oxygen and carbon isotope record of east pacific core v19 30 implications for the formation of deep water in the late pleistocene north atlantic abstract a detailed oxygen and carbon isotope record has been obtained from benthic foraminifera in core v19 30 from the carnegie ridge on the south side of the panama basin expressing these records and the oxygen and carbon isotope records previously published for atlantic core m 12392 on a common timescale it is apparent that the oxygen isotope records are very similar but that the carbon isotope records are quite different by obtaining the carbon isotope gradient between the two sites as a function of time we show that the production of north atlantic deep water has varied over a wide range during the late pleistocene and that the pattern of variation is not simply related to the well known oxygen isotope record although the two oxygen isotope records are very similar changes in the interoceanic gradient are detectable and support the hypothesis that in the glacial mode the north atlantic was colder and less oxygenated than it is today shackleton s 1 1977 interpretation whereby the carbon isotope record from the atlantic core reflects changes in the terrestrial biomass is an over simplification however the record from the pacific core v19 30 probably can be explained in these terms since it probably approximates the carbon isotope record of global mean oceanic dissolved co 2

weichselian land sea interactions western norway norwegian sea abstract six major weichselian glacier expansions including the younger dryas are recorded in western norway three of the advances reached the continental shelf while the others were restricted to the coastal areas during the upper weichselian glacial maximum 18 20 ka there was an ice free corridor between the british and the scandinavian ice sheets in the northern north sea more or less complete deglaciation of southern norway seems to have happened some time around 90 and 70 ka large parts of the norwegian sea were at least seasonally open with influx of atlantic surface water in periods through isotope substage 5d to stage 4 possibly also during a short time interval close to the 2 3 boundary a small area in the southeastern norwegian sea was ice free all these influxes of atlantic water seem to correlate to periods with interstadial conditions in western norway during times with the most extensive continental glaciations there are no traces of any influx of atlantic surface water the western norwegian glacial record and the norwegian sea surface circulation record seem to vary with a ca 20 ka cycle during the weichselian this indicates a dominance of the precessional orbital forcing between the ca 100 ka interglacial glacial interglacial cycle

living coccolithophore communities in the norwegian greenland sea and their record in sediments abstract investigation of epipelagic coccolithophore communities along a transect from the voring plateau off norway to scoresbysund east greenland and comparison with coccolith assemblages in underlying surface sediments reveal that sedimentation of coccoliths is dependent on the following factors 1 composition of the coccolithophore communities and their bloom phases 2 grazing and selective destruction by zooplanktonic organisms 3 type of vertical flux in fecal pellets and 4 varying carbonate dissolution in different water masses dissolution increases towards the boundaries of carbonate sedimentation as a result the original composition of the living communities becomes increasingly obscured in the impoverished taphocoenoses however differential resistance to dissolution of the two primary calcareous nannoplankton species emiliana huxleyi and coccolithus pelagicus is such that occurrence and ratio of the two species in surface sediments reflect the various water masses in the norwegian greenland sea

origin of the northern atlantic s heinrich events as first noted by heinrich 1988 glacial age sediments in the eastern part of the northern atlantic contain layers with unusually high ratios of ice rafted lithic fragments to foraminifera shells he estimated that these layers are spaced at intervals of roughly 10 000 years in this paper we present detailed information documenting the existence of the upper five of these layers in odp core 609 from 50 n and 24 w their ages are respectively 15 000 radiocarbon years 20 000 radiocarbon years 27 000 radiocarbon years about 40 000 years and about 50 000 years we also note that the high lithic fragment to foram ratio is the result of a near absence of shells in these layers although we are not of one mind regarding the origin of these layers we lean toward an explanation that the heinrich layers are debris released during the melting of massive influxes of icebergs into the northern atlantic these sudden inputs may be the result of surges along the eastern margin of the laurentide ice sheet

biostratigraphy of the last glacial period in europe the european early weichselian early wurmian is characterized by two long and relatively warm interstadials brorup and odderade which can be traced and correlated with certainty across large parts of europe the amersfoort interstadial described earlier from the netherlands has been included in the brorup and represents the older part of it both great interstadials were forested in north west central and southern europe in the north conifer forests prevailed giving way towards the south to deciduous forests the climatic gradient was distinctly steeper mainly due to southward displacement of the gulf stream the two great interstadials are synchronous with the isotopic stages 5a and 5c in the deep sea cores subsequent to eemian brorup and odderade and from within the context of a continuous series two additional and clearly delimited interstadials have been recorded in a new standard profile from oerel nw germany these are now described as the oerel and glinde interstadials they were not forested and belong to the early pleni weichselian the lower one oerel can probably be correlated with the 3rd weichselian wurmian interstadial in southern central europe ognon ii durnten samerberg 3 while the upper one glinde has so far no known counterpart for the younger pleni glacial it is assumed that there was a long phase during which it was not too cold the formation of humic layers during this phase took place at different times partly due to local edaphic factors so that the relevant 14c dates show a wide scatter the hengelo and denekamp interstadials represent only slight ameliorations which facilitated the formation of shrub tundra and can be recorded in certain regions only

evaporite karst in sicily karst areas are distributed over most of sicily the most widespread karst rocks are carbonates particularly limestones but karst phenomena can also be seen in evaporites and particularly in salt mines this report provides an overview of evaporite karst in sicily along with a case history that shows some of the evaporite karst risks to the environment in the centre and south of sicily a thick sequence of messinian evaporite rocks are subject to dissolution from meteoric and formation waters in areas where potassium salts and rock salts are being mined some geomorphologic changes result from the drilling of boreholes and the collapse of underground mines thus lowering or collapsing the land surface an example is the old salt mine muti coffari situated in the commune of cammarata where there is a modification of the surface flow of the river platani meteoric waters and runoff flow down through a borehole enter the underground mine cavity and dissolve the salts and then the resulting brine flows into a branch of the river making it salty field investigations showed the presence of salt along the edges and on the bed of the stream where it comes out of the cave therefore interventions for risk mitigation are necessary since the old mine constitutes a serious danger for damage or collapse of nearby infrastructures and can lead to degradation of the river ecosystem and the natural environment

effects of ice coverage and ice rafted material on sedimentation in the fram strait as little is known about pelagic sedimentation processes in arctic environments1 the interpretation of biological and chemical processes as well as the reconstruction of ancient conditions including those in the glacial north atlantic is difficult here we provide sediment trap results which show that the position of the sea ice boundary significantly influences the particle flux the seasonal variability of the particle flux differed markedly in the various sediment trap sites in fram strait depending on the behaviour of the sea ice under complete ice cover sedimentation is very low whereas maximum sedimentation is found at the ice margin the highest particle flux observed showing a large lithogenic component was observed at the ice edge where the water was warmer 2 c we find that high biogenic opal fluxes are characteristic of the summer ice margin indicating that the sedimentary record of opal fluxes may allow the position of ice margins in the past to be reconstructed

interlaminated ice proximal glacimarine sediments in muir inlet alaska muir inlet in glacier bay alaska is a glacial fjord receiving a tremendous volume of sediment annually the rate of sediment accumulation is greatest proximal to muir glacier about 9 m yr 1 and decreases away from the glacier the primary sediment sources are meltwater streams discharging at subglacial and ice marginal positions to form overflows interflows and underflows continuous turbidity currents overflows and interflows interact with diurnal tidal currents and their volume and sediment concentration varies diurnally and annually with meltwater discharge these effects produce cyclic deposits of a thin fine grained sand or silt lamina that grades normally to a thicker poorly to very poorly sorted mud lamina this lamina couplet is termed a cyclopel underflows are suggested to occur in this glacimarine environment because of conditions unique to subglacial fluvial systems underflow deposits occur only in proximal positions 0 5 km from glacier face and are coarse grained reverse to normal graded and exhibit an increase in sorting and sand content up layer ice rafted debris identified as particles 177 m is ubiquitous though low 5 by weight and occurs as isolated particles frozen pellets or as lenses that in cores may have a lamina appearance proximally ice rafted debris is difficult to identify because proximal sediment is often as coarse grained deposited sediment may be reworked by tidal currents and sediment gravity flows depositional processes operating in muir inlet produce interlaminated sand silt clay that characterizes sediment proximal to a glacier and fines seaward to mud sediment is classified into one of three sediment types 1 1 type i sediment is very fine grained mean 8 65 7 17 o low in sand 0 1 11 2 and very poorly to poorly sorted it is the dominant sediment type in muir inlet and is transported by plumes and deposited by suspension settling 2 2 type ii sediment is fine to coarse grained mean 6 70 3 12 o low to high in sand 5 1 86 6 and very poorly to moderately sorted it represents reworked sediment proximal plume deposits or coarse grained laminae of cyclopels 3 3 type iii sediment is coarse grained mean 3 89 2 38 o high in sand 58 0 100 0 and poorly to well sorted it is deposited by sediment gravity flows or underflows

moisture supply for northern ice sheet growth during the last glacial maximum during the last ice age the barents sea ice sheet began to grow 22 kyr ago1 only 8 kyr before it began to disintegrate2 this implies that the ice must have grown very rapidly from the coast to the edge of the continental shelf such rapid growth of a large ice sheet requires significant amounts of moisture3 but the origin of this moisture has been unclear particularly as the climap climate reconstruction suggests4 5 that the greenland iceland norwegian gin seas were perennially ice covered during this period here we present data from deep sea sediment cores from the fram strait which suggest that relatively warm water from the north atlantic ocean was advected into the gin seas in two short term events 27 22 5 and 19 5 14 5 kyr ago we suggest that the resulting seasonally ice free waters were an important regional moisture source for the barents sea ice sheet and that the gin seas played a much more active role in climate during the last glaciation than has previously been supposed

origin and consequences of cyclic ice rafting in the northeast atlantic ocean during the past 130 000 years deep sea sediment cores recovered from the northeast atlantic ocean were examined in order to elucidate the influence of the earth s orbital parameters on major ice rafting analyses of coarse grained ice rafted debris and planktonic foraminifers revealed a strong reaction to the precession signal since 130 000 yr b p dropstone layers have been deposited each half period of a precessional cycle 11 000 1000 yr ice rafting occurs during times of winter minimum summer maximum insolation and summer minimum winter maximum insolation in the first case high summer insolation forces meltwater discharge from the ice sheets into the polar seas which subsequently enhances formation of sea ice during the winter in the second case growth of continental ice enhances iceberg production which also leads to a salinity reduction of surface seawater both situations result in a southward penetration of polar water thus the marine record of dropstones documents ice rafting not only during weichselian stades but also during cold events within interstades the regularity of ice rafting yields a useful framework to calibrate and elucidate climatic changes not only in the region of the north atlantic ocean but also in remote areas such as the pacific ocean and the antarctic

magnetostratigraphic data from late quaternary sediments from the yermak plateau arctic ocean evidence for four geomagnetic polarity events within the last 170 ka of the brunhes chron summary palaeomagnetic investigations of two sediment cores recovered from rv polarstern near the eastern slope of the yermak plateau sites ps 1533 and ps 2212 reveal convincing evidence for four polarity events of the earth s magnetic field during the last 170 ka a comprehensive rock magnetic study of the sediments proved that fine grained magnetite is the principal carrier of the remanent magnetization no changes in magneto mineralogy across the polarity transitions in the sediments investigated were found calcareous nannofossil biostratigraphy ams 14c accelerated mass spectrometry and oxygen isotope data and 10be and 230th stratigraphies yielded age ranges of 24 29 ka for the mono lake event 34 43 ka for the laschamp event 72 86 ka for the norwegian greenland sea event and 118 128 ka for the blake event two reverse polarity samples at the base of core ps 2212 3 kal are interpreted as the termination of the biwa i event 171 181 ka the events exhibit full inversion of inclination in both cores the data suggest that the transition process of the earth s magnetic field during such polarity events requires some 1 ka

isotopic and hydrochemistry spatial variation of sulfate for groundwater characterization in karstic aquifers the sierra gorda aquifer is one of the most extensive of southern spain the main groundwater discharge is produced at its northern boundary through several high flow springs in this study stable isotopes of dissolved sulfate 34s and 18o and groundwater chemistry were used to determine the origin of the sulfate and to characterize the groundwater flow we sampled the main springs as well as other minor outlets related to perched water tables in order to determine the different sources of so42 e g dissolution of evaporites atmospheric deposition etc the substantial difference in the amount of dissolved so42 between the springs located in its northwestern part 25 mg l and those elsewhere in the northern part 60 mg l suggests zones with separate groundwater flow systems a third group of springs far from the northeastern boundary of the permeable outcrops shows higher so42 content than the rest 125 mg l the isotopic range of sulfate 0 3 to 14 82 v ctd points to several sources including dissolution of triassic or miocene evaporites atmospheric deposition and decomposition of organic material in the soil among these the dissolution of triassic gypsum which overlies the saturated zone as a consequence of the folds and faults that deform the aquifer is the main source of so42 range from 12 79 to 14 82 v ctd this range is typical for triassic gypsum the higher karstification in the western sector together with important differences in the saturated thickness between the western and eastern sectors would also be due to the tectonic structure and could explain the difference in so42 contents in the water this singular arrangement may cause a higher residence time of groundwater in the eastern sector thus a higher contact time with triassic evaporitic rocks is inferred accordingly the stable isotopes of so42 are found to be a valuable tool for identifying areas with different flow systems in the saturated zone of karstic aquifers as well as for evaluating aspects such as the degree of karstification

inception of the northern european ice sheet due to contrasting ocean and insolation forcing about 115 000 yr ago the last interglacial reached its terminus and nucleation of new ice sheet growth was initiated evidence from the northernmost nordic seas indicate that the inception of the last glacial was related to an intensification of the atlantic meridional overturning circulation amoc in its northern limb the enhanced amoc combined with minimum northern hemisphere insolation introduced a strong sea land thermal gradient that together with a strong wintertime latitudinal insolation gradient increased the storminess and moisture transport to the high northern european latitudes at a time when the northern hemisphere summer insolation approached its minimum

the timing of sulfide segregation in a variscan synorogenic gabbroic layered intrusion beja portugal implications for ni cu pge exploration in orogenic settings abstract a growing number of magmatic ni cu sulfide deposits discovered in orogenic environments has renewed the interest on this category and reinforced that most orogenic mafic magmas are pge depleted the beja layered gabbroic sequence lgs was emplaced during the same variscan tectono magmatic event as the aguablanca ni cu pge deposit in spain however no economic mineralization was yet found in lgs here we analyze three sulfide ore showings developed within different environments of lgs that provide a unique frame to assess sulfide segregation in orogenic mafic magmas the internal sulfides hosted at the core of the layered suite the marginal sulfides located at a complex domain where the lgs is intruded by late magmatic anorthosite tonalite trondhjemite att suite and the sulfide veins associated to late magmatic hydrothermal activity for this we performed detailed mineralogical electron probe micro analysis enabling to assess s2 t for sulfide equilibrium whole rock and isotopic sulfur and lead geochemistry for the sulfide occurrences which are further supported by a wide data set available for lgs and related mesocratic suites the internal sulfides developed under low sulfidation non dynamic magmatic conditions similar to those of the accessory sulfides in lgs gabbros they segregated from chalcophile depleted melts at the end of a crystal fractionation cycle without contribution from external sulfur the marginal sulfides have a pyrite bearing magmatic sulfide assemblage hosted in exceptionally coarse grained clinopyroxenites at the lgs sw border the metal poor sulfide veins occur within a metasomatic halo adjoining amphibole albite pegmatoid dykes the latter two sulfide types share geochemical affinities and represent late magmatic systems developed during uplift and intrusion by evolved lower crustal contaminated magmas the marginal sulfides are mafic precursors of the coeval magmatic hydrothermal system to which pegmatoid dykes and sulfide veins are related although estimated primary pge abundances for lgs magmas are within the range of morbs all sulfide types derived from pge ni depleted melts due to sulfide segregation during underplating the presence of deep crustal faults that prevent magma stalling and sulfide saturation at depth is paramount to generate orogenic magmatic sulfide deposits of economic value

gypsum karst sivas turkey the gypsum karst units which are spread over a large area in the vicinity of sivas and especially in the east of sivas are presumed to be of miocene age geomorphological features include numerous collapse dolines the seyfe and goydun springs have high discharge rates of water of unsuitable quality ec 13 000 mho cm lakes are formed in the collapsed gypsum areas and the water quality of these lakes is poor hafik lake todurge lake western lota lake eastern lota lake etc the water quality of the kizilirmak river part of which is in this region is not good enough for drinking water or irrigation

correlation of the eemian and the weichselian with deep sea oxygen isotope stratigraphy abstract the eemian interglacial was defined in the netherlands and is correlated all over northern europe it is now demonstrated that the eemian was the last interglacial in europe thus it is obvious that it should correlate with either the entire stage 5 in the deep sea oxygen isotope stratigraphy or with parts of stage 5 several observations prove that the eemian correlates with substage 5e the two other peaks in stage 5 correlates with the warm interstadials brorup and odderade in northern europe

hydrochemistry and solution rates in gypsum karst case study from the western ukraine the gypsum karst in the western ukraine spreads through a large territory covering more than 20 000 km2 and is represented by a range of stages evolutionary types from deep seated through subjacent to entrenched correspondingly hydrogeological settings of karst development circulation patterns and chemical characteristics of groundwaters differ substantially between the respective areas based on 1 800 analyses this paper summarises hydrochemistry of the gypsum hosting miocene aquifer the majority of sampling has been performed in conjunction with a study regime of gypsum solution rates by means of standard tablets in this study which included 53 tablet stations representing varying conditions of water rock interaction 644 weight loss measurements were made over the period 1984 1992 the highest rates are characteristic of entrenched karst although active dissolution is localised along well defined sinking streams with short underground courses rare vertical percolation paths and the water table lower but still quite substantial rates are characteristic of subjacent and deep seated confined karst however the overall dissolution removal is greater due to higher flow through the gypsum and the larger area of rock solvent contact the results are generalised in order to derive the approximate solution rates characterising major situations and to be suitable for modeling purposes

pliocene pleistocene ice rafting history and cyclicity in the nordic seas during the last 3 5 myr a continuous 3 5 myr ird record was produced from ocean drilling program odp site 907 a timescale based on magnetic polarity chrons oxygen isotope stratigraphy for the last 1myr and orbital tuning was developed the record documents a stepwise inception of large scale glacial cycles in the nordic seas region the first being a marked expansion of the greenland ice sheet at 3 3 ma a second step occurred at 2 74 ma by an expansion of large scale ice sheets in the northern hemisphere ice sheet variability around the nordic seas was tightly coupled to global ice volume over the past 3 3 myr between 3 and 1 ma most of the variance of the ird signal is in the 41 kyr band whereas the last 1 myr is characterized by stronger 100 kyr variance the gamma ray porosity evaluator grape density record is closely linked with ird variations and documents sub orbital variability resembling the late quaternary heinrich bond cycles

sediments in arctic sea ice implications for entrainment transport and release despite the arctic sea ice cover s recognized sensitivity to environmental change the role of sediment inclusions in lowering ice albedo and affecting ice ablation is poorly understood sea ice sediment inclusions were studied in the central arctic ocean during the arctic 91 expedition and in the laptev sea east siberian arctic region expedition 1992 results from these investigations are here combined with previous studies performed in major areas of ice ablation and the southern central arctic ocean this study documents the regional distribution and composition of particle laden ice investigates and evaluates processes by which sediment is incorporated into the ice cover and identifies transport paths and probable depositional centers for the released sediment in april 1992 sea ice in the laptev sea was relatively clean the sediment occasionally observed was distributed diffusely over the entire ice column forming turbid ice observations indicate that frazil and anchor ice formation occurring in a large coastal polynya provide a main mechanism for sediment entrainment in the central arctic ocean sediments are concentrated in layers within or at the surface of ice floes due to melting and refreezing processes the surface sediment accumulation in central arctic multi year sea ice exceeds by far the amounts observed in first year ice from the laptev sea in april 1992 sea ice sediments are generally fine grained although coarse sediments and stones up to 5 cm in diameter are observed component analysis indicates that quartz and clay minerals are the main terrigenous sediment particles the biogenous components namely shells of pelecypods and benthic foraminiferal tests point to a shallow benthic marine source area apparently sediment inclusions were resuspended from shelf areas before and incorporated into the sea ice by suspension freezing clay mineralogy of ice rafted sediments provides information on potential source areas a smectite maximum in sea ice sediment samples repeatedly occurred between 81 n and 83 n along the arctic 91 transect indicating a rather stable and narrow smectite rich ice drift stream of the transpolar drift the smectite concentrations are comparable to those found in both laptev sea shelf sediments and anchor ice sediments pointing to this sea as a potential source area for sea ice sediments in the central arctic ocean sea ice clay mineralogy is significantly different from deep sea clay mineral distribution patterns the contribution of sea ice sediments to the deep sea is apparently diluted by sedimentary material provided by other transport mechanisms

distribution of large emiliania huxleyi in the central and northeast atlantic as a tracer of surface ocean dynamics during the last 25 000 years the coccolithophore species emiliania huxleyi is characterized by a wide range of sizes which can be easily distinguished in the light microscope in this study we have quantified the abundance of

late eemian warming in the nordic seas as seen in proxy data and climate models 1 we analyze a transient simulation of the last glacial inception in a climate model of intermediate complexity focusing on sea ice ocean circulation dynamics in the north atlantic and nordic seas as northern high latitude summer insolation decreases toward the end of the eemian interglacial arctic sea ice export to the north atlantic increases this surface fresh water transport weakens deep water formation in the north atlantic and the near surface circulation of the subpolar gyre as a consequence the relative contribution of subpolar gyre waters to the atlantic inflow into the nordic seas is reduced giving way to more warm and saline subtropical waters from the north atlantic current we thus find an episode of relatively high heat and salt transport into the nordic seas during the last glacial inception between 119 000 and 115 000 years before present this stabilizes deep ocean convection in the region and warms scandinavia during a phase of low insolation these findings are in good agreement with proxy data from the nordic seas and north atlantic at the end of the warm interval sea surface temperature drops by about 3 c marking the onset of large scale glacier growth over scandinavia

patterns of ice rafted detritus in the glacial north atlantic 40 55 n the observation by heinrich 1988 that during the last glacial period much of the input of ice rafted detritus to the north atlantic sediments may have occurred as a succession of catastrophic events rekindled interest on the history of the northern ice sheets over the last glacial period in this paper we present a rapid method to study the distribution of these events both in space and time using whole core low field magnetic susceptibility we report on approximately 20 cores covering the last 150 to 250 kyr well defined patterns of ice rafted detritus appear during periods of large continental ice sheet extent although these are not always associated within their maxima most of the events may be traced across the north atlantic ocean for the six most recent heinrich layers hl two distinct patterns exist hl1 hl2 hl4 hl5 are distributed along the northern boundary of the glacial polar front over most of the north atlantic between 40 and 50 n hl3 is more restricted to the central and eastern part of the northern atlantic the nd sr isotopic composition of the material constituting different heinrich events indicates the different provenance of the two patterns hl3 has a typical scandinavia arctic icelandic young crust signature and the others have a large component of northern quebec and northern west greenland old crust material these isotopic results obtained on core su 9008 from the north american basin are in agreement with the study by jantschik and huon 1992 who used k ar dating of silt and clay size fractions of an eastern basin core me 68 89 these data confirm the large spatial scale of these events and the enormous amount of ice rafted detritus they represent

hydrochemical evaluation of groundwater quality in the cavuscayi basin sungurlu corum turkey the purpose of this study is to investigate the quality and usage possibility of groundwater in the cavuscayi basin and suggest the best water structure for the groundwater use results from hydrochemical analyses reveal that groundwater is mostly affected by salty na cl waters of the incik formation and brackish ca2 mg2 so 4 2 waters of the bayindir formation the alibaba saltpan discharged 2 l s from the incik formation is used for salt production in the basin salinity risk increases with depth and along the groundwater flow direction therefore shallow water and trenches opened in the alluvium aquifer at the east of the basin were determined to yield suitable water with no na and cl contamination following the heavy rainy period waters of less salinity and conductivity are possibly used for agriculture

a stratigraphic study of late quaternary sediments on the voring plateau eastern norwegian sea abstract four gravity cores from the voring plateau west of the nordland coast in northern norway have been studied about 250 000 yrs of continuous hemipelagic sedimentation is represented in the cores this period has been divided into seven lithostratigraphic units and four planktonic foraminiferal assemblage zones to improve the reliability and precision of the isotopic stratigraphy a graphic comparison with several isotopic records previously described in the literature has been performed a taxonomy of 36 isotopic events is established following prell s technique the majority of these events seem to be recognizable in the isotopic records from the norwegian sea during the glacial stages however several local events are caused by influxes of isotopically light meltwater comparisons between the records indicate a general trend toward decreasing sedimentation rates with increasing distance from the continental margins for isotope stages 2 3 4 and 6 only small variations in sedimentation rates are observed during stages 5 and 7 comparisons with the land based stratigraphy of northwest europe indicate that the main glacials and interglacials as well as the fana and the torvaldstad interstadials are recognizable in the marine sequences correlations to the bolling and allerod interstadials and the younger dryas stadial is obscured by a period of rapid influx of meltwater at about 15 14 ka followed by a period of high influx of clastic material

last interglacial surface water conditions in the eastern nordic seas inferred from dinocyst and foraminiferal assemblages marine sediments from the voring plateau norwegian sea have been studied for their dinoflagellate cyst dinocyst and foraminiferal content in order to reconstruct sea surface conditions in the eastern norwegian sea during marine isotope stage mis 5e in combination with stable oxygen isotope and ice rafted detritus ird data the variations in foraminiferal and dinocyst assemblage composition reflect a stepwise transition from the final phase of deglaciation termination ii into typical interglacial conditions this stepwise change is repeated subsequently during the cooling conditions of glacial inception towards mis 5d the interval studied is characterized by relatively high abundances of bitectatodinium tepikiense in comparison to present day values in the area indicating a larger seasonal temperature amplitude with enhanced surface water stratification during mis 5e the important occurrence of the warm temperate dinocyst spiniferites mirabilis s l concurrent with subpolar foraminifers turborotalita quinqueloba globigerina bulloides and globigerinita glutinata reveals that most pronounced interglacial marine conditions prevailed in the area just prior to the transition towards mis 5d the late stratigraphic position of this phase in the interglacial is verified by comparison with dinocyst data from south of iceland manifesting its over regional implication besides the good agreement in dinocyst and foraminiferal assemblage changes the variations in and between both fossil assemblages also point to the existence of some significant surface water variability in the eastern norwegian sea during mis 5e

aminostratigraphy of european marine interglacial deposits molluscan fossils collected from shallow water marine sediment across nw europe and nearby arctic regions have been analysed for the extent of isoleucine epimerization dl ratio in indigenous protein residues the dl ratios confirm that essentially all classical eemian sites from nw europe are of the same age and are correlative with the type locality near amersfoort in the netherlands shells from interglacial marine sediment beneath the type weichselian till in poland also correlate with the type eemian site dl ratios in holsteinian marine shells 0 29 are substantially higher than in their eemian counterparts 0 17 late cromerian shells yield even higher ratios 0 46 dl ratios in late glacial shells 0 06 and middle weichselian shells 0 09 permit differentiation from modern 0 01 and last interglacial material based on the position of the matuyama brunhes boundary and the differences in dl ratios the eemian must correlate with isotope substage 5e whereas the holsteinian is most likely substage 7c possibly stage 9 but certainly younger than stage 11 intra saalian warm periods may be terrestrial equivalents of the younger substages of stage 7 extensive pre eemian marine sediments along the sw coast of denmark previously correlated with the holsteinian are shown to be of late cromerian age the underlying till there is the first widespread evidence of a pre elsterian till in nw europe dl ratios in molluscs from last interglacial sites along the arctic coast of the ussr the arctic islands and eastern greenland are substantially lower than in their european counterparts due to their low thermal histories the combined mid and high latitude data are used to develop a predictive model for the expected dl ratio in any of several moderate epimerization rate taxa for last interglacial sites with mean temperatures between 20 and 15 c not all sites could be unambiguously assigned to an established interglacial the fjosanger norway and margareteberg sweden sites previously thought to be eemian yield dl ratios higher than in secure nearby eemian material it is yet unresolved whether these are aberrant sites or if they predate the last interglacial in situ shoreline deposits encountered in borings in sw belgium and in exposures on the belgium coastal plain contain molluscs that yield dl ratios intermediate between secure eemian and late weichselian ratios raising the possibility that a late stage 5 high sea level event attained near modern levels in the southern north sea basin resolution of these uncertainties is the focus of future work

reflection of scandinavian ice sheet fluctuations in norwegian sea sediments during the past 150 000 years the record of glacier fluctuations in western scandinavia as reconstructed from continental data has been correlated with records of ice rafted detritus ird from well dated sediment cores from the norwegian sea covering the past 150 000 yr b p the input of ird into the ocean is used as a proxy for ice sheet advances onto the shelf and thus for the calibration of a glaciation curve the marine results generally support land based reconstructions of glacier fluctuations and improve the time control on glacial advances the saalian ice sheet decayed very rapidly approximately 125 000 yr b p in the early weichselian a minor but significant ird maximum indicates the presence of icebergs in isotope substage 5b especially between 95 000 and 83 000 yr b p reduced amounts of calcareous nannofossils indicate that surface waters were influenced by meltwater discharges during isotope substages 5d and 5b an extensive build up of inland ice began again during isotope stage 4 but maximum glaciation was reached only in early stage 3 58 000 53 000 yr b p marine sediments have minimum carbonate content indicating strong dilution by lithogenic ice rafted material generally the ird accumulation rate was considerably higher in stages 4 2 than in stage 5 a marked peak in ird accumulation rates from 47 000 to 43 000 yr b p correlates well with a second middle weichselian ice sheet advance dated by the laschamp olby paleomagnetic event minimum ice extent during the alesund interstade 38 500 32 500 yr b p and several glacial oscillations during the late weichselian are also seen in the ird record of several late weichselian glacial oscillations on the shelf at least four correspond to the north atlantic heinrich events ice sheet behavior was either coupled or linked by external forcing during these events whereas internal ice sheet mechanisms may account for the noncoherent fluctuations

linking physical property records of quaternary sediments to heinrich events ice rafted debris in high latitude ocean sediments represent a complex record of the changing paleoenvironment of the oceans and in particular of the growth and decay of ice sheets along the margins of high latitudes physical properties measured on sediment cores taken from the rockall plateau were examined to determine the distribution of ice rafted debris layers and heinrich events in the northeastern north atlantic these sediment core records may provide one of the keys to reconstruct the iceberg flow between the northeastern atlantic and the norwegian sea magnetic susceptibility ms and gamma ray attenuation porosity evaluator grape density changes of these cores revealed that since about 65 ka dropstone layers are recorded in both ms and grape data of rockall plateau sediments rockall plateau sediments show peaks in physical properties that correlate with heinrich events h1 h2 h4 h5 h6 heinrich layer 3 was not observed the stratigraphy and physical properties represent the heinrich layers h1 14 15 ka ms 52 cgs 1 64 g cm3 h2 23 ka ms 64 cgs 1 8 g cm3 h4 41 ka ms 53 cgs 1 75 g cm3 h5 50 ka ms 53 cgs 1 75 g cm3 h6 64 ka ms 100 cgs 1 69 g cm3 heinrich events at rockall plateau sites point to a northward flow of icebergs in the northeastern atlantic which may indicate a flow pattern to regions north of 54 n

late quaternary stage 2 and 3 meltwater and heinrich events northwest labrador sea two major meltwater events are documented in cores from the nw labrador sea one occurred ca 20 000 14c yr b p in association with deposition of a major detrital carbonate unit both prior to and after this event 18o values of near surface planktonic foraminifera were 4 5 indicating fully enriched glacial values a younger event ca 14 000 14 c yr b p is characterized by a dramatic change in 18o from 4 5 to 2 0 and coincided with the retreat of ice from the outer se baffin shelf possibly into hudson strait these meltwater events coincide with heinrich h layers 1 and 2 from north atlantic sediments the 14 000 14c yr b p meltwater event indicates that the eastern margin of the laurentide ice sheet also underwent rapid retreat at approximately the same time as other ice sheet margins around the ne north atlantic a third major detrital carbonate event at the base of hu87 033 009 possibly correlative with heinrich layer 3 occurred ca 33 960 675 14 c yr b p however this is older than the accepted date for h 3 of 27 000 14c yr b p and may be h 4

late quaternary calcium carbonate sedimentation and terrigenous input along the east greenland continental margin nine large box cores collected in the western greenland iceland norwegian gin sea were analyzed for calcium carbonate content and coarse fraction components stratigraphic control is based on oxygen isotope records performed on four of the cores all cores were correlated using oxygen and carbon isotope data fluctuations in calcium carbonate content coarse terrigenous particle content and volcanic ash beds glacial and interglacial cycles are documented by a number of terrigenous particle events and differentiated calcium carbonate production which can be correlated to major paleoceanographic and paleoclimatic shifts in the older core sections extensive deposition of ice rafted detritus ird persisted until about oxygen isotope stage 9 and document a relatively stable environment in this area strongly influenced by cold surface water masses the following interval was characterized by variations in the general surface water circulation pattern although high amounts of ird are still present in iceland sea sediments pronounced shifts in terrigenous input and pelagic carbonate records were identified close to the oxygen isotope stage full size image 1 k and full size image 1 k boundaries indicating massive melting of icebergs in the western gin sea these enormous inputs of debris were followed by an increase in calcium carbonate production caused by maximum intrusion of warm atlantic surface waters relatively high calcium carbonate contents also show that only little dilution by fine grained material and a minimum of ice melting occurred during these warm phases during oxygen isotope stage 5 conditions were more uniform indicating a less pronounced westward penetration of atlantic waters as compared to the holocene the last glacial stages 4 2 is characterized by the occurrence of heinrich like events although high ird contents were present throughout this interval a distinct contrast between the northernmost cores and the cores in the south is indicative of a rather strong westward penetration of atlantic water in the north and of an area dominated by cold water east of the kolbeinsey ridge during the holocene however conditions west of jan mayen seem to have remained constantly dominated by cold surface waters throughout the whole time investigated

the decay of the barents ice sheet as documented in nordic seas ice rafted debris abstract a large marine based ice sheet that covered the barents sea and svalbard during the height of the weichselian glaciation began to disintegrate at 15 ka the decay produced enormous quantities of icebergs that drifted parallel to the norwegian continental margin southward and northwestward into the fram strait this drifttrack is reflected by a trace of ice rafted clastic sedimentary rocks from the bottom of the barents sea in deep sea sediments of the norwegian sea and the fram strait the petrographic composition of ice rafted lithic particles dropstones 0 5 mm in late quaternary 20 ka recent deep sea sediments of the norwegian greenland sea was analyzed in order to determine the source areas of the dropstones the dropstone provenance was deciphered from the regional distribution of some precisely defined lithotypes during the maximum glaciation between 20 and 15 ka the norwegian sea received crystalline rocks primarily from western norway but also from svalbard and the northwestern british isles the greenland sea was supplied with clay silt and sandstones from central and northern east greenland and rocks from circum arctic areas at 15 ka a dramatic shift in provenance from crystalline rocks to clastic sedimentary rocks is recorded in the dropstone composition of the northern and eastern norwegian sea this impulse was the ultimate result of the deterioration of the barents ice sheet the dispersal area of clastic rock fragments reaches from the barents shelf between 72 and 76 n and 15 and 20 e to the voring plateau eastern norwegian sea at 67 n and 5 e the main direction of iceberg drift was to the south and southeast after an initial period of only 500 years duration and extremely high dropstone deposition rates the influx from the barents shelf ceased and gradually changed into the modern surface current system

kinematic and structural development of the cankiri basin central anatolia turkey a paleostress inversion study three different deformation phases have been recognized in the southern part of the cankiri basin from 1 the major structures and 2 through using paleostress inversion techniques for fault slip data the deformation phases recognized from the paleostress data are correlated with those recognized from the major structures and dated accordingly the first phase occurred in the late paleocene to pre burdigalian and is characterized by an oblique r2 and nne ssw to ne sw trending subhorizontal r1 and wnw ese to nw se trending r3 patterns which indicate transcurrent deformation associated with a combination of thrusting and strike slip faulting transpression possibly due to indentation of the kirsehir block to the sakarya continent the second phase occurred from the burdigalian to the serravallian and is characterized by a subvertical r1 and oblique r2 and r3 which indicate oblique extension associated with normal faulting possibly due to a post orogenic collapse the third deformation phase is characterized by a vertical r2 while the other stresses were horizontal which indicate regional transcurrent tectonics which is correlated with the current transcurrent tectonics controlled by the north anatolian fault zone d 2003 elsevier science b v all rights reserved

glacimarine processes and inductive lithofacies modelling of ice shelf and tidewater glacier sediments based on quaternary examples abstract three variables control the type of glacial debris source and where and when debris is introduced to an ocean 1 type of glacial ice source ice sheet or valley glacier 2 condition of a grounded glacier melting freezing or frozen base and cold or warm internal ice and 3 type of glacier front ice shelf or tidewater using these variables in different combinations eight glacimarine regimes are postulated to exist by integrating information from holocene sediment and pleistocene glacimarine sequences with the eight inductive regimes lithofacies relationships are predicted and modelled the models show a complexity of glacimarine lithofacies the importance of recognizing this complexity lies in realistic interpretations of ancient sequences ice shelf sediment may be limited in the geologic record because of tectonic and climatic constraints required for ice shelf formation alternatively in some tidewater glacier regimes larger volumes of glacimarine sediment are produced than in ice shelf regimes ice proximal sediment is distinctive especially near subglacial meltwater stream effluxes ice shelves and tidewater glaciers may produce similar ice proximal lithofacies e g morainal bank associations and laminites in certain regimes however details of lithofacies may aid in distinguishing ice shelf from tidewater regimes ice shelf and tidewater iceberg zone sediment can be distinguished from each other if basal and high level englacial debris can be distinguished ice shelf zone sediment out from the grounding line has a basal debris source high level englacial debris is deposited in more distal ice shelf zones resulting in sediment by pass in corresponding positions of a tidewater glacier regime iceberg rafted debris comprises mixed basal and high level englacial debris deeper water zones receive large volumes of sediment when a melting freezing base grounding line is at the edge of a continental shelf when the grounding line retreats sediment supply may be drastically reduced because of a back sloping continental shelf and trapping by morainal banks cool water bioclastic carbonates may accumulate once a grounding line has retreated although ice shelf iceberg zones are more extensive than those in tidewater regimes ice shelf icebergs have low debris content and resulting ice rafted debris may be scarce the smallest volume of sediment is produced by a frozen base ice sheet ending as a tidewater front and the largest volume by a melting freezing base valley tidewater glacier glacimarine sediment has a relatively high preservation potential near continental interiors or margins however at continental margins mass flow olistostrome and tectonic melange deposits may be preserved with glacimarine diamictites these deposits may be difficult to distinguish from each other especially if metamorphosed such as at a convergent margin the models presented do not fully represent the glacimarine environment because many other variables are omitted however the principal concepts of generating glacimarine lithofacies associations are considered continued research will verify if each regime exists and will provide data on those regimes that exist today to compare and modify these models

geological and environmental implications of the evaporite karst in spain in spain evaporite outcrops cover approximately 7 of the total area of the country most of the evaporitic formations are made up of ca sulfates gypsum anhydrite or ca sulfates and halite certain paleogene marine evaporites also contain k mg chlorides and some tertiary continental formations bear substantial amounts of na sulfates in the subsurface glauberite and thenardite mesozoic evaporitic formations commonly wedge out towards the ground surface passing into condensed sequences and dissolution collapse breccias some of these highly porous breccias constitute major regional aquifers in several areas interstratal karstification of the evaporites has given rise to gravitational deformations such as basin structures monoclines and collapse structures covering several square kilometers that record a cumulative subsidence in excess of 200 m teruel and calatayud grabens a widespread consequence of evaporite dissolution processes in spain is the hydrochemical degradation of surface waters some of the largest and most outstanding lake systems from an environmental perspective occur in karstic depressions developed in evaporitic formations fuente de piedra gallocanta bujaraloz and banolas lakes sinkhole activity is a major geohazard in several evaporite karst areas the sinkhole risk has a particularly high impact in sectors where tertiary evaporites are overlain by quaternary alluvial aquifers calatayud zaragoza and madrid areas some of the detrimental effects of subsidence include severe damage to historical monuments calatayud the demolition of a whole village puilatos or the derailment of a freight train zaragoza area the deepest gypsum caves are found in triassic diapiric structures el sumidor cave 210 m deep and the longest ones are developed in horizontally lying neogene sequences sorbas caves and estremera maze cave the cardona diapir hosts salt caves up to 4 300 m long whose genesis is related to flooding of mine galleries caused by the interception of a phreatic conduit the main anthropogenic impacts on the endokarstic systems are related to the disposal of wastewaters and the destruction of caves by quarrying the fluvial valleys that cross tertiary evaporitic outcrops commonly show peculiar geological characteristics related to dissolution induced synsedimentary subsidence phenomena 1 thickened alluvium filling dissolution basins up to several tens of kilometers long and more than 100 m deep the largest thickenings are found in areas where the bedrock contains halite and glauberite 2 superimposed alluvial units locally bounded by angular unconformities 3 abundant deformational structures and paleosinkholes related to the rockhead and or interstratal karstification of the substratum these fluvial valleys typically are flanked by a prominent gypsum escarpment rock falls favored by the dissolutional enlargement of joints derived from these scarps are the type of mass movement which has caused the highest number of casualties in spain

arctic ocean deep sea record of northern eurasian ice sheet history the sediment composition of deep sea cores from the central arctic ocean the fram strait and the yermak plateau was analyzed for several parameters to reconstruct the history of marine paleoenvironment and terrestrial glaciation in the last 200 000 years layers with high amounts of coarse terrigenous ice rafted debris ird and often high contents of smectite were deposited during extensive glaciations in northern eurasia when ice sheets reached the northern continental margins of the barents and kara seas and discharged icebergs into the arctic ocean intercalated layers with relatively low ird and smectite contents but abundant planktic foraminifers in the coarse fraction were deposited during periods of atlantic water inflow to the arctic ocean and seasonally open waters leads in a sea ice cover with only few icebergs in the arctic ocean high ird contents in the sediments reflect the presence of ice sheets on the kara and barents seas shelves and the hinterland during the entire oxygen isotope stage 6 ca 190 130 ka in substage 5b ca 90 80 ka at the stage boundary 5 4 around 75 ka and in late stage 4 early stage 3 ca 65 50 ka these results are in excellent correlation with those from recent field work in northern scandinavia european russia siberia and on the shelves relatively low amounts of ird in central arctic ocean sediments from the late weichselian glacial maximum ca 24 18 ka correlate well with the recent reconstruction of a very limited eastern ice sheet extension during this time oxygen and carbon isotope records of planktic foraminifers from the analyzed sediment cores show a number of prominent excursions which can be interpreted as evidence for freshwater events in the arctic ocean the synchroneity of freshwater events and ird input suggests a common source strongest events were associated with deglaciations of the barents and kara seas after the ice sheets had blocked the outflow of large rivers for several millennia the outflow of freshwater from large ice dammed lakes occurred at ca 130 80 75 and 52 ka freshwater events in the central arctic ocean during the last deglaciation ca 18 ka were relatively small compared to the previous events this indicates that during most of the late weichselian glacial maximum a river outflow from northern siberia to the arctic ocean was possible atlantic water inflow to the arctic ocean and seasonally open waters in the ice leads occurred during the interglacials ofoxygen isotope stage 1 and substage 5e during several interstadials stage 3 substages 5a and 5c and to a lesser degree within stadials and glacials stages 2 4 and 6 with the exception ofthe interglacials these periods were times ofstrong ice growth on the continents as revealed by terrestrial data the coincidence suggests that open waters in the arctic ocean and the nordic seas were an important moisture source in addition to more southerly sources which fostered the growth of ice sheets on northern eurasia

changes in the oceanic 13c 12c ratio during the last 140 000 years high latitude surface water records detailed records of the carbon and oxygen isotopic ratios of neogloboquadrina pachyderma are compared between nine high latitude sediment cores from the northern and southern hemispheres covering the last 140 000 yrs the strong analogies between the 13c records permit to define a 13c stratigraphic scale with three clear cut transitions simultaneous with the oxygen isotopic transitions 65 125 kyrs 54 65 kyrs and 21 13 kyrs the 13c records of n pachyderma in the high latitude cores which follow the changes in 13c of the surface water tco2 near areas of deep water formation present trends similar to the benthic foraminifera 13c records in cores v19 30 and m12 392 although amplitudes of the isotopic shifts are different this implies that a large part of the observed variations represents global changes in the carbon distribution between biosphere and ocean the 13c12c ratios of n pachyderma in the north atlantic cores display larger regional variations at 18 kyrs b p than at present to explain these differences we have plotted the 18 kyrs b p 13c values of n pachyderma from 17 cores distributed n of 40 n comparison with published surface water temperature distribution at 18 kyrs b p indicates that a strong divergent cyclonic cell centered approximatively 55 n and 15 w was active during most of the last ice age maximum this hydrology analogous to the present weddell sea explains the published evidences of bottom water formation if located on the northern flank of the gyre and the strong polar front on the southern flank probable location of intermediate water formation

the last interglacial glacial cycle in denmark abstract the stratigraphy of late pleistocene interglacial interstadial and stadial deposits in denmark shows radical alternation of marine and terrestrial environments within the last interglacial glacial cycle isotope stages 6 2 climatically dependent environmental changes eustatic and isostatic responses combined with the advance and retreat of glaciers are elements in a chronostratigraphic model for sw scandinavia the late saalian borglum margreteberg interstade isotope stage 6 was characterized by arctic to boreo arctic marine conditions and tundra vegetation the eemian interglaciation isotope substage 5e reflects high sea levels with boreo lusitanian marine faunas and dense temperate forests in the early weichselian brorup interstade isotope substage 5c boreal to boreo arctic seas with relatively low water level prevailed along with open forest vegetation the middle weichselian commenced with arctic seas accompanied by ice rafting and followed by major glacier cover possibly reaching eastern denmark karmoy ristinge goteborg i stade isotope stage 4 the bo older dosebacka hirtshals interstade isotope stage 3 witnessed boreo arctic conditions with ice rafting and the establishment of a park tundra vegetation during the later jaeren goteborg ii vennebjerg stade isotope stage 3 shelf ice appeared in high arctic kattegat and skagerrak along with surging glaciers in the baltic the middle weichselian isotope stage 3 ended with the sandnes mon gardslov interstade park tundra and boreo arctic seas prevailed the late weichselian jylland stade isotope stage 2 comprises complex stadial conditions with glacier advance and retreat the jylland stade peaked with the maximum extension of weichselian glaciers along the main stationary line equivalent to the frankfurt poznan glacial stage on the north european continent

evidence for a steeper eemian than holocene sea surface temperature gradient between arctic and sub arctic regions sediment proxy data from the norwegian greenland and iceland seas nordic seas are presented to evaluate surface water temperature sst differences between holocene and eemian times and to deduce from these data the particular mode of surface water circulation records from planktic foraminiferal assemblages caco3 content oxygen isotopes of foraminifera and iceberg rafted debris form the main basis of interpretation all results indicate for the eemian comparatively cooler northern nordic seas than for the holocene due to a reduction in the northwardly flow of atlantic surface water towards fram strait and the arctic ocean therefore the cold polar water flow from the arctic ocean was less influencial in the southwestern nordic seas during this time as can be further deduced from the eemian data slightly higher eemian ssts are interpreted for the western iceland sea compared to the norwegian sea ca south of 70 n this eemian situation is in contrast to the holocene when the main mass of warmest atlantic surface water flows along the norwegian continental margin northwards and into the arctic ocean thus a moderate northwardly decrease in sst is observed in the eastern nordic seas for this time causing a meridional transfer in ocean heat due to this distribution in ssts the holocene is dominated by a meridional circulation pattern the interpretation of the eemian data imply a dominantly zonal surface water circulation with a steep meridional gradient in ssts

evidence for delayed poleward expansion of north atlantic surface waters during the last interglacial mis 5e the last interglacial marine isotopic stage or mis 5e surface ocean heat flux from the rockall basin ne atlantic towards the arctic ocean was reconstructed by analysing dinoflagellate cyst dinocyst assemblages in four sediment cores together with records of stable isotopes and ice rafted detritus the assemblage data reflect the northward retreat of ice berg laden waters and the gradual development towards interglacial conditions at the transition from the saalian deglaciation termination ii into mis 5e at the rockall basin this onset of the last interglacial is soon followed by the appearance of the thermophilic dinocyst species spiniferites mirabilis with relative abundances higher than those observed at present in the area north of the iceland scotland ridge however s mirabilis only appears in significant numbers during late mis 5e between not vert similar118 and 116 5 ka hence fully marine last interglacial conditions with most intense atlantic surface water influence occurred during late mis 5e in the nordic seas and consequently also farther north in the arctic ocean and at times when northern hemisphere summer insolation was already significantly decreased the stratigraphic position of this late interglacial optimum is supported by planktic foraminifers and contrasts with the timing of the early holocene climatic optimum in this area we interpret the delayed northward expansion of atlantic waters towards the polar latitudes as a result of the saalian ice sheet deglaciation and its specific impact on the subsequent water mass evolution in this region

platinum group elements in svecokarelian nickel copper deposits finland platinum group elements and au have been analyzed from five finnish ni cu occurrences kotalahti vammala laukunkangas hitura and petolahti from a layered mafic intrusion in northern finland siika kaemae and from several weakly mineralized ultramafic bodies in lapland platinum group element values recalculated to 100 percent sulfide are slightly higher for rh pt and pd in the kotalahti deposit pd 72 ppb pd ir 22 6 than in laukunkangas pd 29 ppb pd ir 9 1 and in vammala pd 25 ppb pd ir 9 7 which exhibits the lowest platinum group element values of the ni cu occurrences analyzed the ultramafic hosted hitura deposit with a flat chondrite normalized distribution platinum group element pattern has a platinum group element concentration 20 to 40 times higher than those in laukunkangas and vammala the nickel deposit of petolahti pd 813 ppb in a postsvecokarelian diabase dike has platinum group element values close to those of hitura pd 750 ppb but the pd ir ratio of hitura 4 66 is much lower than that of petolahti 59 7 the slope of the platinum group element distribution pattern for siika kaemae is steep and the deposit has the highest concentrations analyzed in this study pt and pd being up to 656 and 1 790 ppm respectively recalculated to 100 percent sulfides the platinum group element values of the weakly mineralized ultramafic bodies of lapland are very low all well below the values reported from laukunkangas and vammala the hitura type ultramafic intrusion differs markedly from the other analyzed host rocks of the svecokarelian ni cu occurrences and its platinum group element distribution pattern corresponds to the komatiitic character observed also in major and trace elements of the rocks the fractionated platinum group element pattern of the kotalahti and laukunkangas deposits match well with the observations of rock sequences and geochemistry of the host rocks

late pleistocene geomagnetic excursion in icelandic lavas confirmation of the laschamp excursion in 1980 kristjansson and gudmundsson 1 reported a late glacial geomagnetic excursion in three hills in the reykjanes peninsula iceland with shallow negative inclinations and westerly declinations they named it the skalamaelifell excursion more extensive field work has identified the same excursional paleomagnetic direction declination 258 inclination 15 at four additional outcrops in a 10 10 km area in the reykjanes peninsula the excursion lavas are olivine tholeiites with similar petrography and chemical compositions paleointensity determinations by the thellier method average 4 2 0 2 t for 8 samples more than an order of magnitude weaker than the present geomagnetic field in iceland together these results suggest extrusion of the excursion lavas in a very brief span of time probably less than a few hundred years kar dating of the excursion lavas gives a mean age for 19 determinations of 42 9 7 8ka 2 compilation of thirty kar ages of the laschamp and olby flows by three laboratories yield a new age for the laschamp excursion in france of 46 6 2 4ka 2 the age of the excursion in southwestern iceland is statistically indistinguishable from the laschamp excursion at the 95 confidence level and both have very low paleointensities therefore we suggest that the laschamp and olby flows in france and the skalamaelifell units of iceland recorded essentially the same geomagnetic excursion differences in the virtual paleomagnetic poles vgps of these excursions may be due to 1 the probable non dipole character of the geomagnetic field during the excursion 2 rapid geomagnetic secular variation and possible small age differences of the extrusive rocks in france and iceland and or 3 crustal magnetic anomalies which might dominate the local geomagnetic field during the excursion at either or both locations

high resolution 230thex stratigraphy of sediments from high latitude areas norwegian sea fram strait abstract we present data on the average sedimentation rates ranging from 1 6 cm kyr to 3 cm kyr for the last 300 000 years based on 18o analyses of foraminifera in a core from the norwegian sea and 230thex measurements in cores from the norwegian sea and the fram strait arctic ocean furthermore we relate 230thex variations downcore to the various oxygen isotope stages this correlation is tentatively interpreted as being a result of the paleoceanographic and paleoclimatic control of bioproductivity it is shown that based on the average sedimentation rates and characteristic 230thex variations carbonate poor sediment cores from northern latitudes can be correlated

eemian and early weichselian 140 60 ka paleoceanography and paleoclimate in the nordic seas with comparisons to holocene conditions paleoceanographic and paleoclimatic time series were extracted from norwegian iceland and greenland sea the nordic seas sediment sequences covering the time intervals 60 140 ka and 0 15 ka on the basis of stable isotope stratigraphy planktonic foraminiferal faunas and sedimentological methods the proxy temperature records from the norwegian iceland sea display a number of high frequency and high amplitude variations within the last interglacial the eemian indicating marked changes in heat flux at high northern latitudes eemian holocene comparisons document that the climate of the norwegian iceland sea in the last interglacial was less stable than that of the present interglacial and that the distribution of surface water masses in the eemian differed from that of the holocene within the greenland sea uniform cold conditions prevailed throughout both interglacials cooling of the nordic seas as well as the initial growth of the surrounding ice sheets began within the eemian interval before the main increase in global ice volume heat flux to the nordic seas was significantly higher during the interglacials than at any time during the early weichselian 60 113 ka and no marked stadial interstadial changes in sea surface temperature and deep water ventilation are documented in the early weichselian records contrary to the pattern found in north atlantic sediment records however fluctuations in planktonic foraminiferal content planktonic 13c and ice rafting on suborbital timescales mostly comparable in number and age to the stadial interstadial fluctuations in the greenland ice cores are demonstrated in our records the ice rafted detritus records provide a more detailed account of ice sheet variability than previously known for the early weichselian period and demonstrate that glaciers advanced to sea level somewhere around the nordic seas several times during this interval

comment on reflection of scandinavian ice sheet fluctuations in norwegian sea sediments during the past 150 000 years by karl heinz baumann klas s lackschewitz jan mangerud robert f spielhagen thomas c w wolf welling rudiger henrich and heidemarie kassens

meltwater and ice rafting in the southern norwegian sea between 20 and 40 calendar kyr b p implications for fennoscandian heinrich events 1 the timing of meltwater release in the southern norwegian sea in relation to millennial scale climate variability is studied from core md99 2283 based on down core analysis of stable oxygen and carbon isotopes calcium carbonate and ice rafted debris ird between 20 and 40 calendar cal kyr b p strong dansgaard oeschger cyclicity is expressed in increased carbonate content and reduced total organic carbon during warm interstadials and ird marking the end of cold stadials the planktonic 18o record of core md99 2283 compared to available isotopic records in the region confirms the existence of multisourced synchronized meltwater anomalies during heinrich h events 2 to 4 it was found that the sudden release of meltwater occurs near major ice streams and that no significant increase in ird was associated with the peaks of the meltwater events in the southern norwegian sea suggesting meltwater discharges from ice dammed lakes significant meltwater events not related to the h events were also observed between 33 and 35 cal kyr b p indicating that the release of meltwater is not necessarily connected with major cooling and enhanced ird delivery the simultaneous release of fresh water during h events in the nordic seas through icebergs and ice dammed lakes is thought to be the result of sea level increase the meltwater input to the nordic seas provides a significant additional contribution to global sea level rise associated with h3 and h4

short term climate changes in the southern aegean sea over the last 48 000 years abstract high resolution palaeoenvironmental changes corresponding to a mean time interval of 450 years covering the last 48 000 years were examined in a core from the cretan basin in the southern aegean sea the intensity and duration of the climatic and oceanographic events were determined by examining the compositional changes in the planktonic foraminifera and pollen assemblages along with the 18o signal of globigerinoides ruber a reconstruction of sea surface temperatures was attempted using the modern analogue technique mat in total 10 stadials and 6 interstadials occurred over the last 48 000 years these fluctuations in climatic conditions coincide with fluctuations documented in the western and central mediterranean and seem to be associated with dansgaard oeschger events some of these climatic fluctuations are correlated with changes in the vegetation in the surrounding land between 48 and 10 cal kyr bp the most pronounced stadials occurred at 41 cal kyr bp c69 st10 and at 13 cal kyr bp c69 st4 these events are characterized by i high positive 18o values of globigerinoides ruber ii drops in sst and iii increases in aridity these events may be correlated with the heinrich h4 event and the younger dryas event respectively two other stadials at 23 cal kyr bp c69 st6 and at 16 cal kyr bp c69 st5 which are characterized by increases in the abundance of the cold plaktonic foraminifera species and increases in aridity may be correlated with the h2 and h1 events respectively the dominant planktonic foraminiferal species during the stadials witch are correlated with the heinrich events were turborotalita quinqueloba and globorotalia scitula the most pronounced interstadials occurred between 39 5 and 38 5 cal kyr bp c69 ist6 and between 25 and 24 cal kyr bp c69 ist3 and are characterized by depletion in 18o values increases in sst and increases in humidity the former event coincides with the formation of the sapropelitic layer s2 in the holocene the most pronounced stadial occurred between 8 and 6 5 cal kyr bp c69 st2 during the interruption of s1 and is characterized by a reduction in sst and an increase in aridity the most pronounced interstadials of holocene occurred during the formation of s1a and s1b between 9 and 8 cal kyr bp c69 ist1 and between 6 5 and 5 5 cal kyr bp c69 ist2 respectively these events are characterized by depletion in 18o values increased sst and an increase in humidity as is indicated by the expansion of temperate evergreen and mediterranean taxa in the pollen record

evaporite karst problems and studies in the usa evaporites including rock salt halite and gypsum or anhydrite are the most soluble among common rocks they dissolve readily to form the same types of karst features that commonly are found in limestones and dolomites evaporites are present in 32 of the 48 contiguous states in usa and they underlie about 40 of the land area typical evaporite karst features observed in outcrops include sinkholes caves disappearing streams and springs whereas other evidence of active evaporite karst includes surface collapse structures and saline springs or saline plumes that result from salt dissolution many evaporites also contain evidence of paleokarst such as dissolution breccias breccia pipes slumped beds and collapse structures all these natural karst phenomena can be sources of engineering or environmental problems dangerous sinkholes and caves can form rapidly in evaporite rocks or pre existing karst features can be reactivated and open up collapse under certain hydrologic conditions or when the land is put to new uses many karst features also propagate upward through overlying surficial deposits human activities also have caused development of evaporite karst primarily in salt deposits boreholes petroleum tests or solution mining operations or underground mines may enable unsaturated water to flow through or against salt deposits either intentionally or accidentally thus allowing development of small to large dissolution cavities if the dissolution cavity is large enough and shallow enough successive roof failures can cause land subsidence and or catastrophic collapse evaporite karst natural and human induced is far more prevalent than is commonly believed

evidence for massive discharges of icebergs into the north atlantic ocean during the last glacial period sediments in the north atlantic ocean contain a series of layers that are rich in ice rafted debris and unusually poor in foraminifera1 here we present evidence that the most recent six of these heinrich layers deposited between 14 000 and 70 000 years ago record marked decreases in sea surface temperature and salinity decreases in the flux of planktonic foraminifera to the sediments and short lived massive discharges of icebergs originating in eastern canada the path of the icebergs clearly marked by the presence of ice rafted detrital carbonate can be traced for more than 3 000 km a remarkable distance attesting to extreme cooling of surface waters and enormous amounts of drifting ice the cause of these extreme events is puzzling they may reflect repeated rapid advances of the laurentide ice sheet perhaps associated with reductions in air temperatures yet temperature records from greenland ice cores appear to exhibit only a weak corresponding signal moreover the 5 10 000 yr intervals between the events are inconsistent with milankovitch orbital periodicities raising the question of what the ultimate cause of the postulated cooling may have been

sedimentary facies of glacial interglacial cycles in the norwegian sea during the last 350 ka sediment fluxes were highest in the norwegian sea during late glacial early deglacial periods i e at oxygen isotope transition 43 below transition 65 at various levels within stage 6 and below stage 9 dark diamictons deposited at these times reflect intense iceberg rafting in surface waters fed by surges along the front of the marine based parts of the continental ice sheets in the southeastern sector of the norwegian sea the high organic carbon content 0 5 1 3 in these layers reflects input from erosion of terrigenious matter rich sediments outcropping on the shelves partial oxidation of organic matter and decreased deep water renewal may explain the strong carbonate dissolution observed during these periods interglacial environments were strongly variable throughout the last 350 ka circulation patterns of stage 5e best resemble modern conditions while stage 7 and 9 sediments record a much weaker norwegian current

effects of the adjacent evaporitic formations on groundwater quality of alluvial sand gravel aquifers a study in the derincay basin north central turkey evaporite bearing formations extending in large areas in turkey affect quality of water resources the derincay basin is an example to the impacts of evaporites on the adjacent alluvial aquifers miocene pliocene aged evaporites cover nearly one third of the basin and mostly surround the low elevated alluvial sand gravel aquifer the higher quality of the groundwater in the upstream regions where the evaporites do not crop out or partially crop out turns into low to very low quality in the downstream areas due to the large extents of the evaporites waters from the evaporites increase tds ca so4 na and cl in the alluvium aquifer particularly in the downstream region of the basin ec values rise from 1000 1300 s cm to over 5000 s cm from upstream to downstream high salinity but low sodium hazard category for the upstream parts turns into very high salinity and medium high sodium hazard for the downstream regions on the salinity diagram groundwater in the upstream parts falls in good to permissible class however the class turns into permissible to doubtful and doubtful to unusable classes for the downstream on the wilcox diagram ca bicarbonate type in the upstream region turns into ca sulfate type in the downstream region due to the evaporite effect this study indicates three main sources affecting the quality of groundwater of the alluvium aquifer in the derincay basin extent of the evaporite formations in the catchment area recharge from the evaporite springs and dilution with relatively high quality stream waters

ni cu pge deposits in finland geology and exploration potential abstract several types of nickel sulphide deposits occur in finland some of them are also important sources of cu co and pge the main deposit types are related to archaean and palaeoproterozoic mafic to ultramafic rocks palaeoproterozoic metamorphosed black shales of the talvivaara type or the ultramafic and metasomatic calc silicate rocks of the ophiolitic outokumpu association several komatiite hosted ni cu pge deposits have been discovered in the archaean and paleoproterozoic greenstone belts in northern and eastern finland but only one has been briefly mined in 1989 many 2 44 ga palaeoproterozoic mafic ultramafic layered intrusions in finland host contact type pge ni cu deposits and significant reef type pge deposits typically the ni resources are of low grade but large tonnage the mafic ultramafic magmatism at ca 2 06 ga produced significant ni cu pge resources in the central lapland greenstone belt including the kevitsa and sakatti deposits the svecofennian domain in central and southern finland contains hundreds of small ca 1 88 ga mafic ultramafic orogenic intrusions many of these host nickel mineralization nickel exploration potential was evaluated in general based on identification of critical factors within a mineral system framework and a quantitative assessment of the potential occurrence of undiscovered nickel resources the mgo content of the parental magma was estimated for 28 deposits 6 komatiite hosted occurrences and 22 svecofennian orogenic intrusions the estimated mgo content of the parental magmas for the selected deposits varies from around 7 to 15 in basaltic to komatiitic basalt systems and up to 30 in more magnesian komatiitic systems the ni cu value varies mostly between 0 7 and 12 correlating in general positively with the mgo content of the magma exceptionally high or low ni cu values in some deposits may result from for example copper loss during post magmatic processes serpentinization and or metamorphism or part of the sulphide ore zoned by the ni cu value still being unknown recent advances in understanding of komatiites in finland indicates high exploration potential for nickel within the paleoproterozoic komatiitic formations which typically are also significantly enriched in cu and pge however the quantitative assessment of undiscovered nickel resources in finland suggests that the contact type ni cu pge deposits hosted by 2 44 ga mafic ultramafic layered intrusions in northern finland have the greatest potential for hosting undiscovered resources among the assessed nickel deposit types these occur within restricted areas resulting in a high deposit density finally considerable nickel resources might exist in undiscovered talvivaara kevitsa or sakatti type deposits these deposit types should be assessed as soon as more geological information becomes available