the chronology and structure of the western new caledonian barrier reef tracts abstract the mainland of new caledonia grande terre is surrounded by one of the largest continuous barrier reef system in the world in order to study the development history and internal structure of this system drilling operations have been carried out at two sites amedee and kendec islets located on the barrier reef tract extending from the south west 33 to the north west of new caledonia the extracted cores are 128 50 and 148 75 m in length respectively lithological and paleoecological descriptions combined with uranium thorium dating magnetostratigraphy and nannofossil based biostratigraphy allowed a reef evolutionary scheme to be drawn as a result of the interplay between margin subsidence and sea level changes 11 reef units formed successively during interglacial episodes at high sea levels in both sites depending on the subsidence rate of the western shelf margin major building in new caledonia appears to have started during the mis 11 400 000 yr from shallow water carbonate platform deposits older than 780 000 yr comparing development patterns between the new caledonian barrier reef and the australian great barrier reef clearly indicates that both global climate and regional tectonic history have been the major controls on reef initiation and growth along both sides of the coral sea climatic conditions are likely to have not been optimal before the late quaternary probably resulting in luxuriant reef expansion only during the last 400 000 yr

recent mass movement processes on the ebro continental slope nw mediterranean abstract mass movement is an important process controlling the sedimentary structure and growth patterns of the ebro continental slope during recent time at least quaternary about 37 of the slope surface is affected by mass movement features which are variable in distribution size and morphology the northern and central sectors are mainly affected by erosive canyons with gullies on their upper courses and massive and chaotic slump bodies on the middle and lower courses the southern sector is mainly affected by large scale slides 10 km and debris flow deposits in the three sectors the slope is also locally affected by small scale slides

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

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

thick and fast sedimentation in a pleistocene fiord lake of british columbia canada the central interior plateau of british columbia canada is dissected by numerous elongate glacially overdeepened lake basins akin to coastal fiords an air gun seismic reflection investigation 242 km of trackline of okanagan lake 120 km long 3 5 km wide shows that the pleistocene sediment fill is up to 792 m thick and that bedrock has been excavated by repeated pleistocene glacial erosion to nearly 650 m below sea level the depth of bedrock incision below the surrounding plateau is more than 2000 m exceeding that of the grand canyon in arizona the total volume of sediment infill within the narrow trenchlike basin is more than 90 km 3 and several lines of evidence suggest that this fill accumulated rapidly during a single phase of glaciolacustrine sedimentation during late wisconsin deglaciation of the region after 15 ka similar fiord lake basins up to 100 km long are common in the interior of british columbia if the data from okanagan are representative these basins may represent a major previously unrecognized component of the total glacial sediment flux to the ocean overdeepening below sea level and the focusing of large volumes of glacial sediment and meltwater into such basins are of considerable glaciologic significance and may record the fast unstable flow of ice streams during deglaciation of the cordilleran ice sheet

facies characteristics of a proglacial turbiditic sand lobe at svalbard abstract a shallow marine turbiditic lobe inferred to be associated with an ice contact delta was deposited during the last glaciation weichselian at svalbard the norwegian arctic the postglacially raised sandy lobe is exposed in a 200 m long river section and exhibits six units that reflect an early phase of glaciomarine mud deposition followed by three episodes dominated by deposition from sandy turbidity currents the lobe is characterized by a complex pattern of turbidite filled erosional features from thin scour fills reflecting a highly mobile flow pattern to stacked chute fill deposits showing confined flow the sandy turbidites show rhythmic deposition of massive to graded laminae deposited from suspension alternating with faint laminae or ripple cross lamination deposited from tractional transport semi continuous turbidity currents are thought to have been generated by retrogressive slumping of ice proximal well sorted sandy deposits on the delta front and slope the lateral and vertical changes of lithofacies within the sandy lobe are mainly attributed to normal mechanisms of turbiditic lobe growth with only minor effect from synsedimentary glacier terminus movement and minor changes in the meltwater outflow position this detailed mapping of facies changes allows a fairly accurate reconstruction of the axis of the former discharge outlet

deglacial and postglacial sedimentary architecture in a deeply incised paleovalley paleofjord the pennsylvanian late carboniferous jejenes formation san juan argentina quebrada de las lajas near san juan argentina preserves an early pennsylvanian deglacial postglacial succession in a highly confined paleofjord setting the sedimentary succession records four distinct stages in the evolution of the valley fill stage 1 is represented by the deposits of subglacial diamictites ice contact deltas and related deep water lacustrine environments including several subaqueous channels stage 2 records a glacio eustatic marine transgression and a slow down of the clastic supply into the paleofjord stage 3 records a sandy confined turbidite environment stage 4 consists of a coarse grained delta which represents a significant rejuvenation of the sedimentary system in the paleofjord the transition from stage 1 to stage 2 was abrupt and basinwide and has proven to be a good regional correlation marker in this paleovalley the glacio eustatic rise probably caused floating and consequent rapid melting of the valley glacier this resulted in a paleovalley wide turbidite event that is up to 5 m thick and indicates an overall waning character the rapid sediment emplacement in this event and resulting loading of the paleovalley sediments may have helped cause widespread mass transport events at the stage 1 2 boundary all stages show evidence of mass transport related deposits but stage 1 records the most widespread mass transport with a large spectrum of processes represented including coherently slumped material rafted blocks and completely mixed debris flow deposits these mass transport deposits range from a few meters to over 50 m thick and up to hundreds of meters wide and long most of the large mass transport deposits in the lower part of the fjord fill occurred at the transition to stage 2 implicating a rise in relative sea level as a possible trigger for the slope failures additionally stage 3 deposits were affected by several thrust sense dislocations that have large offsets relative to the scale of the sedimentary succession tens to over 50 m vertically and hundreds of meters laterally strata associated with the dislocations exhibit growth indicating very early movement and they are interpreted as the frontal ramp zones of mass transport deposits the abundance and size of mass transport deposits in stages 1 and 3 helped control sediment pathways throughout the paleofjord

sedimentary environments and facies in an arctic basin itirbilung fiord baffin island canada abstract itirbilung fiord typifies a deep arctic basin that experiences episodic sedimentation events cycled principally by aeolian transport nival and glacier melt with punctuations by mass sediment failures a quaternary sedimentary fill exceeding 150 m is found in two of the fjord s four sub basins basin circulation is associated with meltwater influx during the summer wind generated drift during the fall accompanied by deep water exchanges winter isohaline generated circulation and tidal currents which operate over the entire year sediment accumulation decreases down the basin this general trend is interrupted by side entry fan deltas that locally contribute large volumes of sediment basin deposits are largely ponded between the fjord walls although two of the fjord s sills are mantled by hemipelagic deposits five seismo stratigraphic units are identified and may represent sedimentary deposits associated with a single phase of ice sheet advance and retreat the upper three seismic units were cored and contain seven sedimentary facies that show little correlation between sub basins pebbly sandy mud from the melt of debris laden ice burrowed mottled mud reflecting the bioturbation of hemipelagic deposits wispy laminated mottled mud from low velocity currents and or melt out of seasonal sea ice cover and bioturbation laminated sand and mud from the hypopycnal flows from rivers graded coarse sand gravel and pebbly sand and sand reflecting very rapid deposition from high concentration turbidity currents or from sandy debris flows and cross bedded sands that may relate to the reworking of turbidity current deposited sands possibly by reverse flow mechanisms

modelling the thermal perturbation of the continental crust after intraplating of thick granitoid sheets a comparison with the crustal sections in calabria italy thick granitoid sheets represent a considerable percentage of palaeozoic crustal sections exposed in calabria high thermal gradients are recorded in upper and lower crustal regional metamorphic rocks lying at the roof and base of the granitoids ages of peak metamorphism and emplacement of granitoids are mostly overlapping suggesting a connection between magma intrusion and low pressure metamorphism to analyse this relationship thermal perturbation following granitoid emplacement has been modelled the simulation indicates that in the upper crust the thermal perturbation is short lived in contrast in the lower crust temperatures greater than 700 c are maintained for 12 ma explaining granulite formation anatexis and the following nearly isobaric cooling an even longer perturbation can be achieved introducing the effect of mantle lithosphere thinning into the model

evidence of glacial abrasion in the calingasta uspallata and western paganzo basins mid carboniferous of western argentina abstract evidence of glacial abrasion is present in the basal part of the carboniferous section of the calingasta uspallata and paganzo western argentina where subglacial and proximal glacial marine diamictites with pebbly dropstone shales constitute the dominant facies association intraformational striated pavements are exposed in the hoyada verde and leoncito formations of the calingasta uspallata basin marine invertebrate fossils levispustula zone in associated shales indicate a mid carboniferous age for both units a single layer striated boulder pavement is superbly exposed in the hoyada verde formation local a axis clast imbrication in the underlying bouldery diamictite and strong parallel striae on the flattened upper surfaces of boulders indicate a subglacial origin for the pavement paleo ice flow directions have an nne ssw strike the leoncito intraformational pavement is shaped on bioturbated fine grained sandstones with plant remains glacial striations are straight and parallel with subcircular cross sections dome like features are present in the surface which is covered in turn by a sandy bouldery diamictite four striated surfaces are present in the western paganzo basin three of them pavements at the san juan river valley loma de los piojos and agua hedionda are developed on basement rocks they contain parallel to subparallel striations nailhead striations crescentic gouges impact marks and furrows the pavements are overlain by thin up to 1 5 m laterally discontinuous diamictite beds with striated clasts some of them bullet shaped paleo ice flow directions are n ne directed an intraformational pavement is also present at the san juan river valley section it is carved on the top of the basal diamictite and exhibits furrows probably caused by subglacial soft sediment grooving the dispersion of paleo ice flow directions in the calingasta uspallata and paganzo basins indicates i regional slopes toward the north into a brackish water embayment and northwest into the open marine conditions ii glacial erosion by ice grounded below sea level and confined to the margins of the basins

sea level change glacial rebound and mantle viscosity fornorthern europe northwestern europe remains a key region for testing models of glacial isostasy because of the good geological record of crustal response to the glacial unloading since the time of the last glacial maximum models for this rebound and associated sea level change require a detailed knowledge of the ice sheet geometry including the ice thickness through time existing ice sheet reconstructions are strongly model dependent and inversions of sea level data for the mantle response may be a function of the model assumptions thus inverse solutions for the sea level data are sought that include both ice and earth model parameters as unknowns sea level data from fennoscandia the north sea the british isles and the atlantic and english channel coasts have been evaluated and incorporated into the solutions the starting ice sheet for fennoscandia is based on a reconstruction of a model by denton hughes 1981 that is characterized by quasi parabolic cross sections and symmetry about the load centre both global northwestern europe as a whole and regional subsets of the data solutions have been made for earth model parameters and ice height scaling parameters the key results are as follows 1 the response of the upper mantle to the changing ice and water loads is spatially relatively homogenous across scandinavia the north sea and the british isles 2 this response can be adequately modelled by an effective elastic lithosphere of thickness 65 85 km and by an effective upper mantle viscosity from the base of the lithosphere to the 670 km depth seismic discontinuity of about 3 4 1020 pa s the effective lower mantle viscosity is at least an order of magnitude greater 3 the ice thickness over scandinavia at the time of maximum glaciation was only about 2000 m much less than the 3400 m assumed in the denton hughes model 4 the ice profiles are asymmetric about the centre of the ice sheet with those over the western part being consistent with quasi parabolic functions whereas the ice heights over the eastern and southern regions increase much more slowly with distance inwards from the ice margin

seismicity and seismotectonics of norway and nearby continental shelf areas the earthquake activity of norway and nearby offshore areas is low to intermediate with few events above magnitude 5 recent significant improvements in instrumental coverage in parallel with a better utilization of older including historical data have shown that the seismicity in the south is predominantly confined to the coastal areas and to the viking graben while from the northern north sea to svalbard the earthquakes in a broad sense follow the continental margin fifty one focal mechanism solutions from these areas about half of them new reveal stress directions that clearly indicate a connection to the plate tectonic ridge push force at least for the areas at a minimum distance from the continental margin along the margin stress directions also indicate a possible connection to postglacial uplift as well as to lithospheric loading effects a dominance of normal faulting on the landward side and reverse faulting on the oceanic side agrees with this interpretation on a regional level the seismicity in these areas correlate quite well with geologic features such as grabens fault zones fault complexes fracture zones and the margin itself indicating that these structures act in a general sense as weakness zones in the presence of a regionally more stable stress field in the northern north sea however an area with quite anomalous stress orientations with strike slip faulting is found in a region transitional between normal and reverse faulting most of the earthquake foci are confined to the presumably brittle parts of the crust but many events are also located quite close to and on both sides of the moho discontinuity

late paleozoic paleoclimatology of central west argentina abstract based on sedimentologic and paleontological characteristics present in the sedimentary record of the calingasta uspallata and paganzo basins a model of paleoclimatic evolution for the late paleozoic of central west argentina is proposed additional evidence is also provided by data from other basins of southern san rafael and tepuel basins and northern tarija basin west argentina five paleoclimatic stages have been defined paleoclimatic stage i tournalism visean early carboniferous is characterized by temperature and humid preglacial conditions as evidencedin the el raton and maliman formations calingasta uspallata basin plant remains of archeosigillaria and lepidodendropsis zone are present in both units the paleoclimatic stage ii namurian early westphalian middle carboniferous comprises widespread glacial deposits including glaciomarine sequence in the westernmost basins calingasta uspallata western paganzo san rafael and tepuel and terrestrial tillites and glaciolacustrine fine clastics in some areas of the paganzo basin fossils of the levipustula fauna are distinctive in the glaciomarine deposits of this stage and in the overlying postglacial fine clastics of the basal portion of stage iii substage iiia the paleoclimatic stage iii of middle carboniferous late westphalian age corresponds to postglacial transgressions that flooded the previously glaciated shelves in the calingasta uspallata and tepuel basins terminal glaciolacustrine deposits substage iiia indicate of the demise of glacial conditions and coal measures of fluvial affinity in the paganzo basin substage iiib probably this postglacial stage was characterized by high humidity and moderate temperatures this stage is paleobiologi defined by a floral assemblage known as nbg nothorhacopteris botrychiopsis and ginkgophyllum the paleoclimatic stage iv late carboniferous stephanian early permian corresponds to a time interval characterized by seasonally dry climates and a progressive amelioration in humidity clear evidence of these climatic conditions is present in several localities in the paganzo basin the first astherothecae and glossopteris leaves are found finally paleoclimatic stage v middle late permian is dominated by red beds thick eolian sequences and saline lake facies deposited under arid to semi arid conditions coeval volcanism derived from the west is expressed by interbedded tuffs and agglomerates calingasta uspallata paganzo and san rafael basins

paleoseismicity the swedish case abstract sweden is part of an old cratonic area it was repeatedly glaciated during the quaternary after the 20 ka glaciation maximum it has experienced a glacial isostatic uplift of over 800 m numerous paleoseismic indices have been recorded giving evidence of frequent high magnitude earthquakes from the time at around and just after the deglaciation late holocene archaeoseismic fracturing is also reported these observations violate all claims of a possible safe long term repository for high level nuclear waste some 500 m down in the bedrock

glacio seismotectonics ice sheets crustal deformation and seismicity abstract the last decade has witnessed a significant growth in our understanding of the past and continuing effects of ice sheets and glaciers on contemporary crustal deformation and seismicity this growth has been driven largely by the emergence of postglacial rebound models pgm constrained by new field observations that incorporate increasingly realistic rheological mechanical and glacial parameters in this paper we highlight some of these recent field based investigations and new pgms and examine their implications for understanding crustal deformation and seismicity during glaciation and following deglaciation the emerging glacial rebound models outlined in the paper support the view that both tectonic stresses and glacial rebound stresses are needed to explain the distribution and style of contemporary earthquake activity in former glaciated shields of eastern canada and fennoscandia however many of these models neglect important parameters such as topography lateral variations in lithospheric strength and tectonic strain built up during glaciation in glaciated mountainous terrains glacial erosion may directly modulate tectonic deformation by resetting the orogenic topography and thereby providing an additional compensatory uplift mechanism such effects are likely to be important both in tectonically active orogens and in the mountainous regions of glaciated shields in general the short term response to ice fluctuations is similar to the earth s response to fluctuations in water reservoirs with the subsequent increase or decrease in seismicity which depends on the pre existing stress state when the ice fluctuations occur on the spatial scale and magnitude of the late pleistocene glaciation and deglaciation however the viscoelastic response of the earth especially the mantle causes significant changes in crustal deformation and earthquake activity that is spatially extensive and temporally complex the regions of greatest ice thickness and the regions marginal to the late pleistocene ice sheets indicate the most dramatic evidence of earthquake faulting the mantle response to these large ice mass fluctuations and the change in mass between the oceans and land caused and continues to cause measureable crustal deformation at hundreds of kilometres from the ice margins for both tectonically active and cratonic regions palaeoseismic investigations of late pleistocene and holocene faults are an important tool in evaluating earthquake hazard the predicted response of the earth over this time however is very dependent on the model assumed for most regions far more carefully designed field observations are needed to constrain the existing rheological and ice models

recent fault movement and palaeoseismicity in western scotland abstract field study at two locations in western scotland is described and gives evidence for fault movement and seismic activity during the late and post glacial epochs the evidence comprises levelling survey of raised marine shorelines remote sensing study of lineaments radiocarbon dating of quaternary sediment and detailed field examination of faults and fault gouge material vertical fault displacements of up to 3 m are observed on a c 10 500 year old raised marine shoreline on the isle of mull and repeated predominantly lateral movement is observed on a prominent 14 km long fault lineament active since ice retreat and as recently as c 2000 yrs b p the fault movements are located close to the edge of the area formerly covered by the loch lomond readvance ice cap 11 000 10 000 yrs b p they are considered to have been caused by rapid rates of isostatic rebound soon after deglaciation

fennoscandian earthquakes whole crustal rupturing related to postglacial rebound local and regional earthquake locations provide seismic evidence that large shield earthquakes have occurred in northern fennoscandia these paleoearthquakes with fault lengths of up to 160 kilometers and average displacements of up to 15 meters were triggered by nonisostatic compressive stresses caused by the removal of the ice at the end of the last deglaciation the fennoscandian faults were probably formed by single events that ruptured through most of the crust the largest event moment magnitude mw 8 2 was larger than other known stable continent earthquakes outside failed rifts or extended crust

models of glaciomarine sedimentation and their application to the interpretation of ancient glacial sequences abstract this paper argues that glaciomarine environments can be regarded as special glacially influenced types of continental margin environments e g continental shelf slope rise and basin plain knowledge of the stratigraphic architecture and typical sedimentary sequences of non glacial margins is becoming well known but remains limited for those that have been glacially modified the principal influences on sedimentation in these environments relate to the glacial sediment input controlled by relief of basin margin glacier thermal regime and ice flow dynamics and depositional environments influence of traction currents substrate relief and proximity to nearby ice margins typical ranges of sedimentation rates can be established for glacially influenced continental margin environments and these may provide a framework for ancient sequences starvation of sediment supply to glacially influenced continental margins is common the nature of sub ice shelf sedimentation a model that has been applied to many ancient glacial sequences is critically reviewed the significance of such sedimentation in the rock record has probably been exaggerated because of oversimplistic interpretations of diamictite sequences existing process models of glaciomarine sedimentation derived from study of modern environments are sometimes difficult to employ in investigation of ancient sedimentary sequences because simple lithofacies criteria and typical vertical profiles are not available to aid in interpretation in addition compositional data emphasized by many workers for distinguishing glaciomarine from continental glacial diamict ite s frequently fingerprint sediment source and not mode of deposition the importance of facies analysis methods for isolating depositional environments is illustrated by three examples of ancient glaciomarine sequences these are the early proterozoic gowganda formation 2 3 ga of northern ontario canada the late proterozoic port askaig formation 670 ma of scotland and ireland and the late cenozoic yakataga formation 20 ma to recent of the gulf of alaska these examples illustrate the significance of detailed genetic studies of ancient glacial rocks in the interpretation of palaeogeographic and tectonic settings diamictite units in ancient glaciomarine sequences cannot be easily interpreted in terms of climatic or ice advance retreat cycles because of the varied controls on diamict accumulation and diamictite preservation in marine basins

neotectonics and paleoseismicity within the stockholm intracratonal region in sweden abstract a number of sites with fresh faults and fractures have been mapped in detail their postglacial and sometimes late glacial age is confirmed they form simple and similar patterns consistent with stress release due to a combination of acting forces they are associated with the peak rate of glacial isostasy and increased strain rates by two orders of magnitude they often cut straight across bedrock hills between so called weak zones the fault throws correspond to approximately magnitude 7 on the richter scale sedimentary and morphological data confirm the seismo tectonic origin newly discovered large scale network of crossing faults is found to have changed the course of the stockholm esker in a way that reveals at least two major seismo tectonic events this is consistent with paleoseismic events of magnitude 7 or more

climatic control of turbidite deposition on the madeira abyssal plain studies of sedimentation in the southwestern part of the madeira abyssal plain have revealed sequences of turbidites correlatable over thousands of square kilometres turbidites are sediments transported by turbidity currents and represent rapidly accumulated sedimentary units1 in this case in the distal part of the flow they are very fine grained and homogeneous occasionally with silty bases individual turbidites are separated by thin pelagic units which alternate from oozes to pelagic clays a stratigraphy for these pelagic units has been produced from combining coccolith distributions and lithological changes which enables comparison to cores containing only pelagic sediments from outside the turbidite province these comparisons show that turbidity currents cause no significant erosion in the area the major turbidites occur between lithological alternations which reflect global climate changes associated with glaciations and related eustatic sea level fluctuations turbidites have been linked with eustacy on previous occasions but only with low stands of sea level2 3 our work shows that turbidites are more likely to occur during regressions and transgressions rather than in the quiet periods between

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

postglacial faulting in eastern canada nature origin and seismic hazard implications abstract at more than 70 locations in southeastern canada and the adjacent united states tiny bedrock faults displace glacial striations that are about 10 000 years old these reverse faults mostly of small displacement occur in a broad arc from western ontario to newfoundland the faults lie near the margin of the laurentian ice sheet strike generally tangential to it and imply compression nearly normal to the ene directed contemporary regional stress these observations and some age relationships suggest that the faults formed very soon after deglaciation perhaps in the first few thousand years after ice melting in each place and probably represent the release of stresses caused by flexural deformation of the upper crust although the individual offsets are small the faults are believed to be pervasive and individual outcrops reflect amounts of stress relief consistent with stresses implied by the postglacial tilt of nearby lake shorelines

the source and fate of massive carbon input during the latest paleocene thermal maximum lithologic faunal seismic and isotopic evidence from the blake nose subtropical western north atlantic links a massive release of biogenic methane 55 5 million years ago to a warming of deep ocean and high latitude surface waters a large perturbation in the combined ocean atmosphere carbon cycle the largest of the past 90 million years a mass extinction event in benthic faunas and a radiation of mammalian orders the deposition of a mud clast interval and seismic evidence for slope disturbance are associated with intermediate water warming massive carbon input to the global exogenic carbon cycle pelagic carbonate dissolution a decrease in dissolved oxygen and a benthic foraminiferal extinction event these events provide evidence to confirm the gas hydrate dissociation hypothesis and identify the blake nose as a site of methane release