geochemical characterization correlation and optical dating of tephra in alluvial sequences of central western argentina the synthesis of paleoclimatic archives provided by loess and alluvial sequences of central argentina has been hindered by the lack of a cohesive lithostratigraphic framework extending across the chaco pampean plains and catchments of the rios desaguadero colorado and negro this condition originates in part from the dearth of absolute chronological controls the occurrence of discrete tephra layers across this region may provide an opportunity to address this deficiency if a tephrochronological framework can be established the potential of such a project is assessed within the context of a pilot study constrained within alluvial sequences of central western argentina proximal to potential source vents in the southern volcanic zone the intersite discrimination and correlation of tephra layers on a geochemical basis is examined with indirect chronological control for the eruption of each generated by optical dating alluvial sediments on either side of each of five tephra units at a type site were dated using the optically stimulated luminescence of fine silt sized quartz thus providing an age control on each tephra ca 24 000 30 000 32 000 39 000 and 48 000 yr the geochemical composition of each tephra was derived using these data tephra layers at other sites in the study area were geochemically analyzed and in instances of statistical concordance in major oxide structure correlated to the type site and therefore ascribed ages this methodology identified a further sixth volcanic event between ca 24 000 and 30 000 yr not registered by type site tephras the extension of this initial tephrochronological framework beyond the alluvial sequences of central western argentina is encouraged by the occurrence of geochemically distinct tephra verified and dated in this study

modeling semidiurnal internal tide variability in the southern california bight abstractthe regional oceanic modeling system roms is applied in a nested configuration with realistic forcing to the southern california bight scb to analyze the variability in semidiurnal internal wave generation and propagation the scb has a complex topography with supercritical slopes that generate linear internal waves at the forcing frequency the model predicts the observed barotropic and baroclinic tides reasonably well although the observed baroclinic tides feature slightly larger amplitudes the strongest semidiurnal barotropic to baroclinic energy conversion occurs on a steep sill slope of the 1900 m deep santa cruz basin this causes a forced near resonant semidiurnal poincare wave that rotates clockwise in the basin and is of the first mode along the radial azimuthal and vertical directions the associated tidal mean depth integrated energy fluxes and isotherm oscillation amplitudes in the basin reach maximum values of about 5 kw m 1 and 100 m and are strongly modulated by the sprin

quaternary tephrochronology helps define conditioning factors and triggering mechanisms of rock avalanches in nw argentina abstract ten previously defined quaternary tephra layers from northwestern argentina are described here in terms of electron microprobe analyses of glass shards in addition xrf analyses of three tephras alemania buey muerto and el paso ash were performed the alemania ash and buey muerto ash occur within 1 m of each other stratigraphically in several outcrops and exhibit identical glass chemistry as well xrf analyses show that both tephras have identical composition based on stratigraphic relations and age determinations these tephras can clearly be separated as two individual layers tephra ages were defined relatively by ams 14c dates of organic material by 10be surface exposure ages of landslides in stratigraphic association with these tephra layers or directly by 40ar 39ar ages of mineral separates or fission track dating of zircons ages of these tephra layers constrain the temporal distribution of large landslides rock avalanche type in northwestern argentina temporal distribution shows that these large collapses concentrated in deeply incised valleys during climate periods characterized by enhanced precipitation and run off in addition in the tonco valley tephra characteristics also suggest earthquake triggering of coeval landsliding in this valley four landslides one with a 10be age of 7820 830 yr lie in direct contact atop un redeposited paranilla ash showing the coeval age of these landslides the age of the dated landslide deposit coincides with the age of soft sediment deformation structures in nearby lake deposits with an ams 14c age of 7430 7570 cal yr bp

age distribution and stratigraphy of glacier peak tephra in eastern washington and western montana united states tephra layers from williams lake fen wildcat lake and east wenatchee washington and kearns basin lost trail pass sheep mountain bog and marys frog pond montana were analyzed by electron mi

characteristics of tephra in holocene lake sediments on king george island west antarctica implications for deglaciation and paleoenvironment abstract several reworked tephra layers in gravity flow deposits are present in lacustrine core sediments collected from hotel and rudy lakes on king george island south shetland islands maritime sub antarctica this study tests the values of tephra for establishing regional tephrochronologies for lakes in ice covered landscapes in the vicinity of volcanoes the tephra record is more abundant in a long hotel lake core 515 cm long this study uses volcanic glass samples from five tephra layers of hotel lake and from one tephra layer of rudy lake morphologically tephras are mixtures of basaltic and pumice shards both having various degrees of vesicularity major element analyses of glass shards reveal that the majority of the glass fragments belong to basic glass 2 compositionally ranging from basalt to low silica andesite and subalkaline series medium k tholeiites probably sourced from deception island located 130 km southwest of king george island less than 20 of tephra belongs to silicic glass and occurs in three tephra horizons e of hotel lake however source volcano es for about 10 of basic tephra and silicic tephra are not readily identified from nearby volcanic centers except for the studied tephra in rudy lake all tephra samples in hotel lake are not ashfall deposits but reworked and redeposited pyroclasts derived from retreating ice sheet resulting in the occurrence of geochemically equivalent tephra samples in different tephra horizons the dating of the studied tephra horizons represents the timing of deglaciation rather than that of volcanic eruptions the result of this study implies that combined with sedimentological information more chemical criterion is necessary to study tephrochronology and regional correlation and to understand paleoenvironmental changes using tephra

santorini luminescence dating of a volcanic province using quartz abstract we have investigated the application of luminescence dating to the palaeosol underlying the cape riva ignimbrite from the volcanic island of santorini 36 40 n 25 40 e in the aegean sea the history of volcanism in this area is of intrinsic interest and is also of importance to archaeology in the eastern mediterranean a flourishing late bronze age settlement was buried under the volcanic products of the minoan eruption 1640 bc volcanic provinces are notoriously difficult to date using luminescence techniques because volcanic feldspars almost invariably show anomalous fading which can lead to age underestimates of more than 50 quartz does not show anomalous fading but unfortunately it is rare or non existent in volcanic sediments and so it is usually not considered as a potential chronometer we have studied the luminescence characteristics of material extracted from the cape riva palaeosol with good independent age control all samples contain detectable quartz but usually

discriminant function analysis of late quaternary tephras from five volcanoes in new zealand using glass shard major element chemistry abstract the microprobe determined glass shard major element chemistry of tephras derived from five north island new zealand volcanoes mayor island okataina taupo tongariro and mount egmont and younger than ca 20 000 yr b p was subjected to discriminant function analysis four separate approaches were adopted to test the match of the tephras with their known sources 1 an analysis of raw microprobe data 2 an analysis of normalized data 3 an analysis of the data transformed by calculating the log 10 of oxide scores divided arbitrarily by the chlorine content and 4 a repeat of 3 with multivariate outlier scores as determined by principal components analysis deleted all yielded excellent classification functions efficiencies of 91 100 with the eruptives associated with each of the five volcanoes being chemically distinct from one another in each approach the first two canonical discriminant functions accounted for 90 of the variation between groups the removal of multivariate outliers from the data set had only minor effects on the performance of the discriminant function procedures separate discriminant function analysis of the relatively alike taupo and okataina eruptives gave a greater degree of multivariate separation the numerical classifications generated should enable unidentified tephras erupted since ca 20 000 yr b p from the five volcanoes to be provisionally matched with their sources

identification and significance of a visible basalt rich vedde ash layer in a late glacial sequence on the isle of skye inner hebrides scotland this paper reports the discovery of a visible tephra horizon of late glacial age from the site of loch ashik in the isle of skye the inner hebrides scotland although the tephra shards have a bimodal geochemical composition identical to that of the vedde ash a well known marker horizon within late glacial sequences the horizon at ashik is dominated by basaltic shards and devitrified tephra shards giving the layer its characteristic black colour only rhyolitic shards have previously been reported from vedde ash horizons in the british isles this new evidence raises some important questions about the factors that govern the distribution and accumulation of basaltic tephra and about the methods used to detect ash shards in basins distal to centres of volcanic activity copyright 2001 john wiley sons ltd

late quaternary paleosols stratigraphy and landscape evolution in the northern pampa argentina the field properties micromorphology grain size geochemistry and optically stimulated luminescence osl ages of two late quaternary sections have been used to reconstruct the sequence of pedosedimentary processes and to provide insights into landscape evolution in part of the northern pampa of argentina paleosols developed in paludal sediments adjacent to the parana river at baradero and in loess at lozada can both be correlated and linked to other sites thus enabling for the first time the tentative recognition and tracing of a diachronous soil stratigraphic unit that probably spans the equivalent of at least part of marine oxygen isotope stage ois 5 the paleosol at lozada was truncated and buried beneath fluvial sediments during the time span of ois 4 and 3 eolian gradually replaced paludal inputs at baradero over this period and there were also two clearly defined breaks in sedimentation and development of paleosols the period corresponding to ois 2 was marked by significant loess accumulation at both sites with accretion continuing into the mid holocene only at lozada the more developed nature of the surface soil at baradero probably reflects a combination of a moister climate and a longer soil forming interval

a late pleistocene tephra layer in the southern great basin and colorado plateau derived from mono craters california abstract a newly identified tephra in stratified deposits in southwestern utah dated 14 000 14c yr b p may aid in correlating late pleistocene deposits across parts of the southern great basin and west central colorado plateau geochemical analyses of the ash suggest the tephra originated from mono craters california and most probably correlates with wilson creek ash 3 because the ash is 2 mm thick 550 km from its source the event may have been larger than others correlated to mono craters eruptions

the loma seca tuff and the calabozos caldera a major ash flow and caldera complex in the southern andes of central chile a 26 14 km composite ring structure caldera of late pleistocene age has been discovered and mapped near the andean crest in central chile 35 30 s rhyodacitic to dacitic zoned ash flow sheets each representing 150 to 300 km 3 of magma were emplaced 0 8 0 3 and 0 15 m y ago the youngest of the associated collapses was closely followed by resurgent doming of the caldera floor and development of a longitudinal graben postcaldera eruptions of dacite and andesite have persisted into holocene time and active hot springs are abundant along caldera marginal and resurgent fault systems suggesting a significant geothermal energy resource the pleistocene eruption rate of this district and the abundance of older quaternary to miocene ash flow remnants in the 33 s to 36 s segment of the glaciated southern andes indicate that ash flow magmatism has been no less important here than in the arid central andes 16 s 28 s where ash flow sheets are far better preserved

patagonian dust in antarctica abstract recent advances in the knowledge of antarctica have demonstrated that the atmospheric dust trapped in the west antarctica glaciers during is2 4 and 6 has a patagonian origin a climatic scenario is developed in this article in order to explain such a process patagonia is unique as it is the only sizable land mass located in the belt of westerlies in the southern hemisphere the westerlies are formed by cyclonic structures which normally elevate the air masses and aerosols to the upper troposphere there the phenomena of mass compensation occur with the antarctic anticyclone which as any anticyclone sinks air and aerosols to the surface large quantities of loose surficial sediments and atmospheric dust are typical of patagonia and can easily be picked up by the wind according to this scenario which is based on the general atmospheric circulation australia and southern africa are hindered in providing aerosols to antarctica because those territories are located in the subtropical high pressure belt

tephrochronologic constraints on the late pleistocene history of the southern margin of the cordilleran ice sheet western washington abstract an ash layer that appears geochemically correlative with mt st helens tephra set s occurs in a sequence of pleistocene lake sediments in the ohop valley of the southern puget lowland below vashon till deposited during the maximum late pleistocene advance fraser glaciation of the puget lobe of the cordilleran ice sheet the puget lobe reached its maximum southern extent ca 14 000 14 500 yr b p and at least part of set s is evidently somewhat older previous radiocarbon and thermoluminescence dates for set s have ranged from 13 000 to 16 000 yr b p geochemically correlative deposits of set s tephra occur in slackwater sediments coeval with the missoula floods in eastern washington produced by jokulhlaups through the purcell trench lobe of the cordilleran ice sheet these relationships suggest that advances of glacier lobes on the southern margin of the cordilleran ice sheet were nonsynchronous as the pucell trench lobe east of the cascade range advanced to its maximum southern extent prior to the time of the eruption of set s before the puget lobe west of the cascades reached its maximum southern extent

magnetostratigraphy and tephrochronology of an upper pliocene to holocene record in lake sediments at tulelake northern california combined paleomagnetic and tephra chronologies of one of the most complete middle pliocene through holocene stratigraphic records yet recovered in western north america provide a reference section for much of northwestern north america and adjacent pacific ocean five long drill cores of lacustrine sediments at tulelake northern california recovered a nearly continuous 331 m thick record spanning the past 3 m y the brunhes normal polarity matuyama reversed polarity and gauss normal polarity chronozones are recognized within these the jaramillo olduvai reunion and kaena subchronozones are present six short stratigraphic intervals exhibit anomalous remanent inclinations that may record excursions and brief subchrons within the brunhes and matuyama chronozones age estimates suggest correlation of five of the anomalous intervals with 1 one of the biwa excursions at about 18 000 yr b p 2 the mono lake excursion at about 27 000 yr b p 3 the blake reversed polarity subchron at about 114 000 yr b p 4 the kamikatsura normal polarity subchron at about 850 000 yr b p and 5 the cobb mountain normal polarity subchron at about 1 10 ma age of the sixth interval of anomalous inclination is broadly constrained between 117 000 and 180 000 yr b p sixty three individual tephra layers were characterized by electron microprobe and x ray fluorescence analyses of volcanic glass shards identified tephra of relatively well known age include 1 the basal airfall pumice at llao rock 7015 yr b p 2 the trego hot springs bed 23 400 yr b p 3 the olema ash bed between 55 000 and 75 000 yr b p 4 the airfall pumice at cloudcap road pumice castle like tephra 2 about 120 000 yr b p 5 the rockland ash bed about 410 000 yr b p 6 the lava creek b ash bed 620 000 yr b p 7 the rio dell ash bed about 1 45 ma and 8 the bear gulch ash bed about 1 9 ma a sedimentation rate curve based on independently dated tephra and polarity reversals is used to infer age estimates of undated or previously unidentified ash beds some of these ash beds are found over large areas of the western united states and eastern pacific ocean basin and provide widespread horizons for correlation most of the tephra at tulelake records eruptions from the nearby southern and central cascade range of oregon and northern california and the medicine lake highland of northern california deposition took place during most of the past 3 m y within the tulelake basin notable periods of slow or sporadic accumulation or erosion occurred between about 620 000 and 200 000 yr b p and between about 2 5 and 2 1 ma rapid deposition occurred during marine oxygen isotope stage 6 between about 170 and 125 ka regional volcanism during the past 3 m y was markedly episodic with notable volcanic activity from about 2 1 to 1 9 ma and from 0 4 ma to the present

vegetational history of the late glacial holocene transition in the grasslands of eastern argentina abstract palynological records from eight sites located in the eastern plains of argentina from the humid pampa in the east to the xerophytic woodland dry pampa ecotone in the west allow a regional reconstruction of the vegetation of late glacial holocene transition fossil pollen records were interpreted in terms of palaeoenvironmental information using the modern pollen vegetation climate relationship as an analogue although an exact analogue does not exist today late glacial vegetation consisted mostly of psammophytic steppe in large areas of the central and south western pampa grassland which in the south west is associated with a shrub steppe suggesting subhumid dry to semi arid climatic conditions the replacement of dry steppe by humid grassland and the rapid evolution of pond environments during the early holocene starting during the late glacial holocene transition suggests a shift towards subhumid to humid climate conditions the late glacial holocene transition is indicated in the pollen records by repeated abrupt changes in the proportions and concentrations of some taxa such as brassicaceae asteraceae and carduus type in the modern vegetation they represent species of common occurrence in human induced disturbance habitats suggesting an environment that was subject to frequent natural disturbance such as rapid and repeated flooding episodes that inundated the depressions along the valley floodplains caused by unusual rainfall events some species of carduus may have been native and not introduced by the europeans suggesting that late glacial vegetation of the pampa grasslands may account for the abundance of ruderal species of special interest is the presence of myrtaceae in some pollen assemblages between 11 000 and 9000 yr b p at present myrtaceae are not part of the natural vegetation in the pampa grassland their presence in the fossil pollen records may be interpreted as local deposition instead of extra regional origin myrtaceae formed part of the psammophytic steppe and after late glacial holocene transition they disappeared from the regional flora perhaps due to the climatic change that occurred at the beginning of the holocene it is the most significant cause of extending the area of some pampa grassland taxa but it may have reduced the area for others of the late glacial vegetation at least myrtaceae were probably not able to adapt to the new habitats and hence disappeared from the regional flora at the pleistocene holocene transition although other plants may have disappeared as well these cannot be identified because pollen from these plants cannot be differentiated morphologically during the late glacial holocene transition communities with no modern counterparts probably formed and disappeared

late pleistocene mollusc assemblages and inferred paleoenvironments from the andean piedmont of mendoza argentina abstract this paper is focused on the paleoecological analysis of a mollusc succession cropping out on the right margin of la estacada stream in the andean piedmont of mendoza argentina 33 28 s 69 03 w the stratigraphic section mainly composed of fine sands interbedded with levels of silty clays and organic matter records the interval between 35 2 35 5 14c ka b p and 31 5 31 6 14c ka b p the mollusc succession is represented by freshwater and land snails biomphalaria peregrina planorbidae lymnaea viator lymnaeidae succinea meridionalis succineidae rotadiscus amancaezensis charopidae and radiodiscus sp aff radiodiscus quillajicola charopidae the dominance of semi aquatic and hygrophilous land snails suggests the development of a vegetated shallow water body probably a damp habitat occasionally submerged with four main stages of evolution related to fluctuating water levels the abundance of shells together with the stable isotope composition of carbonate shells of l viator 13c and 18o and the presence of radiodiscus sp aff radiodiscus quillajicola and r amancaezensis suggest relatively warm and wet conditions based on its radiocarbon chronology and the paleoecological reconstruction the studied section is recording a mild interval corresponding to an interstadial marine isotope stage 3 of the last glacial cycle

luminescence dating of young volcanic activity in china abstract quartz grains from volcanic deposits younger than 2000 years were dated by the thermoluminescence tl method the equivalent doses were determined with modified pre dose technique using 110 c tl peak tl ages of quartz heated after crystallization are in agreement with historical records and c 14 age of burnt tree age reversing is observed for the crystallized quartz with and without heating this was explained with an initial dose due to the distribution of hole charges

composition and provenance of late pleistocene holocene alluvial sediments of the eastern andean piedmont between 33 and 34 s mendoza province argentina abstract the andean cordillera and its piedmont in the central western argentina has been long considered as one of the main source areas of detritus for the chaco pampean plain sand dune fields and loess loess like deposits of central argentina the main goal of this study is to evaluate the composition of the late pleistocene holocene alluvial deposits of the andes cordillera piedmont from 33 to 34 s the results are interpreted in the context of the regional geology tectonic setting of the study area and its implications in the continent wide perspective of modern alluvial sands proposed by potter 1994 sampling was conducted at the alluvial stratigraphic sequences of four study sites along three andean piedmont arroyos modal mineralogy in the very fine sand fraction 3 phi to 4 phi was determined using standard petrographic microscope methods q f lf average compositions indicate that the late pleistocene holocene very fine grained alluvial sands of the cordillera frontal piedmont reflects the modern lithic arenites of the argentine association reported by potter 1994 the results show two geologically distinct sources in the catchment areas volcaniclastic and metamorphic rocks high concentrations of mica and volcanic glass are likely related to particle morphologies and to the deposition sedimentary environment recorded in the alluvial sequences floodplains the overabundance of micas over the volcanic glass in the mid late holocene alluvial sequence indicates the drainage of a metamorphic area at the expense of other lithological sources source areas are located mainly in the frontal cordillera and to a lesser extent in the piedmont tertiary deposits another likely source for the analyzed quaternary alluvial sediments the mineralogical signature of the late pleistocene and holocene alluvial sequences is in agreement with the composition of the southern pampean sand mantles loess and loess like deposits mainly formed by a volcanic mineral assemblage with source areas placed at the headwaters of the main andean rivers

identification of disseminated trego hot springs tephra in the palouse washington state abstract tephra layers form important chronostratigraphic marker horizons within the wisconsinan loess paleosol stratigraphy of the palouse washington state this paper details the presence of disseminated glass shards of the trego hot springs tephra that has not previously been recognized within the palouse or environs the tephra provides additional chronological control for the regional late wisconsinan stratigraphy and raises the possibility of correlating the paleoclimatic proxy record contained within the palouse to those of lake sequences in oregon california and nevada

model estimates of m2 internal tide generation over mid atlantic ridge topography abstract the conversion of barotropic to baroclinic m2 tidal energy is examined for a section of the mid atlantic ridge in the brazil basin using a primitive equation model model runs are made with different horizontal smoothing 1 5 6 and 15 km applied to a 192 km 183 km section of multibeam bathymetry to characterize the influence of topographic resolution on the model conversion rates in all model simulations barotropic to baroclinic conversion is highest over near and supercritical slopes on the flanks of abyssal hills and discordant zones from these generation sites internal tides propagate upward and downward as tidal beams the most energetic internal tide mode generated is mode 2 consistent with the dominant length scales of the topographic slope spectrum 50 km the topographic smoothing significantly affects the model conversion amplitudes with the domain averaged conversion rate from the 1 5 km run 15 1 mw m 2 4 and 19 higher than for the 6 km 14 5 mw m 2 and 15 km runs 12

tests for optically stimulated luminescence from tephar glass abstract glass 4 11 m samples from 15 volcanic ash deposits were examined for their suitability for optical dating the samples ranged in age from 8 to 500 ka only very weak luminescence was observed using 514 nm green 633 nm red and 880 nm near infra red stimulation an equivalent dose of 29 gy was obtained for mazama ash using near infra red stimulation this result agrees well with that obtained earlier using thermoluminescence and is correct for its age of 7 7 ka

isotopic constraints on the source of argentinian loess with implications for atmospheric circulation and the provenance of antarctic dust during recent glacial maxima we present rare earth element ree and sr nd isotopic data for argentinian loess 28 38 s with two aims 1 to examine the source regions of argentinian loess and the constraints that these put on palaeo wind directions 2 to further investigate the source of antarctic ice core dust and to test the hypothesis that some of it could be derived from a region to the north of patagonia into which the dry dusty westerly dominated patagonian climate expanded during quaternary glacial maxima sr nd isotopic data for argentinian loess from north of 37 s are distinct from patagonian loess compositions in that they have more radiogenic sr 87sr 86sr 0 7059 0 7123 and less radiogenic nd nd 0 8 to 6 4 ree patterns and sr nd isotopic values are relatively homogeneous for multiple samples taken from single loess sections but show significant differences between sections in general there is a northward change from patagonia like ree patterns and isotopic values away from volcanogenic signatures and towards those that are more like the continental crust the latitudinal nd isotopic pattern is remarkably similar to that for andean volcanic rocks and suggests derivation of loess from the andes by more or less direct westerly transport for loess sections in the north the data imply a contribution from palaeozoic gneisses to the northwest in the chilean altiplano sr nd data for extra patagonian argentinian loess north of 37 s do not support a significant role for this source region in supplying dust to antarctica at the last glacial maximum this conclusion contrasts with previous studies that suggest a significant northward shift in the climatic belts and in particular the westerlies and the antarctic polar front during quaternary glacial maxima very systematic relations between the sr nd isotopic composition of loess and their andean source highlights shifts in the sr isotopic composition of loess to more radiogenic values and strongly suggests that the slight offset between patagonian loess and ice core dust identified by previous workers is due to grain size differentiation effects

equilibrium structure and dynamics of the california current system this paper addresses the structure and dynamical mechanisms of regional and mesoscale physical variability in the subtropical northeast pacific ocean using the regional oceanic modeling system roms the model is configured with a u s west coast domain that spans the california current system ccs with a mesoscale horizontal resolution up to as fine as 3 5 km its mean seasonal forcing is by momentum heat and water fluxes at the surface and adaptive nudging to gyre scale fields at the open water boundaries its equilibrium solutions show realistic mean and seasonal states and vigorous mesoscale eddies fronts and filaments the level of eddy kinetic energy eke in the model is comparable to drifter and altimeter estimates in the solutions with sufficiently fine resolution because the model lacks nonseasonal transient forcing the authors conclude that the dominant mesoscale variability in the ccs is intrinsic rather than transiently forced the primary eddy generation mechanism is the baroclinic instability of upwelling alongshore currents there is progressive movement of meanseasonal currents and eddy energy offshore and downward into the oceanic interior in an annually recurrent cycle the associated offshore eddy heat fluxes provide the principal balance against nearshore cooling by mean ekman transport and upwelling the currents are highly nonuniform along the coast with important influences by capes and ridges in both maintaining mean standing eddies and launching transient filaments and fronts

mid holocene glacier peak and mount st helens we tephra layers detected in lake sediments from southern british columbia using high resolution techniques abstract a glacier peak tephra has been found in the mid holocene sediment records of two subalpine lakes frozen lake in the southern coast mountains and mount barr cirque lake in the north cascade mountains of british columbia canada the age depth relationship for each lake suggests an age of 5000 5080 14 c yr b p 5500 5900 cal yr b p for the eruption which closely approximates the estimated age 5100 5500 14 c yr b p of the dusty creek tephra assemblage found near glacier peak the tephra layer which has not been reported previously from distal sites and was not readily visible in the sediments was located using contiguous sampling magnetic susceptibility measurements wet sieving and light microscopy the composition of the glass in pumice fragments was determined by electron microprobe analysis and used to confirm the probable source of this mid holocene tephra layer using the same methods the a d 1481 1482 mount st helens we tephra layer was identified in sediments from dog lake in southeastern british columbia suggesting the plume drifted further north than previously thought this high resolution method for identifying tephra layers in lake sediments which has worldwide application in tephrachronologic paleoenvironmental studies has furthered our knowledge of the timing and airfall distribution of holocene tephras from two important cascade volcanoes

pliocene pedosedimentary cycles in the southern pampas argentina well developed bt horizons of five palaeosols p1 p5 have been recorded previously within a 20 m thick succession of pliocene siltstones and clayey siltstones in the southern part of the buenos aires province of argentina this paper reports a detailed field and micromorphological thin section investigation of a 6 m portion of the sequence encompassing p2 and p3 large scale faunal burrow infillings occur throughout other bioturbation features in the form of channel and spongy microstructures are mainly confined to the siltstones the intervening clayey siltstones bt horizons have been affected more by shrink swell disruption as evidenced by slickensides and a range of striated b fabrics in thin sections clay coatings indicative of illuvial accumulation of clay translocated in suspension from overlying a or e horizons occur in both the siltstones and clayey siltstones the types microstratigraphic associations and depth functions of features are interpreted in terms of changing interactions balances and dominances between sedimentary pedogenic and erosional processes over time thus providing the basis for the pedosedimentary reconstruction of landscape evolution in the region during part of the pliocene represented by the whole p1 p5 sequence 4 5 ma bp it is envisaged that this period was dominated by aeolian deposition although fluvial and mass movement processes probably led to reworking and redistribution of some of the materials overall rates of subaerial deposition however were not substantial pedogenic processes were active throughout the balance between sedimentation and pedogenesis varying over time in a cyclical fashion phases of reduced deposition and establishment of relatively stable land surfaces were marked by the development of argillic soil profiles with clearly defined eluvial and illuvial horizons intervening periods of more rapid accumulation of coarser material were characterized by accretionary soil development and welding of new pedological features on existing soils as the surface accreted first transforming existing eluvial horizons into bct ae horizons siltstones and then encouraging the syndepositional upward extension of these complex horizons the primary basis of the alternating units of siltstones bct ae horizons and clayey siltstones bt horizons lies in the cyclical change in size of particles deposited although pedogenic translocation processes enhanced these textural differences the underlying driving mechanism behind the pedosedimentary cycle can only be speculated upon although it is tempting to relate the sedimentation pattern to climatic fluctuations linked to glacial advances and retreats in the patagonian andes during the pliocene

hydrological variability in southeastern patagonia and explosive volcanic activity in the southern andean cordillera during oxygen isotope stage 3 and the holocene inferred from lake sediments of laguna potrok aike argentina abstract seismic reflection studies in the maar lake laguna potrok aike 51 58 s 70 23 w revealed an erosional unconformity associated with a sub aquatic lake level terrace at a water depth of 30m radiocarbon dated multi proxy sediment studies of a piston core from this location indicate that the sediment below this discontinuity has an age of 45kyr bp oxygen isotope stage 3 and was deposited during an interval of high lake level in comparison to the holocene section geochemical indicators of this older part of the record either point towards a different sediment source or to a different transport mechanism for oxygen isotope stage 3 sediments holocene sedimentation started again before 6790cal yr bp providing a sediment record of hydrological variability until the present geochemical and isotopic data indicate a fluctuating lake level until 5310cal yr bp during the late holocene the lake level shows a receding tendency nevertheless the lake level did not drop below the 30m terrace to create another unconformity the geochemical characterization of volcanic ashes reveals evidence for previously unknown explosive activity of the reclus and mt burney volcanoes during oxygen isotope stage 3

loess correlations between myth and reality abstract the correlation of loess sequences across global hemispheric regional and local scales is one of the most fundamental aspects to loess research however despite recent progress in stratigraphic and chronometric methods the correlation of many loess sequences is often still based on untested assumptions over loess deposition preservation soil type and age as such the aim of this overview is to provide an adequate framework for evaluation of the accuracy of loess correlations applied on different temporal and spatial scales across eurasia this opens up possibilities for detailed temporal and spatial environmental reconstructions across the huge loess provinces of the eurasia and provides a framework for future extension of this to north america additionally we evaluate the potential development of appropriate sub millennial scale loess correlations as well as essentially important chronological approaches for establishing valid correlations between different loess records such as current improvements in tephrochronology 14c and luminescence dating techniques

on the generation and evolution of nonlinear internal waves in the south china sea the nonhydrostatic regional ocean modeling system is applied to the nonlinear internal waves or solitons that are generated at the luzon ridge in the south china sea the luzon ridge near the batan islands is represented by an idealized ridge with a height of 2 6 km on a flat bottom model runs are performed for various ridge shapes and a symmetric tidal forcings the model is in the mixed tidal lee wave regime the barotropic tide over the ridge generates first mode waves through the internal tide release mechanism westward traveling solitons emerge from these first mode waves through nonlinear steepening in the internal tide release mechanism asymmetric tides with strong eastward currents can generate strong westward solitons the eastward current creates an elevation wave with a higher energy density west of the ridge and as soon as the current slackens the wave is released westward on its backslope strong solitons develop the energy density is further enhanced by nonlinearities such as differences in phase speeds and energy fluxes related to lee waves a modal and harmonic decomposition shows the generation of vertical modes and higher temporal harmonics and indicates significant wave wave interaction e g triads in the mixed tidal lee wave regime more energy is contained in the first mode compared to the higher modes hence linear internal tide beams are less well defined and strong solitons develop

late pleistocene and holocene vegetation changes in the arid andean piedmont of central argentina inferred from sediment stable carbon isotopes and c n ratios abstract stable carbon isotopes 13c and c n ratios in bulk sediment organic matter were used as indicators of c3 and c4 vegetation functional types in a ca 40 kyr predominantly alluvial sequence from arroyo la estacada 33 5 s 69 w in the arid andean piedmont of central argentina although this sediment sequence has the potential to contribute to the knowledge of past vegetation dynamics through its fossil pollen content previous palynological studies provided scant information constrained to a few time windows because of poor pollen preservation stable isotope results for the total organic carbon fraction from three lithostratigraphic sections that span the past 40 kyr show shifts in 13c values associated with changing contributions from c3 and c4 plants suggesting this proxy can detect changes in these photosynthetic pathways representative of patagonian and or stream margin macrophytes and monte phytogeographic units respectively climate and local factors such as water availability in the basin are inferred to be the main drivers of vegetation dynamics the c n ratios in a few samples show that organic matter sources are algae and or phytoplankton not solely c3 or c4 vascular plants the 13c record from arroyo la estacada is an example of how isotope geochemistry has overcome difficulties with pollen analysis and provided a reliable tool to investigate past vegetation changes in regions where c3 and c4 are differentially distributed isotope values during part of the marine isotope stage 3 mis 3 and the middle holocene are attributed to c3 local floodplain plants with a little or no contribution from regional terrestrial patagonian vegetation late pleistocene holocene palaeosols have a clear c4 signal of terrestrial dominance representative of monte plants thus carbon isotope values constrain the early times of mis 1 particularly where the pleistocene holocene transition occurs a mixture of c3 and c4 values during the last 3 4 kyr is indicative of environmental conditions that prevail in the region today

the origin of silt particles in the loess question abstract many researchers consider loess as solely the product of glacial activity investigations throughout south america however have demonstrated that loess and loess like sediments can be formed during geological periods when glaciation was absent loess deposits may be derived from volcanic action from weathering processes and as a result of pedogenic activity production of silt regardless of the geologic process can result in loess formation under suitable climatic conditions

long continental records of climate an introduction abstract the symposium on long continental records presented new information on past climates on land it seems that throughout the last 2 5 million years the climate in the middle latitudes changed in the same complex fashion as during the better known late pleistocene and holocene times over 40 interglacial glacial shifts took place during this interval out of those 40 10 12 glacials were markedly stronger and or longer lasting than the others the apparently abrupt shifts from interglacials to glacials were probably gradual oscillatory coolings interrupted by warming episodes in that respect the detailed anatomy of the past climate changes does not differ substantially from the climate oscillations documented by instrumental weather records in the last two centuries the pronounced expansions of dry and cold steppes on land were accompanied by corresponding increases of the ice volume indicated by the oxygen isotope ratio the two exceptions occurred around 1 4 ma ago and 1 6 ma ago the reason for this discrepancy is not known by far the most expressed change of land environments occurred at about 2 4 ma ago

late quaternary vegetational and climatic changes in the pampa grassland of argentina abstract the vegetation and climate of the pampa grassland argentina during the late quaternary are reconstructed from pollen recovered from dated stratigraphic sections from arroyo walls and from archaelogical excavations prior to 10 500 yr b p herbaceous psammophytic steppe existed in the central part of the pampa grassland while xerophytic woodland associated with psammophytic and halophytic steppe occurred in the southwestern part of the pampa these types of vegetation and the continental conditions that prevailed in the area of the present day coast 38 s indicate subhumid dry climate and annual precipitation 100 mm lower than present a subsequent change toward a vegetation characteristic of ponds swamps and foodplains or toward environments with locally more effective moisture occurred ca 10 500 yr b p suggesting annual precipitation close to modern levels or a higher availability of water in the central part of the pampa grassland this type of vegetation existed until 8000 yr b p when it was replaced by grassland communities that lasted until 7000 yr b p in the southwestern part of the pampa grassland this vegetation developed before 7000 yr b p and persisted until ca 5000 yr b p sea level higher than the present ca 6200 yr b p is consistent with sharp modification of the vegetation and development of local halophytic communities dominant at 38 s a return to subhumid dry conditions occurred after 5000 yr b p the late holocene vegetation is characterized by pollen assemblages similar to the psammophytic and halophytic communities of the southern pampa grassland associated with communities with more edaphic conditions at the same time at 38 s a sea level regression is suggested by the dominance of fresh water pollen assemblages and micropaleontological remains the trend toward humid temperate conditions ca 1000 yr b p suggested by vertebrate remains characteristic of temperate and humid conditions as well as a very short but dry episode during the 18th century suggested by the geology are not clearly evidenced in the pollen sequences vegetational and climatic changes are explained by the latitudinal shifts and changes in intensity of the southern atmospheric circulation and changes in sea level

towards a european tephrochronological framework for termination 1 and the early holocene the record of deposition of tephras in europe and the north atlantic during the period 18 5 8 0 14 c ka bp the last termination and early holocene is reviewed altogether 34 tephras originating from four main volcanic provinces iceland the eifel district the massif central and italy have been identi ed so far in geological sequences spanning this time interval most of the records have been based until very recently on observations of visible layers of tephras here we report on the potential for extending the areas over which some of the tephras can be traced by the search for layers of micro tephra which are not visible to the naked eye and on the use of geochemical methods to correlate them with known tephra horizons this approach has greatly extended the area in northern europe over which the vedde ash can be traced the same potential exists in southern europe which is demonstrated for the rst time by the discovery of a distinct layer of micro tephra of the neapolitan yellow tu in a site in the northern apennines in italy far to the north of the occurrences of visible records of this tephra the paper closes by considering the potential for developing a robust european tephrostratigraphy to underpin the chronology of records of the last termination and early holocene thereby promoting a better understanding of the nature timing and environmental e ects of the abrupt climatic changes that characterized this period

interference pattern and propagation of the m2 internal tide south of the hawaiian ridge abstract most of the m2 internal tide energy generated at the hawaiian ridge radiates away in modes 1 and 2 but direct observation of these propagating waves is complicated by the complexity of the bathymetry at the generation region and by the presence of interference patterns observations from satellite altimetry a tomographic array and the r p flip taken during the farfield program of the hawaiian ocean mixing experiment home are found to be in good agreement with the output of a high resolution primitive equation model simulating the generation and propagation of internal tides the model shows that different modes are generated with different amplitudes along complex topography multiple sources produce internal tides that sum constructively and destructively as they propagate the major generation sites can be identified using a simplified 2d idealized knife edge ridge model four line sources located on the hawaiian ridge reproduce the interference pattern of sea surface height and energy fl

quaternary tectonics and seismic potential of the andean retrowedge at 33 34 s the andean retrowedge located between 338s and 348s lies in the transition region of the pampean flat slab subduction zone to the north and a normal subduction zone to the south neo tectonic structures and shallow seismicity are very common north of this segment and become pro gressively less frequent southwards the frontal cordillera and the cerrilladas pedemontanas are the main morphostructures involved in the quaternary deformation of this region the frontal cor dillera is a thick skinned fold and thrust belt uplifted since late miocene time the cerrilladas pedemontanas are low relief hills that represent the mild inversion of the cuyo triassic rift depo centre since pliocene time middle miocene holocene synorogenic strata cover the cuyo basin and surrounding foreland areas the quaternary tectonic evolution of this area has been established through integration of new data from fieldwork in the frontal cordillera piedmont with subsurface information and previously published data mean late pleistocene uplift rates ranging between 0 21 and 0 92 mm a 21 and earthquake minimum moment magnitudes mw o fc 6 4 6 7 have been estimated for the morphostructural units analysed in this manuscript

correlation of distal tephra layers in loess in the channeled scabland and palouse of washington state abstract thirty two distal tephra layers that are interbedded in quaternary loess at 13 sites in the channeled scabland and palouse were sampled as part of a regional study of the stratigraphy and chronology of dominantly windblown sediments on the columbia plateau an electron microprobe was used to determine the elemental composition of volcanic glass in all of the samples and also to determine the composition of ilmenite in 14 of them two of the distal tephra layers correlate with glacier peak eruptions 11 200 yr b p five with mount st helens tephra set s 13 000 yr b p and nine with mount st helens tephra set c ca 36 000 yr b p based on analysis of glass and ilmenite in reference pumices from glacier peak mount st helens mount mazama mount rainier and mount jefferson on the calculation of similarity coefficients for comparisons of both glass and ilmenite reference compositions with those of distal tephras and on considerations of stratigraphic position the composition of glass and ilmenite and the stratigraphic position of one distal tephra layer in the loess suggests that it is from an eruption of mount st helens at least several thousand years older than the set c eruptions glass composition and stratigraphic position of a distal tephra at another site in loess suggested a possible correlation with some layers of the pumice castle eruptive sequence at mount mazama ca 70 000 yr b p but similarity coefficients on ilmenite of only 45 and 48 fail to support the correlation and show why multiple correlation methods should be used similarity coefficients higher than 96 for both glass and ilmenite establish a correlation with mount st helens layer cw for distal layers in two widely separated sites these layers are in sedimentary successions that are closely associated with giant floods in the channeled scabland the 36 000 yr b p radiocarbon age of the mount st helens set c establishes a minimum limiting date for an episode of flooding that predates the widespread late wisconsin floods a correlation of distal tephra layers at two other sites in the scabland and palouse establishes a chronostratigraphic link to a still older episode of flooding within the brunhes normal polarity chron six distal tephra layers in pre late quaternary loess that are not correlated with known or dated eruptions have compositions and distinctive stratigraphic positions relative to magnetic reversal boundaries that make them key markers for future work

local and remote forcing of currents and temperature in the central southern california bight 1 a comprehensive study of the central southern california bight shows that subtidal currents are dominated by relatively long time scales 10 25 days large alongshore scales and significant offshore and upward phase propagation a one dimensional model shows that observed fluctuating poleward propagating speeds 140 260 cm s 1 alongshore pressure gradient disturbances account for a much larger fraction of the alongshore velocity variance than local wind stress at least 40 in both seasons and have the longer periods of the dominant currents with the addition of local wind stress about half the velocity variance can be accounted for and overall about 5 more variance in spring than in summer results are consistent with generation of disturbances by remote wind stress several hundred kilometers equatorward of the bight and alongcoast propagation as low mode coastally trapped waves the large scale remote forcing is also responsible for much of the velocity variance on the adjacent shelf the semienclosed santa monica bay a nonlinear three dimensional model shows that water is pushed into the bay initially as part of a throughflow later becoming an eddy that gradually fills the bay producing counterflow on its shoreward side on the shelf local alongshore wind stress accounts for only 25 of the velocity variance in spring and none in summer the large scale disturbances also produce significant temperature fluctuations throughout the region via lateral advection of the mean alongshore temperature gradient local wind driven coastal upwelling is responsible for temperature fluctuations on the inner shelf during several 2 4 day events in spring but only very near the coastal wall

upper quaternary geology of the lower carcarana basin north pampa argentina abstract the geological evolution of the lower carcarana basin reflects a sequence of dry and humid climates from a geomorphological point of view the area belongs to the pampean eolian system the geomorphological units comprise several fluvial geoforms partially masked by a loess carpet on which eolian erosive forms developed the sedimentary record is not simple the typical profile begins with a predominantly eolian unit composed of silty sand and including two pedogenic levels carcarana fm the formation is the result of the reworking of a dune field in the pampean sand sea is4 it is upper pleistocene in age is 3 another somewhat different climatic deterioration followed related to the begining of the last glacial maximum is 2 which caused the deposition of a loessic mantle tezanos pinto fm subsequent evolution of the climate involved a shift to humid conditions during the hypsithermal period generating a well developed soil at the top of the formation an upper holocene eolian layer san guillermo fm covers the whole sequence at the river margins of the basin the late pleistocene lower holocene eolian deposits are replaced by a complex silty clayey sequence mainly paludal with a soil complex in the middle of the section lucio lopez fm

late quaternary paleoenvironments and paleoclimatic conditions in the distal andean piedmont southern mendoza argentina abstract the andean piedmont of mendoza is a semiarid region covered by extensive and partially vegetated dune fields consisting of mostly inactive aeolian landforms of diverse size and morphology this paper is focused on the san rafael plain srp environment situated in the distal andean piedmont of mendoza 34 30 s and reports the sedimentology and osl chronology of two representative exposures of late quaternary deposits including their paleoenvironmental and paleoclimatic significance eleven facies including channel floodplain fluvio aeolian interaction and reworked pyroclastic and aeolian deposits were described and grouped into two facies associations fa1 and fa2 fa1 was formed by unconfined sheet flows minor channelized streams and fluvial aeolian interaction processes fa2 was interpreted as aeolian dune and sand sheet deposits osl chronology from the srp sedimentary record indicates that between ca 58 39 ka and ca 36 24 ka mis 3 aggradation was governed by ephemeral fluvial processes fa1 under generally semiarid conditions during mis 2 the last glacial maximum ca 24 12 ka a major climatic shift to more arid conditions is documented by significant aeolian activity fa2 that became the dominant sedimentation process north of the diamante atuel fluvial system the inferred paleoenvironmental conditions from the srp sections are in broad agreement with regional evidence

geomorphology and late quaternary of the chaco south america the chaco is a large tropical plain located in the interior of south america consisting of parts of argentina paraguay and bolivia it is 840 000 km2 in area and is characterized by forests savannas and extensive swamps which give it a marked climatic and biogeographic identity it encompasses five huge alluvial fans built by the major rivers which cross the region salado bermejo pilcomayo parapeti and grande the fans are composed of several sedimentary units deposited during different times of the late quaternary under diverse climates two fluvial terraces appear at the apex of each fan the older one is probably late pleistocene in age the second was formed in postglacial times humid climates such as the present one favoured the generation of soils and stable fluvial belts drier climates led to widespread sedimentation along small ephemeral channels and large spill outs during two intervals on in the late quaternary glacial maximum and the late holocene dry climates occurred in the region leading to the formation of dune fields and loess mantles

radiocarbon ages and environments of deposition of the wono and trego hot springs tephra layers in the pyramid lake subbasin nevada abstract uncalibrated radiocarbon data from core plc92b taken from wizards cove in the pyramid lake subbasin indicate that the trego hot springs and wono tephra layers were deposited 23 200 300 and 27 300 300 14 c yr b p uncorrected for reservoir effect sedimentological data from sites in the pyramid lake and smoke creek black rock desert subbasins indicate that the trego hot springs tephra layer was deposited during a relatively dry period when pyramid lake was at or below its spill point 1177 m to the winnemucca lake subbasin the wono tephra layer was deposited when lake depth was controlled by spill across emerson pass sill 1207 m to the smoke creek black rock desert subbasin 18 o data from core plc92b also support the concept that the trego hot springs tephra fell into a relatively shallow pyramid lake and that the wono tephra fell into a deeper spilling lake

quaternary evolution of the cordillera frontal piedmont between c 33 and 34 s mendoza argentina fil zarate marcelo aristides consejo nacional de investigaciones cientificas y tecnicas instituto de ciencias de la tierra y ambientales de la pampa universidad nacional de la pampa facultad de ciencias exactas y naturales instituto de ciencias de la tierra y ambientales de la pampa argentina

geochemical stability of fine grained silicic holocene tephra in iceland and scotland this paper tests two assumptions fundamental to the use of fine grained silicic tephras from iceland for creating chronological frameworks in northwest europe it is shown firstly that glass shards can retain their overall chemical integrity on at least a four millennial time scale in contrasting depositional environments in iceland and scotland and secondly that an acid digestion process the most practical method for extracting tephra from peat does not significantly bias the results of major element analysis by electron microprobe the implication is that there is great potential and an appropriate method for developing both the resolution and the spatial coverage of chronologies based on silicic icelandic tephras in northwest europe

internal tide scattering at the line islands ridge 1 scattering of the m2 mode one internal tide from the line islands ridge is examined with a primitive equation numerical model model runs with baroclinic and barotropic forcing are performed to distinguish scattered from locally generated internal tides tpxo 5 tidal model sea surface elevations provide barotropic forcing while for the run with baroclinic forcing a mode one m2 energy flux of 1000 w m 1 is used to represent energy fluxes emanating from the hawaiian ridge scattering redistributes more energy flux from mode one than is locally generated in mode one for the higher modes scattering and generation contribute equally in terms of the overall energy flux spatial and modal distributions of energy density and flux show internal tide scattering dominates at hutchinson seamount while higher modes are generated locally at sculpin ridge hutchinson seamount s slopes are steeper over a greater continuous area than sculpin ridge scattered energy is found downstream of the steepest topographies similar to simulations with idealized gaussian ridges at the line islands ridge 37 of the incident mode one energy flux is lost because of scattering into modes 2 5 19 dissipation by the model s turbulence parameterization 15 and nonlinear transfer to the m4 internal tide 3 two topex ground tracks pass through the model domain roughly normal to the ridge topography and confirm the general features of the modal and spatial distribution found in the model in the topographically rough western pacific internal tide scattering may be a significant source of energy for mixing away from topography

the cimmerian orogeny in northern iran tectono stratigraphic evidence from the foreland from the permian onwards the gondwana derived iran plate drifted northward to collide with eurasia in the late triassic thereby closing the palaeotethys this eo cimmerian orogeny formed the cimmeride fold and thrust belt the upper triassic middle jurassic shemshak group of northern iran is commonly regarded as the cimmerian foreland molasse however our tectono stratigraphic analysis of the shemshak group resulted in a revised and precisely dated model for the triassic jurassic geodynamic evolution of the iran plate initial cimmerian collision started in the carnian with subsequent late triassic synorogenic peripheral foreland deposition flysch lower shemshak group subduction shifted south in the norian onset of neotethys subduction below iran and slab break off around the triassic jurassic boundary caused rapid uplift of the cimmerides followed by liassic post orogenic molasse middle shemshak group during the toarcian aalenian upper shemshak group neotethys back arc rifting formed a deep marine basin which developed into the oceanic south caspian basin during the late bajocian late jurassic

chronology of late pleistocene pampa loess from the cordoba area in argentina in argentina loess palaeosol sequences were studied from the two sections at monte ralo and corralito located near to the city of cordoba in the east of the pampean ranges infrared optically stimulated luminescence irsl and thermoluminescence tl dating techniques were applied to set up a more reliable chronological framework for the upper pleistocene loess record irsl ages increase with depth and are stratigraphically consistent the oldest loess exposed correlates at least to the penultimate glaciation the luminescence dating study gives evidence for humid climate conditions with soil formation during the last interglacial period and the middle pleniglacial correlating to marine isotope stage mis 5 and 3 respectively three extended periods of soil formation are recorded in the loess palaeosol sequences at the corralito section these buried soils most likely correlate with the last interglacial and early last glacial period during the middle pleniglacial two palaeosols are intercalated in the loess successions in the cordoba area the periods of increased loess accumulation and deposition of loessic sediments correlate with more arid and glacial periods during the early pleniglacial the middle pleniglacial and the late glacial copyright 2009 john wiley sons ltd