two cryogenian glacial successions compared aspects of the sturt and elatina sediment records of south australia abstract two cryogenian glacial sequences the sturt and elatina occur within the adelaide rift complex s australia and are part of an 8 km thick succession recording rodinia fragmentation and subsequent passive margin development we compare and contrast these glacial successions presenting new data including detailed logged sections for both glacial sequences facies analysis reveals a total of six facies associations recording a range of glacial and glacially related processes these are a diamictite facies association ice proximal debris flows a sheet sandstone facies association fluvial deposits a flaser and rhythmically bedded facies association tidal flat a hummocky cross stratified sandstone facies association shoreface to offshore transition zone deposits and an underflow facies association recording offshore deposition a sixth facies association a ferruginous lonestone bearing siltstone is restricted to the top of the elatina formation and records rapid environmental amelioration and emergence from glaciation in the central flinders ranges the sturt succession commences with a glacial erosion surface ges which in agreement with previous workers was probably enhanced by rifting this ges is overlain in ascending order by the pualco tillite holowilena ironstone and wilyerpa formation with the warcowie dolomite member at the base of this latter formation a second ges is preserved within this latter unit and is overlain by a stratigraphic motif that records an alternation of offshore transition zone and offshore deposits significant base level falls within the wilyerpa formation are identified by fluvial deposits sitting disconformably upon offshore deposits in contrast within the elatina formation a single ges is proposed which defines the base of the formation the elatina formation is split into two informal members on the basis of analysis of sediment stacking patterns and the recognition of a sharp stratigraphic surface that divides the formation apart from a locally preserved basal diamictite the lower member consists of fluvial deposits whereas the upper member is dominated by a mixture of tidal flat sediments and debris flow deposits the boundary between these units is therefore interpreted as a hybrid surface recording tidal ravinement in some areas and a glacial advance in others deglaciation left contrasting deposits the sturt deglaciation culminated in deposition of black shale of the tindelpina shale member of the tapley hill formation seemingly as a sheet like deposit over the adelaide rift complex and beyond into the amadeus basin of central australia the elatina deglaciation meanwhile began first with deposition of the sixth facies association ferruginous dropstone bearing siltstone then proceeded with deposition of cap dolostone of the nuccaleena formation

mapping and facies analysis of paleocene mid eocene seismic sequences offshore southern west greenland abstract new interpretations are reported of the sedimentology and sequence stratigraphy of the palaeogene sediments encountered by the boreholes hellefisk 1 ikermiut 1 kang miut 1 nukik 1 and nukik 2 offshore southern west greenland these interpretations together with new biostratigraphic and palaeoenvironmental interpretations have been used to correlate the boreholes and to calibrate seismic sequences interpreted on a grid of reflection seismic data the interpreted seismic sequences lie between major regional unconformities of danian and mid eocene age the new interpretations show that the area offshore southern west greenland was subject to major uplift and erosion during the danian when latest cretaceous sediments were removed sedimentation restarted in the late danian coevally with major volcanism in central west greenland and the start of sea floor spreading in the labrador sea late paleocene sediments were deposited in a predominantly extensional tectonic environment the extensional stresses continued in most areas during the early eocene but in the northern and northwestern part of the basins a transtensional system developed along the strike slip faults that transferred sea floor spreading movements between the labrador sea and baffin bay sediment input to the basins was predominantly from the north possibly from a major river system flowing out of central greenland lesser amounts of sediment came from the east from the mainland of greenland and minor amounts from the west the thickness of total sediment decreases substantially from north to south the sediments were deposited in environments that ranged from fresh water marginal marine to upper bathyal proximal environments are probably generally sand prone but distal environments probably contain larger amounts of mud some of which could contain a mature source rock for oil basin floor fans syn tectonic wedges and turbidite channel complexes that could act as hydrocarbon reservoirs sealed by surrounding muds have been identified in many of the seismic sequences

stratigraphic architecture of the cenozoic succession in the mcmurdo sound region antarctica an archive of polar palaeoenvironmental change in a failed rift setting the victoria land basin forms part of the failed west antarctic rift and preserves a cenozoic succession up to 4 km thick that records the onset of cenozoic glaciation and the history of antarctic glaciation over the past 34 myr this succession is relevant both to investigations of modern climate change and to studies of long term palaeoclimate change in general this study provides a sedimentological and stratigraphic review of the victoria land basin succession based on analysis of several continuous drillcores acquired since the 1970s and supported by seismic stratigraphic analysis of a large array of seismic reflection data an array of fifteen lithofacies is recognized within the victoria land basin cenozoic succession including fossiliferous and diversely bioturbated mudrocks and diatomites texturally mature sandstones and conglomerates mixed mudstones and sandstones with dispersed gravel with restricted bioturbation and diamictites and associated lithologies these facies record a variety of marine glaciomarine proglacial and subglacial environments locally volcanic and volcaniclastic deposits are interbedded in the succession lithofacies are arranged in repetitive vertical stacking patterns depositional sequences that record glacial advance retreat cycles with attendant relative sea level changes seven varieties of depositional sequences stratigraphic motifs are recognized within the succession as a whole and interpreted to record a range of depositional settings from rifts unaffected by glacial ice motif 7 through varying degrees of glacial influence with abundant meltwater contributions motifs 6 to 3 to cold polar glaciated environments such as that of today motifs 2 and 1 overall there is a gradual trend upward through the succession from motif 7 at the base towards motif 1 at the top but the trend is not monotonic a significant conclusion of this work is that a record of dynamic climate and glacial conditions is preserved through the entire 34 myr period of the cenozoic icehouse at least in the victoria land basin intervals characterized by consistent stratigraphic style motifs are recognized throughout the victoria land basin succession these intervals are of 1 to 6 myr duration each containing numerous depositional sequences they are one to two orders of magnitude longer than glacial interglacial cycles and record periods during which environmental conditions varied in an internally consistent manner these intervals are considered to reflect convolutions of orbital parameters that remained stable for periods of 106 a and then switched to alternative configurations such intervals are directly analogous to 1 to 8 myr intervals characterized by glaciogenic strata that are preserved within the late palaeozoic of eastern australia among other areas and may be a recurring stratigraphic response to icehouse climate regimes through geological time

a depositional record of deglaciation in a paleofjord late carboniferous pennsylvanian of san juan province argentina the role of catastrophic sedimentation the combination of high sediment supply rates and ample accommodation within fjords provides high resolution records of deglaciation ancient fjord fills provide the potential for three dimensional views of the evolution of depositional environments in response to changing sediment supply and base level through the deglacial process we describe the fill jejenes formation of a well exposed late carboniferous pennsylvanian glacial valley and its tributaries these deposits record the progressive marine flooding and infilling of topography by glacially derived sediments the geometry of the valley and its tributaries is controlled by the underlying lower paleozoic lithologies a deep valley with steep sides exists where the bedrock is massive limestones and a broader shallower valley exists where the bedrock is generally a fine grained olistostrome the valleys are locally floored with diamictites including both in situ tillites and remobilized diamictites in the trunk valley these are locally overlain by a small shallow water delta the major part of the valley fill consists of a 150 m thick mudstone dominated succession probably generated by plumes of glacial outwash containing numerous dropstones that decrease in abundance down the fjord the mudstones contain numerous thin sandstone and conglomerate turbidites that were supplied laterally via subaqueous gravel fans feeding in from the tributary valleys each of which has a distinctive clast suite related to the local subcrop the entire succession is overlain by 300 m of sandy turbidites of which the upper part includes large mass transport complexes intercalated within the succession in the trunk valley are structureless graded silty mudstones lacking dropstones but with abundant large wood fragments close to the steep western margin of the trunk valley each of these massive mudstones is underlain by a slump or debris flow locally containing meter scale blocks of ordovician limestone from the valley side we interpret these as a consequence of rockfalls from the steeper valley sides triggering debris flows on the subaqueous fjord slopes we suggest that large solitary waves were generated as the rockfalls entered the water traveling along the fjord and stripping vegetation from the shoreline large amounts of mud and silt were thrown into suspension during these events and subsequently settled from suspension to form the structureless graded beds these deposits and other mass flow deposits within the succession emphasize the potential importance of catastrophic sedimentation within deglacial successions

large fluvial systems the atane formation a fluvio deltaic example from the upper cretaceous of central west greenland abstract recognition of major river deposits are crucial to the understanding of palaeogeography and basin evolution this paper describes the geometry of 2 30 m thick fluvial sand bodies which occur in upper cretaceous strata deposited in a major river delta in central west greenland the deposits are cyclic and each cycle can be divided into four genetic facies associations which reflect deposition 1 at the delta front 2 on the delta plain 3 in fluvial channels and 4 during transgression of a delta lobe the cyclicity is attributed mainly to autocyclic shifting of delta lobes the study area is very well exposed and an advanced new photogrammetric system was used both for making accurate vertical profiles and for mapping the horizontal extent of individual sand bodies based on horizontal extent internal architecture and relationship to other facies associations the c 100 investigated sand bodies from the fluvial channel association can be divided into two important types distributary channel sand bodies are the dominant type 80 they vary in thickness from 3 m up to as much as 30 m and reflect the migration and infilling of rather narrow distributary channels that existed on a flat vegetated delta plain the relationship with the surrounding sediments as well as faint epsilon cross beds which extend right through the sand bodies indicate that the thicknesses of the sand bodies approximate the bankfull depth of the palaeochannels many small and medium sized sand bodies have very narrow cross sections and show no signs of lateral migration the preserved geometry of these sand bodies consequently represents the original channel morphology the sand bodies show an increasing degree of migration with increasing thickness and the width thickness ratio increases from c 6 for the smaller sand bodies up to c 20 for the largest the distributary channels were only moderately sinuous with an average sinuosity of 1 2 channel mouth complexes are the other type of fluvial sand bodies 20 they are 3 8 m thick and have a large lateral extent with a width thickness ratio of 50 or more they have an erosive base and occur in the top of the coarsening upward sequences made by the delta front association internal bounding surfaces suggest that these sand bodies were generated by lateral amalgamation of many small channel fills in fan shaped sub deltas at the sea ward end of distributary channels the discharge through the distributary channels has been calculated using the manning equation these calculations indicate that the river system which supplied the atane delta was very large and may well have drained most of the presently ice covered interior of greenland

dinoflagellate cyst biostratigraphy of the upper albian to lower maastrichtian in the southwestern barents sea abstract the present study of five wells from upper albian to lower maastrichtian succession in the southwestern barents sea yields the first dinoflagellate cyst based palynological event biostratigraphy for the area the research focuses on the upper cretaceous kveite and kviting formations due to the lack of formal palynological documentation and enables the formation of a biozonation of greater resolution than currently achievable by micropalaeontology four new interval zones and one abundance subzone are described from base upward palaeohystrichophora infusorioides and palaeohystrichophora palaeoinfusa interval zone intra early cenomanian intra late cenomanian dinopterygium alatum interval zone intra early coniacian late santonian palaeoglenodinium cretaceum interval zone early campanian and the chatangiella bondarenkoi interval zone late campanian encompassing the heterosphaeridium bellii abundance subzone intra late campanian the zones are well correlated to existing palynological zonations from the norwegian greenland sea where the previously described subtilisphaera kalaalliti interval zone intra late albian intra early cenomanian heterosphaeridium difficile interval zone middle turonian to intra early coniacian and cerodinium diebelii interval zone early maastrichtian are recognised these data also reveal the presence of three significant unconformities of late cenomanian early turonian middle campanian and late maastrichtian paleocene age

palynology and sedimentology across a new marine cretaceous tertiary boundary section on nuussuaq west greenland a new northern high latitude cretaceous tertiary k t boundary section has been studied at annertuneq on the north coast of nuussuaq west greenland the boundary section is situated in a succession of homogeneous dark mudstone deposited in a marine slope environment identification of the boundary is based on the presence of the latest maastrichtian palynomorphs palynodinium grallator disphaerogena carposphaeropsis manumiella spp and wodehouseia quadrispina below the boundary and on the first occurrence of the earliest danian species senoniasphaera inornata above the boundary variations in sporomorph and dinoflagellate cyst abundances indicate latest maastrichtian regression followed by early danian transgression the transgressive phase can be subdivided into three high frequency transgressive regressive cycles each cycle indicates upwelling and transgression mixing with low latitudinal water masses and ocean conditions suggested by the peak occurrences of senegalinium spp trithyrodinium fragile and spongodinium delitiense respectively

separation of palaeogene and neogene uplift on nuussuaq west greenland the geological record exposed on nuussuaq central west greenland shows that uplift in the palaeocene probably caused by impact of the iceland plume head was followed by kilometre scale subsidence analysis of apatite fission track and vitrinite reflectance data from borehole samples down to 3 km depth reveals that the samples cooled from maximum palaeotemperatures between 40 and 30 ma followed by two further cooling episodes beginning in the intervals 11 10 and 7 2 ma when the first cooling episode began the samples from the neighbouring gro 3 and gane 1 boreholes were buried 1500 2000 m deeper than at the present day and the palaeogeothermal gradient was 40 48 c km 1 it is not clear whether this cooling involved exhumation or if it was due solely to reduction in heat flow and a drop in surface temperature the two later episodes definitely involved exhumation because by then the palaeogeothermal gradient had declined to a value close to the assumed present value of 30 c km 1 which agrees with estimates from offshore wells the most recent cooling episode corresponds to the incision of the present day relief c 1100 m below the summits around the two boreholes we conclude that the present day high mountains of west greenland were not uplifted during the palaeogene but are erosional remnants of a landmass uplifted during the neogene

debris transport in a temperate valley glacier haut glacier d arolla valais switzerland hambrey m j goodsell becky glasser n f 2005 debris transport in a temperate valley glacier haut glacier d arolla valais switzerland journal of glaciology 51 172 pp 139 146

tidewater glacier beds insights from iceberg debris in kongsfjorden svalbard the sediment in icebergs offers an opportunity to sample the otherwise inaccessible beds of modern tidewater glaciers this paper presents a discussion of the benefits and problems of using iceberg debris to make inferences about the nature of the beds of modern tidewater glaciers as an example we present data obtained from icebergs calved from fast flowing tidewater glaciers in kongsfjorden svalbard sediment samples obtained from 12 icebergs show that clast rich muddy diamicton is the dominant facies although muddy gravel and mud are also present in some debris layers sediment texture and clast shape analyses indicate that most debris in the icebergs is of basal origin micro morphological analyses of thin sections of the diamicton also indicate pervasive deformation of the sediment although individual icebergs only represent small samples of the bed of a tidewater glacier and problems remain in linking iceberg sediments to their pre calving transport history beneath the glacier this method provides a potentially fruitful way of linking sediments to glacier dynamics

pleistocene variability of antarctic ice sheet extent in the ross embayment cores acquired by the andrill mcmurdo ice shelf project and 1b provide the basis for a new sedimentation model for glacimarine depositional sequences that reflect cyclic glacial interglacial fluctuations of a marine based ice sheet in the western ross embayment over the past 2 0 ma notwithstanding periodic erosion during advances of the ice sheet uncertainties inherent to the sedimentological interpretation and a limited number of chronological datums it is clear that subglacial to grounding zone sedimentation was dominant at the and 1b site during the late pleistocene with interglacials being represented only by thin intervals of ice shelf sediment each sequence is characterised by subglacial massive diamictite that pass upwards into glacimarine diamictites and mudstones this provides the first direct evidence that the marine based antarctic ice sheet has oscillated between a grounded and floating state at least 7 times in the ross embayment over the last 780ka implying a milankovitch orbital influence an unconformity in and 1b that spans most 200 kyr of the mid pleistocene transition is inferred to represent widespread expansion of a marine based ice sheet in the ross embayment at 0 8 ma prior to 1 0 ma interglacial periods are characterised by open water conditions at the drill site with high abundances of volcanoclastic deposits and occasional diatomaceous sediments these may have responded to precession 20 kyr or obliquity 40 kyr orbital control the occurrence of 6 7 m of phonolitic glass reworked from mt erebus in interglacial deposits beneath last glacial maximum till requires open ocean or ice shelf conditions in the western ross sea around the drill site within the past 250 ka and implies a ross ice shelf similar to or less extensive than today during marine isotope stage 7 or 5

application of palynological data to the chronology of the palaeogene lava fields of the british province implications for magmatic stratigraphy new high precision ages determined from palynomorph assemblages within intercalated sedimentary deposits are presented for the palaeogene lava fields skye mull and antrim of the british province these data reveal very rapid averaged eruption rates 1 m 200 years and the non synchronous formation of the lava fields eruption of the volumetrically dominant transitional to mildly alkaline lavas of the skye 58 25 58 0 ma and mull post 55 ma lava fields the skye main lava series and the plateau group of mull respectively is separated by the eruption of the morb like preshal more flows of olivine tholeiite found at the top of the preserved sequence on skye and at the base of the mull lava field the lower formation of the antrim lava field correlates with the skye lava field and the upper formation correlates with the preshal more flows the new ages indicate that the eruption of the preshal more flows was synchronous with the main ocean floor spreading event which occurred 500 km to the nw at c 55 ma during chron 24r a combined thinspot and channelized plume model may best explain the temporal and spatial distributions of the lava fields and associated subvolcanic complexes of the british province

high resolution biostratigraphic zonation for the uk central north sea paleocene abstract this paper presents the high resolution biostratigraphic zonation scheme for the paleocene of the central north sea area uk and the application to formation characterization well correlation reservoir modelling and wellsite activities the scheme is developed from detailed and consistently recorded palynological events supported by microfossil data which have been applied successfully to the majority of proprietary biostratigraphic studies from the basin nine zones and 29 subzones have been defined based on first downhole occurrence fdo or abundance events with chronostratigraphic significance and can be consistently correlated across the studied area the nine biozones are described based on a dominant palynological marker from base upward senoniasphaera inornata and spiniferites magnificus danian isabelidinium viborgense and palaeoperidinium pyrophorum selandian cordosphaeridium gracile spiniferites fentonii spiniferites rhomboideus areoligera gippingensis and base apectodinium spp thanetian the defined bioevents have been consistently linked with the published lithostratigraphy stratigraphic sequences and interpreted depositional environments

pliocene pleistocene glaciomarine sedimentation in eastern prydz bay and development of the prydz trough mouth fan odp sites 1166 and 1167 east antarctica abstract lithostratigraphy grain sizes and down hole logs of site 1166 on the continental shelf and site 1167 on the upper slope are analyzed to reconstruct glacial processes in eastern prydz bay and the development of the prydz trough mouth fan in eastern prydz bay upper pliocene lower pleistocene glaciomarine sediments occur interbedded with open marine muds and grade upward into waterlaid tills and subglacial tills lower pleistocene sediments of the trough mouth fan consist of coarse grained debrites interbedded with bottom current deposits and hemipelagic muds indicating repeated advances and retreats of the lambert glacier amery ice shelf system with respect to the shelf break systematic fluctuations in lithofacies and down hole logs characterize the upper pliocene lower pleistocene transition at sites 1166 and 1167 and indicate that an ice stream advanced and retreated within the prydz channel until the mid pleistocene the record from site 1167 shows that the grounding line of the lambert glacier did not extend to the shelf break after 0 78 ma published ice rafted debris records in the southern ocean show peak abundances in the pliocene and the early pleistocene suggesting a link between the nature of the glacial drainage system as recorded by the trough mouth fans and increased delivery of ice rafted debris to the southern ocean

sedimentary evidence of landscape and climate history since the end of mis 3 in the krkonose mountains czech republic abstract a sedimentary core recovered from the cirque basin of labsk d l valley 1039 m a s l in the krkonose mountains reflects the environmental history for approximately the last 30 000 years analyses of magnetic susceptibility carbon content pollen assemblages and macrofossil data in a 15 m thick sediment sequence provide the first continuous record of lateglacial and holocene vegetation history in sudetes region of the czech republic the succession of sedimentary units in the lower part of the core suggests that the cirque was ice free before the onset of the last glaciation at the beginning of marine isotope stage 2 highly variable climate prevailed during this period with cold conditions culminating about 18 cal ka bp cold climates persisted until the lateglacial period evidenced by an identified warming and subsequent cooling event correlated with the younger dryas period sparse treeless vegetation dominated in the catchment area at that time the sequence of interrupted thinly laminated silts reflects the retreat and temporary readvance of a local glacier in the cirque during 12 5 10 8 cal ka bp subsequently the alpine treeline ecotone gradually shifted above the cirque floor palaeoclimatic conditions in the early holocene fluctuated strongly whereas since 5 1 cal ka bp conditions have been more stable pollen based climate reconstructions suggest significant cooling at around 9 8 9 3 7 7 7 5 and 4 0 3 3 cal ka bp spruce forests have dominated the site since 5 0 cal ka bp when the vegetation became similar to the modern one two phases of increased sedimentation were identified within the holocene culminating about 9 2 7 5 cal ka bp and 5 8 5 5 cal ka bp sediment yield was as high as 2 4 mm yr 1 during the period reflecting environmental changes during the atlantic sub boreal transition

dinoflagellate cysts from the upper campanian upper cretaceous of hornby island british columbia canada with implications for nanaimo group biostratigraphy and paleoenvironmental reconstructions abstract thirty mudstone samples from coastal exposures of the northumberland formation on hornby island british columbia canada yielded diverse dinoflagellate cyst and terrestrial sporomorph assemblages a late campanian age for the formation has been well defined through magnetostratigraphy macrofossil biostratigraphy and geochemical studies of the hornby island section dinoflagellate cyst taxa corresponding to 61 genera are exceptionally well preserved and include specimens referable to at least 68 formally established species the earliest occurrences of canninginopsis maastrichtiensis druggidium cf discretum phanerodinium belgicum renidinium cf vitilaire senegalinium simplex spiniferella cornuta and xenicodinium delicatum sensu slimani et al are reported along with the most recent occurrence of senoniasphaera protrusa extending their stratigraphic ranges into the upper campanian the palynomorph assemblages support a late campanian age two dinoflagellate cyst ecozones are recognized ecozone 1 and ecozone 2 assemblages suggest sediment deposition in an inner shelf environment with moderate to high nutrient input and primary productivity

palaeocene biostratigraphy and sequence stratigraphy of the uk central north sea abstract the palaeocene of the central north sea can be divided into four stratigraphic sequences named the ekofisk maureen lista and forties these sequences display consistent and predictable patterns on electric log data and are bounded by high gamma log peaks which represent thin condensed mudstones five additional subsequences are recognized within the lista sequence biostratigraphic analysis has enabled the palaeocene to be divided into six dinocyst zones and 11 subzones based on last occurrence or last abundance events that are considered to have chronostratigraphic significance across the north sea basin the dinocyst zonation has been integrated with bioevents based on other microfossil groups and correlated with onshore nw european sections permitting calibration with the standard worldwide nannoplankton and planktonic foraminiferal zones these bioevents display a consistent relationship with the stratigraphic sequences allowing the construction of a confident stratigraphic framework for the palaeocene

geomorphological and sedimentary evidence of probable glaciation in the jizerske hory mountains central europe abstract the jizerske hory mountains in the czech republic have traditionally been considered to be a highland that lay beyond the limits of quaternary glaciations recent work on cirque like valley heads in the central part of the range has shown that niche glaciers could form during the quaternary here we report geomorphological and sedimentary evidence for a small glacier in the pytlacka jama hollow that represents one of the most enclosed valley heads within the range shape and size characteristics of this landform indicate that the hollow is a glacial cirque at a degraded stage of development boulder accumulations at the downslope side of the hollow probably represent a relic of terminal moraines and the grain size distribution of clasts together with micromorphology of quartz grains from the hollow indicate the glacial environment of a small glacier this glacier represents the lowermost located such system in central europe and provides evidence for the presence of niche or small cirque glaciers probably during pre weichselian glacial periods the glaciation limit 1000 m asl and paleo ela 900 m asl proposed for the jizerske hory mountains implies that central european ranges lower than 1100 m asl were probably glaciated during the quaternary

a glacial lake outburst flood associated with recent mountain glacier retreat patagonian andes harrison s glasser n f winchester v haresign e warren c jansson k 2006 a glacial lake outburst flood associated with recent mountain glacier retreat patagonian andes the holocene 16 4 pp 611 620 sponsorship nerc grant ner b s 2002 00282 carnegie trust for the universities of scotland

a new geomagnetic polarity time scale for the late cretaceous and cenozoic we have constructed a magnetic polarity time scale for the late cretaceous and cenozoic based on an analysis of marine magnetic profiles from the world s ocean basins this is the first time since heirtzler et al 1968 published their time scale that the relative widths of the magnetic polarity intervals for the entire late cretaceous and cenozoic have been systematically determined from magnetic profiles a composite geomagnetic polarity sequence was derived based primarily on data from the south atlantic anomaly spacings in the south atlantic were constrained by a combination of finite rotation poles and averages of stacked profiles fine scale information was derived from magnetic profiles on faster spreading ridges in the pacific and indian oceans and inserted into the south ariantic sequence based on the assumption that spreading rates in the south atlantic were smoothly varying but not necessarily constant a time scale was generated by using a spline function to fit a set of nine age calibration points

architecture of vertically stacked fluvial deposits atane formation cretaceous nuussuaq central west greenland excellent exposures of thick multistorey fluvial deposits from the deltaic atane formation on south east nuussuaq central west greenland show the architecture of up to 100 m thick continuously aggrading fluvial depositional complexes the succession comprises vertically stacked channel belt sandstones separated by thin floodplain deposits with little to no incision between storeys architectural elements and palaeocurrent patterns of channel deposits indicate deposition in large relatively stable low sinuosity rivers probably located within an incised valley gradual transitions from channel to floodplain deposits accompanied by a gradual change from floodplain to spillover sand suggest avulsion on the floodplain as a possible mechanism for the vertically alternating channel and floodplain deposits despite its relative proximity to contemporaneous sea level ca 35 km upstream from the palaeo shoreline the depositional complex is entirely non marine the aggrading nature of the deposits suggests a continuously rising base level coupled with a high and steady sediment supply vertical alternations between floodplain and channel deposits may be forced by subtle interruptions in this balance or autocyclic mechanisms on the floodplain this study provides an example of aggrading lowstand non marine transgressive systems tract deposits

tectonic controls on distribution and stratigraphy of the cryogenian rapitan iron formation northwestern canada paleogeographic data indicate that the neoproterozoic rapitan group accumulated in two spatially related silled basins during the first mid neoproterozoic glacial episode ca 711 ma yet the controls on glaciation reason for basin development spatio temporal relationships among stratigraphic units and constraints on iron formation deposition and distribution in this region and globally at this time have not been adequately explained the lack of a coherent understanding of the group s regional stratigraphy has been a significant barrier to deciphering the geologic history of this critically important succession based on new stratigraphic data and incorporating the results of a related geochemical study the rapitan group accumulated in tectonically complex sub basins of a young rift zone the spatial and temporal dynamics of these sub basins controlled the grain size volume and distribution of detrital sediment predominantly turbidites and diamictites deposited during two glacially influenced episodes with ice cover during an interglacial episode the rotated exposed upper surfaces of newly displaced rift blocks directed drainage away from basin margins precluding significant clastic sediment delivery and subaqueous margins of outboard tilted fault blocks acted as sills that isolated local bottom water allowing the accumulation of an entirely hydrogenous succession jaspilitic and hematitic iron formation two strike parallel normal faults that strongly controlled basin margin development are prominent thrust faults in the present day orogen syndepositional activity of strike normal transfer faults segmented the basins along their length as reflected in pronounced along strike variations in the presence absence thickness and composition of the three stratigraphic units mt berg sayunei and shezal formations and in the presence or absence of iron formation locally 100 m thick top of sayunei formation differential subsidence in actively rifting basins was essential for deposition of rapitan type iron formation but glaciation although coeval with rapitan group accumulation was not a strong control the timing of the onset of glacially influenced sediment deposition in the closely spatially related rapitan similar to 711 ma and mount harper groups similar to 717 ma in northwestern laurentia differs by 6 m y arguing for diachronous sturtian glaciation both locally and globally c 2016 elsevier b v all rights reserved

an antarctic stratigraphic record of stepwise ice growth through the eocene oligocene transition earth s current icehouse phase began 34 m y ago with the onset of major antarctic glaciation at the eocene oligocene transition changes in ocean circulation and a decline in atmospheric greenhouse gas levels were associated with stepwise cooling and ice growth at southern high latitudes the antarctic cryosphere plays a critical role in the ocean atmosphere system but its early evolution is still poorly known with a near field record from prydz bay antarctica we demonstrate that antarctic ice growth was stepwise and had an earlier onset than previously suggested prydz bay lies downstream of a major east antarctic ice sheet drainage system and its sedimentary records uniquely constrain the timing of ice sheet advance onto the continental shelf we investigated a detrital record extracted from three ocean drilling program drill holes within a new depositional and chronological framework spanning the late eocene to early oligocene ca 36 33 ma the chemical index of alteration cia and the s index calculated from the major element geochemistry of bulk samples yielded estimates of chemical weathering intensities and mean annual temperature on the east antarctic continent we document evidence for late eocene mountain glaciation along with transient warm events at 35 8 34 8 ma from 34 4 ma associated with the eocene oligocene transition precursor 18o excursion glaciers advanced into prydz bay coincident with a decline in chemical weathering and temperature we conclude that antarctic continental ice growth commenced with the eocene oligocene transition precursor glaciation during a time of subantarctic surface ocean cooling and a decline in atmospheric pco2 these results call for dynamic high latitude feedbacks that are currently poorly represented in earth system models and emphasize the need for additional near field glacio sedimentological high latitude sea surface temperature and pco2 records across the eocene oligocene transition

middle pleistocene glacier behaviour in the mediterranean sedimentological evidence from the pindus mountains greece detailed sedimentological analyses of diamicton sequences in two areas of the pindus mountains greece indicate multiple episodes of glacier advance and retreat during cold stages of the middle pleistocene these glacial sequences represent some of the most southerly in europe and are important archives of regional and global climate change the pindus glaciers were relatively small by world standards and would have been highly responsive to changes in air temperature and precipitation on mount tymphi at least three phases of glacier advance are recorded within deposits assigned to the skamnellian stage mis 12 further north on mount smolikas a thick multiple diamicton sequence records evidence for multiple glacier advances during both the skamnellian stage and the vlasian stage mis 6 these records highlight the dynamic nature of glacier behaviour in the mediterranean mountains during the middle pleistocene and provide new evidence for unstable cold stage climates

some aspects of the geochemistry provenance and palaeoclimatology of the torridonian of nw scotland geochemical data mostly from mudstones are used in an attempt to investigate some aspects of the palaeoclimatology and provenance of the torridonian succession in nw scotland the basal part of the stoer group which has been interpreted as glaciogenic is thought to have formed in a warm arid setting the presence of oscillation ripples and desiccation cracks in mudstones containing isolated clasts is thought to preclude their interpretation as ice rafted debris some aspects of the major element geochemistry of the stoer group mudstones suggest deposition in an environment with little weathering but chemical weathering is inhibited in both frigid and arid settings and sedimentological evidence favours the latter the stoer group mudstones are enriched in mg ca and na relative to the torridon group samples which are much closer in composition to an average shale estimate paas the cr and ni contents of the stoer mudstones are significantly higher than those of the torridon group samples there is however no evidence that enrichment in these elements was due to contamination with volcanic material like that of the stac fada member the scourian basement appears to be an adequate source of the ni and cr in the stoer group sediments th sc ratios are higher in the torridon than in the stoer mudstones this difference is interpreted as indicating that the stoer mudstones were largely derived from local archaean sources but that the torridon group mudstones incorporated materials from a much wider provenance including younger and recycled materials evidence from rare earth elements also provides evidence for different source terrains for the stoer and torridon groups the torridon group mudstones are more weathered have a higher ree content and display a more prominent eu anomaly lower value for eu eu than do the stoer samples these results support evidence from th sc ratios that the torridon group was derived from a more varied recycled and granite rich terrain than the stoer much of which appears to have relatively local provenance the geochemistry of mudstones can shed considerable light on problems of provenance and palaeoclimatology because many useful trace elements tend to be concentrated in such fine grained rocks and some aspects of their major element chemistry may be related to climatic factors

classification of poorly sorted sedimentary rocks abstract the classification and nomenclature of sandstones has evolved over the years into a system which is now generally accepted as standard however no equivalent system exists for the poorly sorted sedimentary rocks which include grain sizes from clay to gravel a descriptive classification is proposed based on an earlier system but using updated nomenclature and lithological fields such a scheme is needed to clearly define lithological terms currently used in the description of sedimentary sequences

microfossil biostratigraphy of the palaeogene succession in the davis strait offshore west greenland abstract a new microfossil based biostratigraphy of the paleocene and lower eocene sediments of the hellefisk 1 ikermiut 1 kang miut 1 nukik 1 and nukik 2 boreholes offshore west greenland has been established in general the five boreholes contain fairly well preserved diverse microfossil faunas and floras consisting mainly of foraminifera radiolaria ostracods and diatoms the studied interval was subdivided into three foraminiferid biostratigraphic intervals in ascending stratigraphic order the stensioeina beccariiformis praeglobobulimina ovata and pseudohastigerina wilcoxensis intervals and five biostratigraphic intervals based on additional microfossil groups the thalassiosiropsis wittiana fenestrella antiqua coscinodiscus morsianus ostracod aulacodiscus hirtus and cenodiscus cenosphaera intervals the intervals are more easily recognised in the two basinal boreholes ikermiut 1 and kang miut 1 than in the three more nearshore boreholes nukik 1 nukik 2 and hellefisk 1 due to a higher microfossil diversity and abundance

lowstand slope channels of the itilli succession maastrichtian lower paleocene nuussuaq west greenland abstract the maastrichtian lower paleocene itilli slope succession of nuussuaq west greenland consists of an at least 2 5 km thick turbidite succession composed of mudstone thinly interbedded sandstone and mudstone chaotic beds amalgamated sandstone and giant scale cross bedded sandstone the amalgamated and giant scale cross bedded sandstones were deposited in 1 2 km wide slope channels draining basin margin source areas the chaotic beds invariably underlie undisturbed channel fill sandstones suggesting that initially channels were excavated largely by retrogressive slumping of unstable slope mudstones retrogressive slumping was followed by intense channel excavation with continued scouring of channel base and walls before deposition of channel fills from high density turbidity currents it is suggested that destabilisation of the slope mudstones was triggered by drops in relative sea level associated with increased sediment deposition on the slope sequence stratigraphic concepts have been applied to the itilli slope succession the chaotic beds are related to the forced regressive wedge systems tract the sequence boundary is placed at the erosional unconformity separating the chaotic beds from the overlying channel sandstone turbidites and it represents the lowest point of relative sea level fall the channel fill represents the lowstand prograding wedge systems tract and the transgressive systems tract poorly developed highstand systems tract deposits include thinly interbedded sandstones and mudstones and are probably also represented in the redeposited material in the chaotic beds

permian diamictites in northeastern asia their significance concerning the bipolarity of the late paleozoic ice age despite a lack of detailed sedimentologic analyses diamictites in the middle permian atkan formation were previously interpreted as glaciomarine and glacially influenced marine deposits this interpretation allowed this unit to play a prominent role in paleoclimatic and biogeographical reconstructions associated with presumed bipolar glaciation during the late paleozoic ice age lpia in this sense the lpia is considered to be a close analog to bipolar glaciation and climate change during the cenozoic here results are presented that challenge the glacigenic interpretation for these strata and negate interpretations of the bipolar nature of the lpia the 400 to 1500 m thick atkan formation was deposited in back arc basins associated with activity of the okhotsk taigonos volcanic arc along the leading edge of pangea as it drifted across the north polar circle the occurrence of tuffs volcanic clasts and glass shards indicate derivation from a nearby arc cooling and solidification of some clasts during sedimentation is suggested by the occurrence of clasts with embayments and protrusions that extend into the surrounding matrix clasts with columnar like jointing and alteration of the matrix surrounding some clasts ca tims dating of tuff zircons indicate a late capitanian age which is consistent with fossils within the strata bedded diamictites deposited as debrites dominate these diamictites which occur as tens of m thick downlapping packages that thicken then thin upward were deposited as prograding and abandoning sediment gravity flow fans chaotic and folded strata formed as slumps graded sandstones and conglomerates were deposited as turbidites and mudstones were deposited as mudflows low density turbidites and hemipelagic deposits striated clasts and outsized clasts piercing bedding were not observed in the study area strata above and below the atkan formation contain abundant graded beds and deep water trace fossils indicating deposition as turbidites the combination of debrites turbidites slumps volcanic grains clasts glass and tuffs and an absence of glacigenic indicators suggest that atkan strata were deposited in deep water basins associated with the development of the volcanic arc rather than due to glacial activity these findings are significant as they require reconsideration of current views of lpia glaciation and suggest that ice sheets were limited to gondwana

glacigenic and associated marine sediments in the weddell sea fjords of spitsbergen and the barents sea a review abstract studies of glacigenic and associated marine sediments in the weddell sea fjords of spitsbergen and barents sea show that during periods of limited glacial coverage interstadials large amounts of material may be brought into the sea mainly by meltwater the major load is deposited relatively close to the icefront 1 at times of maximum glacial extent grounded ice extends onto the shelf with the shelf edge as the outer limit and land and inner shelf areas are eroded main glacial depositional sites are then the outer shelf and shelf edge the sedimentary environment outside an ice shelf is characterized by low clastic supply mainly deposited from icebergs due to low turbidity and a supply of nutrient rich water biogenic matter accumulates leading to a glaciomarine sequence rich in bioclastics sea level lowering results in grounding and seaward expansion of the ice shelf subsequent eustatic rise causes the grounded ice to float deglaciation and sea level rise reduces clastic input to the shelves glacial sediments are reworked and carbonates may accumulate forming tillite carbonate sequence e g late precambrian break up of marine ice sheets such as the barents sea ice sheet seems to have taken place stepwise in response to eustatic rise and climatic changes

development of sediment landform associations at cold glacier margins dry valleys antarctica hambrey m j fitzsimons s j 2010 development of sediment landform associations at cold glacier margins dry valleys antarctica sedimentology 57 3 857 882 michael hambrey is corresponding author sponsorship marsden fund of new zealand university of otago research committee nerc grant no ner a s 2000 01256

sedimentary response to mantle plumes implications from paleocene onshore successions west and east greenland the uplift history of the upper cretaceous paleocene sedimentary successions underneath the extensive tertiary flood basalts of west and east greenland supports recently described models for the generation of flood basalt provinces in response to rising hot mantle plumes however the sedimentary development indicates that the period of plume related uplift prior to eruption of volcanic rocks was very short 5 m y substantial regional uplift and faulting took place in west and east greenland in the early paleocene to earliest late paleocene resulting in a basinwide unconformity in west greenland the uplift was associated with fluvial peneplanation valley incision and catastrophic deposition in east greenland it was associated with fluvial peneplanation the cumulative uplift in west greenland is probably on the order of several hundred meters whereas in east greenland the observed uplift cannot be quantified in both west and east greenland this phase was shortly followed by rapid major subsidence associated with extensive volcanism it is suggested that this sequence of events reflects the arrival of the north atlantic mantle plume or plumes

neogene glacial record from the sirius group of the shackleton glacier region central transantarctic mountains antarctica neogene glacigenic strata collectively referred to as the sirius group are widely distributed throughout the transantarctic mountains the group is particularly well exposed near the head of shackleton glacier 858109 to 858409s on roberts massif and at bennett platform these deposits are critical for examining the nature of former ice flow from the east antarctic ice sheet into the ross embayment the sirius group rests on a glacially grooved and striated pavement named herein the shackleton erosion surface the sub sirius group surface on roberts massif was of low relief and glaciogenic sediment was deposited on it as a sheet of uniform thickness at bennett platform stratigraphic sections attain a thickness of 110 m thick and are subdivided into the shackleton glacier formation maximum thickness 98 m and the overlying bennett platform formation 44 m separated by an unconformity a third older lithified diamictite containing wood fragments occurs as clasts within these formations and as boulders in the modern lateral moraines of shackleton glacier the dominant facies massive diamict is interpreted primarily as lodgement till other facies indicate glaciofluvial and glaciolacustrine deposition facies associations suggest deposition either by sliding temperate or by polythermal glaciers under much warmer conditions than those of today widespread large and small scale faulting has affected the sirius group and underlying rocks to the extent that inland exposures are over 500 m higher than those to the north over a distance of 30 km thus at the time of deposition of the sirius group the mountains were probably lower and the ice sheet was much thinner

infilling of the younger kathmandu banepa intermontane lake basin during the late quaternary lesser himalaya nepal a sedimentological study the kathmandu and banepa basins central nepal are located in a large syncline of the lesser himalayas the older kathmandu lake evolved during the pliocene and early pleistocene the younger kathmandu lake which is the focus of this study is infilled with late quaternary sediments three formations arranged in stratigraphical order the kalimati gokarna and thoka formations formed during the infilling stage of this lacustrine basin structural and textural sedimentological analyses a chemical survey across the basin and mineralogical investigations of fine grained sediments form the basis of this palaeogeographical study the basin under investigation was covered by a perennial freshwater lake before 30 000 yr bp the lake was infilled with alluvial and fluvial sediments delivered mainly from the mountains north of the basin a fairly low gradient was favourable for the formation of diatomaceous earths carbonaceous mudstones and siltstones which were laid down in the centre of the lake and in small ponds towards the basin edge lacustrine sediments gave way to deltaic deposits spread across the delta plain crevasse splays and anastomosing rivers mainly delivered suspended load for the widespread siltstones and mudstones the proximal parts of the alluvial fluvial sedimentary wedge contain debris flows that interfinger with fine grained floodplain deposits three highstands of the water level 30 000 yr bp 28 000 19 000 yr bp 11 000 4000 yr bp have been recognised in the sedimentary record of the younger kathmandu lake in the late quaternary second order water level fluctuations are assumed to be triggered by local processes damming by tectonically induced landslides first order water level fluctuations are the result of climatic changes copyright 2003 john wiley sons ltd

neogene fjordal sedimentation on the western margin of the lambert graben east antarctica neogene glacial sedimentation east antarctica

particle size scales and classification of sediment types based on particle size distributions review and recommended procedures this paper provides a review of different particle size scales size class terminology and particle size distribution textural classification schemes which are widely used in sedimentology geomorphology soil science aquatic ecology and civil engineering it is concluded that a revised system of size class nomenclature based on the udden 1898 and wentworth 1922 schemes provides the most logical and consistent framework for use with sediments and a wide range of other particulate materials a refined scheme is proposed which has five first order size classes boulder gravel sand silt and clay each of which has five second order subdivisions with limits defined at one phi intervals the scheme is simple and intuitively easy to understand the paper also provides a review of previous schemes that have been proposed to describe and classify sediments on the basis of the proportions of gravel sand and mud or sand silt and clay using trigons also termed ternary diagrams many of these schemes do not have a logical basis and provide limited or uneven resolution new gravel sand and mud and sand silt and clay classification systems are proposed that are both more logical and provide greater discriminatory power than previous schemes they are therefore more suitable for use in environmental and forensic investigations a new microsoft excel program freely available to download from http www kpal co uk allows rapid classification of sediments based on the proportions of gravel sand and mud and sand silt and clay proportions and graphical comparison of the data for different sample groups

the mendel formation evidence for late miocene climatic cyclicity at the northern tip of the antarctic peninsula abstract a detailed description of the newly defined mendel formation is presented this late miocene 5 9 5 4 ma sedimentary sequence with an overall thickness of more than 80 m comprises cyclic deposition in terrestrial glacigenic glaciomarine and marine environments subglacial till was deposited by a thick grounded antarctic peninsula ice stream advancing eastwards through the prince gustav channel crossing the northernmost part of present day james ross island with most of the material carried actively at the base of the warm based glacier the form of the prince gustav channel originated before the late miocene and its present glacial over deepening resulted in multiple grounded glacier advances during the neogene and quaternary the sea prograded from the east and the glacier margin became buoyant building a small ice shelf below and in front of which glaciomarine and marine sediments were deposited these sedimentary deposits are composed of material that was transported mostly by small glaciers and subsequently by the floating ice shelf and by calving icebergs towards the open sea these environmental and glaciological conditions differ strongly from the present cold based local glaciers of james ross island and the antarctic peninsula these changes were triggered by the global sea level fluctuation connected with climatic changes due to antarctic ice sheet build up and decay this reveals late miocene obliquity driven cyclicity with a 41 ka period the mendel formation sedimentary sequence is comprised of at least two glacial periods and one interglacial period sea level rise at the northern tip of the antarctic peninsula between glacial lowstand and interglacial highstand was more than 50 m during the late miocene and was followed by a subsequent sea level fall of at least the same magnitude the presence of well preserved articulated pectinid bivalves support interglacial open sea conditions the re deposition of palaeontological material was shown to be important for the mendel formation reworked pectinid shells revealed an open marine interglacial condition in this part of the antarctic peninsula during the early to mid miocene 20 5 17 5 ma unfortunately relevant sedimentary deposits have not been found on land

devensian glacigenic sedimentation and landscape evolution in the cardigan area of southwest wales hambrey michael davies j r glasser n f waters r a 2001 devensian glacigenic sedimentation and landscape evolution in the cardigan area of southwest wales journal of quaternary science 16 5 pp 455 482 rae2008

an ignimbrite veneer deposit the trail marker of a pyroclastic flow abstract the term ignimbrite veneer deposit ivd is proposed for a new kind of pyroclastic deposit which is found associated with and passes laterally into taupo ignimbrite of valley pond type in new zealand it forms a thin layer mantling the landscape over 15 000 km 2 and is regarded as the deposit from the trailing tail of a pyroclastic flow where a relaxation of shear stress favoured the deposition of the basal part of the flow the ivd differs little in grain size from the associated ignimbrite but it shows a crude internal stratification attributed to the deposition of a succession of layers one after the passage of each pulse of the pyroclastic flow it locally contains laterally discontinuous lenses of coarse pumice lee side lenses on the far vent side of topographic obstacles in nearvent exposures the taupo ivd shows lensoid and cross stratified bed forms even where it stands on a planar surface attributed to deposition from a flow travelling at an exceedingly high velocity an ivd can be distinguished from a poorly sorted pyroclastic fall deposit because the beds in it show more rapid lateral variations in thickness it may show a low angle cross stratification and it contains carbonised wood from trees not in the position of growth from the deposit of a wet base surge because it lacks vesicles and strong antidune like structures and contains carbonised vegetation and from a hot and dry pyroclastic surge deposit because it possesses a high content of pumice and fines the significance of an ivd is that it records the passage of a pyroclastic flow where the flow itself has moved farther on

mid carboniferous deglaciation of the protoprecordillera argentina recorded in the agua de jaguel palaeovalley abstract the agua de jaguel formation near uspallata mendoza province argentina was deposited within a palaeovalley along the southeastern margin of the calingasta uspallata basin adjacent to the protoprecordillera the basal glacigenic sequence of the formation was deposited in the serpukhovian early bashkirian near the beginning of the late palaeozoic ice age the sequence is composed of diamictite conglomerate sandstone and mudrock and records four depositional stages within a palaeofjord 1 morainal bank deposition by a wet based tidewater glacier 2 glacial retreat succession where ice retreated up the fjord out of the immediate area allowing iceberg deposition of dropstones and dump deposits 3 continued glacial retreat with ice receding onto land allowing a shoreface to develop within the palaeovalley and 4 transgression across the shoreface and resumption of iceberg deposition the thickness and facies of this succession are similar to deposits within modern alaskan fjords housing temperate tidewater glaciers comparison of the agua de jaguel formation with alaskan fjords indicates that sequence stratigraphy used for low latitude deposits must be applied with caution as glacimarine ice retreat within a fjord produces strata surfaces that are easily misidentified as flooding surfaces resulting from changes in water depth likewise the transgression during stage 4 is significant as it indicates a rise in sea level that occurred during glaciation of the protoprecordillera thus suggesting that the transgression between stages 3 and 4 was not driven by input of glacial meltwater additionally the sediment geochemistry suggests that the bottom waters of the palaeovalley were anoxic which may help explain the absence of bioturbation in the sequence as well as in other ancient glacimarine palaeovalleys the deglaciation succession and transgression are also recorded in the nearby hoyada verde and tramojo formations so it is proposed that all three formations record one glacial event in the protoprecordillera overlying fluvial and shallow marine strata in the agua de jaguel hoyada verde and tramojo formations show no indication of continued glaciation in the protoprecordillera following stage 4 and equivalent strata the deglaciation succession of the agua de jaguel formation affirms the emerging concept that the late palaeozoic ice age was characterized by alpine glaciers ice caps and small ice sheets that were not massive enough to have driven eustatic fluctuations of 100 m as previously understood and that ice never covered westernmost gondwana during later lpia events

a new depositional model for ice shelves based upon sediment cores from the ross sea and the mac robertson shelf antarctica we document the similarity of depositional facies occurring in gravity cores recovered from two disjunct regions of the antarctic continental shelf the ross sea and the mac robertson shelf the facies sequence model is represented in two cores one collected during the 1995 1 cruise of the r v nathaniel r palmer core nbp95 tc 18 and the other collected by the rsv aurora australis during cruise 149 in 1995 core 149 39gc38 both cores show a succession of facies indicative of ice shelf retreat during the late pleistocene to holocene transition distinct lithofacies range in thickness from a few tens of cm to 1 m and consist of from bottom to top a coarse granulated sandy mud laminated silt and clay structureless silly clay poorly sorted sandy siliceous mud and siliceous mud and ooze these facies represent the passage of distinct depositional regimes across the core sites including sub ice shelf beneath a basal debris zone sub ice shell distal to a debris zone calving line transition and open marine this facies model represents an advance in our understanding of glacial marine stratigraphy for the antarctic continental shelf and will provide the basis for more realistic palaeoglacial reconstructions

dinoflagellate cyst stratigraphy of the palaeogene strata from the hellefisk 1 ikermiut 1 kangâmiut 1 nukik 1 nukik 2 and qulleq 1 wells offshore west greenland abstract a new palaeogene dinoflagellate cyst stratigraphy from offshore west greenland has been described based on the strata from the hellefisk 1 ikermiut 1 kang miut 1 nukik 1 nukik 2 and qulleq 1 wells twenty one palynological intervals are defined from the late eocene to the late early paleocene this stratigraphy has been correlated with a new microfossil zonation and previous established north sea zonations the stratigraphy and well correlation are based on last appearance datum events and abundances of stratigraphically important species from 355 samples 148 of which are sidewall core samples a major middle eocene hiatus spanning the early lutetian and a major early paleocene hiatus spanning the late santonian late cretaceous to the early danian have been recognised from the offshore deposits

discriminating glacier thermal and dynamic regimes in the sedimentary record abstract this paper provides a description and evaluation of the sedimentary facies and environments associated with a range of glacier thermal and dynamic regimes with additional consideration given to the tectonic context new and previously published data are evaluated together and are presented from modern terrestrial and marine glacial sedimentary environments in order to identify a set of criteria that can be used to discriminate between different glacier thermal regimes and dynamic styles in the sedimentary record sedimentological data are presented from a total of 28 glaciers in 11 geographical areas that represent a wide range of contemporary thermal dynamic and topographic regimes in the context of landsystems representatives from terrestrial environments include temperate glaciers in the european alps patagonia new zealand the cordillera blanca peru cold glaciers in the dry valleys of antarctica and the antarctic peninsula region and polythermal valley glaciers in svalbard northern sweden the yukon and the khumbu himal nepal the glaciomarine environment is illustrated by data from cold and polythermal glacier margins on the east antarctic continental shelf and from a polythermal tidewater glacier in svalbard along with general observations from temperate glaciers in alaska these data show that temperate glacial systems particularly in high relief areas are dominated by rockfall and avalanche processes although sediments are largely reworked by glaciofluvial processes debris in polythermal glaciers is both thermally and topographically influenced in areas of moderate relief debris is mainly of basal glacial origin and the resulting facies association is dominated by diamicton in high relief areas such as the himalaya the debris load in polythermal glaciers is dominated by rockfall and avalanche inputs resulting in extensive accumulations of sandy boulder gravel cold glaciers are dominated by basal debris entrainment but sediments are little modified from the source materials which are typically sandy boulder gravel from older till and sand from glaciofluvial glaciolacustrine and aeolian sources similar facies associations but with different facies geometry and thickness occur in equivalent glaciomarine settings application of these concepts can aid the interpretation of glacier thermal regime and hence palaeoclimate in quaternary and ancient glacial systems

neoproterozoic ice sheets and olistoliths multiple glacial cycles in the kingston peak formation california the kingston peak formation is a diamictite bearing succession that crops out in the death valley region california usa an exceptionally thick 1 5 km outcrop belt in its type area the kingston range provides clear insights into the dynamics of mid cryogenian sturtian ice sheets in laurentia seven detailed logs allow the lateral and vertical distribution of facies associations to be assessed we recognize 1 diamictite facies association ice proximal glacigenic debris flows 2 lonestone bearing facies association ice marginal hemipelagic deposits and low density gravity flows with iceberg rafting 3 pebble to boulder conglomerate facies association ice proximal cogenetic glacigenic debris flows and high density turbidites 4 megaclast facies association olistostrome and hemipelagic sediments subject to ice rafting and 5 interbedded heterolithics facies association low density turbidites and hemipelagic deposits the stratigraphic motif allows three glacial cycles to be inferred across the range ice minimum conditions interrupting the kingston peak succession are associated with the development of an olistostrome complex succeeded by a thick accumulation of boulder conglomerates deposited during ice readvance the data testify to a strong glacial influence on sedimentation within this ancient subaqueous succession and to highly dynamic ice sheet behaviour with clear glacial cycles during the sturtian glaciation

standardizing texture and facies codes for a process based classification of clastic sediment and rock abstract proposed here is a universally applicable texturally based classification of clastic sediment that is independent from composition cementation and geologic environment is closely allied to process sedimentology and applies to all compartments in the source to sink system the classification is contingent on defining the term clastic so that it is independent from composition or origin and includes any particles or grains that are subject to erosion transportation and deposition modifications to folk s 1980 texturally based classification that include applying new assumptions and defining a broader array of textural fields are proposed to accommodate this the revised ternary diagrams include additional textural fields that better define poorly sorted and coarse grained deposits so that all end members gravel sand and mud size fractions are included in textural codes revised textural fields or classes are based on a strict adherence to volumetric estimates of percentages of gravel sand and mud size grain populations which by definition must sum to 100 the new classification ensures that descriptors are applied consistently to all end members in the ternary diagram gravel sand and mud according to several rules and that none of the end members are ignored these modifications provide bases for standardizing vertical displays of texture in graphic logs lithofacies codes and their derivatives hydrofacies hydrofacies codes are nondirectional permeability indicators that predict aquifer or reservoir potential folk s 1980 ternary diagram for fine grained clastic sediments sand silt and clay size fractions is also revised to preserve consistency with the revised diagram for gravel sand and mud standardizing texture ensures that the principles of process sedimentology are consistently applied to compositionally variable rock sequences such as mixed carbonate siliciclastic ramp settings and the extreme ends of depositional systems

late cretaceous tertiary sediments offshore central west greenland lithostratigraphy sedimentary evolution and petroleum potential five dry exploratory wells were drilled through upper cretaceous and tertiary sediments on the west greenland shelf in 1976 and 1977 two of these entered precambrian basement two bottomed in paleocene or upper cretaceous basalt and one in campanian mudstone on the basis of samples and logs supplied to the geological survey of greenland the sedimentary sequence has been divided into seven new formations the campanian narssarmiut formation consisting of coarse basement wash and black mudstone the campanian to eocene ikermiut formation consisting of marine organic rich mudstone the upper paleocene to eocene hellefisk formation comprising shallow marine to paralic sandstone and mudstone the eocene nukik formation consisting of turbiditic sandstone and mudstone the eocene to oligocene kang miut formation of shelf to shallow marine clean and argillaceous sandstone the oligocene to neogene manitsoq formation consisting of coarse paralic to fan delta sandstone and the neogene ataneq formation con

inner shelf to lower shoreface hummocky sandstone bodies with evidence for geostrophic influenced combined flow lower cretaceous west greenland abstract hummocky sandstone bodies were deposited on the margin of an early cretaceous rift basin in an overall progradational inner shelf to lower shoreface unit excellent outcrops of this unit permitted a detailed study of sedimentary structures and paleocurrents in relation to sandstone geometries the sandstone bodies are lensoid and 0 5 4 m thick with lateral extensions from a few meters to more than 30 m laterally they pinch into thin sandstone sheets that continue for at least 130 m along the entire outcrop or swell within a distance of 20 30 m to form another sandstone lens the lower boundaries are sharp with local erosional relief up to 1 m hummocky cross stratification wave ripple cross lamination and low angle cross stratification are closely interbedded within the sandstone aminated mudstone beds 10 60 cm thick separate the sandstone bodies and are generally continuous over the entire length of the outcrop sedimentary structures in the sandstone bodies were produced by high energy wave generated oscillatory currents and unidirectional geostrophic currents vertical stratification successions from individual storm events reflect deposition during both increasing storm current velocity succeeded by waning storm deposits and more typically waning storm facies successions deposition of the unusual vertical successions was probably controlled by an episodically high sediment supply the local presence of the hummocky sandstone bodies on a regional scale was controlled by a paleogeographic setting where the bathymetric contours locally caused geostrophic cu rents to decelerate

multiple point geostatistical simulation with adaptive filter derived from neural network for sedimentary facies classification abstract sedimentary facies distribution is a vital reference for oil and gas exploration in an offshore area one of remaining questions in a marine exploration area is to acquire an accurate sedimentary facies map with limited loggings and a set of indirect information previous studies are largely based on geological parameters and structures for estimating the sedimentary distributions while some other researches employ machine learning algorithm to participate the classification tasks based on accessible datasets however the application of either method alone still cannot overcome the information limitation or the low accuracy of final results this study is a kind of attempt to introduce machine learning algorithm into traditional multiple point geostatistical simulation mps with seismic and logging information for increasing the applicability of multiple point geostatistical simulation and solving the previous mentioned problems of sedimentary classification the filter generation auto encoder fae using in this work is constructed by an encoder a decoder and a classifier which are designed for generating adaptive filters of mps maintaining the stability of data extraction and introducing the constraints of sedimentary facies separately for applying these adaptive filters into mps the distance function need to be modified to meet the requirement of indirect information without prototypes then the multi distances function is able to measure the relationship among a known pattern a nearby layer related simulated points and seismic attributes after that the sedimentary maps can be obtained by this method with great continuity in horizontal and vertical direction at the mean time and its effectivity has been verified by the loggings in this area furthermore the 3 d sedimentary facies map have valuable meanings for both petroleum exploration and geological engineering in an area with limited information

glaciar leon chilean patagonia late holocene chronology and geomorphology harrison s glasser n f winchester v haresign e warren c duller g a t bailey r ivy ochs s jansson k kubik p 2008 glaciar leon chilean patagonia late holocene chronology and geomorphology the holocene 18 4 pp 643 652 sponsorship nerc university of st andrews american alpine club british geomorphological research group dudley stamp memorial trust royal scottish geographical society quaternary research association carnegie trust for the universities of scotland