fossils from quaternary fluvial archives sources of biostratigraphical biogeographical and palaeoclimatic evidence fluvial sedimentary archives have the potential to preserve a wide variety of palaeontological evidence ranging from robust bones and teeth found in coarse gravel aggradations to delicate insect remains and plant macrofossils from fine grained deposits over the last decade advances in quaternary biostratigraphy based on vertebrate and invertebrate fossils primarily mammals and molluscs have been made in many parts of the world resulting in improved relative chronologies for fluviatile sequences complementary fossil groups such as insects ostracods and plant macrofossils are also increasingly used in multi proxy palaeoclimatic and palaeoenvironmental reconstructions allowing direct comparison of the climates and environments that prevailed at different times across widely separated regions this paper reviews these topics on a regional basis with an emphasis on the latest published information and represents an update to the 2007 review compiled by the flag inspired igcp 449 biostratigraphy subgroup disparities in the level of detail available for different regions can largely be attributed to varying potential for preservation of fossil material which is especially poor in areas of non calcareous bedrock but to some extent also reflect research priorities in different parts of the world recognition of the value of biostratigraphical and palaeoclimatic frameworks which have been refined over many decades in the core regions for such research particularly for the late middle and late pleistocene of nw europe has focussed attention on the need to accumulate similar palaeontological datasets in areas lacking such long research histories although the emerging datasets from these understudied regions currently allow only tentative conclusions to be drawn they represent an important stage in the development of independent biostratigraphical and palaeoenvironmental schemes which can then be compared and contrasted

tectonic classification of cenozoic iberian foreland basins abstract the iberian microcontinent stands out because of its intense alpine intraplate deformation this is reflected in a large number of cenozoic basins of very different sizes most of the contacts between topographic highs and basins are thrust or strike slip faults all these basins seem to have undergone a common sedimentary evolution comprising four stages initiation of sedimentation intense syn tectonic infilling change from endorheic to exorheic drainage and accelerated erosion related to fluvial incision this simple evolutionary model shows a migration from east to west in which basins are still tectonically active at the atlantic margin of iberia this common evolution is also found in a series of geometrical characteristics such as the ratio r of length of strike slip fault and length of thrust fault that are very similar in both types of basin border settings thrust related basins are mainly associated with segmented pop downs whereas the main basins have the characteristics of open ramp basins strike slip related basins are mostly transpressive structures although small pull apart basins are usual along the vilarica and messejana faults for basin areas larger than 100 1000 km 2 a constant r value of 0 6 is found including the ebro duero madrid lower tagus and badajoz basins within the iberian microcontinent the total amount of cenozoic contractional deformation was distributed between strike slip and thrust faults with an r ratio close to 0 6 however for small basins this parameter seems to depend on the type of fault range or deformation belt pure strike slip transtension transpression and pop up independently of its local tectonic development

evidence for pleistocene wet aeolian dune and interdune accumulation s pedro da maceda north west portugal outcrops and cored counter flushed boreholes in the coastal area between espinho and aveiro north west portugal were investigated to reconstruct the changing patterns of sedimentation during the late pleistocene holocene to obtain a common comparison basis the grain size data from outcrop and borehole samples were analysed the outcrops and the cored parts of the boreholes were dated by radiocarbon and optically stimulated luminescence the results show that on top of pebble rich beds of fluvial origin a wet aeolian dune and interdune environment was active during the later part of the pleistocene turning to dry aeolian at the transition to the holocene the data indicate also that aeolian accumulation was controlled by vegetation changes climate and groundwater table fluctuations during the holocene a podzol formed on the pleistocene dunes and extensive vegetation precluded major aeolian accumulations remobilization of sand started again because of human deforestation and last but not least the little ice age

moored observations of western boundary current variability and thermohaline circulation at 26 5 n in the subtropical north atlantic abstract a 5 8 year time series of moored current meter observations is used with hydrographic section data cme model results and gridded wind fields over the north atlantic to describe the mean structure and variability of circulation and volume transports east of abaco bahamas at 26 5 n a mean antilles current with 5 sv of northward transport is confined against the bahamas boundary in the upper 800 m and combines with approximately 19 sv of florida current transport to balance the sverdrup interior circulation and does not contribute to interhemispheric exchange the mean transport of the deep western boundary current dwbc off the bahamas is approximately 40 sv of which 13 sv compensates the upper branch of the thermohaline circulation requiring a 27 sv deep recirculation robust annual and semiannual cycles of meridional are found in both moored observations and model results with remarkable agreement in amplitude 13 sv and phase maximum northward transports occur in winter and summer

crustal structure of mainland china from deep seismic sounding data abstract since 1958 about ninety seismic refraction wide angle reflection profiles with a cumulative length of more than sixty thousand kilometers have been completed in mainland china we summarize the results in the form of 1 a new contour map of crustal thickness 2 fourteen representative crustal seismic velocity depth columns for various tectonic units and 3 a pn velocity map we found a north south trending belt with a strong lateral gradient in crustal thickness in central china this belt divides china into an eastern region with a crustal thickness of 30 45 km and a western region with a thickness of 45 75 km the crust in these two regions has experienced different evolutionary processes and currently lies within distinct tectonic stress fields our compilation finds that there is a high velocity 7 1 7 4 km s layer in the lower crust of the stable tarim basin and ordos plateau however in young orogenic belts including parts of eastern china the tianshan and the tibetan plateau this layer is often absent one exception is southern tibet where the presence of a high velocity layer is related to the northward injection of the cold indian plate this high velocity layer is absent in northern tibet in orogenic belts there usually is a low velocity layer lvl in the crust but in stable regions this layer seldom exists the pn velocities in eastern china generally range from 7 9 to 8 1 km s and tend to be isotropic pn velocities in western china are more variable ranging from 7 7 to 8 2 km s and may display azimuthal anisotropy

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

s wave tomography of the crust and uppermost mantle in china 1 we use 280 000 local and regional arrival times from 13 105 local earthquakes recorded by 220 seismic stations to determine a three dimensional s wave velocity structure of the crust and uppermost mantle under china and surrounding regions we use a traveltime tomography code that accommodates a heterogeneous crust and varying moho depth the grid for tomographic inversion is 1 1 in the horizontal direction and 10 km in depth our results show that large velocity variations of more than 6 exist in the crust and upper mantle in the china region the velocity image of the upper crust correlates with surface geological features crustal heterogeneity is clearly observed and velocity changes are visible across some of the large fault zones in tibet low velocities exist in the thick crust and high sn velocities exist in the southern and eastern parts low velocity zones beneath volcanic sites and the rifts are clearly observed in our tomographic results under the tengchong hainan and changbai volcanic areas strong low velocity zones are visible down to the upper mantle indicating the existence of magma chambers beneath the volcanoes

direct observations of the current structure east of the bahamas quasisynoptic absolute velocity sections were obtained in the western north atlantic to the east of the bahamas on five cruises from 1992 to 1994 showing complex spatial and temporal variability of the currents throughout the water column lowered acoustic doppler current profilers were used on all cruises for comparison an acoustically tracked free fall profiler was used on the august 1992 and june 1993 cruises where simultaneous profiles from both methods are available depth averaged differences are less than 0 01 m s 1 in the ensemble mean and standard deviation though small the mean difference appears to be statistically non zero for one of the two doppler profilers used no cause has been found the individual velocity sections show a banded structure of currents in the offshore direction with strong baroclinic and depth averaged components extending over the full sampling domain two sections show a picture of the southward flowing deep western boundary current dwbc differing from previous observations during august 1992 and june 1993 the mean dwbc core was located more than 100 km offshore in observations prior to 1990 it was usually near 50 km offshore net southward transport below 800 m integrated from the coast to 400 km offshore varied from 15 to 50 sv with a mean of about 40 sv 1 sv 1 106 m s 1 our mean is consistent with previous estimates our sections add new evidence that the transport is highly variable to at least 400 km offshore

seismic imaging of the downwelling indian lithosphere beneath central tibet a tomographic image of the upper mantle beneath central tibet from indepth data has revealed a subvertical high velocity zone from 100 to 400 kilometers depth located approximately south of the bangong nujiang suture we interpret this zone to be downwelling indian mantle lithosphere this additional lithosphere would account for the total amount of shortening in the himalayas and tibet a consequence of this downwelling would be a deficit of asthenosphere which should be balanced by an upwelling counterflow and thus could explain the presence of warm mantle beneath north central tibet

variability of shallow and deep western boundary currents off the bahamas during 2004 05 results from the 26 n rapid moc array data from an array of six moorings deployed east of abaco bahamas along 26 5 n during march 2004 may 2005 are analyzed these moorings formed the western boundary array of a transbasin observing system designed to continuously monitor the meridional overturning circulation and meridional heat flux in the subtropical north atlantic under the framework of the joint u k u s rapid climate change rapid meridional overturning circulation moc program important features of the western boundary circulation include the southward flowing deep western boundary current dwbc below 1000 m and the northward flowing antilles current in the upper 1000 m transports in the western boundary layer are estimated from direct current meter observations and from dynamic height moorings that measure the spatially integrated geostrophic flow between moorings the results of these methods are combined to estimate the time varying transports in the upper and deep ocean over the width of the western boundary layer to a distance of 500 km offshore of the bahamas escarpment the net southward transport of the dwbc across this region inclusive of northward deep recirculation is 26 5 sv sv 10 6 m 3 s 1 which is divided nearly equally between upper 13 9 sv and lower 12 6 sv north atlantic deep water nadw in the top 1000 m 6 0 sv flows northward in a thermocline intensified jet near the western boundary these transports are found to agree well with historical current meter data in the region collected between 1986 and 1997 variability in both shallow and deep components of the circulation is large with transports above 1000 m varying between 15 and 25 sv and deep transports varying between 60 and 3 sv much of this transport variability associated with barotropic fluctuations occurs on relatively short time scales of several days to a few weeks upon removal of the barotropic fluctuations slower baroclinic transport variations are revealed including a temporary stoppage of the lower nadw transport in the dwbc during november 2004

the late quaternary coastal forests of western iberia a study of their macroremains plant remains collected from the portuguese coast some of them in situ were examined to provide local information on the vegetation of the iberian atlantic area over the last 35 000 years pinus gr sylvestris nigra from the wurm period was identified in sandy soils along with quercus gr robur petraea and fraxinus sp the presence of in situ remains of this pinus group on the northern portuguese coast indicates the local temperature and precipitation conditions that must have reigned at this time thirty two in situ pinus pinaster remains close to the mouth of the river tagus show the importance of this taxon in this area during the first half of the holocene other holocene macroremains indicate the presence of non riparian taxa quercus gr robur petraea and castanea sp hygrophilous plants fraxinus sp populus sp alnus sp and sambucus sp and shade intolerant taxa erica cinerea vagans

fluvial deposits as an archive of early human activity progress during the 20 years of the fluvial archives group fluvial sedimentary archives are important repositories for lower and middle palaeolithic artefacts throughout the old world especially in europe where the beginning of their study coincided with the realisation that early humans were of great antiquity now that many river terrace sequences can be reliably dated and correlated with the globally valid marine isotope record potentially useful patterns can be recognized in the distribution of the find spots of the artefacts that constitute the large collections that were assembled during the years of manual gravel extraction this paper reviews the advances during the past two decades in knowledge of hominin occupation based on artefact occurrences in fluvial contexts in europe asia and africa as such it is an update of a comparable review in 2007 at the end of igcp project no 449 which had instigated the compilation of fluvial records from around the world during 2000 2004 under the auspices of the fluvial archives group an overarching finding is the confirmation of the well established view that in europe there is a demarcation between handaxe making in the west and flake core industries in the east although on a wider scale that pattern is undermined by the increased numbers of lower palaeolithic bifaces now recognized in east asia it is also apparent that although it seems to have appeared at different places and at different times in the later lower palaeolithic the arrival of levallois technology as a global phenomenon was similarly timed across the area occupied by middle pleistocene hominins at around 0 3 ma

lagoa da apulia a residual lagoon from the late holocene nw coastal zone of portugal the lagoa da apulia is a unique feature in the nw coastal zone of portugal a remaining form from a lagoon complex system that during the late holocene was dominant in the region this system was mainly neotectonically controlled occupying a depressed area bounded by faults on a palaeozoic rocky lower platform today observable on beaches at low tide with the intention of knowing the main architecture of the palaeo lagoon geophysical prospecting with gpr and resistivity was carried out accordingly six cores were taken and the sedimentary and mineralogical facies and diatom and foraminifer contents were analysed and five rich organic layers were dated by radiocarbon analysis with the data an evolutionary environment reconstruction model was created for this palaeo lagoon and the main structural features of the neighbouring area

variability of the deep western boundary current at 26 5 n during 2004 2009 five years of data from a line of dynamic height moorings dhm bottom pressure recorders bpr and pressure equipped inverted echo sounders pies near the atlantic ocean western boundary at 26 51n are used to evaluate the structure and variability of the deep western boundary current dwbc during 2004 2009 comparisons made between transports estimated from the dhm bpr and those made by the pies demonstrate that the two systems are collecting equivalent volume transport information correlation coefficient r 0 96 root mean square difference 6 sv 1 sv 10 6 m 3 s 1 integrated to 450 km off from the continental shelf and between 800 and 4800 dbar the dwbc has a mean transport of approximately 32 sv and a standard deviation during these five years of 16 sv both the barotropic full depth vertical mean and baroclinic flows have significant variability changes exceeding 10 sv on time scales ranging from a few days to months with the barotropic variations being larger and more energetic at all time scales the annual cycle of the deep transport is highly dependent on the horizontal integration distance integrating 100 km offshore yields an annual cycle of roughly similar magnitude but shifted in phase relative to that found from current meter arrays in the 1980 1990s while the annual cycle becomes quite weak when integrating 450 km offshore variations in the dwbc transport far exceed those of the total basin wide meridional overturning circulation standard deviations of 16 sv vs 5 sv transport integrated in the deep layer out to the west side of the mid atlantic ridge still demonstrates a surprisingly high variance indicating that some compensation of the western basin deep variability must occur in the eastern basin published by elsevier ltd

deep seismic reflection evidence for continental underthrusting beneath southern tibet the himalaya and adjacent tibetan plateau constituting earth s largest region of elevated topography and anomalously thick crust formed as a consequence of cenozoic collision between india and asia itself considered the archetypal continent continent collision1 3 here we report the first results from an attempt to image the structure of the crust beneath this region using deep seismic reflection profiling our 100 km long profile acquired in the tethyan himalaya shows a mid crustal reflection that prob ably marks the active thrust fault along which the indian plate is underthrusting southern tibet upper crustal reflections with geo metries suggestive of large scale structural imbrication of the upper crust and moho reflections from the base of the double normal thickness crust underlying the region these results lend substantial support to the view that crustal thickening beneath southernmost tibet was accomplished by wholesale underthrusting of indian continental crust beneath the structurally imbricated upper crust comprising the tethyan himalaya

reconciling lithospheric deformation and lower crustal flow beneath central tibet a viscous region with deformable boundaries is used to model simultaneous crustal flow and lithospheric coupling in northern tibet this model suggests that 1 the deformation of northern tibet is different from that of southern tibet because of structural differences between the regions 2 the viscosity contrast between the crust and the mantle lithosphere is relatively small beneath northern tibet and 3 crustal flow is compatible with crust mantle coupling under these conditions

stress pattern in portugal mainland and the adjacent atlantic region west iberia the portuguese mainland territory is located close to the azores gibraltar plate boundary in a tectonic setting responsible for significant neotectonic and seismic activities however few data concerning the present regional lithospheric stress field were available as testified by recently published maps of stress indicators for the europe and mediterranean regions one of the authors already presented a synthesis on this subject cabral 1993 where geological and geophysical stress indicators were considered in this paper we introduce new information mainly a considerable amount of borehole breakout data the updated data set comprises 32 reliable stress indicators showing a mean azimuth of 145 standard deviation 21 for the maximum horizontal stress direction shmax on the average the geological data are rotated clockwise and the focal mechanism data deviated anticlockwise to that azimuth while the borehole elongation results are consistent with the mean shmax trend these differences in stress trend suggest a regional progressive rotation of the shmax direction from nnw sse to wnw ese since the upper pliocene to estimate stress trajectories new and published stress indicators in the adjacent atlantic area and northern africa were also investigated showing a very uniform nw se shmax trend in west iberia a high level of horizontal compressive stress acting oblique to the western portuguese continental margin is inferred and interpreted in view of a proposed regional geodynamical model of activation of this passive margin with the nucleation of a subduction zone in the atlantic sw of iberia at the gorringe submarine bank which is propagating northward along the base of the continental slope at the transition between thinned and normal continental crust

rayleigh wave phase velocities small scale convection and azimuthal anisotropy beneath southern california 1 we use rayleigh waves to invert for shear velocities in the upper mantle beneath southern california a one dimensional shear velocity model reveals a pronounced low velocity zone lvz from 90 to 210 km the pattern of velocity anomalies indicates that there is active small scale convection in the asthenosphere and that the dominant form of convection is three dimensional 3 d lithospheric drips and asthenospheric upwellings rather than 2 d sheets or slabs several of the features that we observe have been previously detected by body wave tomography these anomalies have been interpreted as delaminated lithosphere and consequent upwelling of the asthenosphere beneath the eastern edge of the southern sierra nevada and walker lane region sinking lithosphere beneath the southern central valley upwelling beneath the salton trough and downwelling beneath the transverse ranges our new observations provide better constraints on the lateral and vertical extent of these anomalies in addition we detect two previously undetected features a high velocity anomaly beneath the northern peninsular range and a low velocity anomaly beneath the northeastern mojave block we also estimate the azimuthal anisotropy from rayleigh wave data the strength is 1 7 at periods shorter than 100 s and decreases to below 1 at longer periods the fast direction is nearly e w the anisotropic layer is more than 300 km thick the e w fast directions in the lithosphere and sublithosphere mantle may be caused by distinct deformation mechanisms pure shear in the lithosphere due to n s tectonic shortening and simple shear in sublithosphere mantle due to mantle flow

luminescence dating of interglacial coastal depositional systems recent developments and future avenues of research abstract luminescence dating offers new opportunities to explore the evolution of quaternary marine coastal facies and landforms this review highlights the main advances in luminescence geochronology of interglacial coastal sediments through the analysis of 547 luminescence ages most of which were published during the last decade the majority of these reported luminescence investigations have been carried out along passive margin coasts since the turn of the century the discovery of a normalization procedure known as single aliquot regeneration sar has drastically reduced data scatter and improved precision with the consequence that quartz sar optically stimulated luminescence osl has become the dating protocol of choice for the last interglacial lig period a more complex technique known as thermally transferred osl tt osl is presumably proposed for dating older interglacials of the mid pleistocene and beyond feldspar luminescence is increasingly being applied to dating pleistocene sea level high stands due to a much higher dose saturation level than quartz osl the use of feldspar irsl infrared stimulated luminescence is limited by the occurrence of variable but ubiquitous anomalous fading af following the advent of af correction methods several middle pleistocene sites have been amenable to dating albeit with significant related uncertainties recently new protocols involving the measurement of post ir irsl at elevated temperatures have yielded relatively coherent ages for interglacial sediments up to ca 300 ka quartz osl tt osl af corrected irsl and post ir irsl ages are generally correlated with periods of sea level high stands a few ages are reported from the early and middle part of the middle pleistocene as mis11 9 and more commonly mis7 high stands are documented in strongly uplifting active margin coasts however by far the most obvious age peak corresponds to the end of the lig the mis5e shoreline is probably the most studied and luminescence dated coastal feature of all as the chronology of the sea level markers is crucial to assess global eustatic sea level variations through the course of the last interglacial nevertheless the observed abundance of young 100 120 ka luminescence ages for presumed mis5e sediments may underline methodological issues and or reflect the higher preservation potential of late regressive sequences on the other hand the occurrence of geographically distant reports of mis5a high stand might reflect a true eustatic origin for this event age analysis supports the impression of general reliability of luminescence for the timing of former sea level high stands there is a clear need to address issues in dose rate variability in the phenomenology of fading in feldspar and in the behaviour of luminescence growth with dose both in laboratory and natural conditions these could be addressed and properly evaluated by dating different minerals as multiple or single grains with consequent variable internal dose rates more robust practices in the application of luminescence dating techniques could eventually constrain the age uncertainties to no better than 2 3 therefore the strength of luminescence as a dating tool is more in terms of its extended age range and the ubiquity of datable material

lithospheric thickness of the chinese continent abstract we invert for the upper mantle temperatures of the chinese continent in the depth range of 70 240 km from a recent s velocity model the depth where temperatures intersect a mantle adiabat with a potential temperature of 1300 c is in close correspondence with the top of the seismic low velocity zone for most regions this correspondence implies that seismic lithosphere estimated from short time scale seismic information may be equivalent to the long time scale geodynamical lithosphere defining the 1300 c adiabat as coinciding with the lithospheric base we estimate the seismic thermal lithosphere thickness the estimated thickness shows obvious dependence on the tectonic settings beneath eastern china which mainly belongs to the circum pacific tectonic domain it has a thickness of 100 km and beneath the qinghai tibet plateau and south to the tarim craton which belong to the tethyan tectonic domain it has a thickness of 160 220 km the lithospheric thicknesses of the three large para platforms cratons range from 170 km for the western yangtze 140 km for tarim and 100 km for sino korean the three cratons may have been reshaped by phanerozoic tectonic activities and are thinner than most cratons in other continents

rayleigh wave tomography of the northeastern margin of the tibetan plateau abstract the convergence between the indian continent and the southern margin of eurasia has eventually led to the growth of the tibetan plateau eastward various models have suggested that a large scale flow in the lower crust or and the asthenosphere is responsible for the uplift of eastern tibet it has also been suggested that the continental flow may move around the thick lithosphere of the ordos plateau and the sichuan basin in order to investigate the validity of the crust mantle flow and its possible path we have used rayleigh wave tomography with sensitivity kernels to estimate both the phase velocity structure 20 143 s and the shear wave velocity structure 0 200 km across the northeastern margin of the tibetan plateau from the surface to 100 km our shear wave velocity model shows a prominent low velocity anomaly beneath northeastern tibet suggestive of a warm lithosphere its boundary lies at 105 e longitude which borders the western ordos plateau and sichuan basin from 125 km to 200 km our shear wave velocity model shows a low velocity channel beneath the qilian qinling orogen that lies between the ordos and sichuan blocks this channel may represent the asthenosphere given the fact that the lithosphere is 120 150 km thick in northeastern tibet and the qinling orogen we also inverted for the anisotropy parameters in the study area simultaneously with the velocity parameters the dominant fast direction is nww see generally consistent with the sks splitting results the calculated shear strain from gps and the fault slip rate measurements furthermore the fast directions in our anisotropic model vary only slightly with periods and the anisotropy magnitudes at long periods 100 143 s are large and exceed those at short medium periods 20 80 s indicating potentially although not necessarily vertically coherent deformation from the crust to the asthenosphere and possibly large deformation in the asthenosphere the deformation seems to be linked to the southeastward extrusion tectonics caused by the collision boundary force

holocene evolution on galician coast nw spain an example of paraglacial dynamics abstract the recent evolution and the present coastal dynamic in middle atlantic latitudes as the coast of galicia can be considered in a paraglacial context the fossilization of eemian coastal landforms by deposits developed under cold conditions followed by a paraglacial environment during the holocene transgression the characteristics of the different types of deposits and the rising sea level curve controlled the evolution of the coastline showing the co existence of bluff retreat and continental sedimentation

high resolution record of northern hemisphere climate extending into the last interglacial period high resolution record of northern hemisphere climate extending into the last interglacial period

shore platform abrasion in a para periglacial environment galicia northwestern spain abstract the schmidt rock test hammer was used to study the effect of abrasion on shore platforms in galicia northwestern spain on platforms where tidally induced weathering salt wetting and drying etc is dominant rock strength is significantly lower than in areas where abrasion is or has been active in the recent past this suggests that abrasion removes weathered surface material exposing the stronger less weathered rock below abrasion downwearing measured with a transverse micro erosion meter ranged between 0 13 and 1 8 mm yr 1 over the last year most active abrasion occurs in the upper part of the intertidal zone but weathering is slowly destroying formerly abraded surfaces at lower elevations these abandoned surfaces were abraded by materials supplied by erosion of fluvio nival and periglacial slope deposits that covered or partially covered parts of the galician coast during the middle and late weichselian during the holocene rising sea level and erosion of the slope deposits caused the abrasion zone to gradually migrate up to its present position near the high tidal level the spatial and temporal role of abrasion on this coast is therefore closely associated with the exhumation and inheritance of ancient platform surfaces from beneath weichselian deposits

diagnosing the influence of mesoscale eddy fluxes on the deep western boundary current in the 1 10 storm ncep simulation abstractusing a 0 1 ocean model this paper establishes a consistent picture of the interaction of mesoscale eddy density fluxes with the geostrophic deep western boundary current dwbc in the at

characterization and dating of coastal deposits of nw portugal minho neiva area a record of climate eustasy and crustal uplift during the quaternary abstract this study presents the characterization and numerical dating of quaternary coastal deposits of nw portugal located between the mouths of the minho and neiva rivers they record continental small alluvial fans and streams and transitional aeolian dunes interdune ponds estuary sandy and gravelly beaches paleoenvironments quartz and k feldspar optically stimulated luminescence osl dating is employed as well as ams 14 c dating a staircase of coastal terraces abrasion shore platforms was identified altimetry a s l and ascribed to the following probable marine isotope stages mis t1 20 18 m mis11 t2 ca 13 m mis9 t3 9 3 7 3 m mis7 t4 5 5 4 5 m mis5 t5 3 5 2 0 m mis5 the terraces have some preserved sedimentary facies that includes coeval beach sediments on the lowest four a late pleistocene to holocene sedimentary cover comprises four sub units a the lower sub unit corresponding to ferruginous stream deposits and aeolian dunes dated ca 67 61 ka mis4 probably related with sub humid to arid mid cold conditions b on the slopes the lower sub unit is overlapped by sandy silty colluvium and sandy alluvial deposits dated ca 56 28 ka mis3 and probably reflecting cold mid cold and wet dry climate conditions c this sub unit is topped by soliflucted lobes and sandy silty silty deposits recording cold and dry climate dated 20 13 ka mis2 and d a top sub unit dated to 16 18th century recording little ice age events consisting of fluvial sediments coeval with temperate climate evolving to aeolian dunes from the maunder minimum cold windy dry conditions

sea level changes during the pleistocene holocene in the nw coastal zone of portugal research was undertaken to establish the present coastal dynamics of the area south of espinho portugal with special emphasis on the migration inland of beaches and the retreat of cliffs during at least the last century besides the holocene units the silvalde paramos tijuca formation 2310 80 yr bp to 500 80 yr bp and the cortegaca beach formation 6850 60 yr bp to 950 80 yr bp a pleistocene unit the maceda beach formation 29 600 690 yr bp to 14300 160 yr bp with trunks of pinus sylvestris was recognized the cortegaca beach formation comprises a truncated podzol profile the al horizon dating from 3490 60 yr bp to 950 80 yr bp the study and the dating of the pleistocene and the holocene formations suggest a model of evolution related to sea level fluctuations and neotectonics during the interval between 29 000 690 yr bp and the post xvth century little ice age the final purpose of the research is to apply the results to the prediction of the coastal zone evolution and particularly to influence policy with respect to coastal zone management this policy must take into account the inland migration of the beaches and the cliff retreat as a consequence of the natural dynamics of the earth that cannot be arrested or controlled by man

high resolution mantle tomography of china and surrounding regions 1 a high resolution p wave tomographic model of the crust and mantle down to 1100 km depth under china and surrounding regions is determined by using about one million arrival times of p pp pp and pcp waves from 19 361 earthquakes recorded by 1012 seismic stations the subducting pacific slab is imaged clearly as a high velocity zone from the oceanic trenches down to about 600 km depth and intermediate depth and deep earthquakes are located within the slab the pacific slab becomes stagnant in the mantle transition zone under east china the western edge of the stagnant slab is roughly coincident with a surface topographic boundary in east china the active changbai and wudalianchi intraplate volcanoes in northeast china are underlain by significant slow anomalies in the upper mantle above the stagnant pacific slab these results suggest that the active intraplate volcanoes in ne china are not hot spots but a kind of back arc volcano associated with the deep subduction of the pacific slab and its stagnancy in the transition zone under the mariana arc however the pacific slab penetrates directly down to the lower mantle the active tengchong volcano in southwest china is related to the eastward subduction of the burma microplate the subducting indian and philippine sea plates are also imaged clearly the indian plate has subducted down to 200 300 km depth under the tibetan plateau with a horizontal moving distance of about 500 km high velocity anomalies are revealed in the upper mantle under the tarim basin ordos and sichuan basin which are three stable blocks in china

late pleistocene raised beaches of coastal estremadura central portugal abstract we present new stratigraphic sedimentological and chronological data for a suite of tectonically raised beaches dating to marine isotope stages 5 4 and 3 along the estremadura coast of west central portugal the beach deposits are found in association with ancient tidal channels and coastal dunes pollen bearing mud and peat and middle paleolithic archaeological sites that confirm occupation of the coastal zone by neanderthal populations the significance of these deposits is discussed in terms of the archaeological record the tectonic and geomorphic evolution of the coast and correlation with reconstructions of global climate and eustatic sea level change direct correlation between the estremadura beach sections is complicated by the tectonic complexity of the area and the age of the beach deposits which are near or beyond the limit of radiocarbon dating evidence from multiple sites dated by ams radiocarbon and optical luminescence methods suggests broad synchroneity in relative sea level changes along this coast during marine isotope stage 3 two beach complexes with luminescence and radiocarbon age control date to about 35 ka and 42 ka recording a rise in relative sea level around the time of heinrich event 4 at 39 ka depending on assumptions about eustatic sea level at the time they were deposited we estimate that these beaches have been uplifted at rates of 0 4 4 3 mm yr 1 by the combined effects of tectonic halokinetic and isostatic processes uplift rates of 1 2 mm yr 1 are likely if the beaches represent sea level stands at roughly 40 m below modern as suggested by recent eustatic sea level reconstructions evidence from coastal bluffs and the interior of the study area indicates extensive colluvial fluvial and aeolian sedimentation beginning around 31 ka and continuing into the holocene these geomorphic adjustments are related to concomitant changes in climate and sea level providing context that improves our understanding of late pleistocene landscape change and human occupation on the western iberian margin

optically stimulated luminescence dating of a danish eemian coastal marine deposit a test of accuracy abstract it is difficult to test convincingly luminescence dating techniques beyond the range of 14c and yet this is essential if claims that optically stimulated luminescence dating using quartz can reach back to beyond 105 years are to be given credence one possible approach is to use coastal marine sand identified as eemian by an examination of the palaeoecology the eemian period in northern europe is considered to last from 132 to 116 ka marine samples are likely to be linked most closely to at least part of this period and modern coastal sands are known to be well bleached thus from a luminescence dating perspective eemian marine sand can be considered to be of known age and it is very likely to be well bleached we have examined such a known age deposit on the east coast of jutland consisting of about 10 m of fine sand grading up from silty clays and clays in the lower part of the section this material is confidently expected to have been deposited during the very late saalian and early mid eemian 133 125 ka we report on the ages of 25 samples associated with this profile the observed overall precision is compared with the calculated precision on individual ages and the mean value of all the ages is compared with the expected mean of 130 ka

extension in the graben systems around the ordos china and its contribution to the extrusion tectonics of south china with respect to gobi mongolia the graben basins around the ordos block are major tectonic features of late cenozoic extension in north china this paper gives a synthetic view of the basic characteristics of the graben basins and of the kinematics of the graben bounding faults this view is based on the available geological data spot imagery analysis field observations and focal mechanisms of earthquakes from this region these graben basins have been grouped into two major systems the yinchuan hetao graben system along the northern and northwestern margins of the ordos and the weihe shanxi graben system along the southern and eastern margins of the ordos crustal deformation along these graben systems involves normal slip on ne sw striking graben bounding faults normal right lateral and normal left lateral slip on nne ssw and wnw ese striking faults respectively this fault pattern is consistent with nw se trending extension the amount and rate of deformation resulting from this extension have been estimated from geological data using a cross sectional area balance and the extensional factor method deduced from the tilt of faulted blocks the results of these estimates show that the uppermost pliocene quaternary extension rate in a nw se direction is in the order of 1 6 mm yr 1 across the weihe graben 0 5 mm yr 1 across the central shanxi graben on the southeastern margin of the ordos block and 3 1 mm yr 1 across the linhe graben on the northwestern margin of the ordos block the extension across these graben systems is accompanied with counterclockwise rotation of continental blocks in north china ordos taihang shan north china plain a kinematic model is proposed in which the late cenozoic extension and block rotation in north china are interpreted as the effect of the eastward termination of the left lateral slip haiyuan fault and kunlun taibai fault system the ordos block rotates counterclockwise as a result of the push of tibet through the left lateral strike slip haiyuan fault and the liupan shan thrust and fold belt the extension along the weihe shanxi graben system may represent the effect of the left lateral slip on the kunlun taibai qinling fault system the rough estimates of the extensional deformation around the ordos block indicate that this contributes to about 5 2 mm yr 1 of left lateral movement in a n125 e direction between south china and gobi mongolia this motion adds to the left lateral slip on the qinling fault zone about 7 2 mm yr 1 in a n90 e direction between the qinling shan and the hua shan north china thus the eastward motion of south china with respect to gobi mongolia is partitioned between normal faulting around the ordos and strike slip faulting in the qinling shan it is estimated to be in the order of 12 4 mm yr 1 in a n105 e direction during the quaternary

shear wave splitting in the southern margin of the ordos block north china 1 the southern margin of the ordos block in north china marks the transition from a stable cratonic block to active transextensional deformation in the weihe graben driven by the northeastward expansion of the tibet plateau we deployed 29 portable digital stations across this boundary and studied the upper mantle anisotropy using sks splitting the anisotropy is weak t 0 5 s at stations within the ordos block and in the north weihe graben but strong t 1 23 0 39 s in the south weihe graben and qinling orogen further south the directions of the fast s wave are 98 7 subparallel to the orientations of surface structures and the gps site velocities relative to stable asian continent we suggest that this e w oriented anisotropy is the result of both the collision between the north and south china blocks in the mesozoic and the eastward upper mantle flow driven by the indo asian collision

subduction of the indian lithosphere beneath the tibetan plateau and burma abstract subduction of the indian lithosphere under eurasia plays an important role in the tectonic evolution of the tibetan plateau and surrounding regions to improve our knowledge of pertinent mantle structures through tomographic imaging we combine p wave arrival time data from temporary arrays in tibet and stations of the chinese seismograph network with reprocessed data from the international seismological centre the new images reveal considerable spatial variations in mantle structure along the collision zone and the horizontal distance over which presumed continental indian lithosphere slides northward beneath the plateau decreases from west where it underlies the himalayas and the entire plateau to east where no indication is found for present day underthrusting beyond the himalayan block and indus tsangpo suture p wavespeed appears low in the shallow mantle beneath much of central and eastern tibet these observations suggest that indian lithosphere underlies only the southwestern part of the plateau and that the central and northeastern part is underlain by lithosphere of asian origin the continental parts of the indian plate that currently underthrust or subduct below the plateau appear generally detached from the oceanic slab fragments that subducted longer ago and that have been detected deeper in the mantle except perhaps in the central part of the collision zone 80 90 e this suggests that ongoing india eurasia collision must increasingly be driven by other forces such as subduction of the indian plate further west and east e g beneath indochina our images reveal structures associated with eastward subduction along the burmese arc southeast of the eastern himalayan syntaxis the tengchong volcanic complex in southwest china is marked by slow wave propagation to 150 km depth suggesting a causal link to subduction along the burmese arc the low velocities beneath the red river fault region extend to greater depth and may be related to upper mantle processes further southeast

propagation pathways of classical labrador sea water from its source region to 26 n 1 more than two decades of hydrography on the abaco line east of the bahamas at 26 n reveals decadal variability in the salinity of classical labrador sea water clsw despite the long distance from its source region in the north atlantic ocean hydrographic time series from the labrador sea and from the abaco line show a pronounced step like decrease in salinity between 1985 and 1995 in the labrador sea and between 1995 and 2010 at the abaco line suggesting a time lag between the two locations of approximately 9 years the amplitude of the anomaly at the abaco line is 50 of the amplitude in the labrador sea a similar time lag and reduction of amplitude is found in the high resolution ofes model in which salinity anomalies can be observed propagating through the deep western boundary current as well as through a broad interior pathway on its way south to the abaco line the clsw becomes 8 standard deviations saltier due to isopycnal mixing with mediterranean outflow water mow climatological data in the north atlantic suggests that the mixing ratio of mow to clsw at the abaco line is 1 4 and that no variability in mow is required to explain the observed variability at the abaco line the data studied here suggest that decadal clsw anomalies stay relatively coherent while getting advected despite the important role of interior pathways

late pleistocene and holocene environmental changes in the coastal zone of northwestern portugal this paper examines the quaternary changes in the coastal zone of northwestern portugal through the relationship between sediments and landforms by interpolating the available data from geomorphology lithostratigraphy sedimentology and geochronology it was possible to reconstruct existing palaeoenvironments the oldest of which date back to the last interglacial the main landforms are a high and a low platform bounded by scarps river sands and silty sediments formed in a lacustrine environment antas formation mis 5 are associated with the high platform two deposits are associated with the low platform the cepaes formation mis 3 consisting of a lower set of river sand beds and an upper gravel beach bed and the agucadoura formation mis 1 consisting of holocene lagoonal beds copyright 2006 john wiley sons ltd

oblique stepwise rise and growth of the tibet plateau two end member models of how the high elevations in tibet formed are i continuous thickening and widespread viscous flow of the crust and mantle of the entire plateau and ii time dependent localized shear between coherent lithospheric blocks recent studies of cenozoic deformation magmatism and seismic structure lend support to the latter since india collided with asia 55 million years ago the rise of the high tibetan plateau likely occurred in three main steps by successive growth and uplift of 300 to 500 kilometer wide crustal thrust wedges the crust thickened while the mantle decoupled beneath gently dipping shear zones did not sediment infilling bathtub like of dammed intermontane basins formed flat high plains at each step the existence of magmatic belts younging northward implies that slabs of asian mantle subducted one after another under ranges north of the himalayas subduction was oblique and accompanied by extrusion along the left lateral strike slip faults that slice tibet s east side these mechanisms akin to plate tectonics hidden by thickening crust with slip partitioning account for the dominant growth of the tibet plateau toward the east and northeast

tectonic and lithological controls on fluvial landscape development in central eastern portugal insights from long profile tributary stream analyses abstract this study examines the long profiles of tributaries of the tagus and zezere rivers in portugal west iberia in order to provide new insights into patterns timing and controls on drainage development during the quaternary incision stage the studied streams are incised into a relict culminant fluvial surface abandoned at the beginning of the incision stage the streams flow through a landscape with bedrock variations in lithology mainly granites and metasediments and faulted blocks with distinct uplift rates the long profiles of the analyzed streams record an older transitory knickpoint knickzone separating 1 an upstream relict graded profile with lower steepness and higher concavity that reflects a long period of quasi equilibrium conditions reached after the beginning of the incision stage and 2 a downstream rejuvenated long profile with steeper gradient and lower concavity particularly for the final reach which is often convex the rejuvenated reaches testify to the upstream propagation of several incision waves interpreted as the response of each stream to increasing crustal uplift and prolonged periods of base level lowering by the trunk drainages coeval with low sea level conditions the morphological configurations of the long profiles enabled spatial and relative temporal patterns of incisions to be quantified the incision values of streams flowing on the portuguese central range pcr ca 380 150 m are variable but generally higher than the incision values of streams flowing on the adjacent south portugal planation surface spps ca 220 110 m corroborating differential uplift of the pcr relative to the spps owing to the fact that the relict graded profiles can be correlated with the tagus river t1 terrace 1 1 0 9 my present in the study area incision rates can be estimated 1 for the streams located in the pcr 0 38 0 15 m ky and 2 for the streams flowing on the spps 0 22 0 12 m ky the differential uplift inferred in the study area supports the neotectonic activity of the bordering faults as proposed in previous studies based upon other geological evidence

a monitoring design for the atlantic meridional overturning circulation 1 current hydrographic data can provide snapshots but no continuous timeseries of the meridional overturning circulation moc using output from two eddy permitting numerical ocean models we test the feasibility of a monitoring system for the moc in the north atlantic the results suggest that a relatively simple arrangement using moorings placed across a longitude depth section and the zonal wind stress is able to capture most of the moc strength and vertical structure as a function of time being closely related to the transport of energy to the north atlantic measuring the moc would open the prospect of having continuous information about a key element of northern hemisphere climate

evolution and inheritance of a rock coast western galicia northwestern spain there is increasing evidence that shore platforms and other elements of rock coasts may be inherited at least in part from interglacial stages when sea level was similar to today s most of this evidence which includes ancient beaches and datable terrestrial deposits has been obtained from areas of resistant slowly eroding rock where the platforms often appear to be much too wide to have developed since the sea reached its present level it is much more dif cult to demonstrate that inheritance has occurred in areas of weaker rock which generally lack any datable material the coast of western galicia in northwestern spain has shore platforms in igneous and metamorphic rocks that were deeply weathered during the tertiary these platforms are closely associated with ancient beaches from the last interglacial stage and associated periglacial and uvio nival deposits that covered and fossilized most of the eemian platforms and cliffs during the late middle and late weichselian glacial stage the sedimentary processes and the thickness and facies of the sediments were determined by the height aspect and gradient of the coastal mountains and their distance from the coast radiocarbon dating sedimentary analysis and platform morphology indicate that the shore platforms of galicia have been inherited from at least the last interglacial stage they were fossilized in places beneath thick weichselian deposits and then exhumed during the holocene transgression the abundant evidence for inheritance in galicia has important implications for other coasts in fairly weak rocks where such evidence is generally lacking copyright 2003 john wiley sons ltd

a two dimensional gravest empirical mode determined from hydrographic observations in the subantarctic front abstract south of australia where the baroclinicity in the subantarctic front extends almost to the seafloor the geopotential height of the sea surface and the vertical acoustic travel time exhibit a tight empirical relationship to each other and to the entire vertical structure of temperature t p salinity s p and specific volume anomaly p measurements of provide proxy estimates of the profiles tg p sg p and g p based on a two dimensional gravest empirical mode gem representation of the vertical structure fitted to 212 hydrographic stations a seasonal model was fitted in the near surface layers using additional historical data at each depth in the range 150 3000 dbar more than 96 of the variance in both the t and fields is captured by the gem representation during the subantarctic flux and dynamics experiment mar 1995 mar 1997 inverted echo sounders ies and current meters were moored in a 2d array along the woce sr3 transect south of australia at each i

the geological evolution of the tibetan plateau the geological evolution of the tibetan plateau is best viewed in a context broader than the india eurasia collision zone after collision about 50 million years ago crust was shortened in western and central tibet while large fragments of lithosphere moved from the collision zone toward areas of trench rollback in the western pacific and indonesia cessation of rapid pacific trench migration 15 to 20 million years ago coincided with a slowing of fragment extrusion beyond the plateau and probably contributed to the onset of rapid surface uplift and crustal thickening in eastern tibet the latter appear to result from rapid eastward flow of the deep crust probably within crustal channels imaged seismically beneath eastern tibet these events mark a transition to the modern structural system that currently accommodates deformation within tibet

slowing of the atlantic meridional overturning circulation at 25 n the atlantic meridional overturning circulation carries warm upper waters into far northern latitudes and returns cold deep waters southward across the equator its heat transport makes a substantial contribution to the moderate climate of maritime and continental europe and any slowdown in the overturning circulation would have profound implications for climate change a transatlantic section along latitude 25 n has been used as a baseline for estimating the overturning circulation and associated heat transport here we analyse a new 25 n transatlantic section and compare it with four previous sections taken over the past five decades the comparison suggests that the atlantic meridional overturning circulation has slowed by about 30 per cent between 1957 and 2004 whereas the northward transport in the gulf stream across 25 n has remained nearly constant the slowing is evident both in a 50 per cent larger southward moving mid ocean recirculation of thermocline waters and also in a 50 per cent decrease in the southward transport of lower north atlantic deep water between 3 000 and 5 000 m in depth in 2004 more of the northward gulf stream flow was recirculating back southward in the thermocline within the subtropical gyre and less was returning southward at depth

upper mantle seismic velocities and anisotropy in china determined through pn and sn tomography 1 we have obtained velocity images of the uppermost mantle beneath china by performing tomographic inversion of both pn and sn traveltimes from the annual bulletin of chinese earthquakes 99 139 pn arrivals and 43 646 sn arrivals were selected pn anisotropy was also obtained simultaneously with pn velocity average pn and sn velocities are 8 05 and 4 55 km s respectively and maximum velocity perturbations are about 3 4 the pn and sn velocities are low in eastern china and high in western china particularly high velocities are associated with old basins for example tarim junggar turpan hami qaidam and sichuan and stable craton for example ordos low sn velocities are found mainly throughout north china in addition velocities are relatively low beneath the central tibetan plateau and the north south seismic zone along 103 e in tarim and central china where we observe strong anisotropy the fast pn velocity directions are consistent with the directions of maximum principal compressive stress as well as directions of crustal movement determined from global positioning system beneath the india eurasia collision zone the pn anisotropy direction is parallel to the collision arc and nearly perpendicular to both the direction of maximum compression and crustal movement resulting from pure shear deformation both the velocity variations and anisotropy indicate that the tibetan plateau was extruded and the mantle material beneath the plateau has flowed around the east himalaya syntax while the remaining material has diverted northwestward beneath the tarim basin

labrador sea water tracked by profiling floats from the boundary current into the open north atlantic fifteen profiling floats were injected into the deep boundary current off labrador they were ballasted to drift in the core depth of labrador sea water lsw at 1500 m depth and were deployed in two groups during march and july august 1997 initially for about three months the floats were drifting within the boundary current and the flow vectors were used to determine the mean horizontal structure of the deep labrador current which was found to be about 100 km wide with an average core speed of 18 cm s 1 north of flemish cap the boundary current encounters complicated topography around orphan knoll and there the lsw outflow splits up into different routes one obvious lsw path is eastward through the charlie gibbs fracture zone and another route is a narrow recirculation toward the central labrador sea a surprising result was that none of the floats were able to follow the boundary current southward to the grand banks area and exit into the subtropics trajectories and temperature profiles of the eastward drifting floats indicate the importance of the north atlantic current for dispersing the floats even at the level of lsw

ambient noise rayleigh wave tomography in western sichuan and eastern tibet abstract we perform rayleigh wave tomography in western sichuan and eastern tibet by applying the ambient noise method to broadband data recorded at 49 stations from the sichuan digital seismic network cross correlations of vertical component ambient noise data are computed in one hour segments and stacked over 7 months from june to december 2007 then rayleigh wave group dispersion curves from 6 to 48 s were measured using the multiple filter analysis method group velocity maps at periods from 8 to 44 s were inverted the resulting group velocity maps generally show good correlations with tectonic features the sichuan basin is clearly resolved with lower group velocities at the short periods 8 to 20 s due to thick sedimentary layers and a prominent low velocity zone exhibits in the middle crust beneath the eastern margin of the tibetan plateau the longmen shan thrust belt marks not only the rapid lateral velocity variation between the topographically high tibetan plateau and low elevation sichuan basin but also the transition from the thick crust beneath the tibetan plateau to the normal continental crust beneath the sichuan basin

variability in deep western boundary current transports preliminary results from 26 5 n in the atlantic 1 transport fluctuations of the deep limb of the meridional overturning circulation moc near the western boundary are presented from a line of inverted echo sounders bottom pressure sensors and a deep current meter east of abaco island bahamas at 26 5 n from september 2004 through september 2005 the mean southward flow between 800 dbar and 4800 dbar was 39 106 m3 s 1 with a northward recirculation of 28 106 m3 s 1 leaving a net southward flow of 11 106 m3 s 1 as the through flow of the deep western boundary current dwbc the mean southward dwbc flow essentially equals previous values that were measured at the same location by arrays of current meters deployed from 1986 to 1992 dwbc transport spectra indicate that barotropic and baroclinic changes have very similar energy levels at most periods less than 10 days and that barotropic changes dominate at periods of 10 80 days

western boundary current structure and variability east of abaco bahamas at 26 5 n abstract during april 1987 to june 1988 a four mooring transport resolving current meter array was deployed in a section extending 70 km eastward from abaco bahamas at 26 5 n mean currents in the upper layer 800 m showed a clockwise rotation that appears to be associated with a small scale quasi permanent anticyclonic gyre centered just northeast or the bahamas deep mean currents were persistenly southward and indicated a strong deep jet the deep western boundary current dwbc reaching core speeds of 20 cm s 1at 2500 m depth about 25 km seaward of the western boundary vertically integrated meridional volume transport over the section showed a surprisingly large variability ranging from approximately 20 sv northward to 70 sv southward 1 sv 106m3s 1 the mean meridional volume transport was 30 sv to the south with about 3 sv flowing northward above 800 m which could be produced by a weak antilles current and 33 sv flowing southward below 800 m the deep southward transport of 33 sv i

large scale distributed deformation controlled topography along the western africa eurasia limit tectonic constraints in the interior of the iberian peninsula the main geomorphic features mountain ranges and basins seems to be arranged in several directions whose origin can be related to the n s plate convergence which occurred along the cantabro pyrenean border during the eocene lower miocene time span the iberian variscan basement accommodated part of this plate convergence in three e w trending crustal folds as well as in the reactivation of two left lateral nne ssw strike slip belts the rest of the convergence was assumed through the inversion of the iberian mesozoic rift to form the iberian chain this inversion gave rise to a process of oblique crustal shortening involving the development of two right lateral nw se shear zones crustal folds strike slip corridors and one inverted rift compose a tectonic mechanism of pure shear in which the shortening is solved vertically by the development of mountain ranges and related sedimentary basins this model can be expanded to nw africa up to the atlasic system where n s plate convergence seems also to be accommodated in several basement uplifts anti atlas and meseta and through the inversion of two mesozoic rifts high and middle atlas in this tectonic situation the microcontinent iberia used to be firmly attached to africa during most part of the tertiary in such a way that n s compressive stresses could be transmitted from the collision of the pyrenean boundary this tectonic scenario implies that most part of the tertiary eurasia africa convergence was not accommodated along the iberia africa interface but in the pyrenean plateboundary a broad zone of distributed deformation resulted from the transmission of compressive stresses from the collision at the pyrenean border this distributed intraplate deformation can be easily related to the topographic pattern of the africa eurasia interface at the longitude of the iberian peninsula shortening in the rif betics external zones and their related topographic features must be conversely related to more local driven mechanisms the westward displacement of the exotic alboran domain other than n s convergence the remaining nnw sse to nw se latest miocene up to present convergence is also being accommodated in this zone straddling iberia and morocco at the same time as a new ill defined plate boundary that is being developed between europe and africa

sea level variations during marine isotope stage 7 and coastal tectonics in the eastern seto inland sea area western japan relative sea level rsl observations for marine isotope stage mis 7 were obtained from three sites higashinada kakogawa and mitsu of the eastern seto inland sea area western japan we evaluated the magnitude of sea level highstands during mis 7 and the local tectonics based on rsl records of this coastal area for this purpose we analyzed diatom assemblages and sedimentary sulfur and carried out tephra analysis we also constructed a linear age model to determine the depositional ages of the sediments using altitudes of astronomical age control points obtained mainly from the present diatom data at the mitsu site rsls were estimated to be 22 87 0 50 m at the mis 7 5 highstand peak 234 6 ka below 20 17 m at 211 2 ka and below 20 00 m at 209 9 ka with a tectonic subsidence rate of 0 11 0 02 m ka since the last interglacial maximum at the mitsu site the elevation of the tectonically corrected mis 7 5 highstand peak may have been 2 94 5 19 m the tectonically corrected sea level elevations during mis 7 3 are inferred to have been below 3 06 4 72 m at 211 2 ka and below 3 09 4 70 m at 209 9 ka comparisons between the diatom inferred rsls and the isotopically derived sea level curve indicate that the mis 7 3 highstand peak was above 18 m and may have been lower than the mis 7 5 and 7 1 highstands based on the isotopically derived sea level curve and the rsl data from higashinada and kakogawa a tectonic subsidence rate of 0 26 0 32 m ka was derived for higashinada and a tectonic uplift rate of 0 17 m ka and 0 43 m ka and 0 26 m ka and 0 42 m ka these values indicate the intensity of crustal movements associated with active faulting of the rokko awaji fault system along this tectonically active coast

interpretation of seismic surface waves in regional networks joint estimation of wavefield geometry and local phase velocity method and numerical tests summary teleseismic surface waves in general strongly deviate from plane waves as is evident from the analysis of surface wave data recorded with dense networks this causes conventional ray based tomographic techniques to break down if applied to network surface wave data we present a new inversion method based on the acoustic wave equation and applicable to vertical component surface wave data which successfully deals with non plane wavefield geometries the basic idea of the method is a joint estimation of the incoming wavefield and heterogeneous structure within the network region crucial to the success of the method is an adequate parametrization of the incoming wavefield which is realized using hermite gaussian basis functions additionally we apply a constraint on the wavefield parameters that expresses the idea that the samples of the wavefield taken at the station locations should be representative for the wavefield in the whole network region in this way wavefields that show stronger fluctuations in spectral amplitude than observed at the stations are rejected to represent heterogeneous structure within the network region we use an expansion into 2 d hermite gaussian functions provided that the density of stations is sufficient the proposed method retrieves heterogeneous structure in the network region very well it is not sensitive to noise or non uniform azimuthal coverage of earthquakes moreover it yields smoothed versions of the true model if the roughness of the latter has been underestimated in the inversion conversely if the true model is much smoother than anticipated inspection of the trade off between model smoothness and data misfit allows us to find the correct model the limiting factor for the inversion is the density of stations which must allow for a reliable interpolation of the observed wavefield within the network therefore in order to perform regional surface wave studies it is essential to deploy seismic stations in the region of interest itself

is vegetation responsible for glacial inception during periods of muted insolation changes the marine isotope stage 11 interglacial centred at similar to 400 ka appears to be the best candidate for understanding climatic changes in the context of low insolation forcing such as that of our present interglacial direct correlation between terrestrial pollen and marine climatic indicators and ice volume proxy from deep sea core md01 2447 off northwestern iberia shows for the first time the phase relationship between southwestern european vegetation sea surface temperatures in the northeastern atlantic mid latitudes and ice volume during mis 11 a warmest 32 000 years long period and three following warm cold cycles occurred synchronously on land and ocean the end of the warmest period sees the glacial inception which coincides with the replacement of warm deciduous forest by conifer pine fir expansion in northwestern iberia and consequently with the southward migration of the tree line in high latitudes in response to declining summer insolation as weak insolation changes alone cannot account for ice growth the associated vegetation changes must now be considered as a potential major feedback mechanism for glaciation initiation during mis 11 c 2005 elsevier ltd all rights reserved

vertical structure and transport on a transect across the north atlantic current near 42 n time series and mean a new method is presented for combining historical hydrography with the acoustic travel time measurements from an inverted echo sounder ies to obtain time series of full water column profiles of temperature t and specific volume anomaly hydrography is used to demonstrate that profiles constructed from the ies measurement account for more than 90 of the t and variance through the main thermocline range horizontal gradients between neighboring pairs of instruments when combined with measurements from bottom pressure sensors and deep current meters provide accurate estimates of absolute geostrophic velocity profiles a section of iess and current meters across the north atlantic current nac along world ocean circulation experiment line acm6 near 42 5 n is analyzed using these methods and the eulerian mean temperature and absolute velocity sections are calculated the mean transport for the combined nac and northward flow within the inshore portion of the mann eddy is 146 13 106 m3 s 1 the temporal standard deviation of the northward transport is 41 106 m3 s 1 arising not only from changes in the transport of the nac but also from lateral shifts of the currents and eddies captured by the fixed span of moorings assumption of a level of no motion at the bottom and at 2000 dbar underestimates the true absolute transport by 33 or 60 respectively historical measurements indicate that 50 60 106 m3 s 1 circulates within the mann eddy adjacent to the north atlantic current thus 86 96 106 m3 s 1 appears to be throughput at the acm6 line because the throughput observed on the acm6 line considerably exceeds the combined historical estimates of northward and eastward outflow from the newfoundland basin of 30 106 m3 s 1 these measurements suggest a substantial 50 106 m3 s 1 recirculation or southward flow within the newfoundland basin in addition to the historical recirculation within the mann eddy

constraining the extent of crust mantle coupling in central asia using gps geologic and shear wave splitting data abstract we have obtained constraints on mechanical crust mantle coupling for tibet and yunnan indo china by comparing the observed surface deformation field inferred from gps and quaternary fault slip rate data with the mantle deformation field inferred from several sks shear wave splitting data sets we first determined whether the anisotropy is dominantly asthenospheric or lithospheric by testing simple models of both types against the observed values of the fast polarization direction which is assumed to be parallel to the horizontal projection of the direction of maximum shear for asthenospheric flow we solved for a best fitting uniform sub asthenospheric velocity model for eurasia the fit however was not satisfactory rms misfit 20 solving for separate uniform flow fields in each region improves the fit 15 for tibet 11 for yunnan although the resulting flow fields are inconsistent with several geophysical and geological constraints and thus considered unlikely we then considered lithospheric models for tibet vertically coherent deformation i e maximum shear direction from surface deformation is parallel to yields an improved match 11 for left lateral shear both the goodness of fit and the dominance of left lateral surface faulting in tibet argue for a lithospheric source of anisotropy the misfit for yunnan is large for either right 53 or left lateral 49 shear which argues for complete crust mantle decoupling in yunnan we show that the fast polarization directions throughout both the tibet and yunnan region can be fit by a single lithospheric dynamic model in which there is strong coupling between crust and mantle beneath tibet but a complete decoupling between crust and mantle beneath yunnan crust this dynamic model predicts left lateral maximum shear directions within the mantle that align with fast polarization directions in both regions 9 these maximum shear directions within the mantle align with the left lateral maximum shear directions in the crustal deformation field in tibet but are not in yunnan our results have the following implications first the coherence between crust and mantle deformation in tibet implies strong crust mantle mechanical coupling since this is the only way that crustal buoyancy forces required to account for the surface deformation field can be transmitted into the mantle this behavior is consistent with a uniform strength lithosphere or strong crust but not with a substantially weaker crust for example it is inconsistent with the popular jelly sandwich rheology and thus precludes behavior such as large scale lower crustal flow in tibet the crust mantle coherence is also incompatible with mantle delamination second crust mantle decoupling within the yunnan lithosphere argues that mantle deformation there is controlled only by boundary conditions crustal buoyancy forces are not transmitted into the mantle beneath yunnan moreover the dynamic model for the mantle shows that the yunnan crust is moving south with respect to the mantle at rates as high as 30 mm yr third there is a fundamental rheological lithospheric transition between tibet and yunnan that may provide a key to understanding this significant orogen

a low velocity belt beneath northern and eastern tibetan plateau from pn tomography 1 new pn tomography on tibetan plateau tp and neighboring region is conducted with data assembled from various sources the improved pn tomographic image delineates several distinct geophysical regimes that are approximately separated by geological boundaries at surface dense distribution of the stations in the eastern half of the plateau allows us to infer a 3d view of crustal thickness variation of the region the most striking feature is the bended low velocity belt lvb which extends from west to east beneath qiangtang block and songpan ganzi fold belt sgfb in northern tp and then turns consistently southward with sgfb beneath eastern tp and further south to indo china the consistency between geological boundaries on surface and sharp velocity contrast boundaries in uppermost mantle may suggest strong deformation coupling between crust and at least uppermost mantle if not whole lithosphere a north south striking lvb is also observed cutting through the southern tp coinciding with the yadong gulu rift at surface our tomographic results are generally consistent with dynamic models that involve with underthrusting in the southern tp shortening in the northern tp and extrusion to the east and the southeast furthermore our results suggest significant east west variations in the structure and dynamics