorph assemblage composition

seven ambiguities in the mediterranean palaeoenvironmental narrative abstract a review of seven outstanding issues on mediterranean palaeoenvironments is presented these are related to the dominant orbital pacing of climate variability the length of the interglacial vegetation succession the influence of the african summer monsoon the seasonality of precipitation during boreal insolation maxima the moisture balance during glacial maxima and the appearance of the mediterranean type climate rhythm and evolution of mediterranean sclerophyllous plants what emerges is that 1 marine 18oplanktonic and sst records show that precession has been a fundamental tempo of mediterranean climate change representing both a low latitude signal runoff from north africa and the direct influence of insolation at mediterranean latitudes but high latitude glacial effects 41 kyr and 100 kyr cycles became superimposed after 2 8 ma sapropel and dust deposition patterns in marine cores reveal that obliquity also has an effect on mediterranean climate through dry wet oscillations which are independent of glacial interglacial variability 2 the temperate part of interglacial vegetation succession has a duration of approximately half a precession cycle this persisted during the interval of obliquity dominated glacial cycles 2 8 1 ma with distinct forest successions following the precessional cycles however these are not always separated by an open vegetation phase because of minimal ice growth producing an impression of a prolonged interglacial forest interval 3 the effect of an enhanced african monsoon during summer insolation maxima has been mainly indirect in terms of nile discharge and runoff along the north african coast leading to increased freshwater input into the mediterranean sea reduced deep water ventilation and sapropel deposition 4 the notion of an accentuated summer rain regime in the northern mediterranean borderlands also contributing to a freshening of the mediterranean sea during boreal insolation maxima is not supported by the available evidence which suggests increased summer aridity 5 recent improvements in chronological precision and data resolution point to an increase in aridity and decreased temperatures during the last glacial maximum 21 2 ka but suggest an increase in effective moisture during the immediately preceding interval of 24 27 ka 6 the mediterranean type climate is not exclusively a post 3 6 ma phenomenon but may have appeared intermittently during the course of the tertiary or before 7 if that is the case then the paradigm that the sclerophyllous evergreen habit represents a pre adaptation to summer drought may need re evaluation

migration origination and extinction of southern hemisphere brachiopods during the middle carboniferous abstract the migration patterns and latitudinal diversity gradients of early and middle carboniferous articulate brachiopod genera from the paleoequatorial zone and southern hemisphere are consistent with the paleoclimatic history of these intervals interpreted from the study of paleoequatorial and northern hemisphere forms both poles apparently became warmer between the middle and late visean south polar cooling associated with glaciation probably began in the late visean at this time 44 of 92 southern hemisphere nonequatorial genera migrated toward the equator the north pole remained warm into the namurian a and cooled during the namurian a to b both northern and southern hemisphere non equatorial genera reacted to high latitude warming with significant increases in percent origination genera from all latitudinal zones responded to high latitude cooling with significant increases in percent extinction during the namurian a to b when both poles were cool a small but statistically significant number of equatorial genera 8 out of 70 migrated out of the equatorial zone into the non equatorial northern hemisphere no similar migration into the southern hemisphere occurred at this time perhaps due to the steep latitudinal temperature gradient several lines of evidence suggest that the latitudinal temperature gradient was steeper in the southern hemisphere than in the northern hemisphere whereas percent origination in northern non equatorial latitudes rose significantly following north polar cooling origination rates in southern non equatorial latitudes did not rise significantly following south polar cooling southern hemisphere non equatorial brachiopods suffered a greater loss of diversity during the interval of polar cooling than either equatorial or northern hemisphere non equatorial brachiopods and there may be namurian tillites within 20 s of the paleoequator veevers and powell 1987

palynological evidence for the astronomical origin of lignite detritus sequence in the middle pleistocene marathousa member megalopolis sw greece the marathousa member middle pleistocene strata in the fluvio lacustrine megalopolis basin southwest greece displays distinct but complicated lithological cycles comprising first order alternation of lignites and detrital muds and second order alternation expressed by frequent intercalation of organic layers palynological evidence indicates that the lithological cycles are driven by the earth s orbital forcing all the lignite seams yield temperate oak forest whereas the detrital beds provide semi arid steppe mainly of artemisia this means that the first order lithological cycle represents the glacial interglacial cycle i e the 100 kyr eccentricity cycle providing a timescale of at least 350 kyr to the marathousa member pollen also detects smaller scale climate fluctuations in many of the subordinate organic layers with the total number of fluctuations being five in a complete lignite detritus couplet this means that the second order lithological cycle reflects the 21 kyr insolation cycle a tentative phase relation between the lithological cycles and the astronomical cycles is shown based on palynostratigraphy and electron spin resonance dating lacustrine environments with increased water tables are implied for the glacial periods sedimentologically in contrast to local swamp vegetation for the interglacial periods the subordinate organic layers were formed under intermediate environments climate water depth etc between full glacials and interglacials 2002 elsevier science b v all rights reserved

the global frasnian famennian kellwasser event during the uppermostp gigas conodont zone p linguiformis zone the stepwise frasnian extinction culminates in the global transgressive regressive frasnian famennian kellwasser event most pelagic organisms of the tropical marine environment are more or less affected by this mass extinction during the early upper devonian extinction rates are clearly related to the deposition of black shales and the storage of a great amount of organic carbon in the shelf sediments contemporaneous positive excursions of the 13c recorded from pelagic limestones of europe and australia prove a worldwide change in the co2 content of the oceans surface water which is in balance with the atmosphere if the climate is controlled by the co2 content of the atmosphere a cyclic operation process might have developed with the succession transgression high organic production deposition of organic carbon lowering of co2 in the atmosphere icehouse effect polar glaciation regression erosion of organic carbon and re supply of co2 to the ocean and atmosphere greenhouse effect deglaciation transgression during the change from a greenhouse to an icehouse effect an overturn of the anoxic oceans probably was one of the causes for the mass killing of low latitude marine organisms

marine peloids a product of bacterially induced precipitation of calcite high magnesian calcite peloids are a common constituent of cemented marine carbonate accumulations they are abundant and well developed within both isolated microcavities and surface crusts the nuclei of marine peloids are composed of fossil bacterial clumps encased within anhedral submicron to micron sized high magnesian calcite crystals the marine peloids are similar to silt sized particles found in travertine deposits that also are composed of fossil bacterial clumps and their surrounding calcite coronas these similarities include size 20 60 mu m a cloudy brown nucleus and rims of clear euhedral crystals in addition previous studies have established the presence of fatty acids of bacterial origin within peloidal deposits and enriched stable isotopic signatures have been interpreted as recording organic fractionation concomitant with calcite precipitation these characteristics all indicate that the nuclei of many peloids originate as calcite precipitates within and around clumps of bacteria and that this precipitation was induced by the vital activity of bacterial colonies

middle cambrian siliceous sponge calcimicrobe buildups daegi formation korea metazoan buildup constituents in the aftermath of the early cambrian extinction event abstract numerous decimetre to metre scale carbonate buildups dominated by siliceous sponges and the calcimicrobe epiphyton are reported from the middle cambrian series 3 daegi formation of korea these siliceous sponge epiphyton buildups consist predominantly of grey micritic boundstones with dark clots and or white clumps the boundstones contain sponge spicule networks interpreted as the calcified remains of siliceous sponges the white clumps and dark clots in the boundstones represent variously preserved epiphyton siliceous sponges form constructional pore space and are commonly encrusted by epiphyton the sponges were probably the primary frame builders providing substrates for the attachment and subsequent growth of epiphyton epiphyton is considered to be a binder when covering the surface of siliceous sponges and a subordinate frame builder when filling depositional voids created by siliceous sponges or growing on top of other epiphyton growth bundles the siliceous sponge epiphyton buildups of the daegi formation show similarities to previously described late cambrian furongian anthaspidellid calcimicrobe buildups from iran and the usa together with recently reported examples from the zhangxia formation of eastern china the sponge epiphyton buildups from korea represent some of the oldest metazoan calcimicrobe buildups after the extinction of most archaeocyaths at the end of the early cambrian series 2 this implies that the incorporation of metazoans in middle cambrian series 3 carbonate buildups occurred much earlier than previously known the buildup forming siliceous sponges described in this study demonstrate that their role in early phanerozoic carbonate buildups has been grossly underestimated

on the influence of a surface coastal front on near inertial wind induced internal wave generation 1 a numerical model is used to examine the wind induced near inertial internal waves in the coastal region in the presence of a surface front initial calculations with the front separating a well mixed coastal region from a stratified offshore area in an infinite sea domain showed that away from the front surface inertial oscillations are dominant near the front on the positive vorticity side superinertial internal waves are generated and propagate offshore in an analogous manner to that found when stratification intersected a coastal boundary however in the case of a coastal boundary the no flow condition at the coast produced inertial oscillations at depth phase shifted by 180 from those at the surface on the negative vorticity side of the front internal waves at the subinertial frequency are trapped between the well mixed region and the front some inertial energy is found at depth in the frontal region although the large scale features of the distribution of inertial energy are independent of vertical eddy viscosity parameterization its magnitude depends upon it in the case of a stratified nearshore region and an offshore front near inertial waves generated at the coast were trapped between the coastal boundary and the front which results in a surface region of enhanced inertial energy this gradually decreased with time as inertial energy diffused to depth this timescale depended upon vertical eddy viscosity magnitude

travertines depositional morphology and the bacterially constructed constituents abstract investigation of travertine accumulations throughout central italy and the west central u s has shown that the carbonate is precipitated in response to both inorganic and organic processes individual deposits range up to 85 m thick and hundreds of square kilometers in areal extent all of the carbonate is low magnesian calcite water chemistry temperature and morphology of the accumulation greatly influence the constituents comprising these deposits harsh environmental situations favor inorganic deposits while increasingly more moderate conditions result in the formation of a greater abundance of organically precipitated material morphological variations of travertine deposits recognized include 1 waterfall or cascade 2 lake fill 3 sloping mound fan or cone 4 terraced ound and 5 fissure ridge gross morphology internal stratification and constituents comprising these deposits vary systematically depending upon the type of accumulation and chemistry of the waters bacterially precipitated calcite forms a large percentage of the carbonate in many travertine accumulations exceeding 90 of the framework grains comprising some of the lake fill deposits bacteria are among the first taxa to inhabit and reproduce in harsh spring environments and produce a variety of fascinating constituents the bacteria are primarily rods generally 0 2 m in diameter and less than 1 0 m in length the rods readily decay resulting in calcite crystals loaded with micropores the basic building block of bacterially constructed travertine is a clump of bacteria averaging 20 m in diameter enclosed in a single crystal of calcite aggregates of these crystals produce a variety of deposits including 1 crudely laminated carbonate mud 2 finely laminat d layers of mud 3 intraclasts 4 foam rock and 5 shrubs the shrubs are most striking commonly forming layers 1 3 cm thick but also producing bacterial pisoids at some locales bacterial stromatolites composed of layers of shrubs alternating with finely laminated layers of bacterial mud comprise essentially the entire deposit the shrub layers are the result of flourishing summer growth of bacteria and furthermore show remarkable daily laminae 0 1 0 5 mm thick the importance of bacteria in the formation of travertine and their universally recognized abundance in modern sediments provides an impetus for a reexamination of the role of bacteria in the origin of other types of ancient deposits

cryptalgal metazoan bioherms of early ordovician age in the st george group western newfoundland bioherms are common in the st george group a sequence of shallow water carbonate rocks deposited on the western continental shelf of iapetus ocean they range from small heads and metre sized mounds to extensive banks and complexes many metres thick and hundreds of metres in lateral extent the cores of these bioherms are principally composed of thrombolites unlaminated branching columnar stromatolites structures quite distinct from laminated stromatolites which are common in intertidal beds associated with thrombolites is a diverse fauna of burrowing invertebrates trilobites nautiloids pelmatozoans brachiopods gastropods rostroconchs and archaeoscyphiid sponges on the basis of framework building components three main bioherm types are distinguished 1 thrombolite mounds 2 thrombolite lichenaria or sponge mounds and 3 thrombolite lichenaria renalcis reef complexes the framework of the last is the most complex with abundant cavities and a demonstrably uneven growth surface of thrombolites corals and free standing renalcis heads walls and roofs some cavities were active sediment conduits while others were protected their roofs draped with renalcis and their walls coated by cryptalgal laminites these bioherms possess the attributes of shallow water ecologic reefs they span a critical time gap in the development of reefs the transition period from algal dominated bioherms of the precambrian and cambrian to the metazoan dominated bioherms of the middle ordovician and remaining phanerozoic

late pliocene northern hemisphere glaciations the continental and marine responses in the central mediterranean abstract detailed pollen analyses and oxygen isotope records of three foraminiferal species globigerina bulloides uvigerina peregrina and cibicides pachyderma from the semaforo and vrica composite sections crotone southern italy have been compared to the global climatic changes depicted by late pliocene early pleistocene foraminiferal 18o records of site 607 in the north atlantic and hole 653a in the tyrrhenian basin west mediterranean major overturns in the mid altitude vegetation are shown near isotopic stages 82 60 58 and 50 at about 2 03 ma 1 6 ma and 1 37 ma according to the raymo et al 1989 and ruddiman et al 1989 timescales at the same dates glacial 18o maxima either became higher or display step increases in the western mediterranean or in the open ocean as well this suggests that size increases of northern hemisphere ice sheets were the driving factor for regional or local marine and continental environmental changes within the mediterranean basin near isotopic stages 62 60 close to the conventional plio pleistocene boundary the climatic conditions severed enough within the mediterranean basin to modify the continental environment as depicted by a sudden increase of artemisia percentages while the first significant southward migration of the north polar front may have been recorded by an influx of left coiling neogloboquadrina pachyderma in the central mediterranean it also appears that boreal guests entered the mediterranean during phases of 18o enrichment of foraminiferal calcite there does not seem to be any discrepancy between the climatic concept of the pliocene pleistocene boundary and its chronostratigraphic definition

peloidal fabrics in upper jurassic reefal limestones weald basin southern england abstract coraliferous limestones from the corallian group upper jurassic of subsurface of the weald basin southern england record the localized development of superimposed patch reefs and banks the reefal limestones exhibit a variety of peloidal fabrics in particular well sorted peloids 10 60 m in diameter with a well developed euhedral rim of fibrous sparry calcite around a micritic anhedral nucleus they occur in confined intraskeletal pores corals molluscs and borings growth cavities between framebuilders and as stromatolitic crusts the peloids in interskeletal cavities and as crusts resemble microbial precipitates and merge into spongiostromate fabrics the distribution of these peloidal fabrics seems to be facies related and is best developed in zones which had relatively low framework growth rates low sedimentation rates and moderate energy levels the peloids are identical in form and occurrence to those in some ancient and quaternary reefs the association of the peloids with stromatolitic coatings and spongiostromate fabrics leads us to interpret the peloids as microbial precipitates either by direct precipitation or by induction the abundance of microbial carbonate in these reefal limestones places them in an intermediate category between frame built reefs and microbial mud mounds

paleoenvironments and growth of early neoproterozoic calcimicrobial reefs platformal little dal group northwestern canada abstract although the calcimicrobial reefs of the basinal little dal group 780 ma are well described little is known about related shallow water facies to the southeast study of these platformal carbonates shows that they represent inner mid and shallow outer ramp zones of a homoclinal storm influenced ramp seven depositional sequences are recognized and correlated with reef bearing strata in the little dal basin and in the shaler supergroup of victoria island reef distribution is distinctly depth partitioned across the little dal ramp inner and mid ramp carbonates contain meter scale mounds patch reefs and biostromes composed of fine grained stromatolites including tungussia baicalia and jurusania these reefs are strikingly similar to those reported from coeval shallow water strata in the shaler supergroup of victoria island and the bitter springs formation of australia multi storey stromatolitic biostrome bioherm complexes greater than 100 m in height seem to be restricted to the mid ramp zone of the little dal ramp and probably reflect high rates of subsidence in the mackenzie basin calcimicrobial reefs occur only in the deepest water strata of the study area associated with outer ramp sediments these reefs contain calcified cyanobacterial filaments in varying degrees of preservation and are petrographically indistinguishable from the kilometre scale basinal calcimicrobial reefs to the northwest the association of calcimicrobial reefs with deep low energy environments suggests initial establishment of reef building calcimicrobes in deep water benthic environments

sulphide mineralised algal breccias in a devonian evaporitic lake system orkney scotland abstract algal breccias in the middle devonian of orkney scotland are mineralised by sphalerite galena and minor celestite and barite the algal sediment is dolomicritic having an internal thrombolitic texture and micrite walled tubules referable to girvanella in some samples the thrombolitic texture is replaced by sulphide minerals and sulphides are attached to organic tissues circumstantial evidence suggests that algal sediment helped to localise sulphide mineralisation possibly by the reductive nature of its organic content the mineralisation was later remobilised into vein deposits the mineralised algal breccias are concentrated within erosive runnels that appear to be aligned normal to the palaeoshoreline of a devonian lacustrine system widespread gypsum pseudomorphs in the lake sediments show that sulphate was readily available for reduction to sulphides

holocene sedimentology and coastal geomorphology of zakynthos island ionian sea a history of a divided mediterranean island the island of zakynthos is one of the most seismically active areas in the mediterranean region because it is located very close to the convergent boundary between the african and eurasian plates its evolution during the holocene has been influenced by tectonic activity catastrophic events and relative sea level changes the scope of the present paper is to examine the holocene palaeoenvironmental changes of the coastal areas of zakynthos island using a multidisciplinary approach combining sedimentological and palaeontological data with 14c and osl dating from four cores of a maximum depth of 30 m the integrated results reveal that sea level and tectonic activity have brought significant modifications in the coastal geomorphic settings of the island during the past 10 000 yr b p the depositional environments and the palaeontological biofacies document four main geomorphological evolutionary stages of the island we identified fully marine and lagoonal deposits with marine influence before 4100 yr b p as well as brackish and freshwater limnic depositional environments around 4100 yr b p to present the interpretation of our data indicates that zakynthos island was separated into two main parts before the middle neolithic period around 7500 yr b p with vasilikos peninsula in the se being isolated from the main island the fact that zakynthos island was a divided mediterranean island for a significant period of time in its prehistory is of great importance to understand better the archaeological landscapes of zakynthos and the other ionian islands

the last 1 35 million years at tenaghi philippon revised chronostratigraphy and long term vegetation trends abstract in addition to being of interest to ancient greek and roman historians the site of philippi ne greece has long been noted in quaternary circles for providing the longest continuous european pollen record spanning the last one million years here the original age model is re evaluated and a new marine terrestrial correlation is proposed an astronomical calibration procedure based on a correspondence between changes in certain vegetation elements and march and june perihelion configurations suggests that the base of the sequence extends back to 1 35 million years ago the revised chronological framework for the tenaghi philippon sequence provides an opportunity to examine the long term behaviour of individual taxa and vegetation trends within the context of global climate changes comparisons reveal a close correspondence between the terrestrial and marine records in terms of orbital and suborbital variability however joint time frequency analysis of the arboreal pollen record shows that the obliquity and eccentricity precession signals persist into the 100 kyr and 41 kyr worlds respectively suggesting the operation of additional climate mechanisms that are independent of high latitude glacial interglacial effects unlike ice core and marine sequences no change in the magnitude of interglacial tree population expansions is observed after the mid brunhes event instead the tenaghi philippon record suggests a major shift in the vegetational composition of interglacials after mis 16 with the establishment of forests of reduced diversity and a modern appearance

vegetation and palaeoclimatic reconstruction of the sousaki basin eastern gulf of corinth greece during the early pleistocene abstract pollen analysis was performed on a lower pleistocene lacustrine sedimentary sequence outcropping in sousaki basin eastern gulf of corinth greece for the first time the palynological assemblages revealed a stable climate with regard to the glacial interglacial climate variability timescale with minor fluctuations in humidity expressed as a relatively wet phase between 13 1 and 19 3 m and some transient increased aridity and humidity events a mediterranean type of vegetation presenting altitudinal zonation was evidenced for the first time in this region pinus and quercus dominate accompanied by other arboreal and non arboreal plants the presence of rare taxa such as taxodiaceae engelhardia liquidambar tsuga and cedrus in very low percentages shows that these taxa remained in the area as relicts sometime between 2 8 and 1 5ma palaeovegetation patterns from the balkan peninsula are lacking especially during the early pleistocene thus in this study a palaeoclimate reconstruction of the early pleistocene sousaki basin based on palynological data is presented accentuating the effect of global climate changes in an area where no other similar records exist

quaternary neotectonics of the south aegean arc abstract the sedimentary and tectonic quaternary evolution of the south aegean arc has been interpreted from 8000 line km of sparker seismic reflection profiles the older parts of basins formed by e w trending faults and accumulated hemipelagic sediment younger active faulting trends nnw in the western part of the arc and ene in the eastern arc the ene trending faults record sinistral strike slip motion broadly parallel to the convergence direction of the aegean anatolian and african plates the north south faults in the western arc are similar to those on land in the south peloponnese chronology is estimated from sedimentation rates in cores and from stacked progradational units on basin margins controlled by eustatic changes in sea level the younger fault pattern developed at 0 6 0 8 ma in the western and central arc but progressively younger in the southeastern part of the arc the older basin fill with e w faults is of early quaternary and pliocene age an older regional unconformity corresponds to an early pleistocene unconformity in the cretan basin particularly in the area east of santorini faulting has resulted in startling changes in palaeogeography such that some areas were late pliocene basins positive features during the pleistocene and then subsided 600 m in the last 0 2 ma such rapid basin inversion resulted in uplift of stratified hemipelagic muds which were deformed by creep or failure so that debris flow deposits accumulated in valleys and ponded basins these fundamental tectonic changes in the past two million years indicate that much of the deformation resulting from the interaction of the eurasian african and anatolian aegean plates is taken up at the southern margin of the aegean microplate probably because subduction of the african plate has slowed as a result of collision of continental crust regional fault patterns are a consequence of spatially varying effects of subduction roll back

vegetation response to upper pliocene glacial interglacial cyclicity in the central mediterranean abstract new detailed pollen analysis of the lower part of the upper pliocene semaforo section crotone italy documents cyclic behavior of vegetation at the beginning of the northern hemisphere glaciations the competition between four vegetation units subtropical humid forest deciduous temperate forest altitudinal coniferous forest and open xeric assemblage probably reflects modifications of vegetation belts at this montane site several increases in herbaceous open vegetation regularly alternate with subtropical humid forest which expresses rapid climatic oscillations the complete temporal succession deciduous forest rich in quercus followed by subtropical humid forest taxodiaceae and cathaya then altitudinal coniferous forest tsuga cedrus abies and picea and finally herbaceous open vegetation graminae compositae and artemisia displays the climatic evolution from warm and humid interglaciation to cold and dry glaciation it also suggests an independent variation of temperature and humidity the two main climatic parameters the vegetation history of southern calabria recorded in the semaforo section have been correlated with the 18o signal established in the atlantic ocean

anatomy of a phylloid algal buildup raytown limestone iola formation pennsylvanian southeast kansas u s a abstract quantitative petrography and temporal spatial relationships of microfacies were used to interpret the depositional history of iola carbonates the paola limestone consisting of four microfacies was deposited on a carbonate ramp and appears to record the maximum transgression within the iola cycle of deposition the overlying raytown limestone was composed of nineteen microfacies arranged in three vertically successive depositional models of similar general configuration these models revealed an initial bioclastic bar evolving upward into a complex bioaccumulated bioconstructed phylloid algal buildup the latter was replaced landward by a siliciclastic distal deltaic environment and graded basinward into upper ramp and lower ramp carbonates locally restricted circulation caused the development of hypersaline conditions the shallowing upward depositional evolution of the phylloid algal buildup consisted of four distinct stages bioclastic hydrodynamic buildup bioaccumulation bioconstruction and bioclastic destruction in storm dominated conditions and intermittent emergence diagenesis of iola microfacies was complex and included marine phreatic 1 bioturbation syneresis micritization micrite lithification and hardground genesis freshwater vadose phreatic undersaturated 1 dissolution of evaporites moldic dissolution collapse brecciation and vadose silt infiltration marine phreatic 2 isopachous rim and botryoidal cementation freshwater phreatic saturated 2 sparite cementation and extensive neomorphism deep burial anhydritization dolomitization stylolitization and silicification and late uplift fracturation and cementation most of the diagenesis was microfacies specific