quaternary sediments and environments on the continental shelf off northern norway abstract based on lithologic palaeontologic and chronostratigraphic investigations of close to 200 gravity cores from troughs deep banks and shallow banks the following late quaternary environment can be outlined in the weichselian deposition of basal tills was followed by deposition of laminated clay in a sea ice environment later a pebbly pelite was deposited in the troughs at the same time as the banks were iceberg ploughed then 13 000 yrs b p a period with incipient winnowing occurred on the deep banks and deposition of sandy pelite took place in the troughs the holocene commenced with a marked environmental change due to intrusion of atlantic water the fauna changed from arctic to boreal high energy winnowing forming a lag deposit took place on the banks and high accumulation rates in the troughs occurred due to the winnowing and sediment influx from the downwasting continental icesheet during the later part of the holocene the winnowing diminished on the deeper banks on the shallow banks and on the shelf break it still prevails and in the troughs calcareous sandy mud is being deposited the surface sediments comprise three main facies bouldery and pebbly sand sand and sandy mud whose distribution mainly depends on the prevailing bottom current regime the composition of the older quaternary sediments is demonstrated by some selected seismic profiles

recent sedimentation and organic carbon burial in a shelf sea the north sea to obtain a carbon budget of the north sea recent sedimentation rates and organic carbon and nitrogen concentrations were determined on 27 box cores from the shallow north sea with a water depth 200 m and a surface area of 500 103 km2 the sedimentation rates in these box cores range from 5 to 35 cm 100 year 1 corg concentrations are 0 05 1 based on these numbers and published data the total amount of corg buried in the shallow north sea is calculated as 1 105 tons year 1 in large parts of the shallow north sea recent sedimentation is nearly absent reworking of relict deposits and partial mixing of these deposits with small amounts of recent fine grained sediments by biological and physical processes and human activities beam trawl fishery result in apparent sedimentation rates which are likely to exceed the real net sedimentation rates considerably the results of this study suggest that the majority of the organic matter is exported from the shelf over the shelf edge into the norwegian sea and into inner shelf deeps skagerrak and norwegian channel coarse grained shelf sediments are only of minor significance for the preservation of organic matter

late quaternary relative sea level changes and the role of glaciation upon continental shelves sea levels of the past 20 kyr are largely determined by the response of the earth to the last ice age consequently sea level indicators are an important source of information about the interaction between cryosphere and hydrosphere and the solid earth based on the material presented at a recent european science foundation conference the present paper pin points some of the topics currently under discussion with respect to sea level evidence found on continental shelves these topics include possible effects of erosion and changes in palaeotidal ranges on indicators of former relative sea levels as well as the problems involved in the determination of palaeo water depth in addition to former sea levels more evidence is being gathered for substantial small scale patterns in the sea level changes at or nearby to the former ice margins these patterns are not reproduced by the available geophysical models which reconcile on first order level only the large scale pattern

hydrogeochemistry of the meade thrust allochthon southeastern idaho u s a and its relevance to stratigraphic and structural groundwater flow control abstract groundwater flow patterns in the folded carbonate sandy and shaly strata of the meade thrust allochthon southeastern idaho u s a were investigated using classical geochemical and isotopic techniques samples from 38 springs and wells were analyzed for major ions 18 o and 2 h and samples from nine springs were analyzed for radiocarbon content and 13 c two major groundwater regimes were identified aquifers of the upper regime tier one are restricted to strata above the phosphoria formation their waters circulate within a few hundred meters of the surface discharge waters are of recent meteoric origin having temperatures of 12 c or less and are generally undersaturated with respect to calcite and have ca mg of 2 5 groundwater flow is generally bedding plane controlled and discharge is along bedding and thrust splay surfaces no indication of significant groundwater circulation between this and underlying strata tier two was found aquifers of the lower regime tier two are restricted to consolidated strata below the phosphoria formation which generally hydraulically isolates them from tier one aquifers groundwater flow in tier two circulates as much as 1900 m below land surface discharge waters have high temperatures up to 26 c stable isotopic data suggest the temperatures have not been elevated above 100 c the discharge waters are saturated with respect to calcite have ca mg of 3 4 and have mean subsurface residence times of 12 500 20 500 yr estimated from radiocarbon data these spring waters are evolving co 2 g possibly from the upward diffusion along faults and have deposited massive amounts of travertine groundwater flow is generally bedding plane controlled and discharge is along deep seated extension and thrust faults based on maximum circulation depth and estimated depth of the meade thrust fault tier two aquifers appear to be contained within the allochthon with no evidence found suggesting they communicate with deeper circulating systems tier three

trace and rare earth element geochemistry in tourmaline and cassiterite from the yunlong tin deposit yunnan china implication for migmatitic hydrothermal fluid evolution and ore genesis abstract yunlong tin deposit is a medial sized hydrothermal deposit in western yunnan province of china this deposit is unusual because the tin mineralization occurs exclusively within the migmatite bodies the genesis of the ore deposit has been hotly debated and various models have been proposed including granite related magmatic hydrothermal and migmatitic hydrothermal origins this paper reports a systematic trace and rare earth elements ree geochemical study in tourmaline and cassiterite from the orebodies and associated migmatites from the yunlong tin deposit tourmaline and cassiterite from this deposit show light ree lree enriched patterns with variable eu and ce anomalies consistent with hydrothermal fluids being derived from local high grade metamorphism and migmatization the data suggest that tourmaline and cassiterite were likely precipitated from migmatitic hydrothermal fluids and indicate that the yunlong tin deposit was probably formed during migmatitic hydrothermal process the high concentrations of transition metals e g sc ti v cr mn and zn in tourmalines are also consistent with this model the high concentrations of sn sr and especially sc v and cr in tourmalines can be used to discriminate tourmaline from barren deposits relative to those associated with economic tin mineralization

initiation of fennoscandian ice sheet retreat during the last deglaciation although the retreat history of the southern margin of the laurentide ice sheet during the last deglaciation has been well known for several decades1 3 and recently supported by evidence from accelerator mass spectrometer ams radiocarbon dating of meltwater in the gulf of mexico4 and the north atlantic subtropical gyre5 the retreat history of the fennoscandian ice sheet before 13kyr ago is still poorly documented from ams 14c dating and isotopic analysis of a rapidly deposited series of supra till sediments in the norwegian channel north sea we find that the southern margin of the fennoscandian ice sheet was in retreat by 15 kyr bp before present approximately 2 000 yr earlier than previously supposed oxygen isotope analyses in the channel sediments confirm earlier evidence from deep norwegian sea sediment cores for low salinity due to ice sheet discharge beginning 15 14 5 kyr bp ref 6 recent recalibration of the 14c timescale indicates that the onset of deglaciation within the norwegian sea occurred during an interval of rapidly increasing summer insolation beginning 18 000 calendar yr bp ref 7 suggesting that ice sheet retreat may have been caused by increasing insolation acting on a particularly climate sensitive ice sheet configuration fresh water and icebergs discharged into the norwegian sea at this time reached the north atlantic and may have contributed to a brief interval of extreme oceanic cooling8 and reduced production of north atlantic deep water9 10 these factors may also have helped to briefly reverse the deglaciation trend erie interstade already underway in north america

complete archive of late turonian to early campanian sedimentary deposition in newly drilled cores from the tarfaya basin sw morocco an expanded succession of organic rich marlstones and limestones deposited in the tarfaya basin provides an outstanding opportunity to closely retrace climate evolution and sea level changes during the cretaceous greenhouse period we present high resolution x ray fluorescence xrf scanning and bulk carbon and oxygen isotope records from two newly drilled sediment cores in the tarfaya atlantic coastal basin which recovered a continuous upper turonian to campanian succession of 290 m thickness the xrf core scanning records reveal three long term oscillations in the abundance of terrigenous elements increase of al ti k si and fe normalized against ca which correspond to progressive transgressive phases followed by rapid regressions during the coniacian and early santonian sea level highstands during this interval corresponding to the coniacian santonian oceanic anoxic event 3 oae 3 are characterized by overall oxygen depleted to anoxic conditions at the seafloor indicated by the high organic carbon content the presence of laminations and low log mn s high log v ca and high log br ca the upper santonian interval marks the transition from anoxic to oxic bottom water conditions prevalent through the early campanian the composite bulk carbonate 13 c curve exhibits strong similarities to the global stacked 13 c reference curve characterized by negative excursions in the early coniacian navigation and east cliff events and late santonian bracketed by the haven brow and buckle events and by positive excursions in the latest turonian hitchwood event middle coniacian wight fall event and at the santonian campanian boundary during the early campanian enhanced accumulation of fine grained carbonate and clay rich hemipelagic sediments increasing bulk carbonate 18 o and low log br ca and log v ca values indicate climate cooling associated with a substantial improvement in bottom water ventilation two long term 13 c cycles of 2 m y duration probably related to variations in earth s orbital eccentricity are associated with the long term cooling trend initiating the campanian maastrichtian climate transition toward a cool greenhouse state

origin and evolution of two contrasting thermal groundwaters co2 rich and alkaline in the jungwon area south korea hydrochemical and isotopic evidence in the jungwon area south korea two contrasting types of deep thermal groundwater around 20 33 c occur together in granite compared to shallow groundwater and surface water thermal groundwaters have significantly lower 18o and d values 1 lower in 18o and negligible tritium content mostly 2 tu suggesting a relatively high age of these waters at least pre thermonuclear period and relatively long subsurface circulation however the hydrochemical evolution yielded two distinct water types co2 rich water pco2 0 1 to 2 atm is characterized by lower ph 5 7 6 4 and higher tds content up to 3300 mg l whereas alkaline water pco2 10 4 1 10 4 6 atm has higher ph 9 1 9 5 and lower tds 254 mg l carbon isotope data indicate that the co2 rich water is influenced by a local supply of deep co2 potentially magmatic which enhanced dissolution of silicate minerals in surrounding rocks and resulted in elevated concentrations of ca2 na mg2 k hco3 and silica under lower ph conditions in contrast the evolution of the alkaline water was characterized by a lesser degree of water rock granite interaction under the negligible inflow of co2 the application of chemical thermometers indicates that the alkaline water represents partially equilibrated waters coming from a geothermal reservoir with a temperature of about 40 c while the immature characteristics of the co2 rich water resulted from the input of co2 in na hco3 waters and subsequent rock leaching

pattern style and timing of british irish ice sheet retreat shetland and northern north sea sector the offshore sector around shetland remains one of the least well studied parts of the former british irish ice sheet with several long standing scientific issues unresolved these key issues include i the dominance of a locally sourced shetland ice cap vs an invasive fennoscandian ice sheet ii the flow configuration and style of glaciation at the last glacial maximum i e terrestrial vs marine glaciation iii the nature of confluence between the british irish and fennoscandian ice sheets iv the cause style and rate of ice sheet separation and v the wider implications of ice sheet uncoupling on the tempo of subsequent deglaciation as part of the britice chrono project we present new geological seabed cores geomorphological marine geophysical and geochronological data from the northernmost sector of the last british irish ice sheet north of 59 5 n to address these questions the study area covers ca 95 000 km2 an area approximately the size of ireland and includes the islands of shetland and the surrounding continental shelf some of the continental slope and the western margin of the norwegian channel we collect and analyse data from onshore in shetland and along key transects offshore to establish the most coherent picture so far of former ice sheet deglaciation in this important sector alongside new seabed mapping and quaternary sediment analysis we use a multi proxy suite of new isotopic age assessments including 32 cosmogenic nuclide exposure ages from glacially transported boulders and 35 radiocarbon dates from deglacial marine sediments to develop a synoptic sector wide reconstruction combining strong onshore and offshore geological evidence with bayesian chronosequence modelling the results show widespread and significant spatial fluctuations in size shape and flow configuration of an ice sheet ice cap centred on or to the east of the orkney shetland platform between 30 and 15 ka bp at its maximum extent ca 26 25 ka bp this ice sheet was coalescent with the fennoscandian ice sheet to the east between 25 and 23 ka bp the ice sheet in this sector underwent a significant size reduction from ca 85 000 to 50 000 km2 accompanied by several ice margin oscillations soon after connection was lost with the fennoscandian ice sheet and a marine corridor opened to the east of shetland this triggered initial and unstable re growth of a glaciologically independent shetland ice cap ca 21 20 ka bp with a strong east west asymmetry with respect to topography ice mass growth was followed by rapid collapse from an area of ca 45 000 km2 to ca 15 000 km2 between 19 and 18 ka bp stabilizing at ca 2000 km2 by 17 ka bp final deglaciation of shetland occurred ca 17 15 ka bp and may have involved one or more subsidiary ice centres on now submerged parts of the continental shelf we suggest that the unusually dynamic behaviour of the northernmost sector of the british irish ice sheet between 21 and 18 ka bp characterized by numerous extensive ice sheet ice mass readvances rapid loss and flow redistributions was driven by significant changes in ice mass geometry ice divide location and calving flux as the glaciologically independent ice cap adjusted to new boundary conditions we propose that this dynamism was forced to a large degree by internal glaciological factors specific to the strongly marine influenced shetland ice cap

the role of diagenetic carbonate concretions in the preservation of the original sedimentary record the upper cretaceous organic rich limestones and marls of the tarfaya basin of southwest morocco contain numerous calcite concretions which formed during early diagenesis relative textural similarities are observed both in the concretions and in the host sediments however the biological content of the concretions is considerably higher than in the host marls and limestones evidence for fossil dissolution in the host marls and the absence of concretions in some fossil rich zones suggest that the difference in fossil abundance between the concretions and host rock is a function of dissolution rather than preferential precipitation in fossil rich areas consequently the carbonate concretions appear to represent the memory of the sediment and allow quantification of the original biological components and are potential tools for estimating the original biological material deposited in the soft sediments

the last glacial maximum in the north sea basin micromorphological evidence of extensive glaciation despite a long history of investigation critical issues regarding the last glacial cycle in northwest europe remain unresolved one of these refers to the extent timing and dynamics of late devensian weichselian glaciation of the north sea basin and whether the british and scandinavian ice sheets were confluent at any time during this period this has been the result of the lack of the detailed sedimentological data required to reconstruct processes and environment of sediments recovered through coring this study presents the results of seismic sedimentological and micromorphological evidence used to reconstruct the depositional processes of regionally extensive seismic units across the north sea basin thin section micromorphology is used here to provide an effective means of discriminating between subglacial and glacimarine sediments from cored samples and deriving process based interpretations from sediment cores on the basis of micromorphology critical formations from the basin have been reinterpreted with consequent stratigraphic implications within the current stratigraphic understanding of the north sea basin a complex reconstruction is suggested with a minimum of three major glacial episodes inferred on at least two occasions during the weichselian devensian the british and scandinavian ice sheets were confluent in the central north sea whilst micromorphology can provide much greater confidence in the interpretation of late quaternary offshore stratigraphic sequences it is noted that a much better geochronology is required to resolve key stratigraphic issues between the onshore and offshore stratigraphic records copyright 2006 john wiley sons ltd

foraminiferal response to sea level change organic flux and oxygen deficiency in the cenomanian of the tarfaya basin southern morocco the mohammed plage coastal section and well s13 in the tarfaya basin southern morocco are key sections to investigate the subsidence of the basin and the cenomanian eustatic sea level history results from a canonical correspondence analysis cca based on benthic foraminiferal assemblage counts and additional proxies percent planktic foraminifera planktic foraminifera morphogroups total organic carbon content toc show a general deepening trend for the investigated sections the most important factor identified in the ordination of species and samples is water depth the cca identifies bolivina anambra globulina lacrima lenticulina spissocostata and spiroplactammina sp as typical shallow water species praebulimina nannina gavelinella dakotensis gavelinella sp saccammina alexanderi and valvulineria lenticula as deep water species and gabonita levis gabonita obesa neobulimina albertensis lingulogavelinella asterigerinoides lenticulina gaultina haplophragmoides gigas haplophragmoides bauchensis and trochammina taylorana as unrestricted or intermediate species the temporal succession of benthic foraminiferal assemblages indicates repeated periods of shallowing within the general deepening trend in particular within the lower portion of the sections rotalipora brotzeni and r reicheli planktic foraminiferal zones restricted assemblages occurred when intensification of the oxygen minimum zone inhibited a diverse benthic community abundant high organic flux indicators at the base of the mohammed plage section indicate that an upwelling cell off northwest africa was already active during the early cenomanian c 2004 elsevier b v all rights reserved

the northern sector of the last british ice sheet maximum extent and demise abstract strongly divided opinion has led to competing apparently contradictory views on the timing extent flow configuration and decay mechanism of the last british ice sheet we review the existing literature and reconcile some of these differences using remarkable new sea bed imagery this bathymetric data provides unprecedented empirical evidence of confluence and subsequent separation of the last british and fennoscandian ice sheets critically it also allows a viable pattern of ice sheet disintegration to be proposed for the first time covering the continental shelf around the northern united kingdom extensive echosounder data reveals striking geomorphic evidence in the form of tunnel valleys and moraines relating to the former british and fennoscandian ice sheets the pattern of tunnel valleys in the northern north sea basin and the presence of large moraines on the west shetland shelf coupled with stratigraphic evidence from the witch ground basin all suggest that at its maximum extent a grounded ice sheet flowed from se to nw across the northern north sea basin terminating at the continental shelf edge the zone of confluence between the british and much larger fennoscandian ice sheets was probably across the northern orkney islands with fast flowing ice in the fair isle channel focusing sediment delivery to the rona and foula wedges this period of maximum confluent glaciation c 30 25 ka bp was followed by a remarkable period of large scale ice sheet re organisation we present evidence suggesting that as sea level rose a large marine embayment opened in the northern north sea basin as far south as the witch ground basin forcing the two ice sheets to decouple rapidly along a north south axis east of shetland as a result both ice sheets rapidly adjusted to new quasi stable margin positions forming a second distinct set of moraines c 24 18 ka bp the lobate overprinted morphology of these moraines on the mid shelf west of orkney and shetland indicates that the re organisation of the british ice sheet was extremely dynamic probably dominated by a series of internally forced readvances critically much of the ice in the low lying north sea basin may have disintegrated catastrophically as decoupling progressed in response to rising sea levels final stage deglaciation was marked by near shore ice streaming and increasing topographic control on ice flow direction punctuated retreat of the british ice sheet continued until c 16 ka bp when following the north atlantic iceberg discharge event heinrich 1 ice was situated at the present day coastline in nw scotland

late devensian to early holocene palaeoenvironmental changes in the viking bank area northern north sea abstract lithological and macrofaunal analysis of vibrocores collected from northwest of the viking bank enables the devensian to holocene strata to be subdivided into eight informal units three of which occur widely in the northern north sea for the viking bank area it is suggested that sea level was more than 100 110 m below that at present between 15 500 and 13 600 bp a time when some parts of the area were dry land and others covered by a shallow high arctic sea sea level may have been even lower more than 140 m below its present level prior to 15 500 bp during the windermere interstadial 13 000 11 000 bp polar water was replaced by atlantic water and the environment was low arctic with a regime of strong tidal currents sea level at approximately 12 000 bp had risen to some 80 100 m below present the loch lomond stadial and early holocene generally were characterised by high arctic followed by boreo arctic to boreal faunas relatively low energy conditions and probably rapidly rising sea level

foraminiferal stratigraphy and environment of late weichselian deposits on the continental shelf off troms northern norway abstract based on the analysis of 8 selected gravity cores from the upper sediment layers of andfjorden and malangsdjupet off northern norway six late weichselian foraminiferal assemblage zones are defined the two oldest assemblage zones 8 and 7 are found in basal tills and contain mixed faunas reworked and deposited by glaciers which reached the shelf edge during the early late weichselian during the earliest phase of the deglaciation of the continental shelf a sparse fauna characterized by buccella frigida zone 6 was deposited zone 5 is dominated by cassidulina laevigata and a fairly high content of planktic foraminifera indicating periods of ice free normal marine surface waters during a glacial advance between 14 000 and 13 000 b p the fauna zone 4 was dominated by elphidium excavatum this fauna reflects near glacial conditions characterized by unstable bottom water conditions the last c 500 years of this period suffered from oxygen depleted bottom waters zone 3 formed between 13 000 and 10 000 b p comprises several species e g cassidulina reniforme nonion barleeanum n labradoricum and cibicides lobatulus during the first 2000 years of this period the fauna reflects a climatic amelioration e g an increase in temperature salinity and current activity probably due to intrusion of atlantic water during the younger dryas zone 3 reflects a climatic deterioration

upper cretaceous palaeoenvironments and benthonic foraminiferal assemblages of potential source rocks from the western african margin central atlantic abstract upper cretaceous benthonic foraminiferal assemblages clay minerals kerogen types and carbonate microfacies are examined in organic rich sediments from western african coastal basins along a latitudinal transect extending from southern morocco to nigeria samples from onshore sections of the tarfaya basin southern morocco from dsdp site 369 from offshore commercial wells on the casamance shelf senegal from dsdp site 367 from odp site 959 and from onshore sections of the benue trough in nigeria are analysed organic rich sediments from these sites are characterized by smectiterich clay mineral assemblages high amounts of marine organic matter and a typical benthonic foraminiferal biofacies dominated by buliminids and bolivinids benthonic foraminifera provide robust proxy indicators of palaeoproductivity and organic matter flux to the seafloor the palaeobiogeographic distribution of benthonic foraminiferal biofacies can be used to identify areas and stratigraphic intervals of hydrocarbon accumulation lower turonian benthonic foraminiferal assemblages exhibit extremely low diversity and are strongly dominated by a gabonita biofacies in contrast to coniacian to maastrichtian assemblages which display higher diversity and contain numerous species of buliminella praebulimina afrobolivina bolivina and orthokarstenia the palaeobathymetric distribution of these high productivity benthonic foraminiferal biofacies reflects the establishment of a productivity driven oxygen minimum zone along the western african shelf associated with an upwelling system active off coastal africa during most of the late cretaceous the extent of the high productivity equatorial belt appears to have shifted latitudinally during the late cretaceous as sea level and circulation patterns changed the zone of highest productivity was broadest in the early turonian when it coincided with the maximum sea level rise and highest atmospheric temperature in the late cretaceous

isoleucine epimerization in quaternary benthonic foraminifera from the norwegian continental shelf a pilot study abstract the extent of epimerization of the protein amino acid l isoleucine has been measured in late quaternary benthonic foraminifera found in cores from two areas of the norwegian continental shelf in order to evaluate the potential of this reaction as a geochronological tool measurements were restricted to monospecific assemblages of cibicides lobatulus and elphidium excavatum from 14 c dated and seismostratigraphic units representing a range of ages by comparing with data on the same species from last interglacial and late glacial sites in western norway miller et al 1983 and with the assumption of similar temperature history for the shelf and coastal areas the absolute ages of the samples are discussed of the nine samples analysed one was of holocene seven of late to middle weichselian and one sample of pre weichselian age from this pilot study we conclude that isoleucine epimerization ratios in benthonic foraminifera provide a reliable index of relative age that can be used to correlate sedimentary units that contain in situ faunas and have similar thermal histories absolute ages of the enclosing sediment can be approximated if suitable well studied calibration sites are available

postglacial depositional environments and sedimentation rates in the norwegian channel off southern norway abstract based on seismic profiles multibeam bathymetry and sediment cores an improved understanding of the deglaciation postglacial history of the southern part of the norwegian channel has been obtained the norwegian channel ice stream started to recede from the shelf edge ca 15 5 ka bp 14 c ages are used throughout approximately 500 1000 years later the ice margin was located east of the deep skagerrak trough at that time the norwegian channel off southern norway had become a large fjord like embayment surrounded by the grounded ice sheet along the northern slope and possibly stagnant ice remnants at the southern flank the norwegian channel off southern norway has been the main sediment trap of the north sea and south of egersund more than 200 m of sediments have been deposited since the start of the deglaciation five seismic units are mapped the oldest unit e occurs in some of the deepest troughs and was deposited immediately after the ice became buoyant unit d is acoustically massive and comprises mass movement deposits in eastern skagerrak and south of egersund unit c in the channel southwest of lista egersund is interpreted to comprise mainly bottom current deposits derived from palaeo rivers e g elben during deposition of unit c ca 14 5 13 ka bp there was limited inflow of atlantic water a change in depositional environment at ca 13 ka bp is related to an increased inflow of saline water and more open hydrographic circulation widely distributed acoustically stratified clays of unit b were deposited ca 13 10 ka bp the holocene unit a shows a depositional pattern broadly similar to that of unit b

large scale development of the mid norwegian shelf over the last three million years and potential for hydrocarbon reservoirs in glacial sediments about 3 million years ago major ice sheets developed over scandinavia and began to deliverlargevolumesofsedimenttothemid norwegianshelf theshelfwasbuilt outina prograd ing pattern towards the west and more than 1000 m of sedimentswas deposited over large areas on the middle outer shelf the dominating large scale depositional pattern is a series of prograding wedges and flat lying sheet like units mainly of glacial origin on top of these units are flat lying till units deposited during the last few glaciations commonly separated from the underlying units by one or several erosional unconformities the lithology of these layers is generally fine grained mainly clay and silt but with sporadic clasts up to boulder size based on regional and detailed bathymetry the ice flow pattern from the last glaciation has been reconstructed on the shelf this involved a very dynamic ice sheet with fast flowing ice streams in the transverse cross shelf troughs separated by more passive ice domes on the intermediate shallow banks theicestreamsappeartofollowthecross shelftroughsfromglaciationtoglaciation butoccasion ally they switched to new flow paths the thick quaternary sediments on the outer part of the mid norwegian shelf represent a challenge for hydrocarbon exploration several large slides have occurred from the shelf break and down the continental slope during the last few years there has been an increased focus on investigating the quaternary succession in order to search for hydrocarbon prospects the potential for finding reservoirs in these sediments is discussed and a few examples of gas discoveries are shown the peon gas field c 250 km 2 is located in the gla cially eroded norwegian channel above the upper regional unconformity uru separating flat lying glaciogenic sediments from dipping sedimentary units the reservoir is developed in glacio fluvial sands a few hundred thousand years old and sealed by flat lying glaciomarine sediments and till units

ocean circulation in the norwegian sea during the last deglaciation isotopic evidence abstract three cores from different depths in the southeastern norwegian sea have been investigated for benthic and planktonic foraminiferal stable isotope records the cores confirm that the last deglaciation occurred in two distinct steps the first step termination ia may have occurred at about 13 000 yr b p while the second step took place shortly after 10 000 yr b p the benthic oxygen isotopes reveal strong influence of deglacial intermediate waters possibly flowing in from the north atlantic with a maximum influence at about 12 000 yr b p both carbon and oxygen isotopic records show that bottom water formation in the norwegian sea was reinitiated after 12 000 yr b p during the first part of the deglaciation the deep water circulation pattern may have been opposite to that of the present the oxygen content in the norwegian sea deep water was low during the last glacial maximum and remained low during the first part of the deglaciation due to low vertical circulation rates the large variations in deep water circulation in the norwegian sea during the last deglaciation may have had important consequences for the interchange of co 2 between ocean and atmosphere

middle and late weichselian devensian glaciation history of south western norway north sea and eastern uk data from eastern england scotland the northern north sea and western norway have been compiled in order to outline our current knowledge of the middle and late weichselian glacial history of this region radiometric dates and their geological context from key sites in the region are presented and discussed based on the available information the following conclusions can be made i prior to 39 cal ka and most likely after ca 50 cal ka scotland and southern norway were extensively glaciated most likely the central north sea was not glaciated at this time and grounded ice did not reach the shelf edge ii during the time interval between 29 and 39 ka periods with ameliorated climate including the alesund sandnes and tolsta interstadials alternated with periods of restricted glaciation in scotland and western norway iii between 29 and 25 ka maximum weichselian glaciation of the region occurred with the fennoscandian and british ice sheets coalescing in the central north sea iv decoupling of the ice sheets had occurred at 25 ka with development of a marine embayment in the northern north sea v between 22 and 19 ka glacial ice expanded westwards from scandinavia onto the north sea plateau in the tampen readvance vi the last major expansion of glacial ice in the offshore areas was between 17 5 and 15 5 ka at this time ice expanded in the north western part of the region onto the maloy plateau from norway and across caithness and orkney and to east of shetland from the moray firth the norwegian channel ice stream ncis which drained major parts of the south western fennoscandian ice sheet was active at several occasions between 29 and 18 ka

description and dating of a submerged beach in the northern north sea abstract an assumed submerged beach bordering the northern part of the north sea plateau towards the norwegian trench at 130 to 160 m waterdepth has previously been described based on interpretation of seismic profiling the seismic unit is parallel to the edge of the plateau for at least 50 km with an eastward dipping bedding soil borings and vibrocorer samples reveal that a stiff to hard clay is overlain by a thin lag deposit of coarse material on the plateau by an up to 40 m thick coarsening upwards sequence of sand and gravel on the upper part of the slope and by gradually finer material further eastwards in deeper water a low sea level is also indicated by the foraminiferal faunas and abundant littoral and aeolian textures on quartz sand grains nine radiocarbon datings of shell material found in sand and gravel from about 1 to 23 m below the sea bed gave ages from 10 800 to 12 500 yrs b p we thus consider the interpretation of the edge of the plateau and the top of the slope as a submerged beach built out in late weichselian time to be confirmed by the sample evidence

ice sheet dynamics on the lofoten vesteralen shelf north norway from late mis 3 to heinrich stadial 1 abstract we present an account of the glacial dynamics from late marine isotope stage mis 3 to the heinrich stadial hs 1 on the lofoten vesteralen margin northern norway this account is based on an analysis of the sedimentary stratigraphy on the upper slope close to the ice sheet grounding line at the continental shelf edge and an analysis of the glacial morphology on the shelf areas our results point to a dynamic ice sheet that waxed and waned on the lofoten vesteralen continental shelf from the late mis 3 through the last glacial maximum lgm and the hs 1 glacigenic debris flows and deposition of laminated diamicts suggest that the ice sheet reached the shelf edge on several occasions these are dated to 25 5 ka bp hs3 between 21 1 and 21 7 ka bp 19 5 ka bp 15 6 ka bp and 14 4 ka bp uncorrected 14c ages a contouritic sorted sand sediment unit that formed in a relatively warm interval during late mis 3 suggests that a strong norwegian atlantic slope current also developed during glacial interstadials implying that the oceanic circulation in the eastern norwegian sea was similar as today the general pattern is that the ice sheet advanced onto the shelf during cold period with little influx of atlantic water to the norwegian sea and that it retreated toward the coast during intervals with higher temperatures and higher influx of warm atlantic water the last ice advance to the edge of the continental shelf occurred during hs 1

petrography and geochemistry of cretaceous to quaternary siliciclastic rocks in the tarfaya basin sw morocco implications for tectonic setting weathering and provenance the petrography heavy mineral analysis major element geochemical compositions and mineral chemistry of early cretaceous to miocene pliocene rocks and recent sediments of the tarfaya basin sw morocco have been studied to reveal their depositional tectonic setting weathering history and provenance bulk sediment compositional and mineral chemical data suggest that these rocks were derived from heterogeneous sources in the reguibat shield west african craton including the mauritanides and the western anti atlas which likely form the basement in this area the early cretaceous sandstones are subarkosic in composition while the miocene pliocene sandstones and the recent sediments from wadis are generally carbonate rich feldspathic or lithic arenites which is also reflected in their major element geochemical compositions the studied samples are characterized by moderate sio2 contents and variable abundances of al2o3 k2o na2o and ferromagnesian elements binary tectonic discrimination diagrams demonstrate that most samples can be characterized as passive continental marginal deposits al2o3 na2o ratios indicate more intense chemical weathering during the early cretaceous and a variable intensity of weathering during the late cretaceous early eocene oligocene early miocene miocene pliocene and recent times moreover weathered marls of the late cretaceous and miocene pliocene horizons also exhibit relatively low but variable intensity of chemical weathering our results indicate that siliciclastics of the early cretaceous were primarily derived from the reguibat shield and the mauritanides in the sw of the basin whereas those of the miocene pliocene had varying sources that probably included western anti atlas ne part of the basin in addition to the reguibat shield and the mauritanides

quaternary stratigraphy of the fladen area central north sea a multidisciplinary study based on detailed stratigraphic investigations on a 200 6m long core bgs borehole no 81 26 from the fladen ground area british sector core material from the sleipner field norwegian sector and shallow seismic profiles between the core sites the following conclusions are drawn 1 the north sea was glaciated sometime during th elaterpart of matuyama reversed period a complete glacial interglacial glacial cycle is recorded in these sediments 2 in a period of marine sedimentation in the middle pleistocene a transgression regression cycle under boreal arctic regime is recorded 3 the fladen area has subsided between 0 9 and 0 6 m ka through the later parts of the quaternary 4 a major glacial event dated at between 130 and 200 ka is recorded as a thick till unit in 81 26 this till which was deposited by ice moving from the southwest scotland probably represents a period when the scandinavian and british ice sheets coalesced in the north sea 5 based on the seismic data and the stratigraphy of the sleipner core an ice free open embayment dry land is favoured for the central north sea during the late weichselian 6 from the amino acid data it is shown that there has been an episodic style of sedimentation through the quaternary 7 of the investigated sediments which span the last 1 mill year ca 98 have been deposited under arctic to boreal arctic conditions

light hydrocarbon gases in shallow sediments in the northern north sea abstract large amounts of data on hydrocarbons in shallow marine sediments 0 6 m below sea floor have been gathered on the norwegian sector in conjunction with surface exploration for petroleum seepage in this paper some results from a re investigation of five surveys is presented the surveys include a total of 2136 shallow cores and cover mainly the stord basin and the viking graben areas offshore western norway adsorbed gases interstitial gases headspace gases grain size and inductively coupled argon plasma elemental data have been investigated table 1 the adsorbed methane ranges from 10 to 5000 ppb it has a uni modal distribution with a median concentration of 504 ppb weight weight the interstitial methane ranges from less than 1 to 500 ppb it has a uni modal distribution with a median concentration of 13 4 ppb there are two classes of headspace methane samples a normal class comprising about 90 of the samples lies in the range 0 1 to 500 ppb with a median of 2 1 ppb the second class lies in the range 500 to more than 100 000 ppb with a median of 6990 ppb the ratio of unsaturated to saturated alkane homologues in the interstitial and headspace gasses is on average equal to one and show positive correlation this rules out thermogenic hydrocarbons as a direct source for the headspace and interstitial gasses the proportion of unsaturated hydrocarbons in the adsorbed gas is much lower the highest interstitial methane contents are found in sediments with high contents of coarse material principal component analysis show that the yields dryness and isotopic composition of adsorbed methane correlate positively with the contents of calcium and strontium the sr ca ratio in the sediments and the proportion of silt size material in the sediments we infer from this that a major component in the adsorbed gas is cogenetic with carbonates in the fine fraction probably resulting from in situ bacterial degradation of organic matter distinct and unquestionable regional headspace gas anomalies are found within the quaternary kleppe senior kse formation of soft silty marine glaciomarine clays outside of kse only background levels of headspace methane is observed some of the most prominent headspace gas anomalies correlate very well with a shallow gas accumulation in a sand body just 10 20 m below sea floor we conclude that gas found at the surface has migrated upwards from this sand body the 1 3 c 1 2 c isotopic ratio for the anomalous methane 51 to 100 ppt and its extremely dry characteristics are typical for a biogenic origin we speculate that shallow biogenic gas may be a secondary form of carbon related to leakage from petroleum deposits at depth in this very prolific area

late weichselian and holocene sediment flux and sedimentation rates in andfjord and vagsfjord north norway late weichselian and holocene sediment flux and sedimentation rates in a continental shelf trough andfjord and its inshore continuation vagsfjord north norway have been analysed the study is based on sediment cores and high resolution acoustic data andfjord was deglaciated between 14 6 and 13 14c kyr bp 17 5 and 15 6 calibrated cal kyr bp the vagsfjord basin before 12 5 14c kyr bp 14 7 cal kyr bp and the heads of the inner tributary fjords about 9 7 14c kyr bp 11 2 cal kyr bp in andfjord five seismostratigraphical units are correlated to a radiocarbon dated lithostratigraphy three seismostratigraphical units are recognised in vagsfjord a total volume of 23 km3 post glacial glacimarine and marine sediments was mapped in the study area of which 80 are of late weichselian origin sedimentation rates in outer andfjord indicate reduced sediment accumulation with increasing distance from the ice margin the late weichselian sediment flux and sedimentation rates are significantly higher in vagsfjord than andfjord basin morphology the position of the ice front and the timing of deglaciation are assumed to be the reasons for this late weichselian sedimentation rates in andfjord and vagsfjord are comparable to modern subpolar glacimarine environments of greenland baffin island and spitsbergen downwasting of the fennoscandian ice sheet and winnowing of the banks owing to the full introduction of the norwegian current caused very high sedimentation rates in parts of the andfjord trough at the late weichselian holocene boundary holocene sediment flux and sedimentation rates in andfjord are about half the amount found in vagsfjord and about one tenth the amount of late weichselian values a strong bottom current system established at the late weichselian holocene boundary caused erosion of the late weichselian sediments and an asymmetric holocene sediment distribution copyright 2002 john wiley sons ltd

landform assemblages and sedimentary processes along the norwegian channel ice stream abstract several regional and detailed bathymetric datasets together with 2d and 3d seismic data are compiled to investigate the landform assemblages and sedimentary processes along the former path of the norwegian channel ice stream ncis at the broad scale the glacial geomorphology and sedimentary architecture reveals three different zones along the ice stream path characterized by 1 glacial erosion in the onset zone and inner shelf area 2 sediment transport through the main trunk of the ice stream across the mid shelf and 3 a zone of deposition towards the outer continental shelf edge along the first 400 km of the ice stream bed outer oslofjord skagerrak stavanger a major overdeepening is associated with suites of crag and tail features at the transition from the crystalline bedrock to the sedimentary bedrock together with evidence of glaciotectonic thrusting in the form of hill hole pairs here we interpret extensive erosion of both sedimentary rocks and quaternary sediments this zone is succeeded by an approximately 400 km long zone through which most of the sediments eroded from the inner shelf were transported rather than being deposited we infer that sediment was transported subglacially and is likely to have been advected downstream by soft sediment deformation the thickness of till of inferred weichselian age generally varies from 0 and 50 m and this zone is characterized by mega scale glacial lineations msgls which we interpret to be formed in a dynamic sedimentary system dominated by high sediment fluxes but with some localized sediment accretion associated with lineations towards the shelf break the north sea fan extends to the deep norwegian sea and reflects massive sedimentation of glacigenic debris onto the continental slope numerous glacigenic debris flows accumulated and constructed a unit up to 400 m thick during the last glacial maximum the presence of these three zones erosion transport deposition is consistent with observations from other palaeo ice streams and their significance arises from their potential to feedback and impact on ice stream dynamics

the distribution of living benthic foraminifera on the continental slope and rise off southwest norway abstract surface sediment samples taken by corer from 45 stations on the norwegian continental margin and in the norway basin have been investigated for their benthic foraminiferal content unlike previous studies the living benthic foraminiferal fauna was differentiated from empty tests comprising the foraminiferal death assemblage factor analysis of both the living and dead faunal data reveals six living species assemblages and five corresponding dead assemblages the additional living assemblage is characterized by the arenaceous speciescribrostomoides subglobosum that dominates between 1400 and 2000 m water depth but is rare in the dead faunal data trifarina angulosa and to a lesser extent cibicides lobatulus characterize the shallowest foraminiferal assemblage from 200 to 600 m water depth where it is associated with strong bottom currents and warm saline atlantic water of the north atlantic drift on the slope between 600 and 1200 m water depth themelonis zaandami species assemblage dominates particularly in areas characterized today by rapid sedimentation of terrigeneous material between 1000 and 1400 m depth where the slope is covered by fine grained organic rich terrigeneous mud the living foraminiferal assemblage is characterized bycassidulina teretis andpullenia bulloides below 1400 m three foraminiferal assemblages are found c subglobosum is found from 1400 to 2000 m cibicidoides wuellerstorfi andepistominella exigua predominantly live from 2000 to 3000 m water depth and below 3000 m oridorsalis umbonatus andtriloculina frigida dominate the fauna all of theelphidium excavatum tests found in this study and thecassidulina reniforme tests found above 500 m water depth were found to be reworked analysis of the sediment grain size distribution and the organic carbon content in surface samples from the deepest stations suggest that the abundance ofc wuellerstorfi ande exigua is positively correlated to relatively coarse caused by planktic foraminifera and organic rich sediments whereas high frequencies ofo umbonatus andt frigida coincide with low organic carbon content we suggest thatc wuellerstorfi is adapted to deep sea environments with relatively high food supply tolerating relatively low interstitial water oxygen content whereaso umbonatus may tolerate lower food supply prefering well oxygenated interstitial waters

palaeomagnetic and ams study of the tarfaya coastal basin morocco an early turonian palaeopole for the african plate abstract an early turonian c 93 ma anoxic cyclic marine deposition is registered in the unfolded outcrops from the tarfaya coastal basin where very high sedimentation rates enable the investigation of past geomagnetic field record at high temporal resolution one hundred and fourteen samples have been sampled along a 10 5 m vertical profile c 200 500 ka of orbital scale forced sedimentation rock magnetic investigations reveal mineralogy principally controlled by diamagnetic and paramagnetic behaviour along with very low concentrations of low coercivity ferromagnetic material which is probably magnetite a well defined magnetic fabric can be seen with the minimum susceptibility axis perpendicular to the foliation plane and magnetic lineation compatible with nw african palaeostress since sedimentation times and or the palaeocurrent associated with upwelling system deposition magnetic signature has the potential for performing reliability checks of reversed tiny wiggles which were found in four samples not considered for the tectonic analysis alternating field demagnetization shows a single stable low coercivity directional component the new palaeopole n 88 plat 64 3 plon 256 3 a 95 2 5 k 38 7 obtained after moderate f 0 8 inclination flattening correction is the first early turonian palaeopole for the nw african craton it can contribute to the 90 ma centred sliding window of the different proposed synthetic apparent polar wander paths

geologic co2 input into groundwater and the atmosphere soda springs id usa abstract a set of co 2 flux geochemical and hydrologic measurement techniques was used to characterize the source of and quantify gaseous and dissolved co 2 discharges from the area of soda springs southeastern idaho an eddy covariance system was deployed for one month near a bubbling spring and measured net co 2 fluxes from 74 to 1147 g m 2 d 1 an inversion of measured eddy covariance co 2 fluxes and corresponding modeled source weight functions mapped the surface co 2 flux distribution within and quantified co 2 emission rate 24 9 t d 1 from a 0 05 km 2 area surrounding the spring soil co 2 fluxes 2 d 1 were measured within a 0 05 km 2 area of diffuse degassing using the accumulation chamber method the estimated co 2 emission rate from this area was 49 t d 1 a carbon mass balance approach was used to estimate dissolved co 2 discharges from contributing sources at nine springs and the soda springs geyser total dissolved inorganic carbon as co 2 discharge for all sampled groundwater features was 57 1 t d 1 of this quantity approximately 3 was derived from biogenic carbon dissolved in infiltrating groundwater 35 was derived from carbonate mineral dissolution within the aquifer s and 62 was derived from deep source s isotopic compositions of helium 1 74 2 37 r a and deeply derived carbon 13 c 3 suggested contribution of volatiles from mantle and carbonate sources assuming that the deeply derived co 2 discharge estimated for sampled groundwater features 35 t d 1 is representative of springs throughout the study area the total rate of deeply derived co 2 input into the groundwater system within this area could be 350 t d 1 similar to co 2 emission rates from a number of quiescent volcanoes

sedimentary processes and depositional environments in glaciated fjord systems evidence from nordfjord norway abstract fjords situated in past or present glacial regimes represent important repositories between land masses source systems and the open oceans sink systems newly collected topas high resolution seismic profiles from the previously glaciated nordfjord system on the west coast of norway reveal sedimentary processes and depositional environments within fjords in more detail than before the seismic data show that the fjord basins are characterised by a well laminated lower unit that is overlain by acoustic transparent lensoidal bodies we infer the lower unit which is up to 350 m thick to be composed of glacimarine sediments the transparent bodies represent up to 0 25 km 3 large slide debrites that comprise 14 c yr bp c 15 000 cal yr bp during the last deglaciation the entire nordfjord system was ice free for a short time period before the 1000 year long younger dryas readvance halted the main fennoscandian deglaciation and over ran the eastern part of nordfjord in contrast to the last glacial maximum we suggest that the sediments in the ice covered fjord basins were preserved during younger dryas the rapid isostatic adjustments accompanying the withdrawal of the younger dryas ice sheet promoted conditions for failures we relate the identified nordfjord slide bodies to this paraglacial environment this implies that the acoustic well laminated glacimarine fjord unit has been deposited in about 2000 yr and that sediment rates as high as 20 cm yr have existed during deposition

organic facies variability and paleoenvironmental changes on the moroccan atlantic coast across the cenomanian turonian oceanic anoxic event oae2 abstract the cenomanian turonian boundary is marked by worldwide paleoenvironmental and paleoceanographical changes that are associated with a perturbation of the global carbon cycle and black shale deposition called the oceanic anoxic event 2 oae2 the objective of this study is to precisely characterize the nature of the organic matter its variability paleoenvironmental significance and the preservation conditions of two areas located along the northwest african shelf where large scale organic carbon burial contributed significantly to the global carbon burial associated with oae2 with these premises an organic petrographic and geochemical approach to the cenomanian turonian record of the moroccan atlantic coast allowed the definition of the variability of the organic facies and the paleoenvironmental characterization of the upper cenomanian lower turonian sediments of the agadir section agadir basin and of the lower turonian record of the amma fatma section tarfaya basin at agadir the marine microplankton dominated assemblages with variable degree of amorphization allowed the characterization of a transgressive regressive cycle during the upper cenomanian followed during the lower turonian by a drowning event with establishment of a deep platform environment under reducing conditions increase in efu efv efmo the base of the succession base of w archaeocretacea biozone and the top of the upper cenomanian are characterized by two sea level lowstands and a high energy oxic environment that culminate in emersion surfaces high efmn and low organic matter preservation the organic facies in the lower turonian of amma fatma is largely dominated by bacterial material probably derived from sulfur bacteria indicating an outer shelf setting with some degree of restriction under euxinic conditions high efmo and high primary productivity high efcu efni efzn differences in terms of the redox conditions between the two basins during the lower turonian were determined with anoxia prevailing at agadir while euxinic conditions are established at tarfaya these are explained by different oceanic circulation patterns with the mixing of tethyan waters at agadir high primary productivity is recorded at both locations possibly promoted by the occurrence of upwelling currents this study further corroborates a delay in the anoxia in agadir that during the isotopic excursion of oae2 only reaches slight dysoxia upper cenomanian and the maintenance of reducing conditions in tarfaya post oae2

recent sediment accumulation organic carbon burial and transport in the northeastern north sea abstract organic carbon and nitrogen and sedimentation rate determinations were made of boxcores from the norwegian channel north sea the geographical distribution of recent sedimentation areas were defined by analysis of published data and 3 5 khz penetrating echo sounder data the annual dry bulk sediment accumulation in the northeastern north sea is established at 74 10 6 tons as the average organic carbon content for the norwegian channel and skagerrak kattegat sediments is 0 6 and 1 8 respectively the organic carbon accumulation rate in the northeastern north sea could be calculated the total organic carbon accumulation in the norwegian channel and skagerrak northern kattegat is 0 17 10 6 tons yr 1 and 0 83 10 6 tons yr 1 respectively less than 10 of this is accounted for by local primary production this means that more than 90 of the organic carbon buried in the sediments of the northeastern north sea must have been supplied from different sources terrigenous sources supply 20 of the organic carbon the remainder is marine organic matter produced elsewhere in the north sea or imported from the atlantic ocean norwegian sea and the baltic sea storm wave and current induced near bottom nepheloid layers are the main likely mechanism to transport fine grained sediments and associated organic matter from the north sea plateau into the kattegat skagerrak and norwegian channel

geometry and genesis of glacigenic debris flows on the north sea fan tobi imagery and deep tow boomer evidence abstract acoustic data have been used to study the upper sequence of glacigenic debris flows gdfs deposited during the last glacial maximum on the north sea fan the presumed gdf release area at the shelf break 450 m water depth exhibits a sequence up to 90 m thick thinning to less than 45 m basinward at approx 750 800 m depth on a low slope 0 6 0 8 a seismically featureless sequence at the shelf break changes distinctly the first kilometers basinward showing a significant occurrence of features interpreted as infilled transport chutes the straight or sinuous chutes feed into well defined relief building gdf lobes 10 40 km from the shelf break a lack of failure scarps at the shelf break suggests that the gdfs have been sourced by a relatively continuous release of material flow lines concentrated along the chutes and center of the gdfs suggest a laminar movement pattern in the gdf core supported by passive flanks based on the flow morphology high pore pressure and low sediment strength within a central core of the flow is assumed to have contributed to the mobility of the gdfs dissipation of pore pressure along the margins of the flow may have caused the margins freeze while the sediment in the core remained mobile

late devensian and holocene shorelines of the british isles and north sea from models of glacio hydro isostatic rebound sea level change around the british isles since the time of the last glacial maximum is largely due to of the crustal rebound from the glacial unloading of northern britain and the concomitant melt water loading of the adjacent seas and atlantic ocean minor but not insignificant contributions also result from the rebound caused by the unloading of the distant ice sheets including fennoscandia and north america observations of sea level change for this period constrain the glacio hydro isostatic rebound model parameters describing the effective lithospheric thickness or rigidity and the effective mantle viscosity as well as certain ice sheet characteristics such as the ice thickness at the time of the last glacial maximum the models permit palaeobathymetry and palaeoshorelines to be predicted for the british isles region including the north sea the resulting evolution of the coastlines exhibits a complex behaviour through time one that is quite different from the usual models in which sea level change is assumed to be a function of time only in part this is because of the delayed response of the mantle to the spatially variable and time dependent ice and water loads and in part because the unloading history of the british ice sheet is different from those of the major global ice sheets thus maximum emergence of the north sea occurred after deglaciation had started and lasted for an extended period from about 15 000 to 12 000 radiocarbon years bp during this relative sea level still stand shoreline features could have formed for example along the western edge of the norwegian trough when access to the firths of eastern scotland would have been via a long and shallow marine inlet shoreline retreat across the north sea became relatively rapid after about 10000 years the model predictions for the irish and celtic seas also suggest a complex behaviour with the formation of a wide land bridge between about 20000 and 13 000 years ago the model also suggests that as long as the scottish ice extended across the northern irish sea until about 14 000 years ago there would have been a large freshwater periglacial lake located further south both the predicted sea level height age relations and the shoreline positions are consistent with a large body of observational evidence but some discrepancies occur particularly in northern scotland and ireland where the ice heights may have been somewhat greater than assumed in the model

surficial geology of hecate strait british columbia continental shelf four surficial geological units are defined geophysically for hecate strait on the northern british columbia continental shelf they consist of tertiary bedrock unit 1 unconformably overlain in much of the strait of glacial till unit 2 which is in turn overlain below 200 m water depth by thick silts unit 4 and above 200 m by quaternary sands and gravels unit 3 except in areas where till or tertiary bedrock is at or near surface glacial ice covered most of the strait at some time in the pleistocene but evidence for a late wisconsinan advance is more prevalent in the principal troughs of the strait sea level was as low as the present day 180 m isobath during the late tertiary or early quaternary and possibly as low as 100 m at the end of the pleistocene based on the presence of drainage channels wave cut terraces and both shore oblique and shore parallel sand ridges sedimentary bedforms found ubiquitously above 100 m appear to be in equilibrium with the present hydrodynamic conditions and t

multivariate analysis and quantitative paleoecology of benthic foraminifera in surface and late quaternary shelf sediments northern canada abstract benthic foraminifera in surface sediments from northeastern canada and the beaufort shelf were studied to determine the quantitative relationship between recent assemblage distributions and modern water depth temperature and salinity factor analysis shows that 7 factor assemblages account for 92 of the variance between samples multiple linear regression shows that different factors are significantly related to water depth august bottom water temperature or salinity multiple correlation coefficients for depth temperature and salinity are 0 94 0 72 and 0 92 respectively labrador fjords contain arenaceous faunas dominated by eithersaccammina atlantica andreophax fusiformis or byeggerella advena regression analysis shows that thesaccammina reophax factor is most strongly related to salinity theeggerella factor is related to depth and temperature a fauna dominated bytrochammina nana andbuliminella elegantissima is correlated with warm deep water in davis strait calcareous assemblages dominated byelphidium excavatum orcassidulina reniforme are found in arctic bays and shelf areas these factor assemblages are strongly related to temperature and depth cassidulina is also related to salinity anislandiella helenae fauna on the inner labrador shelf is strongly correlated with depth and salinity anonionellina labradorica fauna in deep shelf basins is closely related to salinity the multiple regression model for the sea bed data estimates water depth august bottom water temperature and salinity within confidence limits of 67 m 1 3 c and 1 0 paleoecological transfer functions were used to quantify environmental changes recorded by the foraminifera in two piston cores on a transect across the labrador shelf paleo depth estimates obtained from the core data produce relative sea level curves which are similar in shape to theoretical curves for this region paleo salinity and temperature estimates for offshore core 12 show that the change from a postglacialnonionellina fauna to a late glaciale excavatum fauna is accompanied by a decrease of about 2 in salinity and 4 c in temperature paleoecological estimates for fjord core 111 show that the change from a modernsaccammina reophax fauna to a mid holocenei helenae fauna corresponds to a salinity increase of 3 5 and temperature increase of 1 2 c

quaternary stratigraphy of the draugen area mid norwegian shelf abstract lithostratigraphic biostratigraphic and chronostratigraphic studies on a 130 m long core from haltenbanken mid norwegian shelf dr 88 30 shows sequences of short episodic glacigenic sedimentation and periods of more continuous marine sedimentation the sediment sequence is dated by palaeomagnetism as well as the amino acid and the strontium isotope methods back to ca 1 1 ma previous seismostratigraphic interpretations placed the regional pliocene pleistocene boundary at ca 90 m depth at the core site this level was dated to be of brunhes matuyama age the study area has been covered by grounded glaciers at least five times during the last 1 1 ma the first expansion of the scandinavian ice sheet was at ca 1 1 ma depositing a diamicton these sediments are overlain by a long sequence of normal marine sediments deposited during both glacial and interglacial conditions two interglacial periods from this sequence have been given an informal interglacial notation except for the glaciation at ca 1 1 ma the glacials during the early pleistocene which are identified in the core were relatively limited a transition to more extensive glaciations occurs in the early middle pleistocene during these more extensive glacial phases major erosion took place along the inner continental shelf this erosional phase resulted in overdeepening of the inner shelf which during the middle and late pleistocene influenced the depositional dynamics in the central and the outer part of the shelf in the study area the middle and late pleistocene periods are dominated by glacigenic sediments with only very thin interglacial sediments occasionally preserved one interglacial period from the middle pleistocene has been given an informal interglacial notation the core has been correlated to cores from the north sea basin on the basis of amino acid stratigraphy and palaeomagnetism the lithological and the foraminiferal stratigraphy indicates a synchronous appearance of the major lithological units and of the fauna assemblages in these areas

late quaternary sediments and stratigraphy on the continental shelf off more trondelag w norway abstract a study of more than 400 bottom sediment samples collected from the continental shelf between the stad peninsula and the halten bank shows that with regard to sediment distribution the area can be divided into two parts 1 a southern area off more with depths mostly less than 200 m and to a great extent covered by winnowed glacial deposits consisting of sand gravel and coarser material and in the depressions covered with sand and pelitic sand and 2 a northern area off trondelag where depths mainly are between 200 m and 500 m and where the sediments show great variation in textural character to a certain degree dependant on depth but also with great differences within areas of the same depths moderately well to poorly sorted sand is present in a broad belt along the outer margin of the shelf and on the slope leading up to the more shelf inside this sand belt the sediments become finer and more poorly sorted with pelitic sand silty sand changing into sandy pelite clayey sand and sand silt clay pelitic gravelly sand occupies large parts of the shelf especially on the western flank of the halten bank and the eastern slope of the haltendjup depression coarse lag deposits are present in the most shallow parts of the halten bank the origin of the surface sediments on the trondelag shelf is thought to represent retransported glacial deposits the material consists of particles winnowed out from the shallow part of the halten bank and from the shallow more shelf to the south the glacial origin of the material is shown by the form and roundness of gravel and stones which agrees with typical glacial deposits and by the form and microtextures of the sand grains the winnowing and retransport of the glacial deposits is shown from the study of cores to have taken place mainly during the last 10 000 years i e during the holocene after the warm atlantic water entered the area of the norwegian continental shelf the sediment transport is a result of the hydraulic regime and in general sediments have been transported from areas of coarse skewed deposits to areas of finer and fine skewed deposits from recent current measurements on the trondelag shelf it seems probable that erosion and transport of sand as well as of unconsolidated silt and clay takes place today at least down to depths of 300 400 m on the continental slope this zone reaches down to 600 700 m the present sediment distribution is therefore thought to represent at least to a certain degree the effect of the present hydraulic regime the lithologic paleontologic and chronostratigraphic investigation of 18 cores from the trondelag shelf and a comparison with cores sampled off stad indicates the following environmental evolution following the retreat of the ice on the continental shelf during the middle weichselian the sea conditions were high mid arctic with a great deal of seaice and icebergs causing ice rafting and the formation of glacial diamictons this environment was succeeded by a somewhat less arctic environment which lasted till about 13 000 yr b p when the sea became distinctly less arctic probably low arctic with a warmer element in the fauna and with less ice rafting this was probably due to a certain influence of atlantic water the change from low arctic to boreal conditions took place about 10 000 yr b p at the same time the hydraulic regime must have changed drastically with currents and waves beginning to have a strong winnowing effect on the bottom sediments this is thought to indicate the real introduction of the atlantic current in the area

a submerged beach between norway and ekofisk in the north sea abstract on a recent geophysical pipeline route survey between the sw coast of norway and the ekofisk oil field in the north sea a submerged beach deposit was discovered the beach is located on the shoulder of the sw slope of the norwegian trench at a water depth of 90 m the beach is similar in structure to a submerged beach previously described for a deposit located 380 km further nnw in the same type of regional environment the shoulder of the western slope this beach is however located 40 70 m deeper suggesting a possible post glacial dipping of the north sea plateau

late weichselian and holocene sediment fluxes of the northern north sea margin abstract an event chronology has been determined for temporal and lateral magnitudes of material fluxes across the northern north sea margin including the norwegian channel and the north sea fan this has allowed the governing factors for the sediment processes on the margin to be estimated the chronological model of selected cores is based on 14 c ams dates regional tephra layers and planktonic foraminiferal stratigraphy based on this chronological framework the core sediments across the north sea margin have been divided into four main climatostratigraphic intervals a oldest dryas 15 13 ka b bolling allerod 13 11 ka c younger dryas 11 10 ka and d holocene 10 0 ka further the holocene period has also been divided into two subperiods the preboreal 10 9 ka and the holocene interglacial 9 0 ka creating five well defined lithological units deposition phases in all of which the deglaciation units 15 9 ka usually constitute 90 of the sediment budget the recognition of an almost identical lithological succession both in the records on the fan and in the high resolution record of the channel suggests that sedimentation on the north sea margin must be governed dominantly by regional sedimentary processes for each time interval the sedimentation rate in the norwegian channel is on average an order of magnitude higher than on the north sea fan diminishing distally from the shelf edge sedimentation under the holocene interglacial period 9 0 ka contrasts totally from the deglaciation pattern controlled dominantly by pelagic productivity in the area close to 50 of the hemipelagic sediments on the north sea margin are of bolling allerod age 15 13 ka this extreme sedimentation resulted from a combination of a rapid sea level rise constantly exposing new areas for marine erosion winnowing and aggressive surface ocean current activity surface ocean currents and the associated bottom currents provide the dominant control on the pattern of deglacial sedimentation on the north sea margin 15 9 ka this is especially apparent during the oldest dryas and the bolling allerod periods where the distribution pattern across the margin is essentially hydrodynamically controlled only during the younger dryas period are the surface ocean processes overprinted by sedimentary processes from melting icebergs the high resolution records reveal that the shifts in the lithological style of sedimentation are directly linked to the rapid reorganisation of the surface ocean system frequently taking place during the deglacial and holocene time period suggesting a fairly regional type of sedimentation pattern as the shift between the different lithological styles of sediments is both abrupt and regional they should be detectable on the seismic high frequency records

the quaternary deposits and landforms of scotland and the neighbouring shelves a review abstract a thick sequence of quaternary sediments up to 1000 m has been deposited in the north sea basin and perhaps five major glacial episodes the first occurring prior to ca 1 8 2 1 ma bp and the last during the late devensian can be recognised between the glacial events periods of low salinity arctic marine or glacio marine sedimentation have been dominant although episodes of ameliorated climate when north atlantic drift waters had access to the north sea have been identified a number of horizons in separate boreholes have been correlated with the last interglacial oxygen isotope stage 5e and a sequence of water mass movements around the scottish coasts can be reconstructed for the last ca 125 ka on land sequences of quaternary deposits relating to several glacial and non glacial terrestrial and marine events occur in different areas but due to poor dating correlation between these sequences cannot yet be achieved in particular north east scotland has a complex glacial history with evidence for ice sheet glaciation on at least four occasions evidence from the outer hebrides north east scotland and the north sea basin indicates that the late devensian scottish ice sheet had a rather restricted extent only reaching a short distance offshore along much of the east and west coasts at this time ice free areas existed in north east scotland on the isle of lewis and probably in caithness and orkney whilst part of the outer shelf around st kilda was dry land a marine embayment extended down the east coast of scotland between the scottish and scandinavian ice sheets and independent ice caps existed on the outer hebrides and probably on shetland deglaciation of the greater part of the country took place prior to ca 13 ka bp whilst the climate was still very cold the ice retreat appears to have been orderly with stagnant ice masses being trapped only in topographically suitable locations a number of retreat stages or minor readvances occurred during the general deglaciation the firth of clyde was one of the last areas outside the highlands to be deglaciated and this occurred in a rapid possibly catastrophic fashion shortly prior to ca 13 ka bp despite the mild climate at the start of the lateglacial interstadial it is not known if there was complete deglaciation prior to the loch lomond readvance the readvance glaciers however may have started to advance during the latter part of the interstadial when declining terrestrial temperatures coincided with a period of mild marine conditions the loch lomond readvance maximum can only be dated to some time after ca 10 9 ka bp and it is likely that final ice free conditions were not achieved until the earliest holocene

cenomanian turonian organic sedimentation in north west africa a comparison between the tarfaya morocco and senegal basins abstract the cenomanian turonian oceanic anoxic event was recognised in north western africa in various depositional settings from abyssal areas to continental shelves to derive information on environmental conditions in these different settings and define a depositional model a petrographical and geochemical study of the organic matter was performed on sediments from the tarfaya morocco and senegal basins the results obtained for these two locations were compared to those of previous studies namely from dsdp wells petrographic and geochemical data allow the differentiation of two main organofacies a shallow depositional facies continental shelf is characterised by low total organic carbon toc contents the second organofacies deposited in the deep marine environment slope and abyssal shows a high toc content 7 the predominance of fluorescing amorphous om combined with high hi values suggests good preservation conditions the s c ratio 0 36 and abundance of organic sulphur compounds support this interpretation and indicate a development of anoxic conditions to explain the organic contrast between both environments a depositional model has been developed which is based on limited water exchange between both depositional settings the main factor which has determined black shale sedimentation is the restricted water circulation related to the presence of isolated depositional environment during atlantic ocean opening compared to present upwelling zones the palaeoproductivity in the studied area was relatively moderate during cenomanian turonian and seems not to be the only determining factor of organic matter accumulation

low temperature diagenetic metamorphic and magmatic contributions of external co2 gas to a shallow ground water system abstract a small 2 low temperature 2 gas overpressured gently dipping paleozoic carbonate aquifer rests on precambrian granite in a narrow canyon along the eastern edge of the rocky mountain front range colorado the carbonate aquifer is bounded on three sides by granite and in the down dip direction by the front range fault the fault in a major continental intraplate zone of weakness along which magmatic fluids and gases could migrate to the surface and near surface from great depths the fault has also overthrusted slices of carbonate and clastic rocks several kilometres below the granitic basement stable isotopic 2 h and 18 o and discharge temperature data suggests that carbonate aquifer ground waters are of meteoric origin and have not circulated to depths greater than the base of the carbonate aquifer 650 m elevated co 2 and the 13 c of hco 3 in the carbonate aquifer suggest an external crustal source of co 2 gas 3 he 4 he o 2 n 2 and ar n 2 gas ratios indicate gas contributions from both magmatic and atmospheric sources atmosphere contributions account for about 25 of the exsolving gas whereas magmatic co 2 accounts for 7 to 14 possible external co 2 sources which are consistent with the mean hco 3 13 c 2 4 pdb are clay carbonate mineral diagenesis or low temperature metamorphism of siliceous carbonate rocks that have been overthrust by 3 to 6 km of granite diagenetic or metamorphic co 2 mixed with some magmatic gas appears to have migrated from the source rock area upward along the ute pass thrust fault until it encountered the shallow carbonate aquifer ground water system where it was further diluted with atmospheric gas

gravel barrier migration and overstepping abstract despite the widespread occurrence of gravel barriers on mid to high latitude coasts understanding of their stability and relationship to gravel deposits on the inner continental shelf remains rudimentary on sand dominated coasts subject to rising relative sea level barrier overstepping has been postulated as a mechanism for preservation of beach deposits on the shelf but direct observation of overstepping events has been lacking observations at a site on the atlantic coast of canada reveal migration of a gravel barrier at 8 m a 1 landward over back barrier mud following abandonment of part of the barrier volume on the shoreface this provides clear evidence for overstepping and suggests that it may play a role in the formation of inner shelf gravel deposits integrity of the migrating stretching barrier depends on continued sediment supply from the headland source to a connecting ridge which must become progressively longer as the landward displacement of the barrier increases

eurasian ice sheet collapse was a major source of meltwater pulse 1a 14 600 years ago rapid sea level rise caused by the collapse of large ice sheets is a threat to human societies in the last deglacial period the rate of global sea level rise peaked at more than 4 cm yr 1 during meltwater pulse 1a which coincided with the bolling warming event some 14 650 years ago however the sources of the meltwater have proven elusive and the contribution from eurasian ice sheets has been considered negligible here we present a regional carbon 14 calibration curve for the norwegian sea and recalibrate marine 14c dates linked to the eurasian ice sheet retreat we find that marine based sectors of the eurasian ice sheet collapsed at the bolling transition and lost an ice volume of 4 5 7 9 m sea level equivalents sle over 500 years during peak melting 3 3 6 7 m sle of ice was lost potentially explaining up to half of meltwater pulse 1a a mean meltwater flux of 0 2 sv over 300 years was injected into the norwegian sea and the arctic ocean at a time when proxy evidence suggests vigorous atlantic meridional overturning circulation our reconstruction shows that massive marine based ice sheets can collapse in as little as 300 500 years marine based sections of the eurasian ice sheet collapsed rapidly during a warming event 14 600 years ago and contributed to the meltwater pulse 1a event according to a recalibrated age model for sediments from the norwegian sea

the history of quaternary sedimentation in the uk sector of the north sea basin reconnaissance seismic and sampling surveys have shown that up to 500 m of lower and early middle pleistocene deltaic sediments are preserved in the uk sector of the north sea the distributions of delta related facies record the progressive expansion of peripheral delta systems northwards across the southern north sea during the early pleistocene a late middle pleistocene unconformity is present throughout the uk sector and sedimentation above the unconformity was dominated by glacial erosional and depositional processes a complex system of deeply incised valleys was eroded during each of three regional middle and upper pleistocene glaciations and the valleys have been filled or partially filled by glaciolacustrine or glaciomarine and interglacial marine sediments the valleys of the earliest elsterian glaciation are up to 400 m deep in the southern north sea the saalian and weichselian valleys are commonly more than 100 m deep they are eroded through their contemporary tills nearshore but occur well beyond the limits of these tills offshore the origins of these valleys are attributed to a combination of fluvial subglacial and periglacial processes

integrated depositional model for the cenomanian turonian organic rich strata in north africa abstract during the late cenomanian early turonian c t oceanic anoxic event oae2 organic rich strata was deposited in rift shelf basins and slopes across north africa and in deep sea basins of the adjacent oceans based on a review of published and unpublished information this paper documents the distribution and organic richness of c t strata across the whole region within a palaeogeographic framework and systematically analyses the conditions and processes which controlled their deposition previously the c t in north africa has been most intensively studied in southern morocco tarfaya and tunisia only little data is availabe for other parts of north africa namely algeria libya and egypt because distribution of c t corg strata there becomes more patchy a general decrease in peak organic richness and black shale thickness occurs from west to east partly as a result of upwelling along the moroccan atlantic coast and the absence of upwelling in the eastern mediterranean area furthermore in the confined central atlantic the oxygen minimum zone omz in many places reached down to the deep sea floor 3 4 km while the lower limit of the omz along the north african tethys was much shallower and underlain by oxic water masses as documented by high resolution biostratigraphic and chemostratigraphic data c t black shale deposition in most areas outside the upwelling zone are restricted to a strong eustatic latest cenomanian transgressive phase triggered by this sea level rise the omz impinged onto the north african continental shelf and the margins of intrashelf basins which mostly formed during the early cretaceous as halfgrabens important units containing c t organic rich strata in the region are the atlantic tarfaya black shales morocco western sahara black shales and phtanites in the moroccan and algerian atlas the bahloul fm in the se constantine basin and in northern and central tunisia the etel fm in the sirte basin the al hilal fm in cyrenaica libya the abu roash fm in the abu gharadig and fayium basins western desert egypt the daliyya fm along the ne sinai palestine isreal coast and the shueib fm in west central jordan

sedimentation history of the northern north sea margin during the last 150 ka the norwegian channel ice stream ncis is one the defining features of the fennoscandian icesheet still little is known of the detailed dynamics of this ice stream in relation to regional changes in ice cover paleoceanographic and climatic changes sedimentological data from core md99 2283 in combination with seismic data allow a detailed chronological reconstruction of the outbuilding of the margin and the ice extent in southern scandinavia through the last 150 ka an integrated stratigraphy of the margin is presented and compared to the glacial history changes in the regional ice cover are reflected in the accumulation rates the clay mineralogy the coarse chalk fraction and the number of ird 2 mm in core md99 2283 while the sedimentation on the north sea fan as derived from seismic data provides direct evidence for the glacial activity at the shelf edge tentative evidence was found for two early weichselian glacial advances in southern scandinavia and possibly scotland at around 110 and 80 ka bp from 42 cal ka bp the ice cover expanded in southern fennoscandia and led to increased deposition on the margin and the occurrence of local melt water outbursts significantly increased accumulation rates coarse chalk local meltwater output and smectite occur during the ice expansion in the north sea from around 34 cal ka bp the main outbuilding phase of the nsf during the last glacial cycle occurred after 30 cal ka bp from around 24 cal ka bp the ncis became highly active and advanced at least three times prior to the final retreat from the shelf edge around 19 0 cal ka bp

submarine slide scars and mass movements in karmsundet and skudenesfjorden southwestern norway morphology and evolution abstract shallow seismic sections multibeam bathymetric images and geotechnical investigations of the seafloor in karmsundet and skudenesfjorden sw norway have revealed the occurrence of large slide scars and associated mass movement deposits the slide escarpments are up to 30 40 m high and 8 km long with up to 20 10 6 m 3 of sediment released during a single event of retrogressive sliding the slide scars show a range of associated seafloor topography reflecting various modes of sediment displacement the variation in the escarpment morphology and sediment deformation style can be attributed to the varied intensity of liquefaction sliding involved mud deposits of allerod younger dryas to early holocene age but partly also deposits older than ca 12 000 14 c years bp the sediment failures were probably triggered by seismic reactivation of a local fault by postglacial regional isostatic rebound prior to failure the seafloor deposits were undercompacted and metastable due to high pore pressure the presence of shallow gas and the relatively steep local slope created by the formation of a major scour trough by sea currents minor gravitational sliding may still occur along some of the escarpments although engineering slope stability analysis indicates that the deposits can be regarded as stable in the present day conditions of static load and the anticipated weak sporadic earthquakes with an occurrence likelihood of 10 4 year and a peak acceleration of 0 25 g

carbon isotope stratigraphy recorded by the cenomanian turonian oceanic anoxic event correlation and implications based on three key localities we present new detailed carbon isotope records for bulk carbonate total organic carbon toc and phytane from three key sections spanning the cenomanian turonian boundary interval eastbourne england gubbio italy tarfaya morocco with the purpose of establishing a common chemostratigraphic framework for oceanic anoxic event oae 2 isotope curves from all localities are characterized by a positive carbon isotope excursion of c 4 for toc and phytane and c 2 5 for carbonate although diagenetic overprinting appears to have obliterated the primary carbonate carbon isotope signal in at least part of the tarfaya section stratigraphically peak 13 c values for all components are followed by intervals of high near constant 13 c in the form of an isotopic plateau recognition of an unambiguous return to background 13 c values above the plateau is however contentious in all sections hence no firm chemostratigraphic marker for the end point of the positive isotopic excursion can be established the stratigraphically consistent first appearance of the calcareous nannofossil quadrum gartneri at or near the cenomanian turonian boundary as established by ammonite stratigraphy in conjunction with the end of the 13 c maximum characteristic of the isotopic plateau provides a potentially powerful tool for delimiting the stratigraphic extent and duration of oae 2 this oceanic anoxic event is demonstrated to be largely if not wholly confined to the latest part of the cenomanian stage

relationship of surface sediments and benthic foraminiferal distribution patterns in the norwegian channel northern north sea abstract our study of the distribution of benthic foraminifers in surface sediment samples from the norwegian channel has shown that eight species and five different assemblages are important the assemblages are dominated by uvigerina peregrina bolivina skagerrakensis cassidulina laevigata elphidium excavatum and bulimina marginata respectively hyalinea balthica melonis barleeanum and trifarina angulosa are also abundant the first four assemblages and their dominant species can be related to certain water masses with known characteristics two species are related to certain types of substrate m barleeanum seems to prefer a fine grained substrate while t angulosa occurs most abundantly where the content of silt and clay is low b skagerrakensis and h balthica occur most abundantly in sediments with a high content of organic carbon while t angulosa shows inverse correlation to the organic carbon content

pleistocene development of the se nordic seas margin abstract throughout the pleistocene the sedimentary environment on the se nordic seas continental slope outer shelf off western norway has been strongly controlled by variability in the norwegian atlantic current nwac glaciations of the shelf areas and sea level changes acoustic and core data from the southern voring plateau show a pleistocene sequence characterised by hemipelagic sediments interfingered by diamictons on the upper slope the area of the 7 25 14 c ka bp storegga slide shows evidence of a long history of pleistocene mega slides during the last interglacial and most likely also during previous interglacials the slide region has been the locus of rapid deposition between water depths of 800 and 1200 m as a result of nwac winnowing along the upper slope the north sea fan region is strongly influenced by glacigenic debris flows gdfs deposited during glacial advances reaching the shelf edge when the norwegian channel was occupied by the norwegian channel ice stream it appears that gdf activity was initiated at ca marine isotope stage 12 interbedded between the debris flow sequences mega slide events such as the more and tampen slides have been identified during glaciations when the entire se nordic seas continental shelf was covered by extensive grounded ice sheets basal till were transported to the shelf edge from where subsequent mass movement occurred during late glaciation early deglaciation meltwater plumes were released at the time of disintegration of ice streams in the norwegian channel as is evidenced from the last deglaciation of the margin at ca 15 14 c ka bp the plume material was transported northwards by currents before rapidly deposited as a thick package within the storegga slide area and on the south voring plateau based on identification and dating of iceberg scourings glacial erosion surfaces and delta deposits on the shelf subsidence rates between 0 7 and 1 2 m ky have been calculated for the last ca 250 ka

mid pleistocene ice drainage pattern in the norwegian channel imaged by 3d seismic abstract several investigations have shown that a huge late weichselian ice stream flowed along the norwegian channel and deposited thick debris flow deposits at the north sea fan the development of the channel is probably mainly a result of several cycles of ice stream activity during the quaternary a merged 3d seismic image shows a lineated relief pattern interpreted as a uniquely well preserved footprint of a moving ice sheet this deep quaternary horizon corresponds to a slightly irregular reflector on top of a parallel layered seismic sequence seismic tie to the troll core 8903 south of the study area shows that the sequence comprises early middle pleistocene marine sediments the pattern of lineations the seismic stratigraphy as well as the chronostratigraphic investigations of the troll core strongly indicate that the image reflects the initial phase of an extensive middle pleistocene glaciation inferred age ca 0 5 ma prior to the development of a massive norwegian channel ice stream the northwesterly oriented pattern seen in the southeastern part of the study area demonstrates that the ice flowed into the channel mainly from the coastal zone north of bergen farther west various sets of fan shaped lineations partly cross each other showing that the 3d image represents a certain short time window in the northern study area the ice flow was dominantly northwards and directed towards the area below the present shallow maloy plateau there are no indications that the glaciers north of sognefjorden affected the marine ice sheet

surficial sediments in the norwegian sector of the north sea between 60 30 and 62 n abstract based on grain size distribution and sea floor photographs the sea bed sediments between bergen and maloy have been divided into four groups a sand with coarse material on the northern part of the north sea plateau and the maloy plateau b very well sorted sand on the southern part of the north sea plateau and the upper part of the western slope of the norwegian trench c silty clayey sand in lower part of the slopes d silty sandy clay in the central part of the norwegian trench large local variations are found in the group a sediments on the maloy plateau partly caused by relict iceberg plough marks the net deposition after the transition to boreal conditions with atlantic water about 10 000 yrs ago is mostly between 0 and 30 cm on the northern part of the north sea plateau and exceeds 200 cm in the deepest parts of the norwegian trench the total thickness of sediments above assumed overconsolidated material has been mapped based on sparker records on the northern part of the north sea plateau the sediment cover above a supposed wavecut platform is less than 1 m over large areas while a late weichselian coastal unit fringing the plateau consists of up to 40 m of sand and gravel on the southern part of the plateau and the upper part of the western slope of the norwegian trench up to 10 30 m of sediments are found probably dominated by sand formed by wave and tidal current action during a period of low sea level in the central part of the trench a total thickness of up to 40 m of clay deposited during varying environments is found most of the investigated area is believed to be underlain by a till deposited by a north northwestward moving ice sheet

quaternary seismic stratigraphy of the north sea fan glacially fed gravity flow aprons hemipelagic sediments and large submarine slides abstract approximately 1000 km of high resolution sleeve gun array transects on the north sea fan located at the mouth of the norwegian channel reveal three dominant styles of sedimentation within a thick 900 m quaternary sediment wedge comprising numerous sequences these are interpreted as terrigenous hemipelagic sedimentation large scale translational slides and aprons of glaciogenic debris flow deposits contributing to considerable fan construction four large buried translational slides involved sediment volumes upwards of 3000 km 3 each and preceded the similarly dimensioned first storegga slide on the ne fan flank several thick 100 m terrigenous hemipelagic deposits apparently represent long lived 150 200 kyr periods of sedimentation whose distribution indicates fan input via the norwegian channel the upper sequences are each made upper sequences are each made up of one or several thick 100 m aprons comprising stacked lensoid and or lobate forms which range from 2 to 40 km in width and 15 to 60 m in thickness they characterize debris flows attributed to periodic input from several phases of a norwegian channel ice stream reaching the shelf edge subsidence in the outer norwegian channel allowed preservation of several glaciation cycles represented by sheet erosion bounded tills and progradational units much of the shelf slope transition has been preserved allowing a preliminary chronology of the fan sequences through correlation with borehole sediments in the norwegian channel debris flows which signal the initial shelf edge glaciation are not recognized from the initial glaciation in the channel 1 1 myr but are associated with a middle pleistocene and all following glacial erosion surfaces ges in the outer norwegian channel this was followed by six further sequences probably totalling over 13 000 km 3 of sediment at least four of these were shelf edge ice maximum events the last of which was late weichselian age 14 c ams considering earlier glaciation related hemipelagic sedimentation material since removed by the large slides and extensive unmapped areas total quaternary fan sedimentation was in the vicinity of 20 000 km 3

late pleistocene sedimentation on the norwegian continental slope between 67 and 71 n abstract the northern norwegian continental margin between 67 and 71 n comprises the gentle slope off the barents sea the relatively steep lofoten islands slope and the step like slope of the voring plateau during the late pleistocene these slopes received large amounts of terrigenous sediments from an extensively glaciated norwegian continental margin through the analyses of 17 gravity cores high resolution 3 5 khz and airgun seismic profiles and sea beam bathymetric data we have examined the late pleistocene sedimentation pattern of this region eight sedimentary facies from the gravity core analysis and seven types of 3 5 khz echo characters indicate that the slopes were moulded by hemipelagic sedimentation commonly associated with iceberg rafting slope failure slump slide and debris flow turbidity currents downslope bottom currents and contour following bottom currents ice rafted debris was dispersed over a broad area including the lower slopes off the barents sea and the lofoten islands and the voring plateau and its outer slope slope failures prevailed on the lofoten islands and voring plateau slopes where the broad glacial margin directly released unsorted glacial sediments during glacial periods on the barents sea slope glacial and reworked shelf sediments were supplied by underflows which were probably caused by cooling of surface shelf water during glacial periods on the upper slope sediments were further transported by turbidity currents and slope crossing bottom currents which excavated numerous small scale channels there are indications of deep sea contour currents at the base of slope and the upper slope off the barents sea and on the voring plateau these currents probably resulted from water exchange between the norwegian greenland sea and the north atlantic ocean during interglacial periods

late cenozoic environmental changes along the norwegian margin abstract our ability to understand the rates and consequences of contemporary climate change is limited by the insufficient duration of instrumental records thus we are not able to fully understand the processes that provide a fundamental control in driving climate changes across different timescales palaeo climate archives like those preserved offshore norway provide our only real window through which to observe long term rates and styles of climate change this paper reviews the extensive geological and geophysical data available from the late cenozoic atlantic margin of norway along the margin periods of erosion and deposition have been controlled by agents including fluvial glacial and oceanographic processes current controlled sedimentation along the margin provides insight into the connection of the arctic and atlantic oceans from the miocene onward plio pleistocene shelf edge progradation of up to 150 km can be linked to the grounding of ice sheets on the continental shelf through observations of buried grounding zone wedges and mega scale glacial lineations the margin is also important for understanding the ability of glaciation to cause topographic relief changes and generate offshore geohazards such as the storegga slide which mobilised some 3000 km 3 of sediments during the holocene whilst the processes operating along the norwegian margin are well understood through the late cenozoic there is little geochronological control with which to constrain the environmental changes that have been observed concomitant with the wealth of knowledge and the extensive data that are currently available we propose that the norwegian margin is an ideal location to be considered for future ocean drilling the observations of multiple processes acting independently and together means ocean drilling could yield information of global significance due to the bridging location of norway s atlantic margin between the arctic and lower latitudes

seafloor glacial features reveal the extent and decay of the last british ice sheet east of scotland three dimensional 3d seismic datasets 2d seismic reflection profiles and shallow cores provide insights into the geometry and composition of glacial features on the continental shelf offshore eastern scotland 58 n 1 2 w the relic features are related to the activity of the last british ice sheet bis in the outer moray firth a landsystem assemblage consisting of four types of subglacial and ice marginal morphology is mapped at the seafloor the assemblage comprises i large seabed banks interpreted as end moraines coeval with the bosies bank moraine ii morainic ridges hummocky push and end moraine formed beneath and at the margins of the ice sheet iii an incised valley a subglacial meltwater channel recording meltwater drainage beneath former ice sheets and iv elongate ridges and grooves subglacial bedforms overprinted by transverse ridges grounding line moraines the bedforms suggest that fast flowing grounded ice advanced eastward of the previously proposed terminus of the offshore late weichselian bis increasing the size and extent of the ice sheet beyond traditional limits complex moraine formation at the margins of less active ice characterised subsequent retreat with periodic stillstands and readvances observations are consistent with interpretations of a dynamic and oscillating ice margin during bis deglaciation and with an extensive ice sheet in the north sea basin at the last glacial maximum final ice margin retreat was rapid manifested in stagnant ice topography which aided preservation of the landsystem record

facies and preservation of glaciogenic sequences from the varanger ice age in scandinavia and other parts of the north atlantic region abstract thickness and facies variations and state of preservation of varangerian glacial sequences are related to the geotectonic settings of the depositional environments from stable continental platform sites only thin remnants of a single glacial advance retreat sequence are preserved in fault basins thickness and lithofacies vary in response to fault movements in the continental platform to shelf region the sequence ranges from thin beds of one single glacial event on the craton to up to some hundred meterswith several glacial advance retreat cycles from shelf sites the stable and slowly subsiding shelf environment has given rise mainly to a thin sequence of diamictite overlain by mudstone in more rapidly subsiding shelves several glacial advance retreat units are preserved together with interstadial and interglacial sediments with total thickness up to several hundred meters the shelf slope environment is probably represented by up to 3000 m thick diamictites the preservation potential during the glacial epoch is primarily controlled by the property of glacier ice sheets to be either erosive or depositional the long term preservation is determined by various factors controlling relative sea level changes the state of preservation during orogenic processes generally decreases from sequences on platform sites to those on distal shelves and shelf slopes

the cenomanian turonian boundary event on the moroccan atlantic margin agadir basin stable isotope and sequence stratigraphy abstract correlations of four sections constrained by stable isotope stratigraphy and micropalaeontology along a 80 km long e w oriented transect from the western high atlas to the present day coast taghazoute show that the cenomanian turonian boundary event ctbe occurred within shallow water oyster bearing limestones and marls and not in the overlying black shale the age of the laminated shale is early turonian as the planktonic marker helvetoglobotruncana helvetica is found from its first centimetres upward the underlying deposits hosting the ctbe event are bounded by two unconformities interpreted as emersion surfaces and represent the strongest seawardshifts of facies in the local cenomanian sedimentary wedge the 13 c anomaly is only recorded in the coastal taghazoute section not in other sections landward meaning that the ctbe occurred here during a short transgressive phase within an overall regressive trend the lower turonian black shale of the taghazoute section is transgressive onto the second unconformity and pass landward to white evenly laminated chert bearing mudstones then to bioturbated mudstones in the easternmost sections of the transect western high atlas

palaeoenvironmental evolution of the late cretaceous sequence in the tarfaya basin southwest of morocco abstract the late cretaceous sedimentary evolution of the tarfaya basin is reviewed based on late albian campanian outcrops and two cored exploration wells s13 and s75 with a stratigraphic range from the early cenomanian to the late turonian standard sedimentological and micropalaeontological methods were used together with clay mineralogy and organic geochemistry two distinct depositional environments were found the first is late albian early middle cenomanian in age and dominated by terrigenous silici and bioclastic sediments containing primarily terrestrial organic matter with a low organic content abundant illite and chlorite eroded from crystalline rocks outcropping in the anti atlas mountain and mauritanides is present as is abundant kaolinite reworked from soils surrounding the tarfaya basin the second environment comprises late cenomanian campanian sediments characterized by pelagic marls and limestones with a high organic content and a abundant pelagic macro and microfauna these sediments which were probably deposited in an upwelling system are characterized by higher contents of smectite

radar facies of paraglacial barrier systems coastal new england usa analysis of a large data base of ground penetrating radar gpr profiles from both natural and developed paraglacial barriers along the coast of new england has allowed identification of eight reflection configurations that characterize this type of mid to high latitude coastal environment bedrock anchor points yield primarily hyperbolic configurations whereas glacial anchor points and sediment source areas are characterized by chaotic parallel and tangential oblique configurations beaches and dunes produce predominantly sigmoidal oblique hummocky reflection free and bounding surface configurations back barrier sediments may yield basin fill configurations but generally include abundant signal attenuating units the gpr data calibrated with information from cores were collected across swash aligned and drift aligned barriers in a variety of wave and tidal energy settings application of a 120 mhz antenna as used in this study enables portrayal of a range of sedimentary units from individual bedforms on single records to entire barrier elements using large numbers of intersecting gpr sections at maximum vertical resolutions that vary between 0 2 m and 0 7 m the most important drawback of gpr in the coastal environment is attenuation of the electromagnetic em signal by layers of salt marsh peat or by brackish or salty groundwater primarily along barrier edges this disadvantage is offset by many benefits data can be collected at rates of several km per day making gpr an excellent reconnaissance tool a core that is used in the calibration of gpr data can be matched with great accuracy to its position on the complementary gpr record allowing detailed correlation between lithostratigraphy and reflection configuration