weichselian and holocene growth of the northern high latitude lofoten contourite drift on the continental slope of norway abstract the weichselian and holocene sediments in the lofoten drift comprise six lithofacies brown sandy mud olive grey mud olive grey laminated mud dark brown mud massive sand and dark grey sandy mud during the weichselian the sediment input to the lofoten drift was from two main sources i e glacimarine sedimentation and ocean current winnowing during the holocene the sediment input was only from winnowing the sediment source area was the voring margin and the continental margin further south the sedimentation rate was 190 cm ka during the late weichelian and 9 cm ka during the holocene the weichselian rates are high compared with the deep sea contourite drifts comprising highly bioturbated sediments and probably explain why bioturbation is less pronounced in these slope drift sediments drifts on glaciated margins as exemplified by the lofoten contourite drift represent areas of high sedimentation rate during glacial maxima sediment input was not restricted to glacial maximum periods for sediments also accumulated during other stadial and interstadial periods

the influence of shelf crossing glaciation on continental slope sedimentation flemish pass eastern canadian continental margin abstract flemish pass is a small perched slope basin seaward of the grand banks on the eastern canadian continental margin glacial ice crossed the grand banks to reach the upper continental slope during some mid to late quaternary glaciations but terminated on the middle shelf 200 km distant at the last glacial maximum this study investigates the effect of ice extent on slope sedimentation processes sediment in flemish pass comprises muds of hemipelagic and proglacial plume origin minor thin bedded turbidite sands and thick bedded mass transport deposits mtds a regional stratigraphy based on 500 km of high resolution seismic profiles and 60 piston cores up to 11 m long was dated using 30 radiocarbon dates the presence of ash zone ii and oxygen isotope stratigraphy this provided stratigraphic control for till tongues in water depths

bed geometry used to test recognition criteria of turbidites and sandy debrites the origin of thick bedded deep water sandstones has generated much controversy in recent years two fundamentally different models have been proposed for beds with the same internal sedimentary characteristics 1 progressive particle settling from the base of a turbulent flow the turbidity current model and 2 en masse freezing of a higher concentration flow the sandy debris flow model these models predict beds with very different geometries turbidites thin gradually whereas debrites have abrupt terminations previous studies have relied upon sedimentary recognition criteria i e sedimentary features in small scale outcrop or core to interpret depositional mechanism in this study depositional mechanism is deduced from bed geometry gained from extensive correlations of individual sandstones preserved in a classic turbidite system marnoso arenacea formation italy this approach allows recognition criteria for turbidites and submarine debrites to be independently tested we find that tabular and tapered sandstones turbidites have distinctly different internal characteristics to beds with abrupt margins debrites turbidites are relatively well sorted often exhibit grading and traction structures and have relatively low matrix mud contents they may also contain massive division floating clasts and inverse grading debrites are moderate to poorly sorted ungraded structureless contain floating clasts and have elevated matrix mud contents these findings have implications for the assessment of submarine gravity flows deposits and reservoir rock characterization

late quaternary stratigraphy and sedimentology of orphan basin implications for meltwater dispersal in the southern labrador sea abstract orphan basin is a deep water basin on the continental margin off newfoundland which throughout the late quaternary received proglacial sediment from local ice that crossed the continental shelf sediment from more distant sources was transported southward in the labrador current as proglacial plumes and in icebergs five sedimentary facies related to glacial processes are distinguished in cores recovered from orphan basin hemipelagic sediment nepheloid layer deposits layered mud beds rich in ice rafted detritus ird sand and mud turbidites and glaciogenic debris flow deposits ird rich beds correspond to periods of intensified iceberg calving and layered mud turbidites and glaciogenic debris flow deposits with glacial meltwater discharge in the late wisconsinan eight periods of meltwater discharge and iceberg calving from the newfoundland ice sheet are interpreted from the sediment facies in orphan basin these discharges coincide with the terminations of the colder periods of the d o cycles recorded in greenland ice cores the oldest minor meltwater event 27 5 28 5 cal ka corresponds to the first late wisconsinan ice advance across the grand banks and ne newfoundland shelf the following three meltwater discharges 23 23 5 23 8 24 5 and 25 27 cal ka deposited sand turbidites and glaciogenic debris flow deposits seaward of trinity trough which was occupied by an ice stream at this time and mud turbidites in the southern part of the basin derived from a mid shelf ice margin on the grand banks four periods of meltwater discharge occurred during the deglaciation and are centered at 15 18 5 19 75 and 20 75 cal ka the youngest is correlated to heinrich event 1 in the literature the 18 5 and 20 75 cal ka events have been recorded in multiple glacial settings in the north atlantic and therefore are interpreted as large scale events of meltwater discharge and iceberg calving but in orphan basin the 19 75 cal ka event is also of similar scale

ore plumes in till glaciers produce boulder trains ore trails and element fans when they override ore bodies or distinctive lithologies their utilization as two dimensional map features has promoted the erroneous perception that maximum concentration of ore in till should be immediately above the ore body available studies of lithic mineral radioactive element and magnetic distributions in till away from known sources indicate that these are frequently three dimensional configurations with shapes resembling smoke plumes drifting laterally the significance for surficial prospecting is that the measured maximum ore concentration may be thus some distance from the ore body frequently 1 10 km and only at depth it extends back to the bedrock source literature review shows that such maximum surficial concentrations well away from sources have been considered anomalies in areas with thin or truncated tills or a high relief bedrock surface the plume may approximate a two dimensional fan or become irregular the e

sea level change along the french mediterranean coast for the past 30 000 years abstract observational evidence for sea level change along the french mediterranean coast has been examined and compared with glacio hydro isostatic models to predict the spatial and temporal patterns of change for about the past 30 000 14c years these predictions are pertinent to discussions of changing ocean volumes during this interval the tectonic stability or otherwise of the coastal areas mantle rheology and the timing of possible human occupation of the now submerged coastal plain and caves such as cosquer cave near marseille the principal results from the analysis are i sea levels along this section of the coast have risen continually since the time of the last glacial maximum lgm and at no time during the holocene has the mean sea level been higher than that of today ii the coast has been tectonically stable between marseille and nice as well as further to the west in roussillon western corsica may have experienced a slow tectonic uplift of between 0 15 0 3 mm year for the past 3000 years but northernmost corsica appears to have been stable during this same interval iii during the lgm sea levels along the coast and immediate off shore areas stood at between 105 115 m below present level the range reflecting the importance of the isostatic contributions during oxygen isotope stage 3 sea levels do not appear to have risen locally above about 60 m iv the rebound parameters describing the mantle rheology and ice sheets required to match the limited observational evidence are consistent with the results of similar analyses carried out for other parts of europe because of its distance from the former northern ice sheets the isostatic factors are particularly sensitive to the value of the lower mantle viscosity v the model predictions for sea level change at the cosquer cave site and for its immediate environments indicate that the cave was last readily accessible before about 10 700 500 14c years about 12 500 500 cal years bp and that the cave entrance was completely flooded by 9000 200 radiocarbon years bp between about 9800 and 10 300 calibrated years bp the cave was above sea level throughout the oxygen isotope stage 3

interbedded late quaternary turbidites and contourites in flemish pass off southeast canada their recognition origin and temporal variation abstract the recognition of contourite and turbidite deposits in deep marine sequences can be challenging as deposits may show similar sedimentary characteristics in flemish pass a small 1100 m deep perched basin along the southeast canadian continental margin both types of deposits occur late quaternary sediments include thin sand layers interbedded with hemipelagic muds the distribution age sedimentary structures and petrology of these sands were used to distinguish between turbidite and contourite deposits which were then characterized by detailed grain size distribution for understanding the conditions leading to deposition of each type seven sediment facies each with a distinctive grain size distribution were recognized they are 1 transported contourites 2 winnowed beds 3 possible jokulhlaup deposits 4 sandy turbidites 5 muddy turbidites 6 hemipelagic sediment and 7 turbidites from well sorted materials sand packets comprised of several stacked turbidite sand beds some with erosive contacts were correlated from the margin to the basin floor showing clear distal fining and creating a small lobe the temporal distribution of the sand beds indicates that most turbidites and contourites were deposited at stadial to interstadial transitions this linkage may be related to variations in the oceanic circulation in flemish pass which winnowed turbidites and may have triggered turbidity currents by moving sands into canyon heads

dansgaard oeschger events is there a signal off the hudson strait ice stream abstract it is generally accepted that the dramatic heinrich h events were principally sourced from the major hudson strait drainage basin of the laurentide ice sheet but it is not known whether the higher frequency dansgaard oeschger d o events have an imprint on sediments deposited during the inter h intervals in ice proximal slope sediments this paper examines this question by an analysis of data from cores on the se baffin slope because the proxies for heinrich events are so massive in scale we removed the major h events h 1 h 2 and h 4 from the records so as to better examine the structure of data in the intervening hemipelagic sediments the period of interest extends between 15 and 40 cal ka interstadial events 2 8 resolution varies with the proxy to between 210 and 700 yrs per sample in hu87033 009 from the lower slope a total of twelve variables for example 18o mass magnetic susceptibility calcite dolomite ratio number of ird 2 mm show a variety of multi millennial oscillations although not all of the same amplitude nor frequency several parameters show little correlation with the gisp2 18o record however a comparison of cie sediment color l from hu87033 009 and hu97048 007 from the upper slope with the gisp2 oxygen isotope record suggests that a substantial correlation exists between the records such changes might be associated with either detrital carbonate content or foraminiferal concentrations analysis suggests however that the first possibility is correct hence suggestive of a glaciological response of the hudson strait ice stream with d o events in the nw labrador sea the sediment records from around h 3 time 30 cal ka show excursions which might be correlative within this event but its amplitude is not unusual compared to events both before and after this reaffirms the argument that h 3 represents a different glaciological response a significant issue discussed in this paper is the inherent ambiguity of correlating records whose errors in the time domain approach that of a dominating periodicity in this case ca 1 5 kyr

the age and chronostratigraphical significance of north atlantic ash zone ii rhyolitic tephra with the geochemical characteristics of north atlantic ash zone naaz ii are described from the giant piston core md95 2006 from the northeast atlantic ocean shard size distribution indicates that the tephra represent a wind sorted primary air fall deposit but with a mode close to 200 m they are too coarse to be air fall deposits at the core site which lies ca 1000 km from the possible tephra source randomly sampled shards reveal a single geochemical population belonging to the icelandic transitional alkali magma series suggesting that they are unlikely to represent ice rafted debris derived from icelandic icebergs the tephra probably represent air fall deposits transported to the core site by sea ice within the northeast atlantic gyre the naaz ii peak coincides with the rapid climate transition cooling at the end of interstadial 15 which can be assigned an age of 53 260 2660 yr bp from direct correlation with the greenland ice core gisp2 record a comparison of the md95 2006 neogloboquadrina pachyderma sinistral relative abundance and gisp2 18o records relative to the naaz ii isochron suggests that this climatic event was synchronous across the north atlantic by direct correlation of interstadial maxima between the two records the gisp2 time scale is transferred to md95 2006 comparison of corrected and calibrated radiocarbon ages derived from monospecific foraminifers with the gisp2 ages at the same stratigraphical horizon suggest major age differences these probably result from large variations in atmospheric 14c concentration and highlight the significant uncertainties associated with radiocarbon calibration during marine isotope stage 3 copyright 2004 john wiley sons ltd

late cenozoic sea level changes and the onset of glaciation impact on continental slope progradation off eastern canada abstract late cenozoic sedimentation from four varied sites on the continental slopes off southeastern canada has been analysed using high resolution airgun multichannel seismic profiles supplemented with some single channel data biostratigraphic ties are available to exploratory wells at three of the sites uniform slow accumulation of hemipelagic sediments was locally terminated by the late miocene sea level lowering which is also reflected in changes in foraminiferan faunas on the continental shelf data are very limited for the early pliocene but suggest a return to slow hemipelagic sedimentation at the beginning of the late pliocene there was a change in sedimentation style marked by a several fold increase in accumulation rates and cutting of slope valleys this late pliocene cutting of slope valleys corresponds to the onset of late cenozoic growth of the laurentian fan and the initiation of turbidite sedimentation on the sohm abyssal plain although it corresponds to a time of sea level lowering the contrast with the late miocene lowstand indicates that there must also have been a change in sediment delivery to the coastline perhaps as a result of increased rainfall or development of valley glaciers high sedimentation rates continued into the early pleistocene but the extent of slope dissection by gullies increased gully cutting episodes alternated with sediment draping episodes throughout the southeastern canadian continental margin there was a change in sedimentation style in the middle pleistocene that resulted from extensive ice sheets crossing the continental shelf and delivering coarse sediment directly to the continental slope

till geochemistry and its implications for mineral exploration southeastern cape breton island nova scotia canada abstract till samples were collected across southeastern cape breton island nova scotia canada at a reconnaissance scale 3 5 km spacing to define regional background levels of base and precious metals in drift and to identify anomalous areas that may indicate mineralization in the underlying bedrock till samples were also collected from detailed sampling grids 100 500 m spacing over three known mineral occurrences to document the nature of glacial dispersal from mineralized sources i e the directions and distance that successive ice flow events have dispersed material and the variation in trace element concentration in till around the bedrock source several areas contain elevated levels of base and precious metals elevated pb and zn concentrations occur along the salmon river valley and are related to glacial dispersal from pb zn mineralization in carboniferous sandstone down northeastward the valley elevated au values in the region up to 78 ppb overlie fourchu group felsic volcanic rocks at a local scale mo and cu have been dispersed at least 500 m to the east of the deep cove pluton by an older eastward ice flow event in the blue mountain area dispersal of sandy metal rich till was mainly northward at stirling exotic red till masks the underlying mineralized bedrock and dilutes the locally derived glacial debris so that there is little geochemical response in the till

contemporary sedimentation in the cocos keeling islands indian ocean interpretation using settling velocity analysis abstract textural parameters of grain size distributions derived from sieve analysis and component analysis have been used to the exclusion of other methods to examine sedimentary processes in modern reef environments however because these methods do not reflect the hydraulic behaviour of bioclastic sediment this study uses settling velocity analysis accounting for grain size density and shape variability and component analysis of separated settling velocity fractions to describe and differentiate bioclastic deposits and infer transport pathways in the cocos keeling islands an indian ocean atoll principal component and cluster analysis of settling 251 samples and component 90 samples characteristics discriminated eight settling velocity and five component classes a derived settling velocity classification reflecting the hydraulic properties of the sediments describes a lagoonward gradient from those with fast settling characteristics on the outer reef flat to those with moderate settling character on sand aprons the active sediment transport system is constrained between these zones component analysis of bulk samples identifies two broad sediment types 1 those with reef derived components found throughout the active transport zone reef flat to sand aprons and 2 those characterised by greater proportions of gastropod and halimeda fragments which are produced and deposited in situ in the lagoon component analysis of settling fractions further resolves details of sediment movement in the active transport zone sediment is transported from the productive reef flat to passage entrances which form initial depositional environments slower settling material is selectively transported from the entrances through the passage conduits to passage exit environments these form the main depositional areas under mean energy conditions during moderate to high energy events sediment is flushed from the passage to sand apron zones with slower settling grains deposited in the deep lagoon sinks results show that settling velocity analysis and component analysis of settling fractions can resolve the nature of sediment transport patterns in reef environments at a much finer scale than studies in which analysis is based on grain size distributions

geological setting and age of the flemish cap granodiorite east of the grand banks of newfoundland flemish cap a large isolated submarine knoll 600 km east of newfoundland consists of a central core of hadrynian rocks and an onlapping sequence of undisturbed to disturbed mesozoic cenozoic sediments the central core of the cap sampled with an electric rock core drill comprises pink fine to medium grained granodiorite dacite and volcanic siltstone the granodiorite samples collected in six out of eight cores are remarkably similar lithologically despite a separation of up to 65 km and probably represent a single pluton the aphanitic dacite and laminated cherty volcanic siltstone have been metamorphosed to subgreenschist prehnite facies but show no evidence of contact metamorphism u pb analyses of coarse and fine zircon fractions from a granodiorite core yielded upper intercepts of 751 and 833 ma respectively although not precise these ages probably represent the age of intrusion sometime in the 750 830 ma range and are older than those reported for similar hadrynian granitic rocks of e

contrasting atmospheric and climate dynamics of the last glacial and holocene periods our present climate is relatively stable compared to that of the last glacial maximum about 20 000 years ago palaeoclimate records obtained from ice cores1 2 and deep sea sediment cores3 for the last glacial period show abrupt temperature changes on timescales of a few hundred years which have been attributed to cycles of ice build up and release associated with large ice sheets dansgaard oeschger cycles and heinrich events 3 and their coupling to ocean circulation4 5 but little is known about the dynamics of the atmosphere during the last glaciation ice sheets influence atmospheric circulation and studies using general circulation models have suggested stormier more variable atmospheric dynamics during the last glacial maximum than today6 9 here we report the results of an analysis of temporal trends over the past 91 000 years in the oxygen isotope signatures of a high resolution ice core record from greenland1 2 this analysis provides direct evidence that atmospheric circulation during the last glaciation was more turbulent than it is today

till geochemical and indicator mineral methods in mineral exploration abstract this paper summarizes advances since 1987 in the application of glacial sediment sampling to mineral exploration drift prospecting in areas affected by continental or alpine glaciation in these exploration programs clastic glacial sediments are tested by geochemical or mineralogical methods to detect dispersal trains of mineral deposit indicators that have been glacially transported from source by mechanical processes in glaciated terrain the key sampling medium till is produced by abrasion crushing and blending of rock debris and recycled sediment followed by down ice dispersal ranging from a few metres to many kilometres as a consequence of the mid 1980s boom in gold exploration the majority of case studies and regional till geochemical surveys published in the past decade deal with this commodity approximately 30 of canada and virtually all of fennoscandia have been covered by regional till geochemical surveys that aid mineral exploration and provide baseline data for environmental agricultural and landuse planning the most profound event in drift prospecting in the last decade however has been the early 1990s explosion in diamond exploration which has dramatically increased the profile of glacial geology and glacial sediment sampling and stimulated changes in sampling and analytical methods

sediment drifts and contourites on the continental margin off northwest britain abstract seismic reflection profiles and short cores from the continental margin off northwest britain have revealed a variety of sediment drift styles and contourite deposits preserved in the northeast rockall trough and faeroe shetland channel the sediment drifts include 1 distinctly mounded elongate drifts both single and multi crested 2 broad sheeted drift forms varying from gently domed to flat lying and 3 isolated patch drifts including moat related drifts fields of sediment waves are locally developed in association with the elongate and gently domed broad sheeted drifts the contrasting styles of the sediment drifts most probably reflect the interaction between a variable bottom current regime and the complex bathymetry of the continental margin the bulk of the mounded gently domed drifts occur in the northeast rockall trough whereas the flat lying sheet form deposits occur in the faeroe shetland channel a much narrower basin which appears to have been an area more of sediment export than drift accumulation patch drifts are present in both basins in the northeast rockall trough the along strike variation from single to multi crested elongate drifts may be a response to bottom current changes influenced by developing drift topography muddy silty muddy and sandy contourites have been recovered in sediment cores from the uppermost parts of the drift sequences on the basis of their glaciomarine origin these mid to high latitude contourites can be referred to collectively as glacigenic contourites both partial and complete contourite sequences are preserved the former consist largely of sandy mid only and top only contourites sandy contourites by their coarse grained nature and their formation under strongest bottom current flows are the most likely to be preserved in the rock record however the very large scale of sediment drifts should be borne in mind with regard to the recognition of fossil contourites in ancient successions

late glacial stratigraphy and history of the gulf of st lawrence discussion the cruise of the c s s hudson in 1990 was a memorable introduction to marine geoscience and north atlantic storms land and sea based geologists were thrown together to link land and sea sedimentary records and get a better understanding of the complex glaciation of atlantic canada atlantic canada is an amalgam of distinctive tectonic terranes where lithic markers can be used to reconstruct glacial flow patterns e g stea and pe piper 1999 provenance analysis can also help to establish correlations between terrestrial and marine stratigraphic records once offshore ice margins and onshore flow lines are linked up former pleistocene glaciers can be modelled stea et al 1998 used these methods to develop an ice advance and retreat history of maritime canada the gulf of st lawrence region was a critical area for the reconstruction and little data was available josenhans and lehman 1999 have made a significant advance in the understanding of the marine record to complete the link with the terrestrial records in the gulf of st lawrence while on the cruise i logged piston cores and examined the lithologies of large 1t iku grab samples from the till units in the gulf of st lawrence that were mapped using high resolution seismic data stea 1991 much of that lithic data was not presented in the summary paper by josenhans and lehman 1999 which is unfortunate because of its important ramifications for ice reconstructions the lithic data and terrestrial radiocarbon dates from the surrounding land areas imply a much greater thickness and extent of late glacial ice than in the model presented by josenhans and lehman 1999 i will briefly review the pebble lithological results addressing the questions of ice flow paths and ice thickness then discuss contradictions between the josenhans lehman model of deglaciation of the gulf of st lawrence and the stea et

contrasting u pb ages from plutons in the bras d or and mira terranes of cape breton island nova scotia u pb dates from zircon titanite and monazite in plutons of the bras d or and mira terranes of southern cape breton island combined with 40ar 39ar and other radiometric age data indicate that th

ice flow history and glacial dispersal patterns southeastern cape breton island nova scotia implications for mineral exploration regional till sampling and stratigraphic studies were completed in southeastern cape breton island nova scotia in 1990 and 1991 to document the directions and distances that successive ice flow events have dispersed material and to document regional till geochemical patterns to aid mineral exploration in this heavily drift covered area three major wisconsinan ice flow events affected the area an early eastward flow followed by a northeastward flow and finally a southward flow the shape and magnitude of dispersal trains in the area are the net result of the three ice flow events which are variable from north to south in the north the northeast ice flow was the dominant erosive and depositional event producing a large northeast trending drumlin field salmon river porphyry clasts and pb and zn rich till from the yava pb mine were dispersed more than 15 km to the northeast in the south eastward ice flow was the dominant erosive and depositional event producing large east trending till ridges dispersal in this area is difficult to detect because exotic red silty till in the giant till ridges masks underlying mineralized bedrock and dilutes the locally derived glacial debris many precious and base metal anomalies and dispersal trains were identified in the regional till samples several of which are related to unknown mineralized sources

contourites and their relevance for mass wasting along the mid norwegian margin between about 12 and 4 3 ma slope parallel bottom currents dominated the neogene sedimentation on the slope of the mid norwegian margin and large scale sediment bodies accumulated to thicknesses up to 1000 m these bedforms are morphologically classified as sheeted and elongated mounded contourite drifts an increase in sediment supply from about 4 to 3 ma due to onshore uplift and glaciation resulted in a massive influx of downslope derived material onto the continental margin only on the voring plateau was contourite sedimentation little affected by this change in sedimentary style during the last 0 5 my contouritic deposits occurred also in the storegga area as 100 150 m thick infill drifts inside the scars of two palaeo slides r and s holocene post slide deposits in the scar of the storegga slide 8 2 ka have the typical morphological features and distribution of contourite drifts with the upslope limit at the lower base of the warm northward flowing north atlantic current at 500 700 m depth and the downslope limit at depths of approximately 1200 m detailed chronostratigraphy of the post slide sediments show relatively constant high sedimentation rates in the order of 1 2 m ky during the last 8000 years this is equivalent to the estimated rates for the older infill drifts the infill drifts consist mainly of clays with silty and sandy lamina and represents marine and glaciomarine conditions the main influence of contourite drifts on slope stability relates to their physical properties forming a more sensitive and brittle deposit than the glacial deposits and their exposure to downslope sedimentation in addition the potential for build up of excess pore pressure due to rapid loading from subsequent glacial depositions their seabed smoothing effect and great lateral extent make the contourite drift deposits particularly important for slope instability in this region

sortable silt and fine sediment size composition slicing parameters for palaeocurrent speed and palaeoceanography fine sediment size 63 ixm is best measured by a sedimentation technique which records the whole size distribution repeated size measurement with intermediate steps of removal of components by dissolution allows inference of the size distribution of the removed component as well as the residue in this way the size of the biogenic and lithogenic noncarbonate fractions can be determined observations of many size distributions suggest a minimum in grain size frequency curves at 8 to 10 ixm the dynamics of sediment erosion deposition and aggregate breakup suggest that fine sediment behavior is dominantly cohesive below 10 1xm grain size and noncohesive above that size thus silt coarser than 10 ixm displays size sorting in response to hydrodynamlc processes and its properties may be used to infer current speed silt that is f mer than 10 ixm behaves in the same way as clay 2 xm useful parameters of the distribution are the 10 63 ixm mean size and the percentage 10 63 ixm in the fine fraction we cannot use size distributions to distinguish the nature of the currents therefore to infer water mass advection speeds i e the mean kinetic energy of the flow ku regions of high eddy kinetic energy ke must be avoided at the present such abyssal regions lie under the high surface k e of major current systems gulf stream kuroshio agulhas antarctic circmpolar current and brazil falldand currents in the argenthe basin this is probably a satisfactory guide for the pleistocene with regard to the carbonate subfraction of the size spectrum size modes due to both cocco iths and foramlnlferal fragments can be recognized and analyzed with the boundary between them again at about 10 lm the flux of less than 10 lm carbonate at pelagic sites above the lysocline is another candidate for a productivity indicator