structural outline of a tertiary basement cored uplift inversion structure in western spitsbergen svalbard kinematics and controlling factors the tertiary fold and thrust belt of spitsbergen can be divided into a western basement involved fold thrust stack and a central eastern foreland fold and thrust belt in western nordenskiold land the first order structure is an ene verging basement cored fold and fault complex involving paleozoic to tertiary strata the northern part reveals an upright monocline geometry of east tilted sedimentary cover units with associated layer parallel to low angle thrusts and folds these structures consist of two populations oriented both parallel to nnw sse and oblique to wnw ese the general structural trend of the fold complex in the central and southern parts of west nordenskiold land the fold complex involves tilted basement cut by steep transverse faults and late normal faults the east limb of the fold complex displays repeated basement and paleozoic strata orustdalen formation in its core and mesozoic triassic strata influenced by map scale chevron folds and two decollement levels all located above an eastward rotated major detachment fault the kleivdalen thrust establishing fold fault relations includes a three stage structural history in the fold complex as follows 1 a phase of early nne ssw shortening associated with wnw ese folds and thrusts and 2 a dominant ene wsw basement involved shortening leading to the first order nnw sse striking fold complex followed by 3 approximately e w extension the resulting structures and structural variability along strike as well as across strike appear to have been controlled by basement and carboniferous basin structures underlying the permian cretaceous platform strata restored stratigraphic sections based on thrust repetition of basement and cover e g within a type section of the carboniferous orustdalen formation support such an interpretation a tentative inversion tectonic model reproduces the position s of local and major thrust ramps and associated folds as a result of inheritance from carboniferous basin structures

evolution of the central tertiary basin of spitsbergen towards a synthesis of sediment and plate tectonic history abstract the central tertiary basin of spitsbergen developed east of a strike slip boundary between the eurasian and greenland plates in response to the initiation of rifting and later seafloor spreading in the norwegian greenland sea using a new plate model for the opening of the north atlantic we attempt to relate the sediment history of the central tertiary basin to its plate tectonic framework and suggest a basin development in four phases the central tertiary basin was formed in the early paleocene during a right lateral strike slip phase after the plate boundary between greenland and svalbard had jumped eastward to the hornsund fault zone phase 1 the onset of seafloor spreading between greenland and eurasia and a drastic counterclockwise change in spreading direction between greenland and north america after chron 25 late paleocene induced compression dominated transpression between greenland and svalbard until chron 24 lower eocene phase 2 the first sedimentary evidence for tectonic uplift along the strike slip zone is found in a wedge shaped delta fan in the northwestern part of the basin strike slip dominated transpression prevailed from chron 24 to chron 21 lower middle eocene contemporaneous with successive basin narrowing and an eastward migration of the depocenter phase 3 after chron 21 lower middle eocene the relative motion between greenland and svalbard first changed to strike slip terminating the transpressional phase and then to transtension after chron 13 lower oligocene phase 4

evidence from svalbard for near freezing temperatures and climate oscillations in the arctic during the paleocene and eocene until recently the arctic was assumed to be characterised by relatively warm conditions throughout the early cenozoic however recent investigations on deep sea drilling cores from northern high latitudes including the arctic ocean give apparently contradicting results here we report the intermittent occurrence of certain temperature indicators in the early tertiary sedimentary sequence on svalbard which may represent the first direct northern high latitude record of cold water temperatures for the early cenozoic glendonites calcite pseudomorphs after calcium carbonate hexahydrate and erratics in otherwise fine grained sediments require near freezing temperatures and the presence of at least seasonal sea ice this succession also contains coal seams and other warm climate indicators but not on the same stratigraphical levels these results imply the occurrence of cooling phases episodically during the warm background climate of the paleocene and eocene suggesting that arctic temperature variability was much greater than previously recognized

downward control of the mean meridional circulation and temperature distribution of the polar winter stratosphere abstract according to the downward control principle the extratropical mean vertical velocity on a given pressure level is approximately proportional to the meridional gradient of the vertically integrated zonal force per unit mass exerted by waves above that level in this paper a simple numerical model that includes parameterizations of both planetary and gravity wave breaking is used to explore the influence of gravity wave breaking in the mesosphere on the mean meridional circulation and temperature distribution at lower levels in the polar winter stratosphere the results of these calculations suggest that gravity wave drag in the mesosphere can affect the state of the polar winter stratosphere down to altitudes below 30 km the effect is most important when planetary wave driving is relatively weak that is during southern winter and in early northern winter in southern winter downwelling weakens by a factor of 2 near the stratopause and by 20 at 30 km when gravity wave drag is not included

biological mats in siliciclastic sediments of the paleoproterozoic gunflint formation northwestern ontario canada the gunflint formation of northwestern ontario canada contains an extensive array of stromatolite morphologies and associated fossilized bacteria it and correlative units in the united states

structure of palaeogene sediments in east ellesmere island constraints on eurekan tectonic evolution and implications for the nares strait problem abstract the nares strait problem represents a debate about the existence and magnitude of left lateral movements along the proposed wegener fault within this seaway study of palaeogene eurekan tectonics at its shorelines could shed light on the kinematics of this fault palaeogene late paleocene to early eocene sediments are exposed at the northeastern coast of ellesmere island in the judge daly promontory they are preserved as elongate sw ne striking fault bounded basins cutting folded early paleozoic strata the structures of the palaeogene exposures are characterized by broad open synclines cut and displaced by steeply dipping strike slip faults their fold axes strike ne sw at an acute angle to the border faults indicating left lateral transpression weak deformation in the interior of the outliers contrasts with intense shearing and fracturing adjacent to border faults the degree of deformation of the palaeogene strata varies markedly between the northwestern and southeastern border faults with the first being more intense structural geometry orientation of subordinate folds and faults the kinematics of faults and fault slip data suggest a multiple stage structural evolution during the palaeogene eurekan deformation 1 the fault pattern on judge daly promontory is result of left lateral strike slip faulting starting in mid to late paleocene times the palaeogene judge daly basin formed in transtensional segments by pull apart mechanism transpression during progressive strike slip shearing gave rise to open folding of the palaeogene deposits 2 the faults were reactivated during se directed thrust tectonics in mid eocene times chron 21 a strike slip component during thrusting on the reactivated faults depends on the steepness of the fault segments and on their obliquity to the regional stress axes strike slip displacement was partitioned to a number of sub parallel faults on shore and off shore hence large scale lateral movements in the sum of 80 100 km or more could have been accommodated by a set of faults each with displacements in the order of 10 30 km the wegener fault as discrete plate boundary in nares strait is replaced by a bundle of faults located mainly onshore on the judge daly promontory

the depositional architecture and facies variability of shelf deltas in the eocene battfjellet formation nathorst land spitsbergen deltas are commonly classified according to their plan view morphology as either river dominated tide dominated or wave dominated however most deltas form under the mixed influence of these processes commonly with laterally varying process regimes it has also become clear that there is a mismatch between the plan view morphology and internal facies composition in some deltas combined outcrop and subsurface data from the eocene battfjellet formation spitsbergen provide an example of ancient shelf deltas that formed under mixed influence internally these shelf deltas are characterized by wave dominated facies that are normally associated with strike extensive nearly linear shoreline sandstones however the formation comprises partially overlapping sandstone bodies of limited lateral extent 20 km in any direction this stacking pattern is attributed to frequent autogenic lobe switching that caused localized and rapid transgressions such processes typify fluvial dominated deltas and occur less commonly in wave dominated ones thus there is an apparent mismatch between inferred plan view morphology and internal facies composition it is argued that the battfjellet deltas were flood dominated and prograded mainly during periods of high fluvial discharge however reworking of the fluvial flood facies by fair weather and storm waves as well as longshore currents resulted in a wave dominated facies character delta lobes undergoing auto retreat were particularly prone to reworking by basinal processes including tidal currents it is suggested that repeated delta progradation from inner shelf settings towards the outer shelf and shelf edge was aided by high sediment supply rather than relative falls in sea level as previously suggested this interpretation is supported by i the lack of major facies dislocations and extensive sub aerial unconformities and ii an overall relative rise in sea level as evidenced by an overall low angle 0 8 to 1 2 ascending shoreline trajectory the latter results from the combined effect of basin subsidence eustatic highstand and sediment compaction

crustal structure of the sheared southwestern barents sea continental margin abstract eighteen expanding spread profiles from the southwestern barents sea continental margin were studied with a variety of seismic interpretation techniques and in conjunction with seismic reflection data the velocity depth profiles from the slope intercept herglotz wiechert and sum methods were compared and contrasted to the velocity depth curve calculated from the iterative forward modelling of the amplitudes the velocity depth profiles derived from the sum and forward modelling of the amplitudes were used to produce synthetics in both the x t and p domains to choose the technique that most accurately represented the data the results showed the oceanic crust at the senja fracture zone to be different from standard oceanic crust with a higher than average velocity for layer 2 of 5 7 6 4 km s 1 and slightly smaller crystalline crustal thickness the continent ocean transition at crustal depths was shown to be narrow in the range of 10 20 km our results were consistent with two different crustal provinces east of the senja fracture zone the tertiary marginal basin and the cretaceous basin region the velocity depth curves enabled us in a gross sense to suggest the depths to deep sedimentary interfaces and the top of the crystalline crust that were normally not observed in the reflection profiles depths down to 20 km were inferred for the base of the sedimentary section in the southwestern barents sea the crust thinned gently towards the continent ocean boundary at the senja fracture zone whereas the crustal thickness changed abruptly below the hornsund fault zone at the margin farther north we associated the change in crustal structure with cenozoic in the thick crust beneath the svalbard platform in the north the depths to mantle determined on the shelf were consistent with that observed on a deep multichannel seismic line that crosses the area

bioclastic carbonate sediments on the southwestern svalbard shelf the poleward continuation of one of the largest known arctic carbonate factories the western spitsbergenbank of the barents sea has been surveyed along the narrow sw svalbard shelf on this shelf formation of cold water carbonate sediments occurs under glaciomarine environmental conditions mya truncata and hiatella arctica colonized a soft glacio marine diamicton 3000 6000 years after the final retreat of the icedome from the sw svalbard shelf since 2600 yr b p an increase of along shelf bottom currents washed out the fine terrigenous deposits leaving behind a shelly lag deposit and winnowed boulders on a morainic shelf topography the most favourable depth interval promoting the establishment of an amalgamated bioclastic blanket is located in 50 80 m water depth in this interval strong bottom currents prevent sedimentation thus facilitating colonisation of filter feeding benthic communities dominated by balanus balanus and chlamys islandica additional skeletal components are supplied by echinoderms bryozoans serpulids brachiopods and gastropods in shallower water depths carbonate production is hampered by intense iceberg scouring and release of ice rafted debris from the still glaciated hinterland of svalbard in deeper water 80 m olive grey muds with dispersed pebbles rich in benthic foraminiferans clinocardium ciliatum and taxodont bivalves are present on all surveyed shelf banks the deepest unit is a blue mud in water depths 120 m with benthic foraminiferans taxodont bivalves and sipunculids compared to spitsbergenbank carbonate production is much more restricted and impoverished on the sw svalbard shelf but is still an instructive modern example for the formation of skeletal carbonates resting on tillites in the geological record

a study of the dynamics of the equatorial lower stratosphere by use of ultra long duration balloons 2 gravity waves in the late southern winter of 1998 centre national d etudes spatiales cnes the french space agency released six 10 m diameter superpressure balloons from a location near quito ecuador three balloons collapsed soon after launching but the remaining three drifted westward for a few weeks at altitudes between 19 and 20 km two of those balloons crossed the pacific ocean before falling above the maritime continent while the other completed a revolution around the earth and crossed the pacific for a second time before its final fall despite the small number and the relatively short duration of the flights the balloons provided a unique in situ data set for the lower equatorial stratosphere this part 1 of a two part paper describes this data set and analyzes outstanding features in the planetary scales part 2 focuses on gravity wave scale it is argued that balloon trajectories over the pacific are primarily determined by the westward drift during the easterly phase of the equatorial quasi biennial oscillation qbo and the meridional velocity field of a mixed rossby gravity yanai wave with an apparent period of 4 days and zonal wave number 4 this wave appears to have two episodes of amplification during the balloon flights it is also argued that the balloons show evidence of oscillations with periods between 2 and 4 days and of a kelvin wave with an apparent period close to 10 days and zonal wave number 1 in this way the balloon behavior provided a pictorial view of air parcel trajectory in the equatorial lower stratosphere it is stated that larger balloon campaigns can provide excellent in situ data sets for studies on the dynamics and composition of the middle atmosphere

continent ocean transition at the western barents sea svalbard continental margin the change in crustal type at the western barents sea svalbard margin takes place over a narrow zone related to primary rift and shear structures reflecting the stepwise opening of the greenland sea regionally the margin is composed of two large shear zones and a central rifted margin segment local transtension and transpression at the plate boundary caused the early cenozoic tectonism in svalbard and the western barents sea and might explain the prominent marginal gravity and velocity anomalies

1891 1883 ma southern bastar cuddapah mafic igneous events india a newly recognized large igneous province abstract a newly recognized remnant of a paleoproterozoic large igneous province has been identified in the southern bastar craton and nearby cuddapah basin from the adjacent dharwar craton india high precision u pb dates of 1891 1 0 9 ma baddeleyite and 1883 0 1 4 ma baddeleyite and zircon for two se trending mafic dykes from the bd2 dyke swarm southern bastar craton and 1885 4 3 1 ma baddeleyite for a mafic sill from the cuddapah basin indicate the existence of 1891 1883 ma mafic magmatism that spans an area of at least 90 000 km2 in the south indian shield this record of 1 9 ga mafic ultramafic magmatism associated with concomitant intracontinental rifting and basin development preserved along much of the south eastern margin of the south indian shield is a widespread geologic phenomenon on earth similar periods of intraplate mafic ultramafic magmatism occur along the margin of the superior craton in north america 1 88 ga molson large igneous province and in southern africa along the northern margin of the kaapvaal craton 1 88 1 87 ga dolerite sills intruding the waterberg group existing paleomagnetic data for the molson and waterberg 1 88 ga large igneous provinces indicate that the superior and kalahari cratons were at similar paleolatitudes at 1 88 ga but a paleocontinental reconstruction at this time involving these cratons is impeded by the lack of a robust geological pin such as a limpopo like 2 0 ga deformation zone in the superior province the widespread occurrence of 1 88 ga intraplate and plate margin mafic magmatism and basin development in numerous archean cratons worldwide likely reflects a period of global scale mantle upwelling or enhanced mantle plume activity at this time

eocene turbidite population statistics from shelf edge to basin floor spitsbergen svalbard abstract there is a need for better tools in the interpretation of depositional sub environments of deep marine facies using seismic scale outcrops of eocene shelf margin clinoforms in spitsbergen we have statistically characterized the turbidite beds in terms of grain size bed thickness and dominant sedimentary structure at four different lowstand sites in individual mappable clinoforms these sub environments include 1 upper slope canyon and gully fill 2 upper to middle slope late prograding wedge 3 lower slope channel levee complex and 4 basin floor fan the falling stage basin floor fan and slope canyon gully deposits are generally coarser grained than the rising stage sub environments they also have far fewer siltstone and mudstone beds and have significantly more beds of upper medium to very coarse grain size compared to the rising stage channel levee and prograding wedge deposits thin beds are particularly voluminous in the late prograding wedge and channel levee systems whereas only the basin floor fans and canyon fill have large numbers of beds thicker than 10 cm turbidity currents deposit sediment at distinctly different sites between shelf edge and basin floor at different times during the development of the base level cycle differences between these sub environments are both qualitative and quantitative and are demonstrable using statistical analysis the results of this statistical analysis from well exposed easily identifiable architectural elements can be used to reconstruct the shelf margins of analogous basins where only sparse outcrop or well data are available

paleomagnetism of permian through early triassic sequences in central spitsbergen implications for paleogeography upper carboniferous through lower triassic sediments from spitsbergen have yielded paleomagnetic results with those for the late gzhelian early permian being the more reliable the corresponding pole 38 n 171 e is fully concordant with the early permian segment of the apparent polar wander path for baltica it does not support hypotheses about post carboniferous mobilism of spitsbergen with respect to stable europe neither mesozoic nor later rifting processes changed the position of spitsbergen considerably in relation to the stable europe

three dimensional properties of andes mountain waves observed by satellite a case study the southern andes region has been clearly identified in previous satellite and balloon observations and in global models as a hot spot of small scale gravity wave activity with monthly mean momentum fluxes exceeding 10 times background values in fall winter and spring seasons this makes this region a focus of interest for global circulation and climate studies we analyze a case study on 8 may 2006 combining observations from the atmospheric infrared sounder instrument on the aqua satellite and the high resolution dynamics limb sounder instrument of the aura satellite to form a three dimensional picture of the wave field the observations show a widespread wave pattern over the southern andes extending eastward over the south atlantic simulations with the weather research forecasting model clearly identify the waves as orographic in origin but the observed wave pattern is far from the simple two dimensional wave field forced by steady flow over a mountain ridge the morphology of the pattern is consistent with three dimensional linear theoretical calculations of downstream propagation and latitudinal focusing of mountain waves into the stratospheric jet the observations confirm the importance of this process in the stratosphere and we find the process also occurring in the global analysis and forecasts from the european centre for medium range weather forecasting our analysis evaluates some strengths and weaknesses of current orographic wave drag parameterizations in global models and the relevance of parameterization assumptions in global models with high resolution copyright 2011 by the american geophysical union

an analysis of the structure and forcing of the equatorial semiannual oscillation in zonal wind the low frequency variability in the equatorial middle atmosphere is dominated by the semiannual oscillation sao and quasi biennial qbo oscillation although the general characteristics and forcing mechanisms of these oscillations are thought to be known these oscillations are still not well reproduced in modeling experiments of the middle atmosphere the relatively long period 1992 1996 of upper atmosphere research satellite uars measurements and u k meteorological office ukmo assimilated model data have been used to examine the zonal wind sao in the upper stratosphere the sao in zonal wind is found to be latitudinally asymmetric about the equator with strongest amplitudes in the southern hemisphere subtropics the latitudinal asymmetry is diagnosed by using the tem momentum equation and ukmo data the asymmetry is mostly due to the different phasing of the peak advective forcing by the mean meridional circulation in each hemisphere the contribution of gravity waves to the zonal wind sao are also explored by using the forcing from a linear gravity wave model gravity waves are found to be the primary source of westerly momentum in each hemisphere during fall and contribute to the latitudinal asymmetry of the sao by having more easterly forcing in the southern hemisphere during summer compared to in the northern hemisphere during summer

tertiary or cretaceous age for spitsbergen s fold thrust belt on the barents shelf several publications propose that main phase fold thrust development on spitsbergen was late cretaceous and not tertiary as previously thought the question of timing is crucial to models for crustal response to transpressive plate motions involvement of tertiary strata in fold thrust structures the sedimentology of the tertiary basin strata and studies of paleo stress field evolution all indicate paleocene to eocene fold thrust development during opening of the norwegian greenland oceanic basin a regional angular unconformity of 1 between paleocene and early cretaceous strata is consistently disconformable to the eye and precludes any significant older deformation in the immediate area pre unconformity deformation was likely strike slip in character and concentrated in the west the proposal for late cretaceous fold thrust belt formation is inconsistent with the geology

gravity wave forcing in the stratosphere observational constraints from the upper atmosphere research satellite and implications for parameterization in global models 1 global models that include parameterized gravity wave effects have an excessively broad range of tuning parameters to choose from that allow a very broad range of gravity wave momentum forcing distributions we derive a set of constraints on gravity wave characteristics near the tropopause from databased estimates of gravity wave effects in the stratosphere we use 5 6 years of upper atmosphere research satellite data and uk met office analyzed wind and temperature fields to first derive estimates of the gravity wave mean flow forcing in the stratosphere we then compare these estimates to a suite of gravity wave model calculations to infer the constraints on the gravity wave characteristics near the tropopause these constraints apply to the portion of the gravity wave spectrum that dissipates in the stratosphere and does not include those that dissipate and drive the mesosphere we focus on equatorial and extratropical regions separately and find substantially different wave characteristics between the two we also find a seasonal variation in gravity wave characteristics in the extratropics near the equator gravity waves assist in driving the quasibiennial and semiannual oscillations and our constraints on gravity waves likely include a blend of characteristics of both ordinary gravity waves and some kelvin wave modes in the extratropics gravity wave forcing primarily assists in the annual winter to summer transition from westward to eastward winds

facies and origin of shales from the mid proterozoic newland formation belt basin montana usa shales constitute more than 60 of the world s sediments yet while facies models for sandstones and carbonates are at a high level of sophistication the study of shales has clearly lagged behind in the mid proterozoic newland formation six major shale facies types deposited in nearshore to basinal environments are distinguished on the basis of bedding characteristics textural features and the proportions of silt clay and carbonate textural features of these shale types are related to sedimentary environments as deduced from associated lithologies the shales are undisturbed by bioturbation and their textural and sedimentary characteristics reflect subaqueous growth of microbial mats erosion and deposition by storms deposition of flocculated vs dispersed clays continuous slow background sedimentation winnowing by waves or currents and subaerial exposure

microbially induced sedimentary structures a new category within the classification of primary sedimentary structures abstract cyanobacterial films and mats syndepositonally influence erosion deposition and deformation of sediments the biomass levels surface morphologies and microbial mats stabilize depositional surfaces and shelter the sediment against erosion or degassing growing microbial mats dredge grains from their substrate upwards whereas cyanobacterial filaments that are oriented perpendicular to the mat surface reach into the supernatant water and baffle trap and bind suspended particles these and similar biotic physical interactions are reflected in syndepositional formation of microbially induced sedimentary structures we distinguish structures on bedding planes leveled bedding surfaces wrinkle structures microbial mat chips erosional remnants and pockets multidirectional ripple marks and mat curls and internal bedding structures sponge pore fabrics gas domes fenestrae structures sinoidal laminae oriented grains benthic ooids biolaminites mat layer bound grain sizes we propose to place this group of microbially mediated structures as a fifth category bedding modified by microbial mats and biofilms in pettijohn and potter s 1964 existing classification of primary sedimentary structures

possible indicators of microbial mat deposits in shales and sandstones examples from the mid proterozoic belt supergroup montana u s a abstract it has been suspected for some time that microbial mats probably colonized sediment surfaces in many terrigenous clastic sedimentary environments during the proterozoic however domination of mat morphology by depositional processes post depositional compaction and poor potential for cellular preservation of mat building organisms make their positive identification a formidable challenge within terrigenous clastics of the mid proterozoic belt supergroup a variety of sedimentary structures and textural features have been observed that can be interpreted as the result of microbial colonization of sediment surfaces among these are a domal buildups resembling stromatolites in carbonates b cohesive behaviour of laminae during soft sediment deformation erosion and transport c wavy crinkly character of laminae d bed surfaces with pustular wrinkled appearance e rippled patches on otherwise smooth surfaces f laminae with mica enrichment and or randomly oriented micas g irregular curved wrinkled impressions on bedding planes h uparched laminae near mud cracks resembling growth ridges of polygonal stromatolites and i lamina specific distribution of certain early diagenetic minerals dolomite ferroan carbonates pyrite although in none of the described examples can it irrefutably be proven that they are microbial mat deposits the observed features are consistent with such an interpretation and should be considered indicators of possible microbial mat presence in other proterozoic sequences

improved middle atmosphere climate and forecasts in the ecmwf model through a nonorographic gravity wave drag parameterization abstract in model cycle 35r3 cy35r3 of the ecmwf integrated forecast system ifs the momentum deposition from small scale nonorographic gravity waves is parameterized by the scinocca scheme which uses hydrostatic nonrotational wave dynamics to describe the vertical evolution of a broad constant and isotropic spectrum of gravity waves emanating from the troposphere the cy35r3 middle atmosphere climate shows the following i an improved representation of the zonal mean circulation and temperature structure ii a realistic parameterized gravity wave drag iii a reasonable stationary planetary wave structure and stationary wave driving in july and an underestimate of the generation of stationary wave activity in the troposphere and stationary wave driving in january iv an improved representation of the tropical variability of the stratospheric circulation although the westerly phase of the semiannual oscillation is missing and v a realistic horizontal distribution of momentum flux in the

geochemical characterization of the depositional environment of paleocene and eocene sediments of the tertiary central basin of svalbard abstract the tertiary central basin ctb of svalbard has been studied extensively in the past because it contains sediments from the paleocene eocene thermal maximum petm previous studies have found that a negative carbon isotopic extrusion cie is presents without showing elevated concentration of organic carbon in this study we extend the record of the ctb with a comprehensive inorganic and organic geochemical data set based on the sediments encountered in the research well bh 10 2008 comprising almost 1100 m of cored sediments major and trace elements analyses in combination with mineralogical carbon isotopic total organic carbon and total sulphur measurements were used to reconstruct the depositional environments of the lower paleocene basilika fm up to the eocene aspelintoppen fm several depositional environments have been suggested which are consistent with the sedimentological interpretation of the respective well section back calculation of the initial organic carbon concentration shows that bacterial sulphate reduction had a major impact on the persevered organic carbon inventory of the lower basilika fm and of the paleocene eocene transition section based on organic carbon loss introduced by bacterial decay as well as measured isotopic composition we estimate an initial isotopic composition of the evaluated sediments which helps to elucidate on the fate of labile organic matter and explains the unusually low organic carbon inventory of the paleocene eocene transition sediments

some features of the climatology of the middle atmosphere revealed by nimbus 5 and 6 abstract a scheme for deriving three dimensional horizontal and vertical velocity fields from global satellite temperature data is described and applied to the new cospar international reference atmosphere cira to illustrate some features of the climatology of the stratosphere and mesosphere the scheme produces horizontal winds that compare well with existing mesospheric climatologies derived from radar and rocket data this is because the drag on the zonal flow is taken into account the drag is large in the mesosphere and is consistent with that produced by breaking gravity waves calculations of qy indicate the possibility of unstable waves in the summer and winter mesosphere in the stratosphere the scheme yields diagnostics of planetary wave propagation which are sometimes similar to those produced by winds from schemes based on just the horizontal momentum equations but in the october southern stratosphere for example there are occasions when the effects of the drag on the zonal flow are requ

the gcm response to current parameterizations of nonorographic gravity wave drag abstract a comparison is undertaken of the response of a general circulation model gcm to the nonorographic gravity wave drag parameterizations of hines warner and mcintyre and alexander and dunkerton the analysis is restricted to a comparison of each parameterization s nonlinear dissipation mechanism since in principle this is the only component that differs between the schemes this is achieved by developing a new more general parameterization that can represent each of these dissipation mechanisms while keeping all other aspects of the problem identical the gcm simulations reveal differences in the climatological response to the three dissipation mechanisms these differences are documented for both tropopause and surface launch elevations of the parameterized waves the simulations also reveal systematic differences in the height at which momentum is deposited this behavior is investigated further in a set of experiments designed to reduce these systematic differences while leaving the det

stability of the nitrogen cycle during development of sulfidic water in the redox stratified late paleoproterozoic ocean nitrogen cycling has been evaluated across a depth transect in the late paleoproterozoic animikie basin north america spanning the end of earth s final period of global iron precipitation and a major transition to euxinic conditions in areas of high productivity sediments from near shore where productivity was highest have 15n compositions up to 3 higher than at more distal sites this suggests that as nh4 mixed vertically upward into the oxic photic zone from the anoxic ocean interior it was either assimilated by organisms or oxidized subsequent enhanced production of n2 by denitrification or anammox anaerobic ammonium oxidation led to the observed increase in 15n close to shore any deficit in biologically available n was overcome by n2 fixing organisms but the input of n with low 15n from this process did not overwhelm the increase in 15n from denitrification because there is no evidence for conditions of severe n stress arising from trace metal limitation particularly mo of n fixation during the transition to euxinic conditions losses of n were either very small potentially because low o2 levels limited nh4 oxidation or alternative pathways that retained n were important the fact that mo appears to have remained bioavailable for n fixation either suggests that the extent or severity of sulfidic water column conditions was not sufficient to quantitatively sequester mo on a global scale or that rivers directly delivered mo to surface waters on the inner shelf the effects of n2 fixation on 15n increased to more distal parts of the shelf consistent with models invoked for modern upwelling zones over broad continental margins

global measurements of stratospheric mountain waves from space temperatures acquired by the cryogenic infrared spectrometers and telescopes for the atmosphere crista during shuttle mission sts 66 have provided measurements of stratospheric mountain waves from space large amplitude long wavelength mountain waves at heights of 15 to 30 kilometers above the southern andes mountains were observed and characterized with vigorous wave breaking inferred above 30 kilometers mountain waves also occurred throughout the stratosphere 15 to 45 kilometers over a broad mountainous region of central eurasia the global distribution of mountain wave activity accords well with predictions from a mountain wave model the findings demonstrate that satellites can provide the global data needed to improve mountain wave parameterizations and hence global climate and forecast models

crustal structure of northwestern svalbard and the adjacent yermak plateau evidence for oligocene detachment tectonics and non volcanic breakup summary in 1999 new seismic refraction data were collected off northwestern svalbard and the adjacent yermak plateau a 260 km long profile provides detailed velocity information for the northeastern edge of the eurasian continent and the adjacent yermak plateau north of forlandsundet graben the depth of the moho varies between 23 and 28 km and remains at this depth to the northern edge of the profile at 81 n the crustal lithology off western svalbard can be related to the basement province west of the raudfjorden fault zone off the northern shoreline of svalbard the structure of the tertiary danskoya basin is mapped below this a late silurian early devonian basin with seismic velocities between 5 1 and 5 8 km s 1 and a thickness of up to 8 km is present a palaeozoic sequence of up to 6 km thickness is expected below the tertiary cover north of the danskoya basin an earlier suggestion that oligocene rift processes affected the southern yermak plateau is confirmed a detachment structure is situated below the palaeozoic basin below danskoya basin which is probably a consequence of simple shear tectonics the middle crust exhibits low seismic velocities above the detachment fault the lowermost crust beneath is slightly contaminated by mantle derived melts which is deduced by the slightly elevated velocities of the lowermost crust these melts can be attributed to decompressive melting caused by modest uplift of the moho during stretching the velocity depth model provides no evidence for large magmatic activity which implies a non volcanic rifted margin history this leads to the assumption that the proposed yermak hotspot during the breakup of svalbard from northern greenland did not exist

the age of the gunflint formation ontario canada single zircon u pb age determinations from reworked volcanic ash the gunflint formation a paleoproterozoic chemical clastic sedimentary assemblage outcropping to the immediate northwest of lake superior became famous in 1954 as containing the oldest fossil assemblage known at that time older microfossils have since been discovered but the gunflint procaryotes remain one of the most diverse precambrian fossil communities the finding of possible multicellular organisms in correlative lithic units in michigan has recently added to the need for an exact age of the formation zircons were extracted from rainout and storm reworked volcanoclastic beds in the upper portion of the gunflint formation a euhedral zircon population has yielded a 1878 3 1 3 million years bp u pb age believed to be nearly synchronous with the depositional age this not only provides a precise age for the community of organisms but also strongly supports a back arc extensional setting for the animikie basin rather than a foreland trough resume la formation de gunflint un assemblage sedimentaire chimique et clastique datant du paleoproterozoique affleurant immediatement au nord ouest du lac superieur est devenue celebre en 1954 car elle contenait les plus an ciens assemblages fossiliferes connus a cette epoque de plus anciens microfossiles ont ete decouverts depuis mais les procaryotes de gunflint demeurent l une des communautes fossiles precambriennes les plus diversifiees la decouverte

iron formations a global record of neoarchaean to palaeoproterozoic environmental history abstract iron formations if represent an iron rich rock type that typifies many archaean and proterozoic supracrustal successions and are chemical archives of precambrian seawater chemistry and post depositional iron cycling given that if accumulated on the seafloor for over two billion years of earth s early history changes in their chemical mineralogical and isotopic compositions offer a unique glimpse into environmental changes that took place on the evolving earth perhaps one of the most significant events was the transition from an anoxic planet to one where oxygen was persistently present within the marine water column and atmosphere linked to this progressive global oxygenation was the evolution of aerobic microbial metabolisms that fundamentally influenced continental weathering processes the supply of nutrients to the oceans and ultimately diversification of the biosphere and complex life forms many of the key recent innovations in understanding if genesis are linked to geobiology since biologically assisted fe ii oxidation either directly through photoferrotrophy or indirectly through oxygenic photosynthesis provides a process for if deposition from mineral precursors the abundance and isotope composition of fe ii bearing minerals in if additionally suggests microbial fe iii reduction a metabolism that is deeply rooted in the archaea and bacteria linkages among geobiology hydrothermal systems and deposition of if have been traditionally overlooked but now form a coherent model for this unique rock type this paper reviews the defining features of if and their distribution through the neoarchaean and palaeoproterozoic this paper is an update of previous reviews by bekker et al 2010 2014 that will improve the quantitative framework we use to interpret if deposition in this work we also discuss how recent discoveries have provided new insights into the processes underpinning the global rise in atmospheric oxygen and the geochemical evolution of the oceans

interactions between mesoscale and submesoscale gravity waves and their efficient representation in mesoscale resolving models abstractas present weather forecast codes and increasingly many atmospheric climate models resolve at least part of the mesoscale flow and hence also internal gravity waves gws it is natural to ask whether even in such configurations subgrid scale gws might impact the resolved flow and how their effect could be taken into account this motivates a theoretical and numerical investigation of the interactions between unresolved submesoscale and resolved mesoscale gws using boussinesq dynamics for simplicity by scaling arguments first a subset of submesoscale gws that can indeed influence the dynamics of mesoscale gws is identified therein hydrostatic gws with wavelengths corresponding to the largest unresolved scales of present day limited area weather forecast models are an interesting example a large amplitude wkb theory allowing for a mesoscale unbalanced flow is then formulated based on multiscale asymptotic analysis utilizing a proper scale separation parameter purely vertical propagation

kinematics of tertiary deformation in the basement involved fold thrust complex western nordenskiold land svalbard tectonic implications based on fault slip data analysis abstract kinematic analysis based on the interpretation of small scale fault and fold data supports a kinematic evolution history involving heterogeneous crustal shortening and uplift and subsequent extension collapse for the major west coast fold thrust complex in western nordenskiold land svalbard this deformation can be divided into three main kinematic events stage 1 represents an early distinctive nne ssw oriented contractional episode that generated layer parallel and low angle thrusts and internal folds stage 1 structures population 1 are arranged in an apparent en echelon geometry and oblique direction relative to the major nne ssw trending fold thrust complex of stage 2 affinity stage 2 structures include ene verging chevron folds and steeply wsw dipping thrusts and duplexes that evolved during a progressive wsw ene oriented contractional episode initial pre fold stratal shortening stage 2a was followed by a continuous buildup of the fold thrust complex and general crustal thickening syn fold stage 2b until a supercritical height thickness was reached post fold stage 2c at this stage a change in the stress field caused failure of the fold thrust complex and continued ne sw directed shortening was accommodated as vertical strike slip faults population 2c late w e to wsw ene directed extension the stage 3 episode was probably related to collapse of the overthickened stage 2 fold thrust complex the detailed reconstruction of kinematic events in western nordenskiold land supports initial breakup of the greenland svalbard area in early paleocene times during dextral nne ssw directed transpression stage 1 the major deformational episode stage 2 probably of mid paleocene to eocene age was characterized by progressive wsw ene directed shortening and was related to decoupled deformation where broad zones of convergent strain were linked to narrow strike slip zones this strain partitioning is considered to have begun when the hornsund fault zone widened into and reactivated the basin bounding faults of the carboniferous st jonsfjorden trough the latest kinematic episode stage 3 is likely of eocene age and may be ascribed to extensional collapse in the hinterland of the western spitsbergen orogenic wedge within a regional dextral transpressive setting

delta influenced foraminiferal facies and sequence stratigraphy of paleocene deposits in spitsbergen abstract the paleocene firkanten formation of the central basin of spitsbergen is a succession of terrigenous clastic sediments interpreted as a major depositional sequence formed in deltaic coastal plain delta front and prodelta environments the present study combines diagnostic features of foraminiferal facies with sedimentary data to elucidate this sequence stratigraphic development deposition was initiated by an early paleocene transgression which led to the deposition of a delta plain to coastal marine sediment package forming the low stand and transgressive systems tracts these includes coal swamp lacustrine lagoonal and barrier deposits the lagoonal shales are characterised by an agglutinated foraminiferal assemblage of extremely low diversity indicative of hyposaline conditions shoreface sandstones overlying the lagoonal strata are interpreted as sand barriers reworked by the advancing transgression these sandstones are succeeded by a package of prodelta silty shales which in the lower part includes the maximum transgressive interval the foraminiferal assemblage of the prodelta shales is also agglutinated but reveals increased diversities suggesting open marine conditions the prodelta shales and overlying delta front sandtones form a succession of coarsening upwards parasequences of deltaic progradation representing the regressive systems tract the entirely agglutinated low diversity nature of the foraminiferal assemblages is in part attributable to the deltaic impact the restricted character of the faunas is additionally accentuated by the effects of the paleogene boreal province

the seasonal evolution of planetary waves in the southern hemisphere stratosphere and troposphere seasonality in planetary wave structure in the southern hemisphere stratosphere and troposphere 1000 1 mb is studied based on eight years 1979 1986 of daily geopotential data emphasis is placed on the distinctive seasonality in the stratosphere along with tracing the stratospheric fluctuations into the troposphere time filtering is used to separate stationary and transient components maximum geopotential height variance is observed in the middle to upper stratosphere in late winter spring with a distinct secondary smaller maximum in late fall early winter these maxima sandwich the strongest mid winter zonal winds this sequence occurs approximately one month earlier in the upper stratosphere two corresponding peaks are observed in stratospheric zonal mean wind and temperature fluctuations the two maxima in stratospheric wave variance are not in agreement with observed seasonal changes in quasi geostrophic refractive index of the zonal mean flow the stratospheric geopotential variance maxima result from nearly equal amounts of stationary and transient zonal wave 1 fluctuations with transient wave 2 also contributing during late winter stationary wave 1 shows intriguing seasonal evolution the early winter maximum is predominantly equivalent barotropic whereas that of late winter spring is highly baroclinic in the stratosphere stratospheric poleward fluxes of heat and momentum both exhibit pronounced maxima during september october these result primarily from the stationary wave 1 contributions and the transients assume a secondary role although not as pronounced as the stationary wave seasonality seasonal differences in transient wave behaviour are also documented including three dimensional propagation characteristics and wave mean flow interaction diagnostics

analysis and 3d inversion of magnetotelluric crooked profile data from central svalbard for geothermal application abstract broadband 0 001 1000 s magnetotelluric mt data along a crooked profile collected to investigate the geothermal potential on spitsbergen could not be fully explained by two dimensional 2d models hence we interpret the data with three dimensional 3d inversion herein to better accommodate 3d features and nearby off profile resistivity structures the full mt impedance tensor data together with the tipper were inverted as a model control a detailed bathymetry is systematically incorporated in the inversion our results from testing different inversion settings emphasised that appropriately choosing and tuning the starting model data error floor and the model regularization together are crucial to obtain optimum benefit from mt field data through the 3d inversion we reproduced out of quadrant impedance components and obtained an overall satisfactory data fit rms 1 05 the final 3d resistivity model displays a complex geology of the near surface region 2 km conductive anomaly confirming the regional nature of the fault the fault zone is positioned between two uplifted basement blocks 1000 m of presumably pre devonian caledonian metamorphic rocks and the fault may have been responsible for deformation in the overlying paleozoic mesozoic unit upper crustal conductive anomalies

impact of the doppler spread parameterization on the simulation of the middle atmosphere circulation using the ma echam4 general circulation model the zonal mean circulation of the middle atmosphere simulated by a general circulation model that includes the doppler spread parameterization of gravity wave momentum deposition is presented to illustrate the impact of the parameterization this simulation is compared to another obtained by using rayleigh friction instead it is found that the doppler spread parameterization improves the extratropical zonal mean circulation in the mesosphere by reducing the strength of the zonal winds above the jet maximum the parameterization also improves the simulation of the equatorial semiannual oscillation in the zonal mean zonal wind at the stratopause by enhancing the eastward phase and its downward propagation

alleviation of a systematic westerly bias in general circulation and numerical weather prediction models through an orographic gravity wave drag parametrization systematic westerly biases in the northern hemisphere wintertime flow of the meteorological office 15 layer operational model and 11 layer general circulation model are described evidence that the failure to parametrize subgrid scale orographic gravity wave drag may account for such biases is presented this evidence is taken from aircraft studies surface pressure drag measurements and studies of the zonally averaged momentum budget a parametrization scheme is described in which the surface stress is proportional to the near surface wind speed and static stability and to the variance of subgrid scale orography the stress is absorbed in the vertical by considering the influence of such gravity wave activity on static stability and vertical wind shear a richardson number dependent wave breaking formulation is devised and the vertical stress profile determined by a saturation hypothesis whereby the breaking waves are maintained at marginal stability it is shown that wave breaking preferentially occurs in the boundary layer and in the lower stratosphere results from a simple zonally symmetric model show how the adjustment to thermal wind balance with a wave drag in the stratosphere warms polar regions by adiabatic descent and decelerates the mean westerlies in the troposphere the influence of the parametrization scheme on integrations of the 11 layer model is described and found to be generally beneficial in a discussion of the reasons why this problem has only recently emerged it is suggested that the satisfactory northern hemisphere winter circulations of previous coarser general circulation models were due to a compensation implied by underestimating both the surface drag and the horizontal flux of momentum by explicitly resolved large scale eddies

sensitivity of the brewer dobson circulation and polar vortex variability to parameterized nonorographic gravity wave drag in a high resolution atmospheric model abstractthe role of parametrized nonorographic gravity wave drag nogwd and its seasonal interaction with the resolved wave drag in the stratosphere has been extensively studied in low resolution coarser than 1 9 2 5 climate models but is comparatively unexplored in higher resolution models using the european centre for medium range weather forecasts integrated forecast system at 0 7 0 7 resolution the wave drivers of the brewer dobson circulation are diagnosed and the circulation sensitivity to the nogw launch flux is explored nogws are found to account for nearly 20 of the lowerstratospheric southern hemisphere sh polar cap downwelling and for less than 10 of the lower stratospheric tropical upwelling and northern hemisphere nh polar cap downwelling despite these relatively small numbers there are complex interactions between nogwd and resolved wave drag in both polar regions seasonal cycle analysis reveals a temporal offset in the resolved and parametrized wave interaction the n

tertiary west spitsbergen fold and thrust belt on broggerhalvoya svalbard structural evolution and kinematics the tertiary fold and thrust belt on broggerhalvoya is characterized by a ne vergent pile of nine thrust sheets the basal sole thrust of the pile is located in precambrian phyllites and climbs up section to the ne the lower thrust sheets consist predominantly of post caledonian cover sediments two thrust sheets in the central part of the pile contain a syncline and anticline on a kilometer scale the kilometer scale fold is cut by juxtaposed thrusts giving rise to the formation of four structurally higher basement dominated thrust sheets a five stage kinematic model is proposed 1 in sequence foreland propagating formation of the lower thrust sheets with ramp flat geometries in response to n s subhorizontal bedding parallel movements 2 change in tectonic transport to more east northeasterly directions and first out of sequence thrusting inversion and uplift of the basement in the hinterland formation of the kilometer scale fold structure 3 truncation of the kilometer scale fold by a thrust fault and stacking of the highest basement dominated thrust sheets by hindward propagating mode of thrust generation 4 n s extension due to extensional collaps of the stack 5 w e extension the strain of the thrust sheets is predominantly compressive with the exception of the structurally highest thrust sheet reflecting a temporal change to a more transpressive regime ramping of some thrust faults is suggested to be in part controlled by reactivated carboniferous normal faults the basal sole thrust of the thrust sheet stack also follows the trend of the kongsvegen fault which showed enhanced activity during late mesozoic early tertiary extension the curvature of the west spitsbergen fold and thrust belt on broggerhalvoya is interpreted to be controlled mainly by oblique ramping on the kongsvegen fault associated with pinning on the nordfjorden block as well as by along strike lithological and thickness variations of the post caledonian strata in addition this suggests that pre existing structures have controlled the tertiary geometry the temporal change in the kinematics during thrust tectonics can be linked with the plate tectonic framework in the arctic during tertiary times

geochemical evidence for volcanic activity prior to and enhanced terrestrial weathering during the paleocene eocene thermal maximum abstract the re os and major element geochemistry of an expanded gray shale sequence from the central basin in spitsbergen svalbard archipelago norway over the paleocene eocene thermal maximum petm is presented the data suggest that a significant volcanic episode as indicated primarily by a large drop in 187 os 188 os occurred just prior to or coincident with the onset of the petm the distinct geochemistry of the inferred ash component is consistent with the geochemistry of contemporaneous ashes previously sampled in denmark and persists in the sedimentary record for 8 ka based on the substantial size of the 187 os 188 os decrease 187 os 188 os 0 23 the volcanic event must have involved widespread ash deposition in the local catchment the terrestrially deposited ash weathered rapidly shifting the 187 os 188 os of the basin water column to 187 os 188 os to more radiogenic values and depositing clastic materials with higher chemical index of alteration and lower na ti persistently anoxic sedimentary pore fluids interpreted to reflect bottom water anoxia initiated close to the onset of the petm anoxic mainly euxinic conditions persisted for 50 ka ending abruptly 55 77 ma anoxia appears related to enhanced high latitude hydrological cycling and consequent basinal stratification during the petm

comparison of gravity waves in the southern hemisphere derived from balloon observations and the ecmwf analyses abstractthe increase of spatial resolution allows the ecmwf operational model to explicitly resolve a significant portion of the atmospheric gravity wave gw field but the realism of the simulated gw field in the ecmwf analyses still needs to be precisely evaluated here the authors use data collected during the concordiasi stratospheric balloon campaign to assess the representation of gws in the ecmwf analyses over antarctica and the southern ocean in spring 2010 the authors first compare the balloonborne gw momentum fluxes with those in ecmwf analyses throughout the campaign and find a correct agreement of the geographical and seasonal patterns however the authors also note that ecmwf analyses generally underestimate the balloon fluxes by a factor of 5 which may be essentially due to the spatial truncation of the ecmwf model intermittency of wave activity in the analyses and observations are found comparable these results are confirmed on two case studies dealing with orographic and nonorographi

rayleigh lidar observations of gravity wave activity in the upper stratosphere at urbana illinois abstract during 13 nights of rayleigh lidar measurements at urbana illinois in 1984 86 thirty six quasi monochromatic gravity waves were observed in the 35 50 km altitude region of the stratosphere the characteristics of the waves are compared with other lidar and radar measurements of gravity waves and with theoretical models of wave saturation and dissipation phenomena the measured vertical wavelengths 2 ranged from 2 to 11 5 km and the measured vertical phase velocities cz ranged from 10 to 85 cm s 1 the vertical wavelengths and vertical phase velocities were used to infer observed wave periods tob which ranged from 100 to 1000 min and horizontal wavelengths x which ranged firm 70 to 2000 km there may be errors in the inferred values of the horizontal wavelengths because they were calculated by assuming that the observed period inferred the intrinsic period dominant wave activity was found at vertical wavelengths between 2 4 km and 7 10 km no significant seasonal variations were evide

sedimentation in paleogene foreland basin spitsbergen the upper part of the sedimentary succession in the tertiary central trough on spitsbergen comprising the hollendardalen gilsonryggen battfjellet and aspelintoppen formations has been studied with respect to basin formation and basin filling thickness data from the lower marine part of this succession indicate an asymmetric thickening to the west distribution of the several theories on how space was generated to accommodate the sequence tectonic subsidence driven by lithospheric loading from the flanking fold and thrust belt appears to be the most probable the position of the basin between the front of the west spitsbergen fold belt and the adjacent craton suggests a foreland basin setting most of the basin fill constitutes a major regressive sequence gilsonry gen battfjellet and aspelintoppen formations deposited by the eastward progradation of a deltaic system evidence of eastward displacement of the depocenter through time together with the incorporation of the orogenic flank of the basin fill into the deformation suggests cratonward migration of the fold and thrust belt foreland basin couplet the present tertiary central trough represents the uplifted remnants of the latest oligocene foreland basin

paleostress stratigraphy a new technique for analyzing tectonic control on sedimentary basin subsidence the authors propose a new technique paleostress stratigraphic analysis based on the orientation of minor structures particularly striated fault surfaces in the strata of sedimentary basins these structures are interpreted to be the response to local or regional stress field controlling subsidence of tectonically active basins a method is used that allows multiple stress tensors to be extracted from a fault population by extracting the stress tensor from the youngest part of a stratigraphic sequence and by imposing that same tensor on the underlying rocks one can in principle isolate the faults associated with the youngest tectonic event by reiterating this procedure on progressively older units until the fault data are exhausted a chronologic succession of paleostress tensors during basin subsidence emerges the authors paleostress stratigraphy to the relatively undeformed paleogene central basin of spitsbergen and its underlying cretaceous strata and define five major paleostress tensors coeval with the earliest stages of the opening of the norwegian greenland sea a late cretaceous dextral transpressive regime was probably responsible for the major pre tertiary unconformity and possibly initiated development of the central basin during subsequent sedimentation movement reversed yielding well constrained sinistral shearing during early danian time a composite compressional event followed that themore authors interpret as being coeval with the culmination of folding and thrusting west of the central basin the youngest strata studied record a final extensional event that they correlate with rifting of spitsbergen from greenland less

implementation of a gravity wave source spectrum parameterization dependent on the properties of convection in the whole atmosphere community climate model waccm 1 this article describes the implementation of a new source spectrum parameterization for convectively generated gravity waves in the whole atmosphere community climate model version 2 waccm2 this parameterization is active in the tropics and is interactive with the underlying convection the gravity wave spectrum at each model grid point and time step is determined based on the convective heating depth tropospheric wind and the convective heating rate this parameterization introduces more realistic spatial and temporal distributions of gravity wave activity and yields gravity wave characteristics related to the underlying wave source we present the estimated gravity wave momentum flux phase speed spectra at 100 hpa as well as the gravity wave drag in the middle and upper atmosphere using the new source spectrum representation we also show the effects of this more physically based parameterization on the structure of the stratospheric and mesospheric semi annual oscillations of the zonal wind compared to a simulation with uniform gravity wave distribution we conclude that the interaction of the gravity wave parameterization with tropospheric characteristics is a positive step toward a more physical representation of the middle and upper atmosphere

middle atmosphere simulated with high vertical and horizontal resolution versions of a gcm improvements in the cold pole bias and generation of a qbo like oscillation in the tropics abstract the large scale circulation in the geophysical fluid dynamics laboratory skyhi troposphere stratosphere mesosphere finite difference general circulation model is examined as a function of vertical and horizontal resolution the experiments examined include one with horizontal grid spacing of 35 km and another with 100 km horizontal grid spacing but very high vertical resolution 160 levels between the ground and about 85 km the simulation of the middle atmospheric zonal mean winds and temperatures in the extratropics is found to be very sensitive to horizontal resolution for example in the early southern hemisphere winter the south pole near 1 mb in the model is colder than observed but the bias is reduced with improved horizontal resolution from 70 c in a version with 300 km grid spacing to less than 10 c in the 35 km version the extratropical simulation is found to be only slightly affected by enhancements of the vertical resolution by contrast the tropical middle atmospheric s

preliminary report on the paleomagnetism of 1 88ga dykes from the bastar and dharwar cratons peninsular india abstract we report the results of a preliminary paleomagnetic study on well dated 1 9 ga dykes from the bastar craton india this suite of nw se trending dykes was linked to similarly aged magmatic activity in the dharwar craton and cuddapah basin in india as part of a large igneous province this igneous activity may have extended across many cratons in the columbia supercontinent including the north china craton laurentia baltica australia siberia and the kaapvaal and zimbabwe cratons southern africa the bastar dykes along with the cuddapah traps and dyke yield a dual polarity magnetization with d 126 i 15 2 k 27 95 11 9 and a corresponding paleomagnetic pole at 31 n 330 e dp 6 3 dm 12 2 the relatively robust paleomagnetic and geochronologic database at 1 85 1 90 ga allow us to test one of the configurations of the supercontinent columbia there are some critical differences between our paleomagnetically based reconstruction and the archetypal and geologically based columbia configuration of zhao et al 2004 most notably siberia india and australia cannot be linked to laurentia in the archetypal columbia fit proposed links between western australia and the kaapvaal and zimbabwe cratons are possible as is the fit between baltica and laurentia the robust paleomagnetic data reported in this paper require that either the columbia supercontinent did not exist at 1 9 ga or requires major modification given that our data provide only a snapshot on the paleoproterozoic we conclude that the columbia supercontinent remains a viable possibility although relationships between individual elements should be re evaluated as more data become available

svartfjella eidembukta and daudmannsodden lineament tertiary orogen parallel motion in the crystalline hinterland of spitsbergen s fold thrust belt within metamorphic basement rocks of the hinterland of spitsbergen s tertiary fold thrust belt a 35 km long zone of notably deformed carboniferous strata and cretaceous intrusives forms a major orogen parallel lineament from svartfjella to eidembukta to daudmannsodden sedl orientations and geometries of map scale fault duplexes and associated fault plane striae populations of folds and associated cleavage and of tension gashes all indicate orogen parallel motion occurred along the sedl structural analyses indicates three phases 1 ene directed overthrusting 2 sinistral motion with a backthrust component and 3 dextral strike slip motion this history indicates a change from orogen perpendicular to orogen parallel movements orogen parallel movement was likely coeval with orogen perpendicular fold thrust transport to the ene in the foreland a model where dextral transpressive motion between greenland and svalbard was decoupled explains the hinterland foreland difference basement fabric aligned with carboniferous carbonates on the steep foreland face of an antiformal stack provided a through going weak surface a prerequisite for decoupling sinistral orogen parallel motion is explicable by short lived episode of sinistral plate motion or by local wedge extrusion during dextral transpression the evolution of decoupling patterns has significant implications for deducing plate motions from local kinematic and paleostress studies

thrust tectonics on broggerhalvoya and their relationship to the tertiary west spitsbergen fold and thrust belt the tertiary fold and thrust belt on broggerhalvoya is characterized by a ne vergent pile of nine thrust sheets the sole thrust of the pile is located in precambrian phyllites and climbs up section to the northeast four lower thrust sheets consisting predominantly of upper palaeozoic sediments are overlain by two thrust sheets in the central part of the stack which contain a kilometre scale syncline and anticline the fold is cut by juxtaposed thrusts giving rise to the formation of three structurally higher basement dominated thrust sheets a multiple stage kinematic model is proposed including 1 in sequence foreland propagating formation of the lower thrust sheets in response to n s subhorizontal bedding parallel movements 2 a change in tectonic transport to ene and out of sequence thrusting and formation of the kilometre scale fold structure followed by 3 truncation of the kilometre scale fold and stacking of the highest basement dominated thrust sheets by hind ward propagating out of sequence thrusting the strain of the thrust sheets is predominantly compressive with the exception of the structurally highest thrust sheets reflecting a temporal change to a more transpressive regime thrusting was followed by 4 n s extension and 5 w e extension comparison of the structural geometry and kinematic evolution of broggerhalvoya with the data reported for the fold belt further south allows us to assume a coeval evolution with the fold belt a latest paleocene early eocene age for the main phase of thrusting is suggested for the west spitsbergen fold and thrust belt the main phases therefore pre date the separation of svalbard and greenland due to right lateral movements along the hornsund fault zone the fold belt s temporal evolution followed by the formation of the forlandsundet graben can be linked with the plate kinematic framework in the span between latest paleocene and middle eocene times

discovery of distal ejecta from the 1850 ma sudbury impact event a 25 70 cm thick laterally correlative layer near the contact between the paleoproterozoic sedimentary gunflint iron formation and overlying rove formation and between the biwabik iron formation and overlying virginia formation western lake superior region contains shocked quartz and feldspar grains found within accretionary lapilli accreted grain clusters and spherule masses demonstrating that the layer contains hypervelocity impact ejecta zircon geochronologic data from tuffaceous horizons bracketing the layer reveal that it formed between ca 1878 ma and 1836 ma the sudbury impact event which occurred 650 875 km to the east at 1850 1 ma is therefore the likely ejecta source making these the oldest ejecta linked to a specific impact shock features particularly planar deformation features are remarkably well preserved in localized zones within the ejecta whereas in other zones mineral replacement primarily carbonate has significantly altered or destroyed ejecta features

constraints on the numerical age of the paleocene eocene boundary here we present combined radio isotopic dating u pb zircon and cyclostratigraphic analysis of the carbon isotope excursion at the paleocene eocene p e boundary in spitsbergen to determine the numerical age of the boundary incorporating the total uncertainty from both radio isotopic and cyclostratigraphic datasets gives an age ranging from 55 728 55 964 ma within error of a recently proposed astronomical age of 55 93 ma combined with the assumption that the paleocene epoch spans twenty five 405 kyr cycles our new age for the boundary suggests an age of 66 ma for the cretaceous paleogene k pg boundary furthermore our p e boundary age is consistent with the hypothesis that the onset of the paleocene eocene thermal maximum petm at the boundary occurred on the falling limb of a 405 kyr cycle suggesting the event was initiated by a different mechanism to that which triggered the other early eocene hyperthermals

spatial variability in oceanic redox structure 1 8 billion years ago the deposition of iron formations ceased about 1 84 billion years ago reconstructions of ocean chemistry suggest that the advent of euxinic conditions along ocean margins preferentially removed dissolved iron from the water column in the form of the mineral pyrite inhibiting widespread iron oxide mineral deposition

an accurate spectral nonorographic gravity wave drag parameterization for general circulation models abstract an accurate method of solution is developed for the warner and mcintyre parameterization of nonorographic gravity wave drag for the case of hydrostatic dynamics in the absence of rotation the new scheme is sufficiently fast that it is suitable for operational use in a general circulation model multiyear climate runs of the canadian middle atmosphere model are performed using the new scheme and these are compared against equivalent climate runs using the full warner and mcintyre scheme which includes nonhydrostatic and rotational wave dynamics the results indicate that the new operational scheme closely reproduces the seasonal distribution of time and zonal mean zonal winds and the seasonal evolution of lower stratospheric temperatures that are obtained when the full warner and mcintyre scheme is used in addition these quantities are shown to compare favorably with observations

microbial signatures in peritidal siliciclastic sediments a catalogue a catalogue of microbial structural signatures is presented based upon the coupling of fundamental biogeochemical microbial processes and local morphogenetic determinants it summarizes a collection of sedimentary structures obtained from two modern siliciclastic peritidal environments in different climatic zones temperate humid mellum island southern north sea subtropical arid coast of southern tunisia textural geometries reveal a high structural diversity but their determinants are primarily based upon six major parameters 1 intrinsic biofactors structural diversification of sedimentary microbial films and mats inherent in the organisms i e their construction morphology growth taxis and behaviour and local abundance of specific morphotypes most prominent are the ensheathed filamentous cyanobacteria microcoleus chthonoplastes and lyngbya aestuarii and the sheathless filamentous cyanobacterium oscillatoria limosa 2 biological response to physical disturbances sediment supply erosion and fracturing of surface layers resulting from desiccation cause growth responses of biofilms and microbial mats 3 trapping binding effects physicobiological processes give rise to grain orientations and wavy to lenticular lamina lamina specific grain arrangements and sucrose calcium carbonate accumulations 4 secondary physical deformation of biogenic build ups mechanical stresses acting upon sediments overgrown and biostabilized by biofilms and mats produce erosional and overthrust structures 5 post burial processes textural fabrics that evolve from mechanical effects of gas formation from decaying mats and features related to the formation of authigenic minerals calcium carbonates calcium sulphates pyrite 6 bioturbation and grazing post depositional structures such as skolithos type dwellings traces of burrowing insects gastropod grazing traces and faecal pellets in synopsis the catalogue firstly comprises a sound set of ubiquitous signatures this uniformity in architectural characteristics is attributed to the presence and local dominance of certain microbes throughout the different settings the catalogue secondly documents signatures that are extremely sensitive to tidal position hydrodynamic regime and overall climatic conditions these kinds of signature indicate narrow facies zones which often coincide with the activity or dominance zones of certain organisms an overview of structures of microbial origin from the fossil record underlines the potential of many of the signatures included in this catalogue to become fossilized and provide strong indicators of former siliciclastic tidal settings

seasonal variation of gravity wave activity at midlatitudes from 7 years of cosmic gps and rayleigh lidar temperature observations seven year series of gravity wave gw potential energy at midlatitude stratosphere 10 to 50 km is constructed by combining temperature profiles provided by constellation observing system for meteorology ionosphere and climate cosmic gps satellite constellation and rayleigh lidar operating at haute provence observatory in southern france the combined series are used to evaluate the representation of gw in modern era retrospective analysis for research and applications reanalysis the seasonal and zonal variabilities of gw activity are diagnosed using zonal wind and wind divergence provided by era interim reanalysis the spatiotemporal distribution of gw activity is found strongly dependent on the zonal wind variation wind divergence and topography we show that anomalies in the wind divergence can serve as a proxy for locating synoptic scale enhancements of gw the analysis provides evidence for orographic gw excitation and the results are compatible with geostrophic adjustment being an additional source of stratospheric gw the seasonal gw variability can be largely explained by interaction with the mean flow and wave propagation

a transpressional origin for the west spitsbergen fold and thrust belt insight from analog modeling 1 the west spitsbergen fold and thrust belt formed along the transform plate boundary between greenland and the western barents sea during paleocene eocene breakup in the northern north atlantic approximately 20 40 km margin perpendicular shortening accumulated in the belt has been attributed to transpression and strain partitioning in a restraining bend but also to head on collision we have applied scaled analog tectonic modeling to test the former hypothesis a pack of brittle quartz sand with a shallow thin layer of silicon putty was deformed by transpression at a 15 convergence angle by movement of a basal plate the kinematics was quantified by means of digital particle image velocimetry the result was a doubly vergent transpressional wedge consisting of a steeply tapered retrowedge and a strongly internally deformed steeply tapered prowedge separated by a central strike slip zone and an adjacent low taper thin skinned fold and thrust belt the doubly vergent wedge evolved through several kinematic phases three main stages were identified namely 1 initial distributed deformation 2 development of an oblique doubly vergent wedge with progressive evolution of local strain partitioning along the marginal shear zones and finally 3 a stage of full strain partitioning between a central strike slip zone and reverse displacement along marginal shear zones with folding and thrusting in a thin skinned belt on the proside the analog model convincingly reproduced the geometry and the kinematic evolution of the west spitsbergen fold and thrust belt supporting the hypothesis of its formation by strain partitioning in transpression with a small angle of convergence and significant lateral displacement

intercomparison of gravity waves in global convection permitting models abstractlarge uncertainties remain with respect to the representation of atmospheric gravity waves gws in general circulation models gcms with coarse grids insufficient parameterizations resul

a new subgrid scale orographic drag parametrization its formulation and testing a scheme for the representation of subgrid scale orography sso in numerical weather prediction and climate models is presented the new scheme arose in part from a desire to represent nonlinear low level mountain drag effects not currently parametrized an important feature of the scheme is that it deals explicitly with a low level flow which is blocked when the effective height of the subgrid scale orography is sufficiently high in this new scheme it is assumed that for this blocked flow separation occurs at the mountain flanks resulting in a form drag this drag is parametrized on model levels which are intersected by the sso and provides a dynamically based replacement for envelope orography the upper part of the low level flow goes over the orography and generates gravity waves at the model resolutions considered t106 and t213 it is assumed that the length scales characteristic of the sso are sufficiently small for the coriolis force to be neglected the various parameters of the scheme are adjusted using an off line procedure in which the scheme is used to estimate the mountain drag and the momentum profiles above the pyrenees and these estimates are validated with the pyrex data forecasts using t106 and t213 resolutions with this new scheme and with mean orography show that the forecast mountain drag consistently reproduces the drag measured during pyrex whenever the flow component normal to the ridge is large isentropic flow diagnostics further show that the new scheme has a realistic impact on the flow dynamics reinforcing the low level wake observed in mesoscale analyses of the flow with this new scheme and a mean orography the ecmwf model outperformed in forecast skill a version of the model which had an envelope orography and the old gravity wave drag scheme while no longer suffering any disadvantages of envelope orography the proposed low level drag parametrization should also be relevant at model horizontal resolutions much higher than t213

the early proterozoic pre iron formation menominee group siliciclastic sediments of the southern lake superior region evidence for sedimentation in platform and basinal settings abstract the early proterozoic menominee group and equivalents of the southern lake superior region everywhere except in the marquette area michigan consist of quartzite gradationally overlain by iron formation with total thicknesses on the order of 0 5 1 km in the marquette area the siamo slate of the menominee group is present conformably between the basal quartzite and overlying iron formation and the total stratigraphic thickness is on the order of 2 km based on variations in regional stratigraphic thicknesses and sedimentary facies analysis it is suggested that the menominee group strata in the marquette area were deposited in a dominantly deeper water basinal environment whereas elsewhere in the lake superior region sedimentation took place in platformal and broad shallower wat r basinal environments the marquette basin filled with material deposited by turbidity currents and pelitic sediments whereas the platformal and broad basinal strata accumulated in a wave agitated offshore shelf environment banded iron formation occurs in both basinal and platformal environments indicating that deposition of these chemical sediments was perhaps independent of local variations in sedimentary tectonic setting the preferred regional tectonic setting evokes shelf and basin sedimentation on a rifted passive continental margin

mat related sedimentary structures in neoproterozoic peritidal passive margin deposits of the west african craton anti atlas morocco abstract proterozoic inliers in the central anti atlas mountains expose predominantly siliciclastic sedimentary successions deposited in peritidal zones along the neoproterozoic continental margin of the west african craton wac the low grade metamorphic and modestly deformed sediments contain a wealth of sedimentary structures related to the former presence and activities of microbial mats and respective physicobiological processes the well preserved structures include wrinkle structures erosion marks microbial sand chips spindle shaped and subcircular microbial shrinkage cracks and possibly gas domes and cabbage head structures thin sections exhibit mat fragments and dispersed grains of hematite limonite after pyrite in fine grained quartzitic storm deposits post storm layers frequently consist of matrix supported sand sized to silt sized grains and are overlain by argillaceous veneers including isolated silt sized grains and black carbonaceous laminae the muddy veneers are considered to represent compacted stacks of microbial mats biolaminites which colonized and biostabilized storm and post storm layers and thus prevented them from eroding in the absence of grazing and burrowing organisms and at suitable depositional and hydrodynamic conditions it may be expected that proterozoic microbial mats extensively grew from the supratidal to the intertidal zones and occasionally e g behind protective barriers in the subtidal zone and beyond mat related structures however need specific conditions for their formation and preservation wrinkle structures erosion marks and microbial sand chips require tractional currents and soon deposition and burial respectively such conditions are preferably met in intertidal and supratidal zones spindle shaped and subcircular cracks require mat shrinkage due to either desiccation or syneresis crack propagation implies progressive shrinkage while superposition of crack generations indicates repeated alternation between mat exposure and flooding respective conditions prevail in the upper intertidal zone gas domes and cabbage head structures are related to the production of gas from decaying organic material beneath a sealing cohesive mat they may be some of the first features formed during genesis of petee structures in the intertidal to lower supratidal zones mat related structures may serve as sensitive facies indicators once their modes of formation are revealed

dinocyst stratigraphy of the valanginian aptian rurikfjellet and helvetiafjellet formations on spitsbergen arctic norway

impact of a spectral gravity wave parameterization on the stratosphere in the met office unified model abstract the impact of a parameterized spectrum of gravity waves on the simulation of the stratosphere in the met office unified model um is investigated in the extratropical mesosphere the gravity wave forcing acts against the mean zonal wind and it dominates over the resolved wave forcing in the extratropical stratosphere the gravity wave forcing gives a small acceleration in the direction of the mean zonal wind both summer and winter stratospheric jets have improved maximum strength and tilt with height when the parameterized gravity wave forcing is included although the southern winter jet is still more vertically aligned than in observational analyses the timing of the seasonal breakdown of the southern winter vortex is also improved by the addition of gravity wave forcing in the tropics the most obvious impact is that the model reproduces the quasi biennial oscillation qbo with a realistic mean and range of periods it also reproduces most of the observed asymmetries between the easterl