detachment folding in the southwestern tian shan tarim foreland china shortening estimates and rates abstract geologic observations of the chinese tian shan foreland reveal active contractional deformation along the entire margin to quantify the amount of shortening and understand the structural style we mapped the stratigraphy and structure of four folds expressed at the western end of the foreland north of kashi in this region upper tertiary through quaternary sediments are conformable but an abrupt transition from parallel to unconformable bedding in the uppermost strata suggests a transition from pre fold strata to strata deposited on a growing fold the folds have very steep 60 90 limbs and are box like to isoclinal suggestive of detachment folding total north south shortening across the center of the region is 9 km of which 5 7 km occurred in the kashi atushi fold system shortening estimates determined with excess area methods for individual folds decrease from a maximum of 6 8 km in the northwest to a minimum of 0 7 km in the southeast timing derived from a paleomagnetic study shows that the transition to syn folding strata occurred 1 2 ma in the middle of the study area resulting in an average shortening rate for the kashi atushi fold system of 5 mm yr if folding was coeval the shortening rate is high compared with foreland deformation east of the study area suggesting that the regional stresses or response of the foreland stratigraphy are unique to the kashi atushi fold system kinematics

kinematic model of active deformation in central asia the velocity field of present day deformation in central asia is modelled using a set of four rotating blocks siberia tarim tibet india on a spherical earth a best fit is inverted on the basis of estimated shortening rates across the main thrust zones himalayas tien shan and measured slip rates along the principal strike slip faults altyn tagh and karakorum separating those blocks the fit to the data implies that nearly all the present convergence between india and asia can be accounted for by slip partitioning on these four zones with as much as 50 absorbed by northeastwards extrusion of tibet this suggests that localised deformation governs the present mechanical behaviour of the central asian lithosphere

meso cenozoic extensional structures in the northern tarim basin nw china meso cenozoic extensional structures are important for understanding the tectonics of the chinese central asia this paper presents a systematic investigation on the meso cenozoic extensional structures in the northern tarim basin close interpretations of seismic data reveal that the meso cenozoic extensional structures were widely developed in the northern tarim basin these extensional structures are regionally composed of many small normal faults which usually group into left or right step en echelon and form several transtensional fault zones combinations of normal faults in profile become small graben horst or staircase like cross sections based on the areal distribution structural style combination relationship formation and evolution time and formation mechanism of the extensional structures we found that the meso cenozoic extensional structures in northern tarim basin can be classified into two conjugate normal fault systems which were formed separately in jurassic early cretaceous and late cretaceous neogene the former is likely associated with the stress relaxation after a collisional orogeny accompanied with a certain degree of anticlockwise rotation of the tarim block relative to the south tianshan the latter is possibly induced by the east by south tectonic escape of the tarim block with a certain degree of clockwise rotation relative to the south tianshan triggered by the far field effect of the himalayan orogeny

structure of the mediterranean undercurrent and mediterranean water spreading around the southwestern iberian peninsula 1 rafos float and hydrographic data are analyzed to investigate the pathways rates and mechanisms of mediterranean water mw spreading into the north atlantic from the gulf of cadiz with an emphasis on processes other than meddies we find that the transition of the mediterranean outflow from a density current to an intermediate depth jet occurs as it enters portimao canyon south of portugal due to rapidly steepening topography and associated turbulent entrainment this feature was not seen in recent plume model simulations due to their use of smoothed topography in addition to the traditional lower salinity maximum or core a denser deeper continuous vein of mw was also traceable from portimao canyon to cape st vincent the mean velocity structure of the mediterranean undercurrent changes from a 30 km wide jet with peak mean westward speed of 0 2 m s 1 along the southern iberian slope to a broader much weaker northward flow with maximum mean speed of only 0 06 m s 1 along the western iberian slope due in part to changes in the bottom slope lower core mw spread mainly 1 southward into the interior gulf of cadiz 2 northward along the western iberian slope and 3 westward into the deep tagus abyssal plain the average spreading rate was 0 01 0 02 m s 1 toward the west northwest direction meddies forming near the slope were found to have an indirect but profound impact on mw spreading often diverting mw approaching from upstream into the interior the results are compared to recent hydrography based studies of mw spreading pathways

two circulation regimes of the mediterranean outflow revealed by lagrangian measurements the eurofloat experiment was a joint initiative to examine the large scale spreading of mediterranean water mw and labrador sea water in the northeast north atlantic rafos float data from the southern mw portion of the eurofloat experiment have been examined in conjunction with historical float data in order to calculate quasi eulerian means in an effort to separate and quantify the constituents of the spreading of the mw tongue east of the mid atlantic ridge while recent studies focussed chiefly on the role of meddies in the shaping of the mw tongue this analysis also examines the tongue s second constituent that is the background non meddy advective and diffusive flow the results suggest the existence of two regimes approximately to the north and south of the 36 n parallel i e the latitude of the gulf of cadiz which are distinguished by different types of dominant spreading mechanisms for mw to the south of the gulf of cadiz the background flow shows an incoherent and weak mean whereas the mean velocity of the salt enhanced meddies is strong and to the southwest in contrast to the north of 36 n the mean velocity of the meddies seems to be less pronounced and the background flow is shown to be a major component in the northwestward spreading of the mw tongue the two regimes are separated by the azores current which previously has been hypothesized to act as a dynamic barrier to the southward advective spreading of the background regime which the meddies are able to penetrate because of their high kinetic energy overall the meddies are calculated to contribute to approximately half of the total salinity anomaly flux

evolution of the turfan basin chinese central asia the turfan basin extends approximately 550 km east west by 100 km north south within northwest china and is located between branches of the intracontinental tien shan orogenic belt at present it is an intermontane foreland basin loaded by southward transported thrust sheets at its northern margin this deformation is a long distance manifestation of the india asia collision but the orientation and location of cenozoic structures is strongly influenced by the pre cenozoic history of the region the exposed basement marginal to the turfan basin consists of volcanics granitoids volcaniclastics and deepwater sedimentary rocks associated with the north tien shan island arc and subduction accretion complexes north of the north tien shan fault this arc had accreted to the central tien shan by late carboniferous to early permian times the north tien shan fault represents a major boundary between paleozoic arcs and accretionary complexes to the north and proterozoic basement of the central tien shan and tarim block to the south postcollisional thrusting appears to have provided a tectonic load for lower permian subsidence and sedimentation early postcollisional strata are turbidites but there was a shoaling of facies until the deposition of permo triassic conglomerates no marine sediments have been deposited in the region since the paleozoic at least two mesozoic episodes of compressional deformation are recorded at the northern margin of the basin which was an intermontane foreland basin during this era lower jurassic fluvial and lacustrine clastic rocks lie above a regional unconformity an oligocene unconformity marks the onset of coarse clastic sedimentation in the cenozoic and probably indicates the start of major compressional deformation related to the india asia collision sedimentation rates have increased through the cenozoic the neotectonics of the turfan basin are dominated by a southward directed thrust system emergent within the basin at the fire mountains range southward directed thrusting appears to have been a feature of mesozoic age tectonics and possibly the late paleozoic tectonics of the basin the most important neotectonic structures in the turfan basin follow older structural trends

cenozoic deformation of the tarim basin and surrounding ranges xinjiang china a regional overview abstract with its central position between the tibetan plateau and the tian shan range the tarim basin is a key element of the cenozoic asian orogenic system however a comprehensive regional study and more particularly the quantification of shortening through this basin and its margins are still needed to understand its role in the cenozoic deformation of asia from a compilation of previous works together with an extensive dataset of satellite field seismic and well data we provide a tectonic map of the cenozoic structures and four balanced geological transects of the tarim basin and its surrounding ranges based on this map and these cross sections we characterize the cenozoic deformation of the original proterozoic tarim block from structural restorations and crustal budgets we also quantify the compressive component of this deformation most of the cenozoic compressive deformation from 94 to 100 is concentrated in the ranges along the block margins to the west up to 78 23 km and 54 24 18 km of crustal shortening are accommodated across the compressive western kunlun and southwestern tian shan ranges while to the east up to 38 6 18 km and 15 20 15 km are accommodated across the transpressive altyn tagh and southeastern tian shan ranges a non negligible amount of compressive deformation up to 6 is also accommodated within the tarim basin by large basement cored uplifts with a vergence synthetic to the deformation of the tibetan plateau edge to the west the bachu uplift absorbs 5 km of the total crustal shortening of the western kunlun thrust system while to the south the tanan uplift accumulates 0 6 km of the altyn tagh strike slip system structural inheritance has a major influence on the cenozoic deformation since 33 3 to 100 of the total shortening is accommodated by reactivated basement structures inherited from the protero paleozoic history of the tarim block finally we argue that the basement cored uplifts in the centre of the basin imply a deformation transfer from the tibetan plateau to the tian shan above a deep crustal decollement decoupling the deforming crust from an underlying rigid mantle

circulation and deep water export at the western exit of the subpolar north atlantic the current system east of the grand banks was intensely observed by world ocean circulation experiment woce array acm 6 during 1993 95 with eight moorings reaching about 500 km out from the shelf edge and covering the water column from about 400 m depth to the bottom more recently a reduced array by the institut fur meerskunde ifm at kiel germany of four moorings was deployed during 1999 2001 focusing on the deep water flow near the western continental slope both sets of moored time series each about 22 months long are combined here for a mean current boundary section and both arrays are analyzed for the variability of currents and transports a mean hydrographic section is derived from seven ship surveys and is used for geostrophic upper layer extrapolation and isopycnal subdivision of the mean transports into deep water classes the offshore part of the combined section is dominated by the deep reaching north atlantic current nac with currents still at 10 cm s 1 near the bottom and a total northward transport of about 140 sv sv 106 m3 s 1 with the details depending on the method of surface extrapolation used the mean flow along the western boundary was southward with the section mean north atlantic deep water outflow determined to be 12 sv below the 27 74 kg m 3 isopycnal however east of the deep western boundary current dwbc the deep nac carries a transport of 51 sv northward below 27 74 kg m 3 resulting in a large net northward flow in the western part of the basin from watermass signatures it is concluded that the deep nac is not a direct recirculation of dwbc water masses transport time series for the dwbc variability are derived for both arrays the variance is concentrated in the period range from 2 weeks to 2 months but there are also variations at interannual and longer periods with much of the dwbc variability being related to fluctuations and meandering of the nac a significant annual cycle is not recognizable in the combined current and transport time series of both arrays the moored array results are compared with other evidence on deep outflow and recirculation including recent models of different types and complexity

north atlantic nordic seas exchanges abstract the northeastern part of the north atlantic is unique in the sense that it is much warmer in the surface than other ocean areas at similar latitudes the main reason for this is the large northward transport of heat that extends to high latitudes and crosses the greenland scotland ridge to enter the nordic seas and the arctic there the warm atlantic water is converted to colder water masses that return southwards over the ridge partly as surface outflows and partly as overflows through the deep passages across the ridge in this paper the state of knowledge on the exchanges especially across the eastern part of the greenland scotland ridge is reviewed based on results from the ices nansen north atlantic norwegian sea exchanges project from the nordic woce project and from other sources the accumulated evidence allows us to describe the exchanges in fair detail the origins of the waters the patterns of their flow towards and over the ridge and their ultimate fate there is also increasing information on temporal variations of the exchanges although dynamical changes are still not well understood quantitative estimates for the volume transport of most of the overflow branches seem reasonably well established and transport measurements of the atlantic inflows to the nordic seas are approaching acceptable levels of confidence which allows preliminary budgets to be presented the deep overflows are driven by pressure gradients set up by the formation of deep and intermediate water the dominance of deep overflows over surface outflows in the water budget argues that this thermohaline forcing also dominates over direct wind stress and estuarine forcing in driving the atlantic water inflow across the greenland scotland ridge while wind stress seems to influence the characteristics and distribution of the atlantic water north of the ridge

directly measured mid depth circulation in the northeastern north atlantic ocean the circulation of water masses in the northeastern north atlantic ocean has a strong influence on global climate owing to the northward transport of warm subtropical water to high latitudes but the ocean circulation at depths below the reach of satellite observations is difficult to measure and only recently have comprehensive direct observations of whole ocean basins been possible here we present quantitative maps of the absolute velocities at two levels in the northeastern north atlantic as obtained from acoustically tracked floats we find that most of the mean flow transported northward by the gulf stream system at the thermocline level about 600 m depth remains within the subpolar region and only relatively little enters the rockall trough or the nordic seas contrary to previous work our data indicate that warm saline water from the mediterranean sea reaches the high latitudes through a combination of narrow slope currents and mixing processes at both depths under investigation currents cross the mid atlantic ridge preferentially over deep gaps in the ridge demonstrating that sea floor topography can constrain even upper ocean circulation patterns

flow through discovery gap abstract a narrow gap discovery gap in the east azores fracture zone at 37 n in the eastern atlantic provides a channel for the exchange of bottom water between the madeira and iberian abyssal basins a detailed survey defines its length 150 km width 10 50 km depth of sills near 4800 m and sediment thickness 0 500 m year long measurements of deep flow are made from six moorings and ten current meters mean flows are about 5 cm s 1 these data are supplemented by 10 days of float tracking near 4700 m and numerous density profiles within and around the gap a persistent southwest northeast flow of dense water is found in discovery gap and the flux of water colder than a potential temperature of 2 05 c is measured to be 0 21 04 106 m3 s 1 this discharge spreads over an area of about 1011 m2 beyond the gap exit where it is warmed both by geothermal heating and by mixing with overlying water an estimate of 1 5 to 4 cm2 s 1 is derived for the diapycnal diffusivity similar to values dete

a statistical description of the mean circulation and eddy variability in the northwestern atlantic using sofar floats abstract velocity data obtained from trajectories of sofar floats launched as part of several experiments carried out in the northwest atlantic during the last two decades are used to give a statistical description of the mean gulf stream and its recirculation the distribution of eddy variability in the region is also presented a mean gulf stream which bifurcates between 55 and 45 w to feed the north atlantic current and a southern recirculation can be clearly identified a weak interior sverdrup flow is also suggested the spatial distribution of eddy variability is consistent with previous descriptions showing a maximum near the gulf stream

preliminary results from directly measuring middepth circulation in the tropical and south pacific as part of the world ocean circulation experiment 300 autonomous lagrangian circulation explorer floats were deployed in the tropical and south pacific to measure the general circulation at 900 m depth most floats measured average currents over 25 submerged days between ascents to the surface for locating and data relay by the end of 1997 over 12 500 observations spanning 840 float years were obtained accuracy of the average velocity is limited by variability some of which is found to arise from steady flows with spatial variations smaller than averaging scales observed 25 day velocities are serially uncorrelated except near the equator where energetic zonal variability has seasonal timescales and appears to be described by a data assimilating ocean circulation model run by the national centers for environmental prediction space time averages of float velocities disclose a general pattern of middepth flow that resembles the surface circulation with the strongest flows of o 3 cm s in the deep antarctic circumpolar current and east australian current the weaker elements of the flow including an interior subtropical circulation with o millimeters per second flows are described by an objective analysis whose accuracy is limited by sampling noise rather than uncertainty of the analysis parameters the subtropical circulation has a gyres within a gyre structure including boundary currents along australia and east of new zealand and a concentrated equatorial limb with surprising strength in the western basin this current is also involved in a tropical gyre with generally eastward flow along the equator in the western basin at least because of strong seasonal scale variability the equatorial zonal currents are not well measured yet but data are still being accumulated comparison with reid s 1997 absolute circulation shows more areas of agreement than of disagreement

discrete eddies in the northern north atlantic as observed by looping rafos floats abstract rafos float trajectories near the 27 5 density level were analyzed to investigate discrete eddies in the northern north atlantic with the objective of determining their geographical distribution and characteristics floats that made two or more consecutive loops in the same direction loopers were considered to have been in an eddy overall 15 24 float years of the float data were in loopers one hundred and eight loopers were identified in 96 different eddies roughly half of the eddies were cyclonic 49 and half were anticyclonic 51 although the percentages varied in different regions a few eddies were quasi stationary for long times one for over a year in the iceland basin and many others clearly translated often in the direction of the general circulation as observed by non looping floats several floats were trapped in eddies in the vicinity of the north atlantic current just upstream west of the charlie gibbs 52 n and faraday 50 n fracture zones which seem to be preferred routes for flow crossing the mid atlantic ridge five floats looped in four anticyclones that translated southwestward away from the eastern boundary near the goban spur 47 50 n these could have been weak meddies forming from remnants of warm salty mediterranean water advected northward along the eastern boundary

cenozoic faults and faulting phases in the western tarim basin nw china effects of the collisions on the southern margin of the eurasian plate abstract the bachu rise in the western tarim basin is the fore bulge of the kunlun late cenozoic intra continental foreland basin system formed under the far field effect of india asia collision cenozoic faults and faulting are abnormally developed in the bachu rise and its adjacent area taking the niaoshan gudongshan area on the southern boundary of the bachu rise as the key study area 5 cenozoic faulting phases were identified in the bachu rise and its adjacent area after careful seismic interpretation they are end cretaceous beginning paleogene ca 65 ma decollement thrusting end paleogene beginning neogene ca 23 ma decollement thrusting end miocene beginning pliocene ca 5 ma basement involved thrusting late pliocene early pleistocene ca 3 2 ma normal faulting middle pleistocene holocene ca

the spatial and temporal evolution of a cluster of sofar floats in the polymode local dynamics experiment lde abstract up to forty neutrally buoyant floats 20 at 700 m 20 at 1300 m were used in the polymode local dynamics experiment lde to provide a quasi lagrangian description of the structure and evolution of the mesoscale eddy field in a limited region characterized by higher kinetic energy levels than those obtained in mode this paper is an overview and summary of the data collected the temporal development of the two level float array is presented in a sequence of maps each spanning five days in these one readily notices an oscillation of floats at 1300 m in a ne sw direction before the cluster breaks apart at 700 m the float cluster subdivides much more rapidly the first setting of 700 m floats drifts to the west the second group launched two months later goes far to the east ensemble averages as a function of time of the floats at 1300 m reveal great sensitivity to the oscillatory velocity field while the array is tight or coherent the corresponding 700 in averages although noisy sho

labrador sea water circulation in the northern north atlantic ocean abstract direct observation of velocities with drifting floats near 1500 m depth in the north atlantic ocean north of about 45 n are combined to derive a new basin wide mean circulation within the layer of labrador sea water lsw inverse methods are used to determine a basin scale circulation constrained by non divergence and conservation of climatological large scale potential vorticity pv with the aim of investigating large scale pv dynamics improving circulation estimates near the basin boundaries and determining the relative amount of recirculation in sub basin gyres with aliased direct velocity data eulerian averages are created from combined datasets and a streamfunction of the non divergent flow is computed from the velocity curl and the imposed boundary conditions unlike deep flow regimes at low latitudes where the mid depth interior circulation is dominated by zonal currents the mid depth subpolar flow is dominated by gyres as suggested by previous estimates of mid depth circulation the lsw layer is rapidly circulating around the periphery of the subpolar basin in northern and western boundary currents recirculation within basins and exchange between the labrador basin and irminger basin is modified by the large scale pv constraints eastward flow across the mid atlantic ridge is concentrated in the charlie gibbs fracture zone with return flow above the reykjanes ridge a weaker subtropical return flow around the azores plateau appears but data are insufficient to map adequately this region

the north atlantic current based on trajectories of satellite tracked buoys and hydrographic sections both dietrich s and worthington s schemes of the north atlantic current are reconsidered ninety satellite tracked buoys have been analyzed in order to distinguish between these schemes neither could be confirmed the north atlantic current appears as a superposition of a broad west wind drift and a frontal jet in the western part of the north atlantic north of 40 n which becomes independent from the subtropical gyre neither a permanent branching suggested by dietrich nor a confinement of the subpolar gyre to the east of newfoundland per worthington can be found the north atlantic current extends over the entire north atlantic carrying more than 20 sverdrups sv toward the north this northward transport is mainly due to the northward flow around flemish cap and a sudden turn of the north atlantic current east of the mid atlantic ridge the buoy tracks have been used to determine speed and direction in the upper layers 100 m we combine these results with hydrographic data in order to obtain an estimate of the mass transport transport across the mid atlantic ridge is based on recent sections fahrbach et al 1985 while transport in the northeastern north atlantic has been derived from the erika dan sections at 53 5 n and 59 5 n according to these two sections the return flow occurs mainly below 1000 m after water mass conversion in the northern areas the results imply that about 7 sv of atlantic water are transformed into deep water in the area between 53 5 n and 60 n

effect of basement structure and salt tectonics on deformation styles along strike an example from the kuqa fold thrust belt west china abstract the kuqa fold thrust belt kftb has a complex thrust system geometry and comprises basement involved thrusts decollement thrusts triangle zones strike slip faults transpressional faults and pop up structures these structures combined with the effects of paleogene salt tectonics and paleozoic basement uplift form a complex structural zone trending e w interpretation and comprehensive analysis of recent high quality seismic data field observations boreholes and gravity data covering the kftb has been performed to understand the characteristics and mechanisms of the deformation styles along strike regional sections fold thrust system maps of the surface and the sub salt layer salt and basement structure distribution maps have been created and a comprehensive analysis of thrust systems performed the results indicate that the thrust fold system in paleogene salt range can be divided into five segments from east to west the kela 3 keshen dabei bozi and awate segments in the easternmost and westernmost parts of the paleogene salt range strike slip faulting and basement involved thrusting are the dominant deformation styles as basement uplift and the limits of the cenozoic evaporite deposit are the main controls on deformation salt core detachment fold thrust systems coincide with areas of salt tectonics and pop up imbricate and duplex structures are associated with the main thrust faults in the sub salt layer distribution maps of thrust systems basement structures and salt tectonics show that paleozoic basement uplift controlled the paleozoic foreland basin morphology and the distribution of cenozoic salt in the kftb and thus had a strong influence on the segmented structural deformation and evolution of the fold thrust belt three types of transfer zone are identified based on the characteristics of the salt layer and basement uplift and the effects of these zones on the fault systems are evaluated basement uplift and the boundary of the salt deposit generated strike slip faults in the sub salt layer and supra salt layers at the basin boundary model a when changes in the basement occurred within the salt basin strike slip faults controlled the deformation styles in the sub salt layer and shear zone dominated in the supra salt layer model b a homogeneous basement and discontinues salt layer formed different accommodation zones in the sub and supra salt layers model c in the sub salt layer the thrusts form imbricate structures on the basal decollement whereas the supra salt layer shows overlapping discontinuous faults and folds with kinds of salt tectonics and has greater structural variation than the sub salt layer

late cenozoic transtensional fault belt discovered on the boundary of the awati sag in the northwestern tarim basin late cenozoic transtensional fault belt was discovered on shajingzi fault belt nw boundary of the awati sag in the northwestern tarim basin and numerous quaternary normal faults were discovered on aqia and tumuxiuke fault belts sw boundary of awati this discovery reveals quaternary normal fault activity in the tarim basin for the first time it is also a new discovery in the southern flank of tianshan mountains shajingzi transtensional fault belt is made up of numerous small normal faults horizontally the normal faults are arranged in right step en echelon patterns along the preexisting shajingzi basement fault forming a sinistral transtensional normal fault belt in profile they cut through the paleozoic to the mid quaternary and combine to form negative flower structures the late cenozoic normal faults on the sw boundary of awati sag were distributed mainly in the uplift side of the preexisting aqia and tumuxiuke basement involved faults and combined to form small horst and graben structures in profile based on the intensive seismic interpretation careful fault mapping and growth index analysis we conclude that the normal fault activity of shajingzi transtensional fault belt began from late pliocene and ceased in late pleistocene mid quaternary and the normal faulting on the sw boundary of awati sag began from the very beginning of quaternary and ceased in pleistocene the normal faulting on awati s sw boundary began a little later than those on the nw boundary the origin of shajingzi transtensional normal fault belt was due to the left lateral strike slip occurred in the southern flank of tianshan and then due to the eastward escape of the awati block a tensional stress developed the normal faults on its sw boundary

the kuqa late cenozoic fold thrust belt on the southern flank of the tian shan mountains the kuqa fold thrust belt kftb a late cenozoic fold thrust belt on the southern flank of the tian shan mountains consists of several deformation zones trending nearly w e the main decollement fault of the kftb gradually rises southwards there are three regional main decollement faults in the triassic dark mudstone paleogene gypsum salt kumugeliemu formation and neogene gypsum salt jidike formation respectively and possibly a fourth in the jurassic coalbed laterally thin skinned structures are developed in the main segments of the kftb whereas thick skinned structures are in the root zone vertically the structural deformation above the cenozoic gypsum salt layers paleogene gypsum salt in the middle segment of the kftb and neogene gypsum salt in the eastern segment is characterized by decollement folding whereas that below is characterized by thrusting the kftb was resulted from the late cenozoic intra continental orogeny in the tian shan area under the far field effect of the india asia collision the deformation of kftb began folding and thrusting ca 23 ma when the far field effect of the india asia collision reached the tian shan area the deformation of kftb accelerated ca 10 5 2 and 1 0 ma in general the evolution of the kftb is forward propagating and the hinter parts of the kftb continue to deform while its front propagates southwards

lagrangian eddy scales in the northern atlantic ocean eddy time and length scales are calculated from surface drifter and subsurface float observations in the northern atlantic ocean outside the energetic gulf stream subsurface timescales are relatively constant at depths from 700 m to 2000 m length scale and the characteristic eddy speed decrease with increasing depth below 700 m but length scale stays relatively constant in the upper several hundred meters of the gulf stream it is suggested that this behavior is due to the lagrangian sampling of the mesoscale field in limits set by the eulerian eddy scales and the eddy kinetic energy in high energy regions of the surface and near surface north atlantic the eddy field is in the frozen field lagrangian sampling regime for which the lagrangian and eulerian length scales are proportional however throughout much of the deep ocean interior the eddy field may be in the fixed float regime for which the lagrangian and eulerian timescales are nearly equal this does not necessarily imply that the deep interior is nearly linear as fixed float sampling is possible in a flow field of o 1 nonlinearity

lagrangian observations of the middepth and deep velocity fields of the northeastern atlantic ocean the circulation of the northeastern atlantic ocean at intermediate depths is characterized by watermass transformation processes that involve iceland scotland overflow water isow from the northeast labrador sea water lsw from the west and mediterranean water from the south field observations were carried out with 89 eddy resolving floats rafos and marvor types the data coverage achieved is remarkably high and enables a comprehensive study of the eastern basins between iceland and the azores the trajectories show typical pathways of the water masses involved and the role that the complex bottom topography plays in defining them the isow paths tend to lean against the slopes of the reykjanes ridge and rockall plateau westward escapes through multiple gaps in the ridge are possible superimposed on a sustained southward flow in the eastern basin along the mid atlantic ridge lsw pathways leading to the eastern basins are subject to high variability in flow direction and eddy activity in addition to a selection of characteristic trajectories maps of the horizontal distributions of lagrangian eddy kinetic energy and integral time scales are presented these reveal distinct areas of intensified mixing in the iceland basin as well as the sharp contrast between the subpolar and subtropical dynamics a self contained eddy detection scheme is applied to obtain statistics on individual eddy properties and their abundance it is suggested that much of the intensified mixing can be related to cyclonic activity particularly in the subpolar region

year long float trajectories in the labrador sea water of the eastern north atlantic ocean abstract year long lagrangian trajectories within the labrador sea water of the eastern north atlantic ocean are analysed for basic flow statistics root mean square velocities at 1750 m depth are about 2 cm s except within the north atlantic current where they are twice as large these values are consistent with previous eulerian measurements and extend those results to a much larger domain of the eastern basin mean flow estimates in boxes large enough to contain about 1 float year of data indicate that labrador sea water having crossed the mid atlantic ridge not resolved near 50 55 n presumably with the north atlantic current partially recirculates to the north in the subpolar gyre as well as entering the subtropical gyre and continuing south and west the circulation of this water mass as defined by the 1 yr average velocities is stronger than traditional models of deep circulation would suggest with an interior flow of roughly 1 cm s mean speeds up to 3 cm s were observed with the highest values near the azores plateau north of 45 n 55 n mean eastward speeds closer to 0 2 cm s were observed wind generated barotropic fluctuations may be responsible for some part of the transport at this depth

late cenozoic tectonics of the kepingtage thrust zone interactions of the tien shan and tarim basin northwest china the kepingtage kalpin thrust zone northwest china is an actively deforming part of the india asia collision system it lies south of the tien shan has an area of 16 000 km2 and consists of arcuate emergent imbricates overall vergence is toward the interior of the tarim basin to the south thrust sheets typically expose upper cambrian to permian platformal strata thrusting is largely thin skinned thin upper cambrian evaporites are likely to be the main decollement horizon the kepingtage thrust zone is the only margin of the tarim basin to deform in this style in the cenozoic it is replaced to the east and west by thrust zones which have propagated shorter distances into the interior of the tarim basin thick up to 10 km mesozoic and cenozoic clastic successions are present and deformed in these regions such successions are not present in the kepingtage thrust zone or the adjacent bachu uplift within the tarim basin because of episodic activity on steep northwest southeast trending thrusts which define the margins of the bachu uplift these mesozoic cenozoic strata may have suppressed the ability of regions along strike from the kepingtage thrust zone to deform by thin skinned thrusting utilizing the upper cambrian decollement the along strike variation in active thrusting at the southern margin of the tien shan is an example of syntectonic sedimentation controlling thrust belt deformation style a balanced section across the thrust zone indicates 28 shortening equivalent to 35 km this is equivalent to an average slip rate of 1 8 mm yr 1 and a strain rate of 4 4 10 16 s 1 assuming deformation began at circa 20 ma active deformation is focused along the frontal thrust the kepingtage fault the northern boundary of the kepingtage thrust zone is formed by the south tien shan fault this major north dipping thrust is seismically active with published earthquake focal depths at midcrustal levels 14 and 18 km it juxtaposes upper carboniferous sedimentary rocks of different facies and different paleozoic deformation histories speculatively it represents a reactivation of a late paleozoic thrust which originated at the boundary between the platformal interior of the tarim block and a deeper water foreland basin to its north

north atlantic ocean surface currents 1 close to 1800 surface drifters are used to investigate the 15 m circulation of the north atlantic ocean the data are used to describe structures of the average eulerian circulation and of the associated eddy variability the data resolve scales on the order of 50 km which have hitherto not been systematically described in particular near shelf breaks and near the most intense currents the gulf stream the north atlantic current nac and the frontal currents of the subpolar gyre this reveals a complex series of quasi permanent eddies meanders and recirculation patterns gulf stream intensity is portrayed as changing abruptly near 54 w east of which it is identified as two current branches centered near 39 and 41 5 n the northern one connecting more directly with the nac and the southern one with the recirculation gyre and the azores current ac many features of the currents are controlled by topography in particular currents are often intensified near shelf breaks or parallel to ridges in the subpolar gyre however the largest northward branch of the nac in the icelandic basin is located near the deepest bathymetry not near steep bathymetry other currents in particular in the subtropical gyre are less clearly related to topography for instance the ac is featured as a zonal eastward current extending far west of the mid atlantic ridge mar to at least 55 w and possibly 63 w in the interior and away from topographic features the eddy kinetic energy eke is the largest where the mean currents are the largest in the subpolar gyre there are striking differences in eke between southward flowing currents the labrador and east greenland current and the northward flowing currents west greenland current and branches of the nac which have higher eke the areas of weakest variability are located in the southwest part of the subpolar gyre northeast of iceland and in the eastern atlantic south of 45 n the ac eddies and the mesoscales south of the canary islands transect this eastern eddy desert drifter trajectories are used as realizations of lagrangian particles in the vicinity of current cores these illustrate the variety of paths or connections between different current systems and demonstrate cross stream dispersions

eddy kinetic energy of the north atlantic subpolar gyre from satellite altimetry the surface eddy kinetic energy field of the north atlantic subpolar gyre 40 65 n 5 60 w is studied using the altimetric satellites geosat 1987 1988 and ers 1 1992 1993 this is on the whole an area of low eddy activity previous studies of the north atlantic have usually concentrated on the highly variable gulf stream system we review what is known of the surface circulation of the region we confirm that there is a close relationship between the eddy kinetic energy and the mean currents and that it is strongly constrained by the topography the eddy field occurs in deep water and follows the contours particularly around the flemish cap high eddy kinetic energy is seen on the flanks of topography and is higher where the slope is steeper this is particularly clear on both east and west flanks of the rockall plateau interannual changes in the currents are revealed by the differences between the geosat and ers 1 eddy kinetic energy maps in some years 1988 and 1992 1993 the northern core of the north atlantic current nac usually assumed to be tied to the charlie gibbs fracture zone 52 n is considerably weaker and may not exist at all while in 1987 there is a distinct core here in 1988 and 1992 1993 the main eddy region shifts farther to the south to about 49 n in 1988 and 50 n in 1992 1993 in 1987 there is also a current core even farther south centered at about 47 n implying that in that year the nac is arranged into two distinct branches

the temporal record of magmatism at cerro uturuncu bolivian altiplano twenty six new 40ar 39ar plateau ages for 23 lavas and domes from the uturuncu volcano in the altiplano of sw bolivia reveal a protracted eruptive history from 1050 5 to 250 5 ka eruptions have been exclusively effusive producing some 50 km3 of high k dacites and silicic andesites bimodal mineral compositions complex mineral textures the presence of andesitic magmatic enclaves within dacites and linear chemical trends on binary element plots all indicate that magma mixing is an important petrogenetic process at uturuncu post 458 ka distinct high and low mgo cr magmas are resolved these magmas erupt during similar times suggesting that eruptions are tapping different parts of the magma system albeit from the same vent system volcanic and petrological features are consistent with the existence of a vertically extensive magma mush column beneath uturuncu and calculated buoyancy forces are sufficient to drive effusive eruptions eruptive activity is episodic with six eruptive periods separated by hiatuses of 50 kyr cumulative volume curves demonstrate that the majority of the edifice formed between 595 and 505 ka the episodicity of eruptions is most likely to be related to fluctuations in the magma supply to the underlying altiplano puno magma body

currents and mixing in the irminger sea and in the iceland basin on the basis of a hydrographic section from the faeroe islands toward greenland along 62m 0n and the deployment of about 20 satellite tracked buoys it is shown that the irminger current branches at the reykjanes ridge its total transport amounts to 17 18 sv the eastern branch of the irminger current 8 sv turns east and enters the norwegian sea both through the faeroe shetland channel 3 sv and by passing northeast of the faeroe islands maximum speeds of 70 cm s 1 are reached at the outer edge of the east and west greenland current very intensive mixing is observed between the four water masses that flow into the irminger basin stirring by eddies plays a dominant role for strong interleaving subsequent salt fingering and double diffusive layering conditions for these processes are optimal nearly everywhere in the irminger sea

drifting buoy in the field of flow of two eddies on east thulean rise northeast atlantic the track of an argos buoy drogued at a depth of 70 m over a year s deployment from april 18 1989 to april 18 1990 in the ne atlantic is described the mean speed of the buoy over a year s period was 1 4 cm s 1 to the ne for 320 days there was little net movement and during this time the buoy spent 66 days in a cyclonic eddy and 130 days in an anticyclonic eddy the anticyclonic eddy diameter was about 200 km and the buoy completed 21 complete revolutions around the eddy center at a radius of 55 km the rotation rate was 10 days in the eye of the anticyclonic eddy the rotation rate was 36 hours the inertial period for the latitude 51 5 n was 15 3 hours and inertial motions were occasionally marked in the anticyclonic eddy the observed inertial period was about half an hour longer than the inertial period corresponding to the latitude both eddies appeared to be partially trapped to east thulean rise water depth 3000 m and moved at a mean speed of about 1 cm s 1 to the nw along the rise following water depth contours though the anticyclonic eddy was stationary for about 50 days over the more central region of the rise the track of an imperfectly drogued buoy in a circular eddy field is then examined analytically a simple balance of stress forces on the drogued assembly is assumed and commonly adopted assumptions for the stress forces are made with assumptions the idealized study shows that under conditions of a steady surface stress a surface wind or current for example a buoy can remain trapped within an eddy field and show no tendency for steady translation in the direction of the surface stress for a clockwise eddy the displacement of the buoy s track is to the right of the surface stress direction for larger surface stresses or time varying winds the buoy may be blown out of an eddy of limited extent

spreading of labrador sea water in the eastern north atlantic the spreading of labrador sea water lsw in the eastern north atlantic south of 55 n is described on the basis of recent high resolution hydrographic lines and using an inverse model of that basin general circulation the isopycnic salinity anomaly relative to a standard s curve is used to detect the main branches and limits of dominant influence of the intermediate water masses the lsw crosses the mid atlantic ridge at latitudes around 50 n with parts spreading farther eastward and southward one southward pathway along the eastern side of the mid atlantic ridge stands out as an eastern basin counterpart of the western atlantic deep western boundary current an entry into the bay of biscay in its northern part is also evidenced with striking similitudes between two data sets from 1974 and 1989 1990 at the southern limit of the lsw extension in the vicinity of the azores biscay rise a marked front exists basinwide around 1800 m with the more saline deep mediterranean water dmw the inverse model velocity field is consistent with most features of the tracer distributions and allows estimation of lsw transports 6 3 1 2 sv of lsw with salinities lower than 34 94 cross the 35 w meridian eastward between 44 n and 54 n one fourth of which recirculates southwestward in the western basin while another fourth turns northward across 54 n and the remaining half proceeds southward in the eastern basin the model circulation suggests that dmw results from mixing between eastern basin lsw and the overlying mediterranean outflow water most probably through double diffusion we finally describe several mesoscale structures of anomalously high lsw influence south of the lsw dmw front notably one sampled by a rafos float the velocity and potential vorticity fields suggest that these lsw eddies are formed through baroclinic instability at the lsw dmw front

magnetostratigraphy of the yaha section tarim basin china 11 ma acceleration in erosion and uplift of the tian shan mountains we report a magnetostratigraphic and rock magnetic study of the yaha section located on the southern flank of the central tian shan mountains asia our results show a two fold increase in sedimentation rate as well as marked changes in rock magnetic characteristics ca 11 ma after 11 ma sedimentation rate remained remarkably constant until at least 5 2 ma these findings are consistent with sedimentary records from other sections surrounding the tian shan we conclude that uplift and erosion of the tian shan accelerated ca 11 ma long after the onset of the collision between india and asia and that the range rapidly evolved toward a steady state geometry via a balance between tectonic and erosion processes

mean circulation and eddy kinetic energy in the eastern north atlantic sixty two satellite tracked buoys have been released in the northern part of the western and central north atlantic during 1981 and 1982 by the institut fur meereskunde universitat kiel federal republic of germany additionally six buoys deployed in spring 1980 by the bedford institute have been taken over mean values and variances about the mean have been calculated for 3 by 3 areas the mean velocities confirm the large scale gyre circulation as deduced from hydrographie data and numerical models the center of the gyre is located at about 33 n eddy kinetic energy decreases east and southward and is concentrated along the north atlantic current it appears that the north atlantic current polar front is the main source of eddy kinetic energy for the northern north atlantic whereas the mid atlantic ridge is no source of eddy energy eddy kinetic energy along the north atlantic current decreases from about 1000 cm2 s 2 near newfoundland to 300 cm2 s 2 west of scotland a homogeneous pool of low eddy kinetic energy less than 100 cm2 s 2 appears in the central north atlantic east of the mid atlantic ridge the level increases towards the european and african shelf where the mean southward flow also becomes stronger the results concern the upper ocean

recirculating components to the deep boundary current of the northern north atlantic abstract the meridional overturning system of the north atlantic is conventionally thought of as transporting warm water 4 c to high latitudes and covd water to low latitudes the northern cold water sources for this system are dense overflow from the nordic seas and less dense water from the labrador sea lsw the overflow components are carried westward by a deep northern boundary current dnbc that is shown here actually to begin southeast of the overflow regions the dnbc lies along the southern side of a system of islands and submarine ridges that divides the nordic seas from the subpolar basins the overflows act to increase the transport of the dnbc and this transport is further increased through the entrainment of warm waters once inside the labrador sea the dnbc is joined by lsw before continuing south to low latitudes as a cold deep western boundary current dwbc however published transport estimates are larger than can be explained by warm water entrainment alone thus indicating entrainment also of recirculating cold components the subject of this paper their sources are shown to be the lsw and cold abyssal waters originating from the southern hemisphere the lsw is entrained downward into the denser part of the dnbc and laterally into the upper part of the dwbc whereas the cold abyssal waters are supplied by an eastern intensified northward flow in the eastern atlantic that serves as the initial source of the dnbc and by a similar northward flow in the western atlantic the meridional overturning system described includes recirculations and poleward transport of cold water in addition tothe components described by the conventional system the cold abyssal waters in both the eastern and western basins have relatively low levels of oxygen and high concentrations of silicate reflecting their southern origin but their influence in the northwestern atlantic is somewhat obscurred by strong recirculating cyclonic gyres in the newfoundland and labrador basins this influence is detected by a deep silicate maximum extending poleward from the mid latitude western atlantic through the two gyres with eastern concentration and recirculating back diluted toward the south in the dwbc within the respective basins such a maximum also extends northward through the irminger basin into the dnbc but there is an ambiguity as to whether this is a direct extension of the signal from the south in the western basin or if it comes from the mid latitude eastern basin by way of westward flow through the charlie gibbs fracture zone it is perhaps consequence of both estimates of the volume transports of the various recirculating cold components indicate that they supply about as much water to the deep boundary currents as do the combined cold water sources in the north

aeolian dust transport and deposition over crete and adjacent parts of the mediterranean sea monitoring of dust deposition at several stations on crete over a three year period has shown that the present day depositional flux is of the order of 10 100 gm 2 yr 1 most of the dust deposition takes place during a few annual dust events which typically last for 1 3 days dust haze episodes are usually associated with southerly or southwesterly winds which transport fine sediment from north africa dust is raised by a wide variety of meteorological conditions which generate strong near surface winds in the source areas but major long range transport events are often associated with cold fronts linked to the passage of deep mid latitude depressions during winter and spring dust haze frequency and deposition rates are highest in western crete and decrease towards the east suggesting that transport from tunisia and neighbouring parts of north africa is particularly important the measured rate of dust deposition is well below the minimum level required for loess formation deposits which have previously been identified as loess are shown to be uncemented marine marls of tertiary age laboratory analysis of red soils surface sediments and bedrock samples has confirmed that many of the soils contain an important aeolian dust component but it is concluded that a more important source of soil parent material is provided by weathering of local rocks many of the soils contain significant amounts of quartz sand which cannot have been transported across the sea from north africa reworking of weathered material and deposited dust is extensive and is accomplished by both aeolian and fluvial processes tectonically controlled depressions in the mountains and parts of the coastal lowlands have acted as long term sinks in which a thickness of several metres of sediment and soil has accumulated during the quaternary

the flux of overflow water through the charlie gibbs fracture zone we report the results of a set of measurements made within the charlie gibbs fracture zone in 1988 1989 the principal data sources are year long current meter records 16 in number and 23 conductivity temperature depth stations the aim was to determine the flux of overflow water passing westward out of the iceland basin in the eastern north atlantic within the fracture zone overflow water is defined either as having salinity greater than 34 94 at the present time or more generally as having a potential density 0 27 8 kg m3 in 1988 1989 the core salinity had a value equal to that reported in 1981 and 1983 but was fresher by about 0 02 than was found in 1964 the flux was estimated twice per day and was found to fluctuate strongly with energy spread in a broad band of periods ranging from 10 to 400 days no annual signal could be detected the mean value was 2 4 0 5 sv less than all previous estimates based on hydrography alone it is suggested that hydrography may systematically overestimate transport because diffusion is neglected flux estimates from current meter arrays are rarely used in initializing numerical ocean models consequently measurements like those reported here are an independent and important means for assessing the performance of such models at the deepest levels water enters the two transform valleys of the fracture zone from the west in the northern valley the flow is periodically flushed out by energetic bursts of overflow water a critical value of an inverse froude number is shown to define the flushing threshold

using hydraulic equivalences to discriminate transport processes of volcanic flows we characterized stratified deposits from the upper toluca pumice at toluca volcano mexico to distinguish the various modes of transport at play in their genesis using the concept of hydraulic equivalence we determined that deposits resulted from a combination of suspended load fallout saltation and rolling in particular some well sorted coarse stratified beds have a single pumice mode most likely indicative of clasts having traveled through both the transport system and the traction bed such beds are likely remnants of the sorting operated within the large scale transport system other coarse beds have pumice and lithic modes suggesting rolling in the traction bed we propose that boundary layer processes control the sorting of those beds and all finer beds by helping to discriminate between transport mechanisms hydraulic equivalences have a general applicability in geophysical flows involving clasts of contrasted densities

a long lived eddy in the iceland basin 1998 a survey was made of a large 100 km eddy in the iceland basin in june 1998 in situ observations from a shallow undulating conductivity temperature depth profiler and vessel mounted acoustic doppler current profiler were used to generate sea surface height along two topex poseidon tracks comparisons were made with the altimetric measurements to arrive at an estimate of the sea surface height for 6 years of topex poseidon altimeter data the 3 month track of a drifting buoy was used to estimate the location of the center of the eddy comparison with the altimetric sea surface height showed that the position of the eddy correlated well with an elevated sea surface signal of 25 30 cm having identified this signal as a characteristic signature of eddies inspection of the 6 year record revealed other similar features whose presence and longevity varied considerably the presence or absence of eddies appeared to link with the large scale variability of the subpolar gyre when the gyre expanded e g 1993 1994 the north atlantic current tended to follow a southerly route and eddies in the iceland basin were few and weak especially compared to periods when the gyre contracted e g 1992 1993 and 1996 1998 and the north atlantic current turned through the iceland basin then saltier water from the eastern north atlantic extended westward into the iceland basin and into large long lived eddies

neogene uplift of the tian shan mountains observed in the magnetic record of the jingou river section northwest china the tian shan mountains constitute central asia s longest and highest mountain range understanding their cenozoic uplift history thus bears on mountain building processes in general and on how deformation has occurred under the influence of the india asia collision in particular in order to help decipher the uplift history of the tian shan we collected 970 samples for magnetostratigraphic analysis along a 4571 m thick section at the jingou river xinjiang province china stepwise alternating field and thermal demagnetization isolate a linear magnetization component that is interpreted as primary from this component a magnetostratigraphic column composed of 67 polarity chrons are correlated with the reference geomagnetic polarity timescale between 1 ma and 23 6 ma with some uncertainty below 21 ma this correlation places precise temporal control on the neogene stratigraphy of the southern junggar basin and provides evidence for two significant stepwise increases in sediment accumulation rate at 16 15 ma and 11 10 ma rock magnetic parameters also undergo important changes at 16 15 ma and 11 10 ma that correlate with changes in sedimentary depositional environments together with previous work we conclude that growth history of the modern tian shan mountains includes two pulses of uplift and erosion at 16 15 ma and 11 10 ma middle to upper tertiary rocks around the tian shan record very young 5 ma counterclockwise paleomagnetic rotations on the order of 15 to 20 which are interpreted as because of strain partitioning with a component of sinistral shear that localized rotations in the piedmont

the mediterranean water tongue and its chlorofluoromethane signal in the iberian basin in early summer 1989 hydrographic observations from the iberian basin demonstrate the variability of water masses in upper and intermediate layers the surveyed area embraces the internal front between water masses from higher latitudes and the mediterranean outflow exhibits several isolated mediterranean eddy meddy structures at middepth and displays the virtual source region for the mediterranean water mw tongue off the portuguese continental slope the description is enhanced by additional chlorofluoromethane measurements which show anomalously high concentrations at middepth due to mixing of mw with the overlying atlantic waters in the gulf of cadiz the geostrophic stream function shows several meddylike features that not only are remarkably extended in the depth range of the mw but are also correlated with surface height anomalies

paleozoic accretion and cenozoic redeformation of the chinese tien shan range central asia the tien shan range in central asia contains two late paleozoic sutures the older southern suture marks the collision of a passive margin at the north of the tarim block and an active continental margin subduction under the latter was to the north the younger northern suture separates a northern carboniferous island arc from an active continental margin developed over a south dipping subduction zone the subduction direction under the island arc is unknown mesozoic elastics were deposited over the doubly sutured orogen rate and energy of sedimentation waned until deposition of oligocene conglomerates above a regional unconformity interpreted as marking the onset of deformation induced by the india asia collision molasse deposition accelerated in pliocene and quaternary time and deposition continues today as active thrusts generate relief paleozoic structures control the gross divergence of cenozoic thrusts across the orogen

hydrography and through flow in the north eastern north atlantic ocean the nansen project abstract the circulation and hydrography of the north eastern north atlantic has been studied with an emphasis on the upper layers and the deep water types which take part in the thermohaline overturning of the oceanic conveyor belt over 900 hydrographic stations were used for this study mainly from the 1987 1991 period the hydrographic properties of subpolar mode water in the upper layer which is transported towards the norwegian sea showed large regional variation the deep water mass was dominated by the cold inflow of deep water from the norwegian sea and by a cyclonic recirculation of lower deep water with a high antarctic bottom water content at intermediate levels the dominating water type was labrador sea water with only minor influence of mediterranean sea water in the permanent pycnocline traces of antarctic intermediate water were found geostrophic transports have been estimated and these agreed in order of magnitude with the local heat budget with current measurements with data from surface drifters and with the observed water mass modification a total of 23 sv of surface water entered the region of which 20 sv originated from the north atlantic current while 3 sv entered via an eastern boundary current of this total 13 sv of surface water left the area across the reykjanes ridge and 7 sv entered the norwegian sea while 3 sv was entrained by the cold overflow across the iceland scotland ridge approximately 1 4 sv of norwegian sea deep water was involved in the overflow into the iceland basin which with about 1 1 sv of entrained water and 1 1 sv recirculating lower deep water formed a deep northern boundary current in the iceland basin at intermediate depths where labrador sea water formed the dominant water type about 2 sv of entrained surface water contributed to a saline water mass which was transported westwards along the south icelandic slope