using 137cs and 210pbex measurements to estimate soil redistribution rates on semi arid grassland in mongolia abstract in this study two small experimental catchments were selected in semi arid grassland in mongolia the kherlen bayan ulaan kbu catchment has been subjected to intensive grazing as a wintering shelter for domestic livestock animals and the number of livestock animals in the baganuur bgn catchment has been increasing over the last few decades the rates and patterns of soil erosion within the catchments were estimated based on cesium 137 137 cs and lead 210 210 pb ex inventories in bulk soil core samples the medium term 40 years soil erosion rates based on the 137 cs measurements indicated that annual soil loss from the kbu catchment was approximately three times greater than that from the bgn catchment the 137 cs derived rates and patterns of soil erosion indicated that soil in the kbu catchment was susceptible to surface erosion with facilitated transport of eroded sediment to the catchment outlet the 210 pb ex derived soil erosion rates were generally greater than those derived from 137 cs in both catchments if we assume that the soil erosion rate has been increasing with increasing domestic livestock numbers the most plausible explanation is that the 210 pb ex derived estimates represent recent increases in soil erosion furthermore the 210 pb ex 137 cs inventory ratio showed a tendency to increase with downslope distance on the eroded hillslope in the bgn catchment assuming that the increase in inventory ratio is a result of constant fallout input of 210 pb ex on the eroded sediment during its transportation along the hillslope the 210 pb ex inventory may not be suitable to estimate soil erosion rates at sites where downslope movement of sediment is slow further discussion regarding interpretation of 210 pb ex derived soil loss is required and the applicability of the 210 pb ex technique on semi arid hillslopes remains to be determined

the petrology of a large intra oceanic silicic eruption the sandy bay tephra kermadec arc southwest pacific abstract the pumiceous pyroclastic deposits known as the sandy bay tuff on macauley island in the kermadec group represent a medium scale silicic eruption in an oceanic subduction setting the sandy bay eruption occurred about 6310 yr bp forming a large submarine caldera in the summit of the mainly submarine and essentially basaltic macauley volcano the sandy bay magma contained

the 137cs technique applied to steep mediterranean slopes part i the effects of lithology slope morphology and land use concentrations in the soil of anthropogenic and natural radionuclides have been investigated in order to assess the applicability of the cs 137 technique in an area of typical mediterranean steep slopes this technique can be used to estimate net soil redistribution rates but its potential in areas with shallow and stony soils on hard rock lithology have not been evaluated so far in this research the validity of using this technique in stony shallow soils at very steep slopes is discussed together with the relations between radionuclide concentrations and other soil properties lithology slope morphology and land use in a mediterranean environment both natural potassium 40 4 k uranium 238 u 238 thorium 232 th 212 and anthropogenic caesium 137 cs 137 radionuclides have been determined in samples taken along slope transects on uncultivated serpentinite soils and cultivated gneiss soils in addition to the radionuclide concentrations parameters such as slope position slope angle aspect soil depth surface stone cover moss litter vegetation cover soil crust stone content and bulk density have been quantified all the natural radionuclides k 40 u 238 th 232 show significantly higher concentrations in the gneiss than in the serpentinite soils opposed to the cs 137 concentration which is found significantly higher in the serpentinite soils probably because of the difference in clay mineralogy the exponential decreasing depth distribution of cs 137 and its homogeneous spatial distribution emphasise the applicability of the cs 137 technique in this ecosystem lithology determines the concentration of natural and anthropogenic radionuclides land use determines the relations between cs 137 concentration inventory and some soil characteristics higher cs 137 concentration and inventory are associated with higher percentages of vegetation cover higher percentage of stones in the soil and higher values of soil bulk density in cultivated gneiss soils slope morphology and land use influence the soil redistribution at slope scale the gneiss slopes show a zonation of four to five areas of differential erosion accumulation processes corresponding with more regular slopes and soil redistribution due to water erosion and to tillage translocation and erosion the serpentinites as an example of a more unstable slope type show more erosion areas with less accumulation downslope and soil redistribution due to water erosion c 2003 elsevier b v all rights reserved

tephra beds in deep sea cores off northern new zealand implications for the history of taupo volcanic zone mayor island and white island volcanoes twenty piston cores were collected from water depths of 650 3300 m from offshore bay of plenty north island new zealand they contain tephra from 11 okataina volcanic centre and 4 taupo volcanic centre rhyolite eruptions during the last 50 kyr that produce a tephrostratigraphic framework across the tectonically and volcanically complex region of southern havre trough alderman trough and the bay of plenty continental shelf this allows correlation between offshore and onshore sequences up to 200 km from source volcanoes covering much of marine isotope stages 3 and 2 the framework temporally constrains poorly dated and newly recognised volcanic events macroscopic tephra layers from the peralkaline mayor island volcano are documented for the first time at pre 50 post 50 40 5 37 4 22 2 and 14 2 ka in addition to the well known 7 ka tuhua event these macroscopic layers represent some of the most explosive events from this volcano and provide new marker horizons they are dispersed up to 90 km north east to east of the edifice minor tephra dispersal is also recorded at 17 8 25 5 35 and pre 50 ka the tephra contain high sio2 73 75 5 wt glass and subordinate basaltic components and each tephra represents a distinct magma batch that can be fingerprinted the mayor island tephra form two temporal trends toward less evolved magma compositions punctuated by a large caldera forming event at 36 ka the historically active andesitic white island volcano does not have widely dispersed tephra and the oldest primary deposit found is 21 ka five pre 50 ka rhyolite eruptions from an unknown taupo volcanic zone source provide evidence for explosive activity in a time interval poorly documented on land the cores demonstrate the patchy and uneven preservation of large magnitude tephra falls caused by local faulting bioturbation and ponding in bathymetrically complex regions reworked tephra layers are common and often lack indicative lithological features such units could easily be misinterpreted as primary events without micro beam geochemical analyses of glass shards

ocean current and temperature time series at brothers volcano 1 time series of currents and temperatures were acquired near surface and at depth on three moorings above brothers volcano 34 52 25 s 179 04 e 25 km west of the kermadec ridge and 300 km northeast of the north island new zealand from september 2004 to may 2005 ocean current time series were previously unavailable within 300 km of this site and few such measurements exist anywhere near magmatically or hydrothermally active volcanoes such as brothers energy in near surface currents 163 527 m depth was primarily subtidal 64 subtidal motions to 527 m depth are shown to be reasonably well correlated with geostrophic currents derived from satellite sea level anomalies although the moorings were separated laterally by only 11 km the upper current meters also recorded significant differences in m2 tidal currents indicating the presence of significant internal tides at this site below volcano summit depth 1220 m the kinetic energy of currents was primarily tidal 54 longer period currents at depth evidenced the influence of volcano topography temperature time series showed a 3 month period of sharply decreased temperature that extended in depth from 163 m to at least 1260 m advanced very high resolution radiometer avhrr sea surface temperature data show colder surface water immediately above and north of brothers over the same time period these data together with the velocity records suggest an anomalous deep cold water mass arrived and lingered over brothers for 3 months in the austral late spring and early summer of 2004 2005

testing the validity of upslope migration in banded vegetation from south west niger abstract recent studies of banded vegetation have suggested a successional model in which bare bands are colonised in a pioneer front on the upslope side of a vegetation band vegetation patterns in south west niger have been interpreted to suggest that spatial transitions reflect this form of temporal succession and in these patterns there is corroborating evidence for slow up slope migration however given the inherent difficulties of long term field experiments there are few data to judge the validity of this model the use of the artificial radionuclide caesium 137 137 cs to provide information on net soil flux over the past ca 30 years offers potential in this regard furthermore the identification of various types of soil crust which can induce different types of hydrological behaviour provides valuable information for predicting soil evolution to test the hypothesis that banded vegetation migrates upslope a 70 m transect encompassing two vegetation bands and a single bare lane was sampled in south west niger the transect was aligned orthogonal to the bands and approximately parallel to the direction of water soil and nutrient flow soil samples for gamma ray spectrometry and particle size analysis were collected along the transect at 21 locations with 1 m intervals in the lower part and three samples were obtained on the upper part prior to collection the soil surface characteristics were examined to distinguish between crust types and to identify the presence of termite activity the results demonstrate the utility of these techniques for examining the net redistribution of soil over a period of three decades and its relations to vegetation succession the amount of soil eroded was found generally to decrease downslope whilst the proportion of fine silt in the soil generally increased downslope these patterns correspond with the location of the erosion and sedimentation crusts identified using a standardised classification the relations between microtopography and net soil flux may also explain some of the spatial variation in soil redistribution processes the intensity of crust and 137 cs measurements on the upslope edge of the lower vegetation band enabled the calculation of the upslope migration rate ca 0 19 0 27 m yr 1 which coincided with independent studies in the same region however because considerable spatial variations in topography and soil flux were found to occur over very small distances further detailed studies over larger areas will be needed

the geochemistry of rock and water samples from curtis island volcano kermadec group southwest pacific abstract curtis island is the emergent summit of a dacitic volcano straddling the kermadec ridge with a well developed crater which exhibits mild solfataric activity apart from several narrow dacitic dykes the island is composed entirely of pumiceous pyroclastic deposits containing clasts which are mainly dacitic to rhyolitic in composition but include rare basalt their chemistry is comparable to that of rocks forming other islands of the kermadec group boiling and hot springs produce dilute acid sulphate waters that are believed to form from steam and h2s gas condensing and mixing with rain water this probably descends into the vent area and is then expelled hydrothermal alteration has produced a mineral suite dominated by natroalunite chlorite quartz diaspore and smectites reflecting both the high al fe and mg contents of the crater floor rocks and the low ph of the altering fluids

influence of inheritance and pedogenesis on heavy metal distribution in soils of sicily italy abstract the recognition of the potential health hazards associated with heavy metals has focused attention on the levels and behaviours of these elements both in natural and contaminated environments various soil types developed from different parent materials in sicily italy have been analysed in order to compare heavy metal distribution under different geopedological conditions total metal concentrations metal partitioning and distribution profiles are discussed in relation to the inheritance factor and pedogenic processes parent material composition largely influences the contents of heavy metals in most of the analysed soils mainly differentiating pedons for their metal concentration on the basis of sedimentary and volcanic parent materials however an exception is represented by the carbonate free alfisols and mollisols which are markedly enriched in heavy metals with respect to the underlying limestones and calcarenites on the basis of chemical and mineralogical results supported by data from sequential extraction sep heavy metal enrichment in these soils is associated with the formation of common to abundant fe mn oxides and clay accumulation for mollisols there is evidence for a major role of organic matter in heavy metal retention in surface horizons in the other pedons pedogenic processes appear to mainly influence the redistribution of heavy metals throughout the soil horizons rather than affecting the total content argillopedoturbation seems to be responsible for a uniform distribution of heavy metals in vertisol profiles on marly clays accumulation of heavy metals in the topsoil of inceptisols on clays with gypsum and entisols on gypsarenites and diatomites is caused partially by adsorption on organic matter and mainly by dissolution of primary gypsum and opal a a pedogenic influence is less evident in young andisols whose heavy metal composition greatly reflects that of hawaiitic pyroclastic deposits interbedded within the profiles however a certain redistribution of cu accumulated as metal organic matter complexes is evidenced in the surface horizon by sep

origin of spectacular fields of submarine sediment waves around volcanic islands understanding how large eruptions and landslides are recorded by seafloor morphology and deposits on volcanic island flanks is important for reconstruction of volcanic island history and geohazard assessment spectacular fields of bedforms have been recognised recently on submerged flanks of volcanic islands at multiple locations worldwide these fields of bedforms can extend over 50 km and individual bedforms can be 3 km in length and 150 m in height the origin of these bedform fields however is poorly understood here we show that bedforms result from eruption fed supercritical density flows turbidity currents in some locations but most likely rotational landslides at other locations general criteria are provided for distinguishing between submarine bedforms formed by eruptions and landslides and emphasise a need for high resolution seismic datasets to prevent ambiguity bedforms associated with rotational landslides have a narrower source with a distinct headscarp they are more laterally confined and internal bedform structure does not suggest upslope migration of each bedform eruption fed density currents produce wide fields of bedforms which extend radially from the caldera internal layers imaged by detailed seismic data show that these bedforms migrated up slope indicating that the flows that produced them were froude supercritical due to the low density contrast between interstitial fluid and sediment the extent and dimensions of submarine eruption fed bedforms is much greater than those produced by pyroclastic density currents on land

tracking textural mineralogical and geochemical signatures in soils developed from basalt derived materials covered with loess sediments sw poland abstract this study investigates the scale of inheritance of signatures typical of loess and basalt derived substrates in soils having both components present as parent material due to past periglacial processes based on field description particle size distribution mineralogy heavy minerals and clay minerals as well as geochemistry we track the signal of both materials local basalt derived and loess derived estimate the maximum thickness of loess mantles and mixed zones having both loess and basaltic components and note the presence or absence of basal layers without allochtonous additions the results show that geochemistry and heavy minerals are the most reliable proxies for a verification of aeolian silt contributions and to define individual layers in complex soil parent materials soil formation in the studied landscape depends on the type of slope sediments typical fine grained weathering of basalt without input from aeolian silt would promote rather vertic development however in thick loess deposits as well as in thin silt textured materials superimposed on clay loam beds clay illuviation dominates development of argic horizons however results in decreasing permeability promoting water stagnation and enhanced degradation processes in clay rich subsoil instead of luvisols stagnosols and retisols developed in the study regions basaltic block covers mixed with loess host cambic horizons based on our findings it seems that at the edge of thin loess deposits no soils exist that developed exclusively from basaltic parent materials

residual flows in cook strait a large tidally dominated strait abstractflows at subtidal frequencies are resolved from 20 months of current observations at multiple sites across the narrows of cook strait new zealand the substantial tidal flows spring tides 3 m s 1 are challenging to measure with moored adcps along strait residual flows are on the order of 0 05 0 1 m s 1 but there were differences across the strait and also through the annual cycle the calculated net residual transport is 0 25 sverdrups sv 1 sv 106 m3 s 1 i e negative sign implies to the south from tasman sea to pacific ocean this is smaller by a factor of 2 3 than that estimated from previous sparse current measurements crucially however these new data also suggest that over the austral summer autumn period there is persistent residual flow northward on the western side of the strait so that the summer autumn net 0 15 sv flow can be separated into 0 065 sv westside and 0 22 sv eastside flow this western northward flow had a seasonal bias appearing only in the summer

small scale features of temperature and salinity surface fields in the coral sea the small scale features in sea surface temperature and salinity fields sst and sss of the coral sea are examined using high horizontal spatial and short term temporal in situ measurements these features are extracted from thermosalinographs tsgs gathered onboard commercial and research vessels and at one long term fixed station the analyses are performed along the vessel tracks and the structures of small scale features are extracted by high pass spatial filtering the original tsg data for sss it is shown that the features at the scale of mesoscale eddies approximate to 100 km vary from about 1 1 to 0 6 psu in the coral sea region processes sustaining such range include rainfall events stirring by mesoscale eddies and the latitudinal displacement of the sharp front associated with the edge of the western pacific warm pool at the seasonal time scales the tsg data have revealed the presence of a sharp front 0 4 0 6 psu between the subtropical and equatorial waters instead of a smooth gradient in the standard sss climatologies within the context of recent remotely sensed observations of salinity this could represent an important limitation for the validation and calibration of satellite products in addition to these spatial considerations temporal variations at one long term station near vanuatu show that the coupled air sea responses to intraseasonal tropical variability such as the madden julian oscillation may have a signature in both sst and sss fields however this response is found to be complex and not necessarily in phase in the coral sea region our results suggest that mjo induced variability on sst and sss exhibit little coherency at the seasonal time scales

submarine pyroclastic deposits formed at the soufriere hills volcano montserrat 1995 2003 what happens when pyroclastic flows enter the ocean the soufriere hills volcano montserrat west indies has undergone a series of dome growth and collapse events since the eruption began in 1995 over 90 of the pyroclastic material produced has been deposited into the ocean sampling of these submarine deposits reveals that the pyroclastic flows mix rapidly and violently with the water as they enter the sea the coarse components pebbles to boulders are deposited proximally from dense basal slurries to form steep sided near linear ridges that intercalate to form a submarine fan the finer ash grade components are mixed into the overlying water column to form turbidity currents that flow over distances 30 km from the source the total volume of pyroclastic material off the east coast of montserrat exceeds 280 106 m3 with 65 deposited in proximal lobes and 35 deposited as distal turbidites

late quaternary tephra layers around raoul and macauley islands kermadec arc implications for volcanic sources explosive volcanism and tephrochronology a suite of deep sea cores were collected along transects up to 100 km across the fore arc and back arc regions of the predominantly submarine kermadec arc near raoul and macauley islands southwest pacific the cores reveal a macroscopic tephra record extending back 50 ka this is a significant addition to the dated record of volcanism previously restricted to fragmented late holocene records exposed on the two islands the 27 macroscopic tephra layers display a wide compositional diversity in glass 50 78 wt sio2 many tephra layers comprise silicic shards with a subordinate mafic shard population this could arise from magma mingling and may reflect mafic triggering of the silicic eruptions broadly the glass compositions can be distinguished on diverging high k and low k trends most likely arising from different source volcanoes this distinction is also reflected in the tephra records exposed on raoul low k and macauley high k islands the likely source areas heterogeneous tephra comprising shards of both high and low k affinity silicic and mafic compositions and more homogeneous tephra with subordinate outlier shard compositions are best explained by post depositional mixing of separate eruption deposits or contemporaneous eruptions evidently the slow sedimentation rates of the calcareous oozes 101 102 mm ka 1 were insufficient to adequately separate and preserve closely spaced eruption deposits this exemplifies the difficulty in assessing eruption frequencies and magmatic trends and erecting a tephrostratigraphy using geochemical fingerprinting in such environments despite these difficulties the ca 5 7 ka sandy bay tephra erupted from macauley island can be correlated over a distance of 100 km extending east and west of the island showing that the mostly submerged volcanoes are capable of wide tephra dispersal hence there is potential for developing chronostratigraphies for the southwest pacific beyond the region covered by the extensive rhyolite marker beds from the taupo volcanic zone

bedforms on the submarine flanks of insular volcanoes new insights gained from high resolution seafloor surveys a comparative analysis of bedform fields along the submarine flanks of insular volcanoes characterized by different morpho structural settings volcanic and meteo marine regimes vanuatu kermadec bismark madeira and aeolian archipelagos is presented here to provide insights on the size distribution morpho dynamic and genesis of such bedforms two main types of bedforms are recognized according to their size location and preconditioning triggering processes small scale bedforms have wavelengths of tens to hundreds of metres and wave heights of metres because of their small size they are typically not recognizable at water depths greater than 400 m from vessel mounted bathymetric surveys however few examples of small scale bedforms are reported from upper volcanic flanks where steep gradients commonly hinder their formation their recognition is mostly limited to the thalweg of shallow and flat bottomed channels that carve the insular shelf on slope gradients 15 small scale bedforms are mostly related to erosional depositional processes due to sedimentary gravity flows that are often the result of a cascading effect between volcanic and non volcanic processes for example flood discharges and retrogressive landslides large scale bedforms occur at all water depths having wavelengths of hundreds thousands of metres and wave heights up to few hundreds of metres the origin of large bedforms is more difficult to ascertain especially if only bathymetric data are available some diagnostic criteria are presented to distinguish between bedforms associated with landslide deposits and those associated with density currents in this latter case relevant sediment sources and slope gradients 8 are key factors for bedform development erosional depositional bedforms are typically related to eruption fed density flows formed during large caldera collapses or to large turbidity flows bedforms generated by turbidity flows are often observed in the lower volcanic flanks where an abrupt decrease of gradients is present often matching a change from confined to unconfined settings in summary this study provides insights to interpret bedforms in modern and ancient marine volcaniclastic settings elsewhere

geochemical behaviour of ni cr cu zn and pb in an andosol cambisol climosequence on basaltic rocks in the french massif central abstract the objective of this study is to identify parameters influencing trace elements te vertical distributions in an andosol andic cambisol climosequence in order to understand processes involved in the current distribution of trace elements from basaltic rocks to associated soils six pedons developed on tertiary massive basaltic formations located at similar position in the hill slopes submitted to the same wet mountainous climate but under various microclimatic conditions altitude and annual rainfall were considered the six studied soils are andic and rich in organo metallic complexes two different and quantitative methods were used to compare the geochemical distributions of major and trace elements both being calculated with ti as invariant element isovolumetric mass balance and enrichment factors anthropogenic pedogenetic microclimatic inherited factors were discriminated anthropogenic influences are pointed out for k in two pedons and for pb in all studied sites distributions of other te are affected by discontinuities between underlying rocks and soil horizons zinc and cu distributions are controlled by organic matter whereas cr and ni distributions are influenced by pedogenetic processes results emphasize the relative trace element immobilization in andic soils under temperate climate

the 137cs technique applied to steep mediterranean slopes part ii landscape evolution and model calibration over the past years the caesium 137 cs 137 technique has been successfully applied in numerous environments all over the world this technique is using the worldwide distribution of the anthropogenic cs 137 radionuclide and its redistribution associated with soil particles as an effective estimation of net soil loss rates in contrast to numerous studies on deep often cultivated clay soils with gentle to intermediate slopes typical mediterranean shallow stony soils on steep slopes have received less attention in this paper the landscape evolution over the past 37 years has been evaluated using the cs 137 technique for two lithological different areas under contrasting land use in the alora case study area malaga spain in soils on gneiss and serpentinite bedrock several transects have been selected on steep slopes up to 35 with mean soil depths from 37 cm for gneiss to 24 em for serpentinite estimating net soil redistribution rates from radionuclide distributions depends on the calculation of the local area reference inventory and the used calibration technique several methods have been tested and final results were found to differ considerably after careful parameter selection the resulting net soil redistribution estimates for the different transects have been compared with simulations of a simple landscape evolution model resulting in different possible scenarios of erosional response total net soil loss for the study area range from 2 3 0 25 to 69 1 7 8 t ha 1 year 1 for serpentinite and gneiss slopes respectively differences in total slope sediment budgets as well as differences along the transeets reveal influences of landscape representation and land use in this case the impact of soil translocation by tillage and resulting erosion rates are far more important than possible parent material induced differences however comparing the two sampled areas not only net rates but spatial patterns as well reveal important differences in distribution over the landscape of net erosion and net sedimentation zones c 2003 elsevier b v all rights reserved

multiple sources for sea rafted loisels pumice new zealand sea rafted loisels pumice is one of the few stratigraphic markers used to correlate late holocene coastal deposits in new zealand along with underlying sea rafted products of the local taupo eruption of ca 1800 yr b p these events have been used to bracket the first arrival of humans at new zealand loisels pumice is dacitic to rhyolitic sio263 78 wt in composition but individual clasts are homogeneous sio2range 1 wt characteristics include very low k2o 0 5 1 75 wt and rb 25 ppm and a mineralogy dominated by calcic and mafic xenocrysts similar features are shared by pumices of the tonga kermadec arc suggesting a common tholeiitic oceanic source interclast diversity of loisels pumice suggests that it is the product of several eruptive events from different volcanoes the differences in glass and mineral compositions found at various sites can be explained if the deposits are from different events a multisource origin can also partially explain the discrepancy in reported14c ages ca 1500 600 yr b p from different localities therefore the value of loisels pumice as a stratigraphic marker is questionable and it does not constrain the arrival of humans the predominant westward drift of historic tonga kermadec arc pumices and prevailing ocean currents suggest a long anticlockwise semicircular transport route into the tasman sea before sea rafted pumice arrival in new zealand the diversity of the pumices indicates that silicic eruptions frequently occur from the predominantly basic oceanic volcanoes

assessment of trace elements in yercaud lake sediments southern india lake sediments are major sink for carbon and trace elements lake water and sediments need to be monitored continuously for environmental and geochemical explorations in the present study sediment characteristics source and distribution of trace metals fe mn cr cu ni co pb and zn of yercaud fresh water lake sediments south india situated at an elevation of 1515 m asl is presented twenty five surface sediments were collected covering the entire expanse of the lake in a gridded pattern detailed chemical analyses reveal the following decreasing order of elements fe cu cr mn zn ni co pb geoaccumulation index enrichment factor contamination factor and pollution load index were calculated to evaluate the ecological impacts of these trace metals in the sediments the index calculation indicates that all the trace elements were derived from natural process but there are indications of anthropogenic activities the study area was found to be highly contaminated with cu moderately contaminated with cr and co considerably contaminated with pb zn and ni and uncontaminated with mn the spatial distribution of the trace elements supports the strong association of sediment fine fraction and organic matter the statistical principal component analysis also confirms that the concentration of cr cu fe and mn was mainly derived from the natural weathering and non point agricultural sources pb and zn arise due to the confluence of sewage effluents traffic and boat activities these elements need to be further evaluated for pollution control and prohibiting further deterioration in the yercaud lake

flows in the tasman front south of norfolk island the tasman front is a narrow band of eastward flowing subtropical water crossing the tasman sea from australia to north cape new zealand it is the link between the two subtropical western boundary currents of the south pacific the east australian current eac off eastern australia and the east auckland current eauc off northeastern new zealand here we report the first direct measurements of flow in the tasman front from a moored array deployed across gaps in the submarine ridges south of norfolk island and hydrographic and adcp measurements during the deployment and recovery voyages the mean flow through the array over july 2003 to august 2004 was found to be eastward only in the upper 800 m with a transport of 6 sv below 800 m a weak westward mean flow 1 5 sv was measured associated with antarctic intermediate water aaiw using sea surface height to account for additional transport south of the moored array results in a total mean eastward transport between norfolk island and north cape new zealand of 8 sv varying between 4 and 18 sv the measurements show that the tasman front is much shallower than either the eac or eauc both of which extend below 2000 m depth has less transport than either the eac or eauc and has instances of flow reversal thus the tasman front is a weaker connection between the eac and eauc than the paradigm of a contiguous south pacific western boundary current system would suggest

137cs dating of lacustrine sediments and human impacts on dalian lake qinghai province china cs 137 and grain size analyses indicate the total amounts of cs 137 deposited by wind and water in the dalian lake of gonghe basin qinghai province the vertical profile of cs 137 in the lacustrine sediments shows three cs 137 activity peaks and one trough the main peak corresponds to the global cs 137 fallout in 1963 the two secondary peaks correspond to the leakage of the chernobyl reactor in 1986 and complete desiccation of the lake in 1994 the trough corresponds to aeolian deposition caused by extensive reclamation of farmland in late 1980s and early 1990s the cs 137 dating was used to evaluate sedimentation rates in dalian lake since 1963 they are divided into three periods two with slow deposition 1963 1986 and 1994 1998 and one with rapid deposition 19861994 cs 137 seems to have the same potential for indicating environmental changes and human interference in the and and semiarid regions as in humid regions c 2002 elsevier science b v all rights reserved

southwest pacific ocean response to a warming world using mg ca zn ca and mn ca in foraminifera to track surface ocean water masses during the last deglaciation in situ measurements of mg ca zn ca mn ca and ba ca in globigerinoides bulloides and globigerina ruber from southwest pacific core top sites and plankton tow are reported and their potential as paleoproxies is explored the modern samples cover 20 degrees of latitude from 34 degrees s to 54 degrees s 7 19 degrees c water temperature and variable influence of subantarctic saw and subtropical stw surface waters trace element signatures recorded in core top and plankton tow planktic foraminifera are examined in the context of the chemistry and nutrient profiles of their modern water masses our observations suggest that zn ca and mn ca may have the potential to trace saw and stw intraspecies and interspecies offsets identified by in situ measurements of mg ca and zn ca indicate that these ratios may also record changes in thermal and nutrient stratification in the upper ocean we apply these potential proxies to fossilized foraminifera from the high resolution core md97 2121 at the last glacial maximum surface water mg ca temperature estimates indicate that temperatures were approximately 6 7 degrees c lower than those of the present accompanied by low levels of mn ca and zn ca and minimal thermal and nutrient stratification this is consistent with regional dominance of saw and reduced stw inflow associated with a reduced south pacific gyre spg upper ocean thermal and nutrient stratification collapsed during the antarctic cold reversal before poleward migration of the zonal winds and ocean fronts invigorated the spg and increased stw inflow in the early holocene together with reduced winds this favored a stratified upper ocean from circa 10ka to the present

from andic non allophanic to non andic allophanic inceptisols on alkaline basalt in mediterranean climate a toposequence study in the marghine district sardinia italy abstract the properties of a non andic allophanic inceptisol pom1 and two andic non allophanic inceptisols flm5 and spm8 representative of a toposequence on basanite rocks of mt st antonio central western sardinia marghine sub region were analyzed to better elucidate factors and processes that lead to a different expression of andic properties and allophane formation in xeric mediterranean environment a series of laboratory techniques including physical chemical micromorphological x ray diffraction xrd scanning electron microscopy sem analyses were used all soils are usually rich in organic carbon dystric at the great group level with saturation base from 72 to 10 and with ph from subalcaline to acidic allophanic inceptisol appears more intensely weathered than non allophanic inceptisols volcanic glass content is in any case negligible pom1 formed on the plateau shows a shallow solum 45 cm with a 2 horizon that meets all the criteria for andic soil properties the amounts acid oxalate extractable al o and si o together with pyrophosphate extractable al p typifies such a pedon as allophanic inceptisol 0 19 p al o 2 the allophanic inceptisol pom1 is located at the plateau of the toposequence where lower surface runoff greater water infiltration rate the absence of significant erosion and colluvial movement may have increased the degree of weathering processes in these conditions the prolonged soil moistness prevents the transformation of short order components on the whole the results emphasize the role of topography and the importance of al fe amorphous compounds in expressing soil andic properties and allophane content versus the volcanic origin of parent material and the insufficiency of volcanic glass the results also suggest that the occurrence of soil with andic properties and significant allophane content in hot and dry environments like the mediterranean climate in sardinia may be more widespread than expected

location and migration of miocene quaternary volcanic arcs in the sw pacific region abstract we report new ar ar and u pb ages from ten rocks in the sw pacific region our results 1 establish a northward late miocene australian plate movement rate of 57 mm a for the lord howe hotspot chain 2 reinforce the previously established widespread nature of early miocene subduction related volcanism in onland and nearshore northern new zealand 3 indicate that leucotonalite xenoliths from raoul island are the products of quaternary kermadec arc magmatism rather than being cretaceous pliocene basement a synthesis of available sw pacific data emphasises that while there is a reasonably complete record of subduction related volcanism from at least 23 ma to the present day the process of back arc basin formation is highly episodic and asymmetric subduction related arcs stabilised along the taupo kermadec tonga arc from 2 ma to the present along the taranaki colville lau trend from 17 6 ma and along the three kings ridge northland plateau northland trend from 23 18 ma south of latitude 25 s back arc basin opening occurred during the early miocene and quaternary arc volcanic episodes but does not appear to have accompanied the 17 5 ma volcanism

magnetic and chemical parameters of andic soils and their relation to selected pedogenesis factors in the case of andic soils developed on volcanic rocks permanently humid conditions are essential for andosolisation processes although volcanic rocks are usually rich in highly magnetic iron oxides knowledge about these minerals in andic soils with respect to the soil development is missing the aim of this contribution is to investigate the relationship between magnetic and basic chemical properties of soils developed on volcanic basement and parameters related to the pedogenesis factors the studied sites are located on basaltic lava flows in the eastern part of the french massif central investigated pedons with alu andic sil andic and vitric properties were pedologically described and analysed by a set of magnetic and soil chemical methods magnetic parameters include low field volume specific and mass specific magnetic susceptibility frequency dependent magnetic susceptibility remanent properties including s ratio and coercivities chemical parameters included the phh2o soil organic matter total cation exchange capacity base saturation and content of fe and al extracted in dithionite citrate acid ammonium oxalate and pyrophosphate solutions micro morphology of andosols and parent material was observed by scanning electron microscopy completed with energy dispersive spectrometry the pedogenesis factors are represented by parent rock age annual precipitation and soil thickness our findings suggest that 1 precipitation is the most important pedogenesis factor with a strong relationship to the relative magnetic grain size concentration of ferrimagnetic minerals aluminium dissolved in pyrophosphate and acid ammonium oxalate and content of organic matter 2 parent material age shows a well pronounced relationship with magnetic grain size parameters represented by the frequency dependent susceptibility and ratio of saturation remanent to saturation induced magnetisation mrs ms selective dissolution parameters and phh2o 3 thickness of soil profile shows a link to mrs ms phh2o and content of organic matter

dating of small gully formation and establishing erosion rates in old gullies under forest by means of anatomical changes in exposed tree roots southern poland abstract small gullies occur in forested gully systems on the undulating loess plateau in southern poland the old gully hillslopes are mainly covered with 200 year old beech trees in contrast with the surface of the summit plateau which is cultivated agricultural land beech roots are exposed in the gullies through erosion wood vessels in the root tree rings divide into early wood and late wood and after the roots are exposed start to make fewer vessels these anatomical changes in root tree rings allow us to date erosion episodes small gullies form in a different manner on the valley floor and on hillslopes in valley bottoms erosion features are often formed at some distance from one another and in time small gullies combine to form a single longer one depending on local conditions such as the hillslope profile hillslopes may exhibit headward erosion or may be eroded downwards hilllope gullies may be transformed into side valleys as a result of gradual widening and deepening dating the exposure of roots indicates that small gullies had already formed in the valley system by 1949 intensive gully erosion was recorded between 1984 and 2002 during intense precipitation in 1984 and of particular note during the extraordinary flood of 1997 which affected all of central europe the mean rate of small gully erosion in the old gully system studied is 0 63 m year on hillslopes the mean gully erosion rate is 0 21 0 52 m year and on the valley bottoms 0 18 1 98 m year high bottom erosion rates resulted from the emergence of long gullies during the erosion episodes in 1984 and 1997 sheet flow in valley floors intensifies at times of heavy rainfall which causes long gullies to form taking into account the fact that conditions favoured erosion the rate at which the old gullies under forest were transformed should be considered slow new side gullies form slowly within the valley and it appears that if erosion progressed at the rate observed new side valleys would take a few hundred years to form

synchrotron based speciation of chromium in an oxisol from new caledonia importance of secondary fe oxyhydroxides in new caledonia the weathering of ultamafic rocks under a tropical climate has led to the residual accumulation of trace elements in lateritic soils widely dominated by fe oxyhydroxides the speciation of trace elements such as cr ni and co in these oxisols remains a major subject of interest regarding mining and environmental issues we have assessed the speciation of chromium in the upper part of an oxisol by combining bulk and spatially resolved chemical analyses epma and sem eds with synchrotron based spectroscopic data exafs and xanes epma indicates that the main hosts for chromium in the bedrock sample are the silicates forsterite enstatite and lizardite hosting of chromium in these easily weatherable mineral species could lead to a significant loss of this element upon weathering however total analyses of major elements indicate only a slight depletion of cr together with an immobility of fe and al and drastic losses of si and mg after the weathering of the bedrock such a low mobility of chromium is likely related to its significant incorporation in goethite and hematite formed after the weathering of fe 2 bearing primary silicates this efficiency of secondary fe oxyhydroxides at immobilizing chromium is demonstrated by quantitative analysis of exafs data that indicates that these mineral species host between 67 and 75 wt of total cr compared to the 18 to 22 wt of total cr hosted by chromite in addition sem observation and sem eds analyses performed on the oxisol samples also show some evidence for chemical weathering of chromite chromite could then represent a past and or present source of chromium upon extended tropical weathering of the studied oxisol rather than a stable host these results emphasize the importance of secondary fe oxyhydroxides compared to cr spinels on chromium hosting in oxisols developed upon tropical weathering of ultramafic rocks although the trapping mechanism of chromium mainly corresponds to incorporation within the structural network of goethite and hematite sorption reactions at the surface of these mineral species could also be involved in such a process in addition considering their potential oxidative reactivity that can generate cr 6 or enhance the chemical weathering of chromite the occurrence of mn oxides could significantly modify the behavior of chromium upon weathering these considerations indicate that further studies are needed to assess the actual potential of chromium release from oxisols developed upon weathering of ultramafic rocks under a tropical climate

estimating mean dynamic topography in boundary currents and the use of argo trajectories a mean dynamic topography mdt is required to estimate mean transport in the ocean to combine with altimetry to derive instantaneous geostrophic surface velocities and to estimate transport from shipboard hydrography a number of mdts are now available globally but differ most markedly in boundary currents and the antarctic circumpolar current we evaluate several mdts in two boundary currents off new zealand in the subtropical western boundary current system east of the country and in the subantarctic front to the south using satellite hydrographic and argo observations near two altimeter tracks argo float trajectories are combined with estimates of shear to produce new mdts along both altimeter tracks sufficiently high numbers of argo floats travel in both boundary currents to allow a useful estimate of the mean flow at 1000 m depth and conservation of potential vorticity is used to account for more realistic flow paths in finding a mdt we show the uncertainties in the estimates of velocity differences between 1000 m and the surface from density climatologies while often not estimated need to be considered the mdt computed from the argo trajectories is generally consistent with the cls09 mdt in both boundary currents and in some locations distinctly different from the mdt using a level of no motion assumption the comparison suggests velocities from argo trajectories can be usefully combined with other observations to improve estimates of flows and mdt in boundary currents

structure and petrology of newly discovered volcanic centers in the northern kermadec southern tofua arc south pacific ocean 1 the nzaplume iii expedition of september october 2004 to the northern kermadec southern tofua nkst arc between 28 52 s and 25 07 s resulted in the discovery of at least seven new submarine volcanic centers and a substantial caldera complex adjacent to the previously known monowai seamount the volcanic centers form a sublinear chain that coincides with the kermadec ridge crest in the south hinetapeka and diverges 45 km westward of the ridge crest in the north v just to the south of where the louisville ridge intersects with the arc all of the centers contain calderas or caldera like structures as well as multiple cones domes fissure ridges and vent fields all show signs of recent eruptive and current hydrothermal activity there are strong structural controls on edifice location with cones and fissure ridges typically associated with faulting parallel to the regional 12 strike of the arc front several of the calderas are ellipsoidal orientated northwest southeast in the general direction of least compressive stress sampled volcanic rocks representing the most recently erupted lavas are all low k tholeiites two of the centers gamble and rakahore yielded only high silica dacite to rhyolite 69 74 wt silica whereas two others monowai and v yielded only basalt to andesite 48 63 wt silica mineral assemblages are plagioclase pyroxene dominated with accessory fe ti oxides apatite olivine and quartz tridymite cristobalite typical of dry volcanic arc systems hornblende occurs only in a felsitic rhyolite from hinepuia volcanic center and zircon is absent glass contents range to 57 in basalts andesites mean 20 and 97 in andesites rhyolites mean 59 and other quench textures including swallow tailed plumose or dendritic crystal forms and crystallites are common most lavas are highly vesicular 63 mean 28 and have low volatile contents mostly 2 wt which together with the occurrence of tridymite or cristobalite indicates explosive eruption and rapid cooling exceptions are rocks from u volcanic center which have low vesicularity and low glass contents across a wide compositional range indicating effusive eruption disequilibrium mineral textures the frequent occurrence of xenoliths and xenocrysts and macroscopic evidence for magma mingling indicate that many of the lavas are hybrids having resided only a short time in upper crustal reservoirs prior to eruption silicic magmas are major components of nkst arc volcanism and caldera formation is the dominant eruptive style the scale of silicic magmatism is in marked contrast to the dominant basaltic andesitic magmatism in the southern kermadec arc with evidence from other arcs silicic magmatism is now recognized as a major feature of intraoceanic arcs globally

grain size areal thickness distribution and controls on sedimentation of the 1991 mount pinatubo tephra layer in the south china sea the june 15 1991 climactic eruption of mt pinatubo produced an extensive largely co ignimbrite derived airfall ash layer on luzon island and across the central south china sea the layer covers an area of 4 105 km2 with a volume of 5 5 km3 near the coast of luzon the deposit consists of two units a normally graded basal ash bed unimodal in grain size and a finer grained internally structureless upper ash bed showing grain size bimodality with increasing distance from the source the coarse particle populations of the two units merge and migrate towards a near constant fine population 11 m the distal region is covered by a fine mode dominated virtually ungraded single ash layer the reversal of the winds from easterly directions at upper tropospheric and stratospheric levels to westerly directions in the middle and lower troposphere indicates that both the coarse and fine mode components fell out from high altitude eruption clouds the high velocity upper level winds however would have transported fine grained ash particles far beyond the south china sea which suggests that their settling was accelerated by aggregation the boundary between the units thus marks a change from fallout of predominantly discrete pyroclasts to simultaneous fallout of aggregated fines and freely falling coarse grained particles the particle populations composing the upper ash bed were almost completely removed from the proximal areas by the upper level winds at lower elevations the counterclockwise circulation of a typhoon over the coastal area advected the ash south and eastward producing a thickness maximum in the medial region at about 160 km from source the strong displacement of fines possibly aided by wind turbulence led to a break in bulk tephra thinning rates close to the coastline in the distal region outside the influence of the typhoon southwest monsoonal winds caused a distinct lobe axis inflection and thickness asymmetry within this region at about 420 km from source fallout of particle aggregates created a second thickness maximum comparison of the field data with previous experimental observations and tephra flux records in the deep sea wiesner et al 1995 carey 1997 mccool 2002 implies that the transport of ash in the water column was largely determined by vertical density currents differences in the reaction of coarse and fine particles to turbulence in the descending plumes probably suppressed the segregation of fines but allowed the coarser pyroclasts to maintain their initial order of arrival at the sea surface considering typical fall rates of convective plumes modifications of the initial fallout position of the particles by the south china sea current system are on the order of only a few kilometers the results suggest that convective sedimentation processes ensure the preservation of atmospheric particle transport directions distances and fallout modes in the deep sea

assessment of vertical contamination of cd pb and zn in soils around a former ore smelter in wallonia belgium concentrations of trace elements cd co cr cu ni pb and zn and major elements ca mg k fe al and mn as well as phkcl and total organic carbon toc were measured on 22 profiles located in a 3 km radius of a former ore treatment plant in wallonia belgium the enrichment factor ef vertical impoverishment factor vif and availability ratio ar were used as diagnostic tools of contamination and migration of cd pb and zn in profiles the data revealed that the soil profiles are significantly contaminated the ranges of efs for cd 17 3570 pb 1 2883 and zn 2 309 are very broad with the higher ef in the topsoil of the profiles vifs of subhorizons are rarely above 1 in the few cases with vif 1 the main factor explaining is the soil type in particular colluvic regosols luvisols and cambisols with shale load cd pb and zn ars are strongly correlated with toc and to a lesser extent with phkcl pb and zn ars are influenced by soil type while land use only has an effect on zn ar the cd availability is independent of these two factors the contents of trace elements measured in soil profiles are very high especially in topsoil at present the cd pb and zn vertical distribution shows a low migration from topsoil to deeper levels however we must not discount the hazard of a future potential transfer

the mean and variability of ocean circulation past northern new zealand determining the representativeness of hydrographic climatologies eastward flow in the tasman sea from the separated east australia current reattaches to the shelf break near north cape new zealand and then continues alongshore to the southeast as the east auckland current a series of three permanent warm core eddies occurs along the offshore side the mean transport of the east auckland current is about 9 sv with an additional 10 sv or more of circulation in the eddies an extensive hydrographic data set archived broad scale expendable bathythermograph xbt data two repeating high resolution xbt transects neutrally buoyant float trajectories and topex altimetric data are used to estimate the temperature and absolute flow fields and to characterize variability the aim is to examine the usefulness of time series information and absolute velocity measurements in the interpretation of hydrographic snapshots and climatologies as well as to describe a region having intrinsic oceanographic interest and complexity issues of representativeness of the hydrographic data of the magnitude and scales of the underlying variability of the existence of permanent fine scale features and of the appropriateness of deep reference levels are addressed directly the relatively well sampled hydrographic climatology is shown to contain the equivalent of as many as 10 independent realizations temperature errors relative to the true mean are typically a few tenths of a degree significant seasonal bias is identified in the surface layer and interannual bias is seen in the position of an eddy near north cape the dynamic height field at 1000 dbar relative to 2000 dbar is similar to estimates based on float trajectories and the assumption of geostrophic dynamics this study underlines the value of time series data in the interpretation of a hydrographic climatology in quantifying the errors in the estimated mean field as well as determining the magnitude and nature of variability it also highlights the fact that the mean circulation of the oceans contains significant mesoscale structure unnoticed in coarsely smoothed climatologies

identification of podzols and podzolised soils in new zealand by relative absorbance of oxalate extracts of a and b horizons abstract a method for separating podzols and podzolised soils from other new zealand soils is proposed the method is based on measurement of the optical density of acid oxalate extracts of soils a number of soil leaching sequences and some individual soils are examined it is assumed that the optical density of the oxalate extracts is due mainly to extracted fulvic acid and that detection of appreciable quantities of this material in the b horizon indicates that podzolisation is an active process in the soil the technique separated the soils of the leaching sequences well following the observable increase of podzolic characteristics with increased leaching when the b horizon a horizon odoe optical density of the oxalate extracts ratios were compared with the criteria for the spodic horizon in soil taxonomy soil survey staff 1975 it was found that all soils with a ratio of less than 1 0 did not satisfy spodic horizon criteria and were not classified as podzol podzolised all the soils examined with ratios 1 0 satisfied spodic horizon criteria or were classified as podzol podzolised usually both

distribution of some selected major and trace elements in four italian soils developed from the deposits of the gauro and vico volcanoes the vertical distribution of 21 elements k ca ti fe mn cr ni cu zn ga as se br rb sr y zr pb th u hg in four italian soils derived from volcanic materials has been investigated most of the elements and in particular lithogenic ones show little enrichment depletion indicating a low degree of weathering and a great similarity to the parent material in relative terms the degree of soil evolution horizon expression and weathering and the depletion of the more mobile elements k ca and sr seem to increase with increasing rainfall and soil age discontinuities in the soil profile due to the accretion of new volcanic material are detectable from the geochemical composition of the horizons some metallic elements such as hg pb cu mn and zn show enrichment in the organic rich horizons o and a but the intensity of enrichment suggests that besides biocycling and weathering processes human activity soil management fertilizing and atmospheric pollution may be significant sources of trace elements

comparison of model and observational ocean circulation climatologies for the new zealand region 1 primitive equation three dimensional regional models driven by global models can be used to generate climatologies of the ocean circulation with 1 12 resolution these model climatologies begin to resolve the coastal circulation and it is appropriate to ask whether they are adequate to replace observational climatologies we compare circulation climatologies derived from a z coordinate 36 vertical layer model run with three different diffusivities with an observational climatology csiro atlas of regional seas cars and with surface velocities derived from lagrangian drifters deployed under the global drifter program gdp all the climatologies capture the major features in the mean circulation south of the chatham rise and east of new zealand the model climatologies agree better with gdp than does cars north of the chatham rise the models overestimate the strength of the east cape eddy wave number spectra from the models suggest that instability processes which are important in the mean are captured with diffusion less than 25 m2 s 1 the model with lowest diffusion may be providing the best estimate of the mean circulation but at the expense of numerical instability

climate dependent chemical weathering of volcanic soils in iceland abstract the major element mobility within soil profiles of brown to gleyic andosols that developed under diverse climatic conditions in iceland is assessed the volcanic soils were selected from areas with good monitoring of annual temperature and precipitation and the degree of weathering and elemental behavior is compared icelandic soils are subject to high fluxes of aeolian dust and at times to tephra ejecta from volcanic eruptions the source of dust input is assessed for each profile based on comparison of the chemical signatures found in the less weathered upper horizons with those of volcanic systems supplying material to source areas results show that tio 2 al 2 o 3 and fe 2 o 3 t and mno are the least mobile species and generally found enriched within more mature horizons the mobile base cations mgo cao and na 2 o are depleted in these horizons as a result of chemical weathering during pedogenesis soils developed in colder climatic conditions with mean annual temperature mat 1 c give values for the chemical index of weathering ciw of 37 45 that reflect only weak chemical weathering soils developed in milder climates mat 2 4 c are more strongly affected by weathering ciw 50 77 the parent material has ciw values of 37 temperature is demonstrated as the dominant variable exerting control on the extent of weathering with only minor mobilization following the incipient near surface weathering stage a robust linear relationship is found between ciw and model mat mat 0 21ciw 8 93 r 2 0 81 this climofunction can deliver proxy climate estimations from volcanic soils and paleosols of basaltic origin in cool to subarctic conditions 2 to 6 c

distal occurrence of mid holocene whakatane tephra on the chatham islands new zealand and potential for cryptotephra studies abstract the whakatane tephra a rhyolitic tephra erupted ca 5500 cal bp from okataina volcanic centre central north island has been identified on the chatham islands which lie 900 km east of christchurch new zealand the visible tephra layer 5 mm in thickness and preserved within peat on pitt island was identified using both radiocarbon dating and analysis of glass shards by electron microprobe whakatane tephra is the first holocene tephra to be identified on the chatham islands and it is the most distal holocene tephra yet recorded in the new zealand region being 850 km from source the pitt island occurrence extends the tephra s dispersal area markedly by an order of magnitude possibly to 300 000 km 2 an estimated dispersal index d of approximately 10 5 km 2 indicates that the eruption generated a very high plinian column possibly exceeding 30 km in height with strong winds blowing the ash plume southeastwards this new discovery of distal whakatane tephra as a thin but visible layer strongly implies that cryptotephras are likely to be preserved on the chatham islands and within adjacent ocean floor sediments therefore the potential exists to develop enhanced cryptotephrostratigraphic records from these distal areas which in turn would help facilitate precise correlation via tephrochronology of palaeoenvironmental records such as nz intimate from mainland new zealand the southwest pacific ocean and the chatham islands

lacustrine sediment chronology defined by 137cs 210pb and 14c and the hydrological evolution of lake ailike during 1901 2013 northern xinjiang china abstract dating lake sediments in arid and semi arid zones by using 137cs and excessive 210pb 210pbex methods is challenging because of the irregular climatic variations and anthropogenic effects here we try to establish the reliable geochronology of the lacustrine core drilled from lake ailike northern xinjiang of china by using 137cs and 210pbex dating methods and improve our understanding of the principal factors that affect the dating results the results indicate that it is important to normalize the 137cs activities by particle size and organic matter in order to diminish their enrichment effects on 137cs activities and thus help us to obtain the accurate 137cs ages the performance of the sediment isotope tomography sit model is better than the other 210pbex derived models the erosion process results in the failure of the commonly used constant rate of supply crs model as well as the low values of the sedimentation rate the 137cs inventory and the post 1963 mean annual flux of 210pbex in ailike core furthermore based on the sit model chronology we further clarify the lake evolution history of the past century and assess the anthropogenic impacts on lake ailike the hydrology of lake ailike was mainly controlled by natural climate before 1960 ce whereas it was completely controlled by intensive human activities after 1960 ce this study supports that the 210pbex based sit model appears to be an adequate method for deriving ages in the lacustrine systems with strong hydrological variability

regional climate variability and ocean heat transport in the southwest pacific ocean the winter of 1992 was the coldest on record in new zealand since the 1940s temperatures in new zealand were as much as 3 c below average with heavy rain and unusual snow the oceanic surface layer in the southwest pacific was also anomalously cold over the same period a world ocean circulation experiment woce hydrographic section p14c between auckland and fiji during september 1992 found cold sea surface temperatures and deep mixed layers near new zealand when compared to 8 years of high resolution expendable bathy thermograph xbt temperature measurements collected along the same transect high nutrient and low dissolved oxygen concentrations in the surface layer indicated recent entrainment of thermocline waters the auckland to fiji xbt section is one of three woce high resolution xbt survey lines in the tasman box region whose boundaries are auckland fiji fiji brisbane and wellington sydney transects plus the australian coast geostrophic shear and transport were estimated from 10 realizations of the tasman box during the period 1991 1993 the time series of geostrophic transport shows that following a convergence in late 1991 early in 1992 there was a substantial divergence of mass in the upper waters equivalent to a thinning of the warm water layer the phase of this anomalous divergence is matched to an observed amplification of the seasonal oceanic heat storage cycle in 1991 1992 the top 200 m average temperature was warmer in the 1992 summer than in 1991 or 1993 but the winter of 1992 was the coldest of the 8 year record along the auckland fiji line the divergence thinning of the warm water layer appears to have preconditioned the region for the exceptionally cold 1992 winter the alternative cool conditions from anomalous air sea heat exchange caused by variability in the wind field is considered unlikely as large fluctuations in heat loss are not observed in the air sea flux data during this period the severe weather conditions and anomalous ocean heat transport are most likely related to the prolonged el nino southern oscillation episode that began in early 1991

petrogenesis of dacite in an oceanic subduction environment raoul island kermadec arc abstract raoul volcano in the northern kermadec arc is typical of volcanoes in oceanic subduction systems in that it is composed mainly of low k high al basalts and basaltic andesite however during the last 4 ka raoul volcano has produced mainly dacite magma in pyroclastic eruptions associated with caldera formation the rocks produced in these episodes are almost aphyric containing only sparse crystals of plagioclase clinopyroxene orthopyroxene and magnetite these apparent phenocrysts have chemical compositions that suggest that they did not crystallise from melts with the chemical composition of their host rocks rather they are xenocrysts and only their rims show evidence for crystallisation from their host melt chemical compositions of samples of the dacites show that each eruption has tapped a distinct magma batch compositional variations through the analysed suite cannot be accommodated in any reasonable model of fractional crystallisation from likely parental magma compositions the hypothesis that best fits the petrology of raoul island dacites is one of crustal anatexis this model requires heating of the lower crust by a magma flux to the point where dehydration melting associated with amphibole breakdown produces magma from a preconditioned source it is suggested that raoul is passing through an adolescent stage of development in which siliceous melts are part of an open system in which felsic and mafic magmas coexist

southwest pacific subtropical mode water a climatology we find that stmw extends across the entire width of the tasman sea in a very broad swath between the tropical convergence in the north just to the south of new caledonia the southeast australian coast in the west to as far south as 39 s likely due to the southward extension of the eac and eastwards along the southern stmw boundary in a meandering pathway that broadly follows the tasman front the total stmw volume across the region i e west of 180 varies seasonally by a factor of more than three between the estimated maximum of 6 6 0 5 1014 m3 in october and minimum of 1 9 0 4 1014 m3 in may interannual variations o 0 5 1014 m3 are also observed in the spatial extent of the thick mode water and its total volume el nino composite maps show an anomalous thickening of the stmw during the el nino year with october positive thickness anomalies in excess of 20 m total volume anomaly of 0 6 1014 m3 manifested throughout the subtropical gyre interior as far north as new caledonia total volume anomalies tend to be positive from january of the el nino year through to the july following 18 months the maximum correlation coefficient r 0 3 between 3 monthly stmw volume anomalies and the southern oscillation index is statistically significant at the 95 confidence level we conclude that during the anomalous cooling of the upper southwest pacific ocean in the el nino year winter time convection and stmw formation is enhanced across the region resulting in an el nino southern oscillation climate signal that is identifiable below the mixed layer by the increased stmw volume which persists through to the following winter finally some evidence for the possible decadal modulation of the stmw variability is also discussed

andosols in germany pedogenesis and properties abstract soils conforming to andosols in the world reference base wrb of soil resources have not yet been recognised in germany the aims of this study were to i show whether some german soils developed in volcanic parent materials are andosols ii investigate their pedogenetic development and iii determine their local distribution we selected a soil on quaternary basalt in the eifel region the windsborn profile and a soil from the summit of the tertiary basaltic stratovolcano vogelsberg the kohlerwald profile northwest of frankfurt am main the windsborn soil is classified as a silic andosol allophane contents are near 10 and allophane globules were identified by transmission electron microscopy tem by progressively constraining field parameters in gis generated maps we found that andosols in the mosenberg chain are confined to a few isolated occurrences the kohlerwald profile in the tertiary vogelsberg is an acid base poor and strongly weathered aluandic luvisol metal humus complexes are the dominant colloidal phase in the topsoil both fep and alp are in excess of feo and alo values our data suggest the presence of phases like hydroxy al e g from al interlayers or poorly ordered gibbsite and opaline silica that are easily attacked by the alkaline ph 9 5 10 5 pyrophosphate extractant but may be resistant to the acid ph 3 oxalate procedure we conclude that there are limited occurrences of silandic andosols in the eifel area germany the windsborn soil is in an early pedogenetic development stage but pedogenesis in the kohlerwald soil has advanced beyond the andosol phase to the stage of clay translocation therefore the existence of aluandic andosols in germany seems possible but remains to be proven

the subtropical mode waters of the south pacific ocean abstract the subtropical mode waters stmw of the southwestern pacific ocean are described including their physical characteristics spatial distribution and temporal variability stmw is a thermostad or minimum in stratification having temperatures of about 15 19 c and vertical temperature gradient less than about 2 c per 100 m typical salinity is 35 5 psu at 16 5 c the stmw layer is formed by deep mixing and cooling in the eastward flowing waters of the separated east australia current surface mixed layers are observed as deep as 300 m north of new zealand in winter in the center of a recurring anticyclonic eddy the stmw thermostad in the south pacific is considerably weaker than its counterparts in the north atlantic and north pacific a contrast that may help to discriminate between physical processes contributing to its formation a quarterly time series of expendable bathythermograph transects between new zealand and fiji is used to study the temporal variability of stmw large fluctuatio

soil erosion and sedimentation indicated by caesium 137 jackmoor brook catchment devon england summary the tracer caesium 137 was used to study the status of soil erosion and sedimentation in the jackmoor brook catchment devon u k it was postulated that 1 sites at the top of a cultivated slope should be most depleted of caesium 137 2 sites at the base of a slope should contain greater amounts of caesium 137 and have a distinctive depth profile 3 hillslope erosion indicated by caesium 137 levels should be related to slope length and angle and 4 caesium 137 levels should discriminate between the chief source of sediment transferred to the stream cultivated soils and uncultivated soils under pasture orchards and woodland these hypotheses were tested in two contrasting physiographic areas of the basin depletion of caesium 137 levels at the top of slopes indicated soil erosion and deeper than plough depth caesium 137 profiles at the base of slopes indicated sedimentation these characteristics were most marked in the steeper upper jackmoor portion of the catchment slope length effects on soil movement were more difficult to ascertain from the caesium 137 levels but soil sampling of contrasting land uses showed that cultivated soils had significantly less caesium 137 probably as a result of soil erosion in general the hypotheses were supported and the utility of the caesium 137 technique was confirmed

influence of convective sedimentation on the formation of widespread tephra fall layers in the deep sea the formation of widespread volcanic ash fall layers in deep sea sediments was investigated experimentally to examine the settling behavior of tephra 20 180 m diameter as it travels from the atmosphere into water using a fallout mass flux rate that was constrained by measurements of distal fallout from the 1980 eruption of mount st helens 0 2 g cm 2 hr the experiments show that particle settling in the water column is dramatically accelerated by the formation of diffuse vertical gravity currents the currents form as a result of convective instabilities that develop in a surface boundary layer when the local particle concentration becomes large at the air water interface the settling velocity of particles drops abruptly and the concentration of particles increases because of the differential in mass flux above and below the fluid surface the implication of the experiments is that deposition of distal tephra fall layers in deep sea sediments may be dominantly controlled by diffuse vertical gravity currents as opposed to passive settling of individual particles through the water column this process greatly reduces the residence time of fine ash in the ocean and diminishes the role of ocean currents in influencing the distribution patterns of individual tephra layers support for this mechanism comes from observations of greatly accelerated tephra settling rates in the south china sea following the 1991 eruption of mount pinatubo in the philippines

chromium and copper in micromorphological features and clay fractions of volcanic soils with andic properties abstract in volcanic soils of the solofrana valley south western italy contamination by cr and cu occurs as a consequence of agricultural practices and surface deposition of polluted river sediments by periodic floods in this study the metal distribution in micromorphological features and clay fractions 1 both cr and cu are present in the subsurface infillings with concentrations of 273 and 243 mg kg 1 in deeper horizons the fragments of stratified fine textured alluvial deposits incorporated in the soil matrix contain low concentrations of both metals 13 63 mg kg 1 for cr and 18 24 mg kg 1 for cu suggesting that cr and cu migration in colloidal or ionic form is restricted to a limited distance the contribution of the clay fraction

glacial interglacial sea surface temperature changes across the subtropical front east of new zealand based on alkenone unsaturation ratios and foraminiferal assemblages 0 are compared to those derived from foraminiferal assemblages using the modern analog technique in two of these cores reconstructions of sst in core tops and holocene sediments agree well with modern average summer temperatures of 18 c in subtropical waters and 14 c in subpolar waters with a 4 5 c gradient across the front down core u37 k 0 sst estimates indicate that the regional summer sst was 4 5 c cooler during the last glaciation with an sst of 10 c in subpolar waters and an sst of 14 c in subtropical waters temperature reconstructions from foraminiferal assemblages agree with those derived from alkenones for the holocene in subtropical waters reconstructions also agree with a glacial cooling of 4 to 14 c in contrast reconstructions for subantarctic pre holocene waters indicate a cooling of 8 c with glacial age warm season water temperatures of 6 c thus the alkenones suggest the glacial temperature gradient across the front was the same or reduced slightly to 3 5 4 c whereas foraminiferal reconstructions suggest it doubled to 8 c our results support previous work indicating that the stf remained fixed over the chatham rise during the last glacial maximum however the differing results from the two techniques require additional explanation a change in euphotic zone temperature profiles seasonality of growth or preferred growth depth must have affected the temperatures recorded by these biologically based proxies regardless of the specific reason a differential response to the environmental changes between the two climate regimes by the organisms on which the estimates are based suggests increased upwelling associated with increased winds and or a shallowing of the thermocline associated with increased stratification of the surface layer in the last glaciation index terms 4267 oceanography general paleoceanography 4850 oceanography biological and chemical organic marine chemistry 1050 geochemistry marine geochemistry 4835 4850 1055 geochemistry organic geochemistry keywords paleoceanography sea surface temperature alkenones southern ocean last glacial maximum

refractory element mobility in volcanic soils refractory trace element concentrations in strongly weathered hawaiian soils ranging in age from 20 to 4100 ka are highly elevated over parent rock values due to extensive mass loss of more soluble major elements during pedogenesis nb and ta exhibit virtually no mobility soil nb ta ratios are within the range of fresh bedrock even when soil nb concentrations are residually enriched by a factor of 10 in contrast al zr and hf are depleted relative to nb in surface soil horizons but are enriched at depth clearly indicating mobility of these elements variations in th nb ratios in soil profiles indicate significant th mobility within the soil column however mass balance calculations require that accretion of th enriched asian dust has resulted in a net increase in th in some soils soils developed on a 150 ka rainfall gradient show that the mobility and loss of zr increase with mean annual precipitation

validating the use of 137cs measurements to estimate rates of soil redistribution by wind abstract wind erosion has degraded over one half billion hectares of land worldwide 137 cesium 137 cs has been used as a tracer to study long term rates of soil redistribution by water and to a lesser extent by wind early studies assumed that the decline in 137 cs activity for a potentially eroded soil relative to that for an uneroded soil was linearly proportional to soil loss more recently models have emerged that consider the effects of soil cultivation and the particle surface area dependent partitioning of 137 cs on soils we investigated the partitioning of 137 cs in wind eroded sediments and with soil surface samples sieved into contiguous ranges of particle sizes we also compared the 137 cs activities and stratification of several adjacent soils with known wind erosion and deposition histories finally we tested 137 cs based soil loss models with measured data from sites with documented histories 137 cs activities and mean particle diameters of aeolian samples agreed well with the 137 cs activities and respective mean diameters of the sieved surface soil samples good agreement between model estimations and measured data indicated that 137 cs models developed to estimate soil redistribution by water were also applicable to soil redistribution by wind provided that the models contained an appropriate particle size correction parameter

contrasting pyroclast density spectra from subaerial and submarine silicic eruptions in the kermadec arc implications for eruption processes and dredge sampling pyroclastic deposits from four caldera volcanoes in the kermadec arc have been sampled from subaerial sections raoul and macauley and by dredging from the submerged volcano flanks macauley healy and the newly discovered raoul sw suites of 16 32 mm sized clasts have been analyzed for density and shape and larger clasts have been analyzed for major element compositions density spectra for subaerial dry type eruptions on raoul island have narrow unimodal distributions peaking at vesicularities of 80 85 whereas ingress of external water wet type eruption or extended timescales for degassing generate broader distributions including denser clasts submarine erupted pyroclasts show two different patterns healy and raoul sw dredge samples and macauley island subaerial emplaced samples are dominated by modes at 80 85 implying that submarine explosive volcanism at high eruption rates can generate clasts with similar vesicularities to their subaerial counterparts a minor proportion of healy and raoul sw clasts also show a pink oxidation color suggesting that hot clasts met air despite 0 5 to 1 km of intervening water in contrast macauley dredged samples have a bimodal density spectrum dominated by clasts formed in a submarine eruptive style that is not highly explosive macauley dredged pyroclasts are also the mixed products of multiple eruptions as shown by pumice major element chemistry and the sea floor deposits reflect complex volcanic and sedimentation histories the kermadec calderas are composite features and wide dispersal of pumice does not require large single eruptions when coupled with chemical constraints and textural observations density spectra are useful for interpreting both eruptive style and the diversity of samples collected from the submarine environment

the denham caldera on raoul volcano dacitic volcanism in the tonga kermadec arc denham caldera on raoul volcano in the tonga kermadec arc is a simple collapse structure it is 6 5 4 km2 across 0 3 km deep represents an erupted magma volume of 8 16 km3 and is considerably larger than previously estimated caldera formation was contemporaneous with an eruption of homogeneous dacitic magma at 2 2 ka tephra from this event is preserved as a pumice fall and pyroclastic flow sequence up to 120 m thick on raoul island offshore this sequence forms a submarine deposit diminishing in thickness from 120 m near the northern caldera rim to 80 m at a distance of 3 5 km where it rests upon an erosional planation surface of 17 20 ka age incised into older volcaniclastic rocks both the caldera volume and ejecta distribution of the 2 2 ka eruption are comparable to the caldera volume and ejecta distribution of the 1883 krakatau eruption resurgent volcanism has built at least six submarine pyroclastic cones along a north northeast trending lineament crossing denham caldera redistribution of pumiceous dacite from these cones including ephemeral islands that emerged during the 1814 and 1870 eruptions has contributed to recent shoaling in denham bay a smaller eruption occurred in 1964 65 and hydrothermal activity persists at several sites along the lineament voluminous felsic volcanism at intra oceanic arcs is usually associated with crustal extension and was unexpected in the tonga kermadec arc however because the tectonic fabric within the active back arc havre trough is oblique to the kermadec arc rifts within the trough apparently propagate to the volcanic front and transfer extensional strain to the arc thereby promoting the ascent of felsic magma the orientation of denham caldera as well as that of macauley caldera 110 km further south thus reflect the stress field of the havre trough and not the predominant field of the arc

demise of one volcanic zone and birth of another a 12 m y marine record of major rhyolitic eruptions from new zealand ocean drilling program sites 1123 and 1124 provide an unprecedented 12 m y record of major rhyolitic eruptions from the coromandel and taupo volcanic zones of new zealand macroscopic tephras n 197 were dated using magnetostratigraphy supplemented by geochemical correlation with subaerial tephra isothermal plateau fission track ages and orbitally tuned stable isotope data eruptions began in the coromandel volcanic zone ca 12 ma 1 6 1 m y earlier than previously known thereafter volcanism was fairly continuous with a tempo and intensity that increased through the late miocene pliocene and into the quaternary when the taupo volcanic zone formed the transition from the coromandel to the taupo zone previously placed as ca 4 2 ma was seamless without obvious breaks or changes in ash composition this well dated history of long lived and productive volcanism allows for more confident correlation with other circum pacific tephra records thus helping confirm the occurrence of widespread coeval eruptions throughout the region

new multibeam mapping and geochemistry of the 30 35 s sector and overview of southern kermadec arc volcanism new multibeam mapping and whole rock geochemistry establish the first order definition of the modem submarine kermadec arc between 30 degrees and 35 degrees s twenty two volcanoes with basal diameters 5 km are newly discovered or fully mapped for the first time giggenbacb macauley havre haungaroa kuiwai ngatoroirangi sonne kibblewhite and yokosuka for each large volcano edifice morphology and structure surficial deposits lava fields distribution of sector collapses and lava compositions are determined macauley and havre are large silicic intra oceanic caldera complexes for both concentric ridges on the outer flanks are interpreted as recording mega bedforms associated with pyroclastic density flows and edifice foundering other stratovolcanoes reveal complex histories with repeated cycles of tectonically controlled construction and sector collapse extensive basaltic flow fields and the development of summit craters and or small nested calderas combined with existing data for the southernmost arc segment we provide an overview of the spatial distribution and magmatic heterogeneity along similar to 780 km of the kermadec arc at 30 degrees 36 degrees 30 s coincident changes in arc elevation and lava composition define three volcano tectonic segments a central deeper segment at 32 degrees 20 34 degrees 10 s has basement elevations of 3200 m water depth and relatively simple stratovolcanoes dominated by low k series basalt basaltic andesite in contrast the adjoining arc segments have higher basement elevations typically 3 km coincide with the shallower arc segments the dominant mode of large caldera formation is interpreted as mass discharge pyroclastic eruption with syn eruptive collapse hence the shallower arc segments are characterized by both the generation of volatile enriched magmas from crustal melting and a reduced hydrostatic load allowing magma vesiculation and fragmentation to initiate and sustain pyroclastic eruptions proposed initiation parameters for submarine pyroclastic eruptions are water depths 70 wt sio2 and a high discharge rate c 2005 elsevier b v all rights reserved

mineralogical and magnetic characterisation of iron titanium oxides in soils developed on two various basaltic rocks under temperate climate abstract the objective of this study was to characterize alteration processes of iron titanium oxides in andic soils developed on basaltic rocks under temperate climate among the magnetic minerals titanomagnetites are the most abundant and represent the major spinel in basalts in order to understand processes involved in the alteration of iron titanium oxides from basaltic rocks associated to soils two pedons developed on tertiary massive basaltic formations submitted to temperate climate were considered the magnetic minerals have been characterized by studying rock and soil magnetic parameters i e magnetic susceptibility and curie temperature chemical composition was investigated by optical and electron microscopy empa sem eds and by micro proton induced x ray emission pixe because mineralogy of the parent rocks controls those of the soils we have first studied the rocks the thermomagnetic curves obtained on the two studied rocks show that initial titanomagnetite is preserved in one sample mc rock while the other pc rock contains near pure magnetite possibly issued from exsolution process microscopic observations confirm the exsolution lamellae on titanomagnetites and show a cr content gradient in chromian spinel partially enclosed in olivine these observations suggest a deuteric alteration the two profiles exhibit increasing curie temperature between the rocks and soil horizons indicating a transformation of magnetic minerals results emphasize the maghemitization of iron titanium oxides in andic soils in a temperate climate

modern sediment dispersal and accumulation on the outer poverty continental margin abstract the poverty margin was sampled in 2005 and 2006 as part of an international initiative to examine the terrestrial and marine sedimentary response to natural and human impacts on dispersal systems at mud dominated coasts the nsf margins source to sink initiative 210pb accumulation rates generally decrease from 1 g cm2 y in the mid shelf depocenter on the outer shelf to 0 1 g cm2 y on the mid slope plateau range 0 04 2 53 g cm2 y higher accumulation rates are observed all along the outer poverty shelf extending over the shelf break onto the upper poverty slope in canyons and gullies rates are fast in gullies that incise into the shelf edge 0 75 1 g cm2 y particularly in the area between waipaoa canyon and poverty canyon and in the axis of poverty canyon 1 29 1 89 g cm2 y below 1200 m water depth rates in the axis of poverty canyon are no more rapid than those found at open slope cores in similar water depths 0 12 0 15 g cm2 y excess 210pb profiles generally exhibit steady state characteristics except in the axis of poverty canyon where non steady state 210pb profiles are observed 137cs was not found above minimum detection limits or above statistical background levels in any cores from the poverty margin 7be was found distributed widely along and across the margin during both summer and winter periods observed to depths of up to 4 cm widespread presence of 7be on the margin in both winter and summer suggests that terrestrially derived sediment is reaching the outer shelf and upper slope throughout the year a sediment budget based on 210pb accumulation rate data shows that approximately 13 18 of the waipaoa annual discharge is accumulating on the outer poverty margin as a whole and approximately 11 15 of the annual discharge is accumulating on the continental slope alone notably approximately 28 of the sediment annually accumulating in the outer margin is being sequestered in slope gullies and canyons although they represent only 6 of the area of the outer margin

geochemical evolution of a palaeolaterite the interbasaltic formation northern ireland abstract the interbasaltic laterites of northern ireland were formed during a period of relative volcanic inactivity by extensive chemical weathering of tertiary basalts they reach a maximum thickness of 30 m and once provided a major source of iron and aluminium ore an extensive database comprising major minor and trace elements has been compiled for 240 samples in order to study the effects of weathering in terms of the changes in whole rock chemistry and mineralogy from basalt through to iron rich crust percolating waters caused degradation of the parent basalt mineralogy and precipitation of neoformed phases principally through incongruent dissolution processes primary olivine plagioclase feldspar and augite were successively broken down and replaced by a mineral assemblage consisting of hematite gibbsite goethite anatase meta halloysite and kaolinite changes in mineralogy facilitated concomitant changes in element concentrations mass balance calculations indicate that all elements were depleted in the iron crust enrichment of al loi cr cu and v occurred in the laterite horizon while enrichment of al loi ba ce cr cu ni and rb occurred in the lithomarge notably yttrium was found to be mobile indicating that weathered basalts should not be used in discrimination of original tectonic environments the severe leaching conditions evidenced by yttrium depletion local aluminium redistribution and iron crust formation are indicative of weathering under a humid sub tropical monsoon climate

sea surface temperatures of southern midlatitudes 0 160 kyr b p 1 late quaternary climate fluctuated between extremes of glaciations lasting 90 kyr on average and interglacial episodes lasting 10 kyr still largely unknown are the spatial and temporal evolution of these global climate states with vigorous debate still underway on the mechanisms responsible for glacial inceptions and terminations though it is widely believed that the southern hemisphere oceans play a central role in global climate changes few paleoclimate records exist from there here we present three new alkenone derived sst records from the midlatitude southern hemisphere spanning the last 160 kyr a full glacial interglacial cycle our subtropical sst records from the last glacial period are characterized by 1 warming 47 23 kyr b p when high latitudes in both hemispheres cooled and 2 milder temperatures during the penultimate glacial period than during the last glacial interval these sst features are found to be of tropical to subtropical wide extent implying increased thermal gradients at times of high latitude ice sheet growth this has implications for the vigor of atmospheric and upper ocean circulation and the transport of heat and moisture to the poles that may have been instrumental in the growth and maintenance of polar ice sheets during glacial periods

glacial interglacial control of terrigenous and biogenic fluxes in the deep ocean off a high input collisional margin a 139 kyr record from new zealand abstract sediment input to the deep ocean off the new zealand collisional plate boundary is large and variable as revealed by a 139 kyr old record from the 34 92 m long core md97 2121 mass accumulation rates mars were derived for terrigenous and biogenic carbonate and silica sedimentary components with temporal control from a stable isotope age model verified by tephra and radiocarbon ages terrigenous mars changed in phase with glacio eustatic fluctuations of sea level highest rates 30 g cm 2 kyr coincided with the late regressive lowstand early transgressive phase of marine isotope stage mis 2 when rivers discharged at or near the shelf edge lesser but still high terrigenous rates 20 30 g cm 2 kyr characterized peak warm phases of early mis 5 and 1 when a strengthened subtropical inflow probably introduced sediment from fluvial and seabed sources to the north of md97 2121 however during prolonged highstands the flux declined as more sediment was retained on a tectonically subsiding shelf with a shore parallel current paradoxically the lowest mars 10 5 g cm 2 kyr occurred in mis 4 either sea level was too high to allow much sediment to escape off shelf or the fluvial input was modest or both these factors despite the terrigenous dominance biogenic mars are high and are 2 4 times larger than sw pacific ocean rates mars were lowest during mis 4 and 3 possibly due to reduced marine production under a lowered input of fluvial micronutrients in contrast mars increased irregularly though glacial maxima to peak at 5 6 g cm 2 kyr carbonate and 2 2 5 g cm 2 kyr silica in early mid mis 5 and 1 such rates reflected the interaction of macronutrient rich subantarctic waters sourced from the south with local micronutrient rich subtropical waters production also responded to warmer temperatures elevated nutrient runoff and a more stratified surface ocean later in mis 5 and 1 fluxes reduced as less productive subtropical waters prevailed that biogenic and aeolian mar profiles are out of phase suggests fe fertilization by aerosolic dust was not a major influence

in situ modification of modern submarine hyaloclastic pyroclastic deposits by oceanic currents an example from the southern kermadec arc sw pacific submarine volcaniclastic deposits both modern and ancient pose a conundrum in distinguishing between syn and post eruptive processes high standing submarine volcanic edifices of the late quaternary southern kermadec arc sw pacific are point sources of pyroclastic hyaloclastic deposits that are bathed and modified by a complex current system of the south pacific gyre flowing southeast along the northern margin of new zealand which in part comprises the anticyclonic flow of the warm cored east cape eddy ece flow of the ece across the southern kermadec arc provides a present day case of extensive and in situ post eruptive textural modification of modern pyroclastic hyaloclastic deposits on the crests and upper flanks of submarine stratovolcanoes photographic observations and limited textural data from seven kermadec volcanoes reveal pervasive evidence of sediment winnowing including crag and tail structures scour and moating around volcanic blocks coarse sand granule lag deposits epifaunal deflection lineated mud streaking and moulded bioturbation mounds and asymmetric current ripple bedforms at water depths of at least 1500 m all bedforms indicate increasing current speed at progressively higher elevations decreasing water depth for each volcano current ripples mostly have discontinuous asymmetric shorted crested linguoid lunate forms below 1000 m water depth progressing to semi continuous asymmetric shorted crested linear sinuous forms above 500 m current elutriation of the kermadec deposits progressively removes fines with decreasing water depth resulting in relatively fines depleted volcaniclastic sands and granules this post eruptive process overprints syn eruptive processes that notionally generate more comminuted fine grained clasts with decreasing water depth as phreatomagmatic explosive eruptions become more vigorous current elutriation also modifies volcaniclastic detritus prior to subsequent removal by episodic mass gravity flow in addition the sand granule traction load driven by current flow moves sediment nearly continuously to gully and rill heads for removal down slope independently of syn eruptive sediment flux the underlying observation is that volcaniclastic deposits rarely reflect just syn eruptive processes and that significant in situ current elutriation of at the least surficial pyroclastic hyaloclastic eruption products can occur on submarine volcanoes threshold current velocities derived assuming unidirectional flow over cohesionless sand lapilli grainsizes and accounting for bed friction yield current velocities at 100 cm above the bed of 15 cm s 1 for water depths 1500 m through to 70 cm s 1 for depths

intermediate depth circulation of the indian and south pacific oceans measured by autonomous floats as part of the world ocean circulation experiment 306 autonomous floats were deployed in the tropical and south pacific ocean and 228 were deployed in the indian ocean to observe the basinwide circulation near 900 m depth mean velocities seasonal variability and lateral eddy diffusivity from the resultant 2583 float years of data are presented area averages local function fits and a novel application of objective mapping are used to estimate the mean circulation patterns of mean circulation resemble those at the surface in both basins well developed subtropical gyres twice as strong in the indian ocean as in the pacific feed western boundary currents tropical gyres are separated by eastward flow along the equator in both hemispheres of both basins although the indian subcontinent splits the north indian tropical gyre the antarctic circumpolar current acc and west wind drifts are prominent in both basins generally tending slightly southward but deviating to the north behind the del cano kerguelen and campbell plateaus and of course south america remarkably the eastern boundaries of the southern subtropical gyres in all three basins apparently occur in the ocean interior away from land the indian ocean s subtropical gyre and perhaps part of the south atlantic s reaches east to a retroflection just upstream of the campbell plateau south of new zealand seasonal variability at 900 m is focused around the equator with weaker variability found near certain bathymetric features there is a remarkable agreement between the observed seasonable variability and that predicted by the jet propulsion laboratory jpl estimating the circulation and climate of the ocean ecco data assimilating numerical model aside from seasonal effects eddy variability is greatest along the equator in tropical and subtropical western basins and along the acc integrals of velocity across regional passages tasman sea mozambique channel provide useful reference for hydrographic analyses of transport across whole ocean basins however the uncertainty associated with the appropriate continuity relation for horizontal flow e g geostrophy vs nondivergence is comparable to the mean flow

the limitations of using 137cs for estimating soil redistribution in semi arid environments the 137cs technique for estimating net ca 30 years soil flux has been used successfully in many environments its widespread use is probably because the 137cs technique overcomes many of the problems of monitoring soil erosion and deposition flux over the medium term 5 to 50 years and at the hillslope scale in this respect the technique probably offers the greatest potential for measuring net soil flux in semi arid environments where soil flux monitoring difficulties are compounded by considerable spatial and temporal variability of the controlling factors however there remain uncertainties in the underlying assumptions of the technique and difficulties in satisfying these assumptions especially in semi arid areas several key assumptions of the 137cs technique for measuring net soil flux in semi arid areas were investigated using data from southwest niger samples were obtained along a toposequence typical of the region and at nested grid nodes stratified using geomorphological information for geostatistical estimation at unsampled locations providing complete coverage of the study area the pervasive occurrence of dust made it difficult to identify an undisturbed site a first approximation of the reference 137cs inventory 2066 125 bq m 2 was provided by modelling the 137cs profile at an unvegetated site despite little evidence in the literature on problems of identifying a reference inventory especially those suffering from wind erosion it is likely that similar problems occur in other semi arid areas problems with the preferential transport of 137cs were identified by expressing the 137cs concentration as a proportion of the weight in each grain size fraction however it was partially accounted for in the calibration relationship by reducing by a factor of 10 the 137cs concentration of soil samples from the plateau it is likely that workers in other semi arid regions have similar problems of preferential transport of 137cs and the method discussed here appears to be a valuable tool to indicate the potential for preferential 137cs movement a large disparity was found between the undisturbed model and the structure of a 137cs profile from a small alluvial fan this was due to the removal of 137cs rich soil and its replacement with soil largely devoid of 137cs which probably originated from gully walls two separate models that related 137cs movement to soil redistribution were used to calculate net soil flux additional modelling would be required to account for 137cs dilution in order to measure net soil flux in gullied and badly eroded rangeland areas net soil flux was calculated at sites along the toposequence at the nested grid sites and at unsampled locations across the study using geostatistics the toposequence samples considerably underestimated the net soil loss relative to the nested grid samples and the geostatistical estimates of net soil flux toposequence sampling does not account for the spatial variation in net soil flux unless very well defined geomorphological units that control the soil redistribution processes are evident this form of sampling is of limited value for investigating the variation of 137cs depth distribution at all but the smallest scale largest areas since it cannot easily be used to determine local variation in soil redistribution processes a small improvement in net soil flux accuracy was provided by the geostatistical estimates relative to the nested grid samples of net soil flux this was thought to be due to the efficiency of the nested grid samples suggesting that geomorphological information can be used to limit the number of samples necessary to encompass several scales of net soil flux variation

volcanic soils of france abstract in france andic soils mainly occur in the massif central andic and other volcanic soils 5000 km 2 and on the vosges and the morvan hercynian massifs in the massif central silandosols on recent pyroclastics are distinguished from aluandosols on older mio pliocene lavas after a brief introduction to the parent materials soil characterisation survey genesis properties and land use are reviewed in two periods from 1960 to 1979 and from 1980 to 2000 soil distribution is related schematically to topo climatic sequences comparing recent pyroclastics to older volcanic lavas an udic or perudic soil moisture regime is the primary factor in andosol genesis in france silandosols occur only on recent pyroclastics and aluandosols on old lavas after reworking by glacial erosion from a mantle of loose and pre weathered materials the anthropic impacts include accelerated erosion and changes in carbon content

towed camera investigations of shallow intermediate water depth submarine stratovolcanoes of the southern kermadec arc new zealand southern kermadec arc stratovolcanoes of predominantly basaltic and andesitic composition provide a depth transect of the transition between effusive and explosive submarine volcanism observations along 4 6 km of towed camera track from the crests and upper flanks of the clark and rumble iii volcanoes reveal a consistent pattern of substrate types that are interpreted to record effusive and explosive eruption processes below 700 m water depth substrates are dominated by massive blocky flows pillow lavas pillow and angular block talus localized sheet flows and minor granule sand volcaniclastic detritus the latter typically forms a substrate mode of 5 20 above 450 m sand lapilli that is in part winnowed and rippled have a substrate mode of 50 100 with minor components of massive flows pillow lavas and coarse talus this difference in abundance of sand lapilli between 450 and 700 m is interpreted to record the transition between effusive and explosive both phreatic and phreatomagmatic eruptions between 600 and 700 m a varied distribution of sand lapilli abundance is interpreted as recording a mix of effusive and explosive eruptions consistent with possible differences in the physical interaction of magma water and known compositional magma heterogeneity

composition of widespread volcanic glass in deep sea sediments of the southern pacific ocean an antarctic source inferred widespread plio pleistocene 2 43 0 06 ma tephra zones recognised in deep sea cores from high latitudes 60 in the southern pacific ocean were thought to have originated from calc alkaline rhyolitic eruptions in new zealand some 5000 km distant electron microprobe analyses of the glasses reveal a wide diversity of alkalic felsic compositions as well as minor components of basic and intermediate glasses incompatible with a new zealand neogene source but similar to contemporaneous eruptives from the antarctic region most tephra zones are trachytic seven zones are peralkaline rhyolite the rhyolitic zones represent a deep sea record of widespread silicic eruptions from continental antarctica possibly marie byrd land the extent of these rhyolitic zones suggest a greater frequency of large explosive eruptions in antarctica than previously documented the coarse grain size of some of the shards up to 3 mm their great distance from the closest sources 1600 km for some cores and the presence of nonvolcanic ice rafted debris indicate some of the glasses especially the more basic compositions may have been ice rafted contrary to previous suggestions of a fallout origin

chemical weathering in the volcanic soils of isla santa cruz galapagos islands ecuador abstract forty three soils 130 horizons sampled by the geo pedological mission organized by the state university of gent belgium in 1962 on isla santa cruz galapagos islands were analysed in order to determine their degree of chemical evolution several weathering indices weathering index of parker wip chemical index of alteration cia chemical index of weathering ciw plagioclase index of alteration pia and silica titania index sti and multivariate statistical analysis principal components analysis based on chemical composition were used with the only exception of the sti the indices were highly correlated r 0 85 the highest wip and sti values 20 9 8 2 and 70 2 2 2 respectively were found for soils developed on basalt flows near the coast slightly lower values wip 16 8 5 1 and sti 61 3 4 were shown by brown soils developed from basaltic flows at elevations between 140 and 225 m a s l while the lowest values wip 9 5 and sti 47 6 8 representing the more weathered materials were found for soils located at the highest elevations 400 m a s l and mostly developed on pyroclastic materials tuff and tephra as the chemical composition of the geological material basalt and tephra is highly homogeneous the degree of weathering is likely to depend on climatic conditions controlled by altitude and orientation on the windward slopes of the island a gradient of increasing weathering is observed from the arid conditions predominant at the coast to elevations of 400 500 m a s l where much more humid conditions prevail principal component analysis on elemental composition also supported the interpretation that the degree of weathering first component and soil horizonation second component are both related to climatic conditions both the variation of the chemical indices and the principal components of the geochemical composition are related to the bioclimatic zones soils with the lowest degree of weathering are located in the arid coastal zone slightly higher intensity was found for soils located in the transition and scalesia zones while the most weathered soils appear in the brown zone compared to other volcanic soils studied in the literature soils from isla santa cruz are in the upper range of chemical weathering intensity only comparable to soils from azores islands and canary islands tenerife and la gomera developed on basalts under oceanic conditions

reduced ventilation and enhanced magnitude of the deep pacific carbon pool during the last glacial period it has been proposed that the ventilation of the deep pacific carbon pool was not significantly reduced during the last glacial period posing a problem for canonical theories of glacial interglacial co2 change however using radiocarbon dates of marine tephra deposited off new zealand we show that deep 2000 m 2000 m and shallow sub surface ocean atmosphere 14c age offsets i e reservoir or ventilation ages in the southwest pacific increased by 1089 and 337 yrs respectively reaching 2689 and 1037 yrs during the late glacial a comparison with other radiocarbon data from the southern high latitudes suggests that broadly similar changes were experienced right across the southern ocean if like today the southern ocean was the main source of water to the glacial ocean interior these observations would imply a significant change in the global radiocarbon inventory during the last glacial period possibly equivalent to an increase in the average radiocarbon age 2 km 2 km of 700 yrs 700 yrs simple mass balance arguments and numerical model sensitivity tests suggest that such a change in the ocean s mean radiocarbon age would have had a major impact on the marine carbon inventory and atmospheric co2 possibly accounting for nearly half of the glacial interglacial co2 change if confirmed these findings would underline the special role of high latitude shallow sub surface mixing and air sea gas exchange in regulating atmospheric co2 during the late pleistocene

correlating tephras and cryptotephras using glass compositional analyses and numerical and statistical methods review and evaluation abstract we define tephras and cryptotephras and their components mainly ash sized particles of glass crystals in distal deposits and summarize the basis of tephrochronology as a chronostratigraphic correlational and dating tool for palaeoenvironmental geological and archaeological research we then document and appraise recent advances in analytical methods used to determine the major minor and trace elements of individual glass shards from tephra or cryptotephra deposits to aid their correlation and application protocols developed recently for the electron probe microanalysis of major elements in individual glass shards help to improve data quality and standardize reporting procedures a narrow electron beam diameter 3 5 m can now be used to analyze smaller glass shards than previously attainable reliable analyses of microshards defined here as glass shards in part 2 of the review we describe critically assess and recommend ways in which tephras or cryptotephras can be correlated in conjunction with other information using numerical or statistical analyses of compositional data statistical methods provide a less subjective means of dealing with analytical data pertaining to tephra components usually glass or crystals phenocrysts than heuristic alternatives they enable a better understanding of relationships among the data from multiple viewpoints to be developed and help quantify the degree of uncertainty in establishing correlations in common with other scientific hypothesis testing it is easier to infer using such analysis that two or more tephras are different rather than the same adding stratigraphic chronological spatial or palaeoenvironmental data i e multiple criteria is usually necessary and allows for more robust correlations to be made a two stage approach is useful the first focussed on differences in the mean composition of samples or their range which can be visualised graphically via scatterplot matrices or bivariate plots coupled with the use of statistical tools such as distance measures similarity coefficients hierarchical cluster analysis informed by distance measures or similarity or cophenetic coefficients and principal components analysis pca some statistical methods cluster analysis discriminant analysis are referred to as machine learning in the computing literature the second stage examines sample variance and the degree of compositional similarity so that sample equivalence or otherwise can be established on a statistical basis this stage may involve discriminant function analysis dfa support vector machines svms canonical variates analysis cva and anova or manova or its two sample special case the hotelling two sample t2 test randomization tests can be used where distributional assumptions such as multivariate normality underlying parametric tests are doubtful compositional data may be transformed and scaled before being subjected to multivariate statistical procedures including calculation of distance matrices hierarchical cluster analysis and pca such transformations may make the assumption of multivariate normality more appropriate a sequential procedure using mahalanobis distance and the hotelling two sample t2 test is illustrated using glass major element data from trachytic to phonolitic kenyan tephras all these methods require a broad range of high quality compositional data which can be used to compare unknowns with reference training sets that are sufficiently complete to account for all possible correlatives including tephras with heterogeneous glasses that contain multiple compositional groups currently incomplete databases are tending to limit correlation efficacy the development of an open online global database to facilitate progress towards integrated high quality tephrostratigraphic frameworks for different regions is encouraged

products of neptunian eruptions a common pyroclastic facies in subaqueous volcanic successions comprises massive to graded very thick several to tens of meters laterally extensive several kilometers beds of nonwelded pumice lapilli with volumes ranging to tens of cubic kilometers this facies may be overlain by laminated ash or bimodal ash and giant 1 m pumice clasts and underlain by coarse lithic breccia the association is inferred to be the typical product of sustained magmatic volatile driven explosive eruptions from vents at water depths of 1300 200 m we propose the term neptunian for such eruptions and their products the eruption column rapidly mixes with the surrounding water cools increases in density and collapses while remaining under water lithic clasts that are too heavy to be entrained in the column are deposited close to the source forming a neptunian lithic breccia pumice lapilli are rapidly waterlogged and form the dominant component in the collapsing column and in eruption fed water supported density currents neptunian density currents hot buoyant giant pumice clasts continue to rise and may reach the water surface before being waterlogged and settling along with temporarily suspended ash forming neptunian suspension deposits eruption magnitude fragmentation mechanisms and juvenile pyroclast characteristics especially vesicularity are very similar in neptunian and plinian style eruptions but column behavior differs primarily because of the contrasting physical properties of the ambient fluid water versus air

organo metallic complexes in an andosol a comparative study with a cambisol and podzol current soil forming processes were studied in a nonallophanic andosol from the vosges mountains north eastern france for this purpose we conducted comparative studies on the organo metallic fraction dynamics of selected profiles of an andosol and other typical soils from this region cambisol and podzol these soils are derived from old volcanic rocks under mesic soil temperature and udic soil moisture regimes the andosol profile displayed the characteristics of nonallophanic andosols large accumulation of humus active al mostly complexed with humus and low ph special attention was given to physical and microbial stability of these organo metallic associations respectively by disaggregation tests and incubation experiments the results indicated that these associations showed a strong resistance against disaggregation by water and against biodegradation moreover the very low concentration of doc al and fe in soil solutions collected by zero tension lysimeters coupled with very low amounts of water dispersed clays obtained after dispersion tests suggested that no significant translocations of these components occurred in this andosol profile low mobility together with a strong resistance against mineralization may account for the large accumulation of carbon in this andosol

magnetic and geochemical characterization of andosols developed on basalts in the massif central france identification of andosols is primarily based upon the content of their colloidal constituents clay and metal humus complexes and on the determining of andic properties this needs time and cost consuming geochemical analyses our primary aim of this study is to describe the magnetic and geochemical properties of soils rich in iron oxides derived from strongly magnetic volcanic basement in this case andosols secondary aim is to explore links between magnetic and chemical parameters of andic soils with respect to genesis factors parent material age precipitation and thickness of the soil profile six pedons of andic properties developed on basaltic lavas were analyzed down to parent rock by a set of magnetic and geochemical methods magnetic data of soil and rock samples reflect the type concentration and particle size distribution of ferrimagnetic minerals geochemical data include soil reaction ph in h2o cation exchange capacity organic carbon and different forms of extractable iron and aluminum content our results suggest the following 1 magnetic measurements of low field mass specific magnetic susceptibility can be a reliable indicator for estimating andic properties and in combination with thermomagnetic curves may be suitable for discriminating between alu andic and sil andic subtypes 2 in the studied andosols strong relationships were found between a magnetic grain size parameters precipitation and exchangeable bases b concentration of ferrimagnetic particles and degree of crystallization of free iron and c parameters reflecting changes in magneto mineralogy and soil genesis parent material age soil depth

fingerprints and age models for widespread new zealand tephra marker beds erupted since 30 000 years ago a framework for nz intimate abstract the role of tephras in the nz intimate project is a critical one because most high resolution palaeoclimatic records are linked and dated by one or more tephra layers in this review first we document eruptive distributional and compositional fingerprinting data both mineralogical and geochemical for 22 key marker tephras erupted since 30 000 years ago to facilitate their identification and correlation we include new glass compositional data the selected marker tephras comprise 10 from taupo and nine from okataina volcanoes rhyolitic one from tuhua volcano peralkaline rhyolitic and one each from tongariro and egmont volcanoes andesitic second we use four approaches to develop 2 age models for the tephras youngest to oldest 1 calendar ages for kaharoa and taupo y were obtained by wiggle matching log derived tree ring sequences dated by 14c 2 whakaipo v was dated using an age depth model from peat 3 14 tephras in the montane kaipo peat sequence waimihia s unit k whakatane tuhua mamaku rotoma opepe e poronui c karapiti b okupata konini waiohau rotorua rerewhakaaitu were dated by simultaneously wiggle matching stratigraphic position and 51 independent 14c age points against intcal04 using bayesian probability methods via both oxcal and bpeat and 4 the five oldest tephras erupted before ca 18 000 cal yr bp were dated by calibrating limited numbers of 14c ages using intcal04 okareka or comparison curves of the expanded cariaco basin sequence te rere kawakawa oruanui poihipi okaia kawakawa oruanui tephra the most widely distributed marker tephra was erupted probably ca 27 097 957 cal yr bp potential dating approaches for the older tephras include their identification in antarctic ice cores if present or annually laminated sediments for which robust calendar age models have been constructed high precision ams 14c dating on appropriate material from environmentally stable sites systematic luminescence dating or new radiometric techniques e g u th he if suitable minerals are available and errors markedly reduced further application of bayesian age modelling to stratigraphic sequences of 14c ages possibly augmented with luminescence ages may help refine age models for pre holocene tephras with the largest errors finally we discuss the critical role these marker tephras play in the ongoing construction of an event stratigraphy for the new zealand region which is a key objective of australasian and southern hemisphere intimate projects