a geomorphological reconnaissance of the submarine part of the east rift zone of kilauea volcano hawaii more than half of the intensely active east rift zone of kilauea volcano crops out underwater along the crest of the submarine puna ridge i present multibeam bathmetry of the entire ridge near bottom photographic and sonar observations of the plunging crest of its deeper distal half and seismic profiles across the ridge tip and the adjacent structural moat analysis of large scale relief small scale topography and superficial rock types indicates that the rift zone is actively propagating across the moat but is probably a superficial structure that does not penetrate the underlying oceanic crust that its tip is covered with large lava flows erupted at high rates and is surrounded with extensive debris flow deposits and that the axial topography at depths of 2 4 km is dominated by gaping fissures and collapse pits showing a preponderance of intrusive rather than extrusive events some aspects of this central volcano rift zone such as its geometry at small lateral offsets resemble those at interplate rift zones along fast spreading mid ocean rises but the great contrast in lithosphere thickness results in fundamental structural differences

global adjustment of the thermocline in response to deepwater formation the global adjustment of the thermocline in response to deepwater formation is studied in a single mode model on a beta plane the signal is carried from ocean to ocean by kelvin waves which travel equatorward along western boundaries eastward across the equator poleward at the eastern boundaries and then eastward around the southern tip of continents into the next ocean basin the interior is filled by rossby waves emanating from eastern boundaries stronger weaker deepwater formation induces an upward downward motion of the main thermocline in the world oceans the adjustment is completed on centennial time scales

oxidative mobilization of cerium and uranium and enhanced release of immobile high field strength elements from igneous rocks in the presence of the biogenic siderophore desferrioxamine b abstract polyvalent trace elements such as the high field strength elements hfse are commonly considered rather immobile during low temperature water rock interaction hence they have become diagnostic tools that are widely applied in geochemical studies we present results of batch leaching experiments focused on the mobilization of certain hfse y zr hf th u and rare earth elements from mafic intermediate and felsic igneous rocks in the presence and absence respectively of the siderophore desferrioxamine b dfob our data show that dfob strongly enhances the mobility of these trace elements during low temperature water rock interaction the presence of dfob produces two distinct features in the rare earths and yttrium rey patterns of leaching solutions regardless of the mineralogical and chemical composition or the texture of the rock type studied bulk rock normalized rey patterns of leaching solutions with dfob show i a very distinct positive ce anomaly and ii depletion of la and other light rey relative to the middle rey with a concave downward pattern between la and sm these features are not observed in experiments with hydrochloric acid acetic acid or deionized water in dfob bearing leaching solutions ce and u are decoupled from and selectively enriched relative to light rey and th respectively due to oxidation to ce iv and u vi oxidation of ce3 and u4 is promoted by the significantly higher stability of the ce iv and u vi dfob complexes as compared to the ce iii and u iv dfob complexes this is similar to the relationship between the ce iv and ce iii pentacarbonate complexes that cause positive ce anomalies in alkaline lakes however while formation of ce iv carbonate complexes is confined to alkaline environments ce iv dfob complexes may produce positive ce anomalies even in mildly acidic and near neutral natural waters siderophore promoted dissolution processes also significantly enhance mobility of other immobile hfse and may not only cause or modify ce anomalies and th u fractionation but also mobilization of and fractionation between zr hf th and redox insensitive rey during weathering pedogenesis diagenesis and incongruent dissolution of particles in seawater and freshwater siderophores may significantly affect the use of hfse as geochemical tools concave downward light rey patterns may be used as a biosignature for water rock interaction in the presence of siderophores enhanced and preferential mobilization of u relative to th in the presence of siderophores may produce th u signals comparable to those indicative of weathering under oxidized conditions which might constrain the use of u concentrations and th u ratios as a paleoredox proxy the enhanced mobilization of zr and especially hf from igneous rocks in the presence of dfob might have implications for the use of the latter as a tracer for the impact of continental weathering on seawater chemistry because siderophore complexes affect the particle reactivity of hf and zr they may prevent effective removal of terrigenous hf and zr during aggregation coagulation of riverine particles in estuaries siderophore promoted solubilization and stabilization might hence be an additional way to transport continental hf and zr to the oceans furthermore siderophore enhanced mobilization may also have implications for the remediation techniques employed to immobilize hfse such as u th and rey at nuclear waste and reprocessing sites and at rey ore processing plants where soils are commonly contaminated with these sometimes radioactive heavy metals

decadal response of global circulation to southern ocean zonal wind stress perturbation abstract a substantial component of north atlantic deep water formation may be driven by westerly wind stress over the southern ocean variability of this wind stress on decadal time scales may lead to circulation variability far from the forcing region the hybrid coordinate ocean model hycom a numerical ocean model is used to investigate the spatial patterns and the time scales associated with such wind variability the evolution of circulation and density anomalies is observed by comparing one 80 yr simulation forced in part by relatively strong southern hemisphere westerlies with a simulation driven by climatological wind the volume transport anomaly takes about 10 yr to reach near full strength in the entire southern hemisphere however in the northern hemisphere it grows for the duration of the run the southern hemisphere indo pacific volume transport anomaly is about twice the strength of that found in the atlantic in the thermocline water exits the southern westerlies belt in a broad f

response of the global ocean to greenland and antarctic ice melting 1 we investigate the transient response of the global ocean circulation to enhanced freshwater forcing associated with melting of the greenland and antarctic ice sheets increased freshwater runoff from greenland results in a basin wide response of the north atlantic on timescales of a few years communicated via boundary waves equatorial kelvin waves and westward propagating rossby waves in addition modified air sea interaction plays a fundamental role in setting up the basin scale response of the atlantic circulation in its subpolar and subtropical gyres in particular the modified ocean dynamics and thermodynamics lead to a depression in the central north and south atlantic that would not be expected from linear wave dynamics moreover the heat content increases on basin and global scales in response to anomalous freshwater forcing from greenland suggesting that the ocean s response to enhanced freshwater forcing would be a coupled problem other parts of the world ocean experience a much slower adjustment in response to greenland freshwater forcing communicated via planetary waves but also involving advective diffusive processes especially in the southern ocean over the 50 years considered here most of the sea level increase associated with freshwater input from greenland remains in the atlantic ocean in contrast ice melting around antarctica has a much reduced effect on the global ocean in both cases none of the basins came to a stationary state during the 50 year experiment

unusual manganese enrichment in the mesoarchean mozaan group pongola supergroup south africa abstract an unusual sediment hosted manganese deposit is described from the mesoarchean mozaan group pongola supergroup south africa mno contents up to 15 wt were observed in marine clastic and chemical sedimentary rocks mn enrichment is interpreted to have resulted from the hydrothermal alteration of manganiferous shale and bif parent rocks the primary mno contents of which are as high as 8 5 wt a detailed mineralogical and petrographic study shows that these parent rocks are characterized by manganoan siderite ferroan rhodochrosite and other mn fe rich mineral phases such as kutnohorite and fe mn chlorite their hypogene alteration gave rise to a diversification of mineral assemblages where ferroan tephroite calcian rhodochrosite rhodochrosite pyrochroite pyrophanite cronstedtite manganoan fe rich chlorite and manganoan phlogopite partially or totally replaced the previous mineral assemblage thermodynamic modeling performed on chlorite phases associated with the described mineral assemblages illustrates a decrease of average crystallization temperatures from ca 310 c during early metamorphic stages to ca 250 c during a hydrothermal stage mineral transformation processes were thus related to retrograde metamorphism and or hydrothermal alteration post dating metamorphism and gave rise to progressive mn enrichment from unaltered parent to altered rocks the timing of hypogene alteration was constrained by 40 ar 39 ar dating to between about 1500 and 1100 ma ago reflecting tectonic processes associated with the namaqua natal orogeny along the southern kaapvaal craton margin manganiferous shale and bif of the mozaan group may represent the oldest known examples of primary sedimentary mn deposition related to oxidation of dissolved mn ii by free oxygen in a shallow marine environment oxygenic photosynthesis would have acted as a first order control during mn precipitation this hypothesis opens a new perspective for better constraining secular evolution of sediment hosted mineral deposits linked to oxygen levels in the atmosphere hydrosphere system during the archean eon

multiple equilibria and low frequency variability of the wind driven ocean circulation abstract the link between low frequency time dependent variability and the existence of multiple unstable steady state solutions in a reduced gravity quasigeostrophic ocean model for the midlatitude wind driven circulation is investigated it is shown that a sequence of successive symmetry breaking pitchfork bifurcations lead to multiple equilibria that differ from each other primarily in the elongation of the recirculation cell in the amount of meandering present in the intergyre jet and in a north south shift in the eastward jet the elongation of the recirculation cells and the meandering of the jet play compensating roles in the establishment of the global energy and vorticity balance the solutions also have distinct energy levels but general agreement between them and the bumps in a histogram of the total energy obtained from a 1200 yr time dependent simulation is not found nevertheless a substantial fraction of the variance 30 can be accounted for by four coherent structures that capture th

on too fast baroclinic planetary waves in the general circulation abstract recent altimetric observations of the ocean surface reveal signatures of long planetary waves near the annual frequency band comparisons of the observed wave speeds and those predicted by standard linear theory suggest that the latter is inadequate as it yields different westward speeds than those measured in the extratropical latitudes the predicted speeds are typically slower than the observations here the problem of long baroclinic wave propagation in a forced stratified ocean is considered theoretically with a view toward explaining these observations of too fast planetary waves from a quasigeostrophic analysis it is argued that baroclinic waves in a sheared environment are accelerated to the west via their interactions with both the mean advective field and the mean potential vorticity field conditions under which the ratio of actual to linear phase speeds matches the observed ratio are computed and found to be typical of the open ocean extensions of these ideas to continuously st

oceanic teleconnections remote response to decadal wind forcing abstract the transhemispheric and interbasin response to time dependent wind forcing localized in the northern hemisphere of a single basin is examined using the reduced gravity shallow water equations in domains of simple geometry on decadal timescales the pressure on the eastern boundary fluctuates synchronously in both hemispheres and thus communicates a signal to latitudes distant from the forcing the signal then penetrates into the interior through westward radiation of rossby waves associated with the eastern boundary pressure fluctuation is a time dependent mass flux across the equator that in a single basin is balanced by a storage of mass in the unforced hemisphere two oceanic basins connected by a reentrant channel at the high latitude edge of the southern hemisphere are then considered again the forcing is confined to the northern hemisphere of one basin only in this geometry the time dependent mass flux across the equator of the forced basin is not entirely balanced within the same ba

heat distribution in the southeast pacific is only weakly sensitive to high latitude heat flux and wind stress the southern ocean features regionally varying ventilation pathways that transport heat and carbon from the surface ocean to the interior thermocline on timescales of decades to centuries but the factors that control the distribution of heat along these pathways are not well understood in this study we use a global ocean state estimate eccov4 to 1 define the recently ventilated interior pacific rvp using numerical passive tracer experiments over a 10 year period and 2 use an adjoint approach to calculate the sensitivities of the rvp heat content rvph to changes in net heat flux and wind stress we find that rvph is most sensitive to local heat flux and wind stress anomalies north of the sea surface height contours that delineate the antarctic circumpolar current with especially high sensitivities over the south pacific gyre surprisingly rvph is not especially sensitive to changes at higher latitudes we perform a set of step response experiments over the south pacific gyre the subduction region and the high latitude so in consistency with the adjoint sensitivity fields rvph is most sensitive to wind stress curl over the subtropical gyre which alter isopycnal heave and it is only weakly sensitive to changes at higher latitudes our results suggest that despite the localized nature of mode water subduction hotspots changes in basin scale pressure gradients are an important controlling factor on rvph because basin scale wind stress is expected to change in the coming decades to centuries our results may have implications for climate via the atmosphere ocean partitioning of heat

geochemistry and origin of basaltic lavas from society islands french polynesia south central pacific ocean the society islands of french polynesia south central pacific ocean are formed predominatly by basaltic lavas of alkaline affinities these intraplate rocks are either ne or hy normative ne normative basaltic lavas are lower in si and heavy rare earth elements and higher in ti v and sr than hy normative the differences are attributed to the contrasting behaviour of amphibole during melting of the upper mantle which in turn may be related to the variation in the depth of melting compared to pyrolite the upper mantle source of the lavas was enriched in incompatible elements

offshore evidence for a huge landslide of the northern flank of tahiti nui french polynesia a bathymetric analysis of the flanks of tahiti nui french polynesia reveals the existence of a major catastrophic north directed landslide during its eruptive history the related debris avalanche da deposits extend north 70 km from the island shore and have a total volume of about 800 km3 two contrasted facies of the debris are recognized 1 relatively small sized material including a few blocks with well developed flow structures elongate downslope directed ridges and transversal pressure ridges and 2 a scattering of large kilometer sized individual blocks that form in part a prominent bathymetric hummock in the proximal central part of the landslide deposits bathymetric analyses suggest that the tahitian failure evolved through two main successive shots the da debris were rapidly overlain by subsequent volcanic material producing a smooth surface down to 1500 m below sea level the on land and offshore structures indicate a listric fault geometry for the landslide scar the volume removed by the landslide is thus estimated between 400 km3 and 450 km3 discrepancy in the volume of the scar and the debris derived from it is due in part to expansion of the debris to fragmentation of the avalanche and to incorporation of sediments comparison with a recently recognized southern tahitian landslide clouard et al 2001 and with landslides recognized around the hawaiian islands and the canary islands shows that the huge northern tahitian landslide described here has a reduced mobility in its central part perhaps the older tetiaroa eruptive complex to the north acted as a buttress to inhibit movement of the da products the northern and southern tahiti nui landslides moved in opposite directions away from the main central e w directed rift zone that served as the main magma feeding structure then the huge northern landslide strongly controlled the later volcano structural evolution by capturing subsequent volcanic activity to the north despite the northwestward displacement of the pacific plate over the society hot spot

late archean initiation of manganese metallogenesis its significance and environmental controls abstract manganese metallogenesis was initiated in a modest scale during the late archean time selectively in india and brazil sedimentary deposits occur in both greenstone belts and high grade granulite terranes in shallow water shelf regimes only and are often intimately associated with stromatolites the changes in the rates of continental crustal growth mantle heat flux and outgassing along with the evolution of tectonic regimes sedimentary environments the state of the biosphere and finally the compositions of interacting atmosphere hydrosphere system from the early to the late archean time have been traced as interdependent parameters and interpreted to explain the first appearance of sedimentary manganese deposits promoted by possibly localized oxygenated environments compared to the spectacular manganese event represented by the giant paleoproterozoic kalahari deposit south africa which is interpreted to have been formed as a consequence of the rapid increase in atmospheric oxygen level ca 2 5 2 4 ga ago the modest initiation of the late archean manganese depositions was triggered by localized photosynthetic oxygen supply forming basin margin oxygen oases as a prologue for the succeeding stratified ocean system the dissolved manganese in the basin water that was oxidized to form shelf type shallow water deposits is suspected by analogy with contemporary banded iron formations bifs but not proved to be of hydrothermal ancestry the initiation of concentrated manganese sedimentation during the late archean by itself provides an evidence for an increase in the oxygen content in the contemporary atmosphere hydrosphere system compared to that in the earlier period supporting the geochemical indications from paleoweathering profiles

thermally forced transients in the thermohaline circulation abstractthe response of a convective ocean basin to variations in atmospheric temperature is explored using numerical models and theory the results indicate that the general behavior depends strongly on the frequency at which the atmosphere changes relative to the local response time to air sea heat flux for high frequency forcing the convective region in the basin interior is essentially one dimensional and responds to the integrated local surface heat flux anomalies for low frequency forcing eddy fluxes from the boundary current into the basin interior become important and act to suppress variability forced by the atmosphere a theory is developed to quantify this time dependent response and its influence on various oceanic quantities the amplitude and phase of the temperature and salinity of the convective water mass the meridional overturning circulation the meridional heat flux and the air sea heat flux predicted by the theory compare well with that diagnosed from a series of numerical model

tahiti geochemical evolution of a french polynesian volcano the island of tahiti the largest in french polynesia comprises two major volcanoes aligned nw se parallel with the general trend of the society islands hotspot track rocks from this volcanic system are basalts transitional to tholeiites alkali basalts basanites picrites and evolved lavas through k ar radiometric dating we have established the age of volcanic activity the oldest lavas 1 7 ma crop out in deeply eroded valleys in the center of the nw volcano tahiti nui while the main exposed shield phase erupted between 1 3 and 0 6 ma and a late stage valley filling phase occurred between 0 7 and 0 3 ma the sw volcano tahiti iti was active between 0 9 and 0 3 ma there is a clear change in the composition of lavas through time the earliest lavas are moderately high sio2 evolved basalts mg number mg mg mg fe2 42 49 probably derived from parental liquids of composition transitional between those of tholeiites and alkali basalts the main shield lavas are predominantly more primitive olivine and clinopyroxene phyric alkali basalts mg 60 64 while the later valley filling lavas are basanitic mg 64 68 and commonly contain peridotitic xenoliths olivine orthopyroxene clinopyroxene spinel isotopic compositions also change systematically with time to more depleted signatures rare earth element patterns and incompatible element ratios however show no systematic variation with time we focused on a particularly well exposed sequence of shield building lavas in the punaruu valley on the western side of tahiti nui combined k ar ages and magnetostratigraphic boundaries allow high resolution age assignments to this 0 7 km thick flow section we identified an early period of intense volcanic activity from 1 3 to 0 9 ma followed by a period of more intermittent activity from 0 9 to 0 6 ma flow accumulation rates dropped by a factor of 4 at about 0 9 ma this change in rate of magma supply corresponds to a shift in activity to tahiti iti we calculated the composition of the parent magma for the shield building stage of volcanism assuming that it was in equilibrium with fo89 olivine and that the most primitive aphyric lavas were derived from this parent by the crystallization of olivine alone the majority of the shield lavas represent 25 to 50 crystallization of this parent magma but the most evolved lavas represent about 70 crystallization from over 50 analyzed flow units we recognize a quasi periodic evolution of lava compositions within the early robust period of volcanic activity which we interpret as regular recharge of the magma chamber approximately every 25 10 kyr volcanic evolution on tahiti is similar to the classic hawaiian pattern as the shield building stage waned the lavas became more silica undersaturated and isotopic ratios of the lavas became more morb like we propose that the society plume is radially zoned due to entrainment of a sheath of viscously coupled depleted mantle surrounding a central core of deeper mantle material all parts of the rising plume melt but the thermal and compositional radial gradient ensures that greater proportions of melting occur over the plume center than its margins the changing composition of tahitian magmas results from lithospheric motion over this zoned plume magmas erupted during the main shield building stage are derived mainly from the hot incompatible element enriched central zone of the plume late stage magmas are derived from the cooler incompatible element depleted viscously coupled sheath a correlation between pb ce and isotope ratios suggests that the society plume contains deeply recycled continental material

some geochemical indicators for discrimination between diagenetic and hydrothermal metalliferous sediments abstract two types of metalliferous sediments are known hydrothermal associated with tectonic faults and diagenetic enriched in precipitates from seawater they are similar in their appearance and chemical composition only the first type is an indicator for hydrothermal discharge therefore in exploration criteria for differentiating between the two are needed four possible indicators have been investigated and are discussed a differences in p y correlation b differences in cr zr correlation c different distribution patterns of ree and d different as contents the as content is easy to determine and seems to be at the present time the most suitable criterion for determining the genesis of the metalliferous sediments

styles of eruptive activity on intraplate volcanoes in the society and austral hot spot regions bathymetry petrology and submersible observations submersible observations carried out in the society and austral hot spot regions south pacific during the teahitia ii cruise 1988 1989 enable us to propose a model relating the style of volcanism to the depth of eruption on large intraplate seamounts 1 the bases of volcanic edifices are characterized by broad flat flows formed during a high rate of discharge of a very fluid magma on the sea floor 2 the edifices flanks deeper than 500 m are mainly made up of bulbous tubular pillows and large drained lava tunnels occurring on slopes steeper than 60 70 these lava flows occur on lateral volcanic vents about 200 300 m high along linear rift zones which are formed on the flank of the major edifices 3 volcanic ejecta due to hydromagmatic eruptions occur at shallow depths 500 m in height are individual conical features built at a high rate of volcanic discharge localized along radial linear eruptive fissures called rift zones the slopes located between the rift zones are covered by talus material are limited and unimportant mass wasting sector collapse features were observed on the edifices the conical shaped features are the primary morphology of the intraplate volcanoes formed during edifice growth which is closely linked to the hydrostatic pressure of the magmatic column the mean values of the slopes 11 17 of intraplate seamounts are the same as those of subaerial intraplate shield volcanoes when the seawater hydrostatic pressure is taken into account

morphological and structural studies of the society and austral hotspot regions in the south pacific abstract the southeastern extension of the society teahitia hotspot and austral macdonald hotspot volcanic chains were extensively studied 1986 1989 using multi channel echo sounding seabeam bottom imaging systems and submersible dives sea floor within these hotspot regions consists of recently constructed submarine highs built on crust that shows morphological and structural discontinuities with the surrounding ancient abyssal hill regions 4200 m in depth recent volcanic and hydrothermal activity is present on several volcanoes within the society hotspot and on the macdonald volcano previous studies carried out in the society hotspot region showed several geological provinces 1 1 eight major highs 1000 m in height which extend from above sea level down to a depth of 3750 m these features have been formed by lateral eruptive events along rift zones which are aligned along four main structural directions n150 180 n80 n30 40 and n110 which correspond to the orientations of ancient ridge axes transform faults and riedel type shear zones respectively 2 2 the sea floor which slopes away from the base of each major volcano 3750 4200 m depth has an average slope of 0 5 and is characterized by smooth topography and volcanic cones less than 500 m high 3 3 the surrounding abyssal hill region which has an average slope of 0 1 near the society hotspot consists of faulted terrane with a n170 orientation and ancient elongated structural highs from the structural lineations observed in the society hotspot volcanoes a reconstruction of volcanic features has been made it is proposed that the formation of the seamounts occurs in an organized fashion along pre existing preferential structural orientations that are associated with zones of crustal weakness

a simple model of the decadal response of the ocean to stochastic wind forcing abstract a simple linear model is used to estimate the decadal response of the extratropical ocean to wind stress forcing assuming a flat bottom a mean state at rest and no dissipation the barotropic fields are governed by a time dependent sverdrup balance the baroclinic ones by the long rossby wave equation the ocean is bounded by a coast in the east and a radiation condition is used in the west at each frequency the baroclinic response consists of a forced response plus a rossby wave generated at the eastern boundary for zonally independent forcing the response propagates westward at twice the rossby phase speed the wind stress is assumed to be stochastic with a white frequency spectrum so the model represents the continuous excitation of the ocean interior by the weather fluctuations the model predicts the shape and level of the frequency spectra of the oceanic pressure field and their variation with longitude and latitude the baroclinic response is spread over a continuum of frequencies

mehetia island south pacific geology and petrology of the emerged part of the society hot spot abstract mehetia is the youngest island of the society hot spot chain representing the summit of a large submarine volcanic edifice 4035 m in height its conical shape results from strombolian type eruptions mehetia comprises two major volcanic formations the old edifice made up of interbedded pyroclastic rocks and lava flows forms the main part of the island the base of its stratigraphic pile is dated at 70 000 75 000 yr b p by k ar younger events 31 000 yr b p have built up a volcanic cone with a summit hydromagmatic crater and emplaced lava flows extending south of the island where they overlie coral reef limestones between the two eruptive periods an erosional phase caused the partial destruction of the old edifice six successive stages of construction of the island are described from stratigraphic relations mehetia does not show any indication of present day volcanic or fumarolic activity but should be considered as an active volcano as evidenced by the 1981 volcanoseismic crisis mehetia lavas include oceanites primitive and evolved alkali basalts and basanites together with rare hawaiites and mugearites two main petrogenetic processes i e accumulation and crystal fractionation are inferred from bulk rock composition and microprobe data on phenocrysts oceanites are derived from basalts through accumulation of olivine and clinopyroxene major and trace elements trends suggest evolution through crystal fractionation processes involving olivine clinopyroxene and fe ti oxides

diverse basalt types from loihi seamount hawaii loihi seamount is the southeasternmost active volcano in the hawaiian emperor volcanic chain the seamount is considered representative of the early phase of hawaiian volcanism because of its youth small size and location near the melting anomaly seventeen dredge stations recovered transitional basalt alkalic basalt and basanite in addition to the expected tholeiitic basalt four flows of alkalic basalt contain common small dunite xenoliths the recovered samples have thin palagonite rinds and almost no manganese on the glassy surfaces we estimate that the lavas are less than about 4 000 yr old and many are less than 1 000 yr old loihi seamount is apparently in a transitional growth phase between the early eruption of alkalic lavas and the commonly observed subaerial tholeiitic eruptive phase previously thought to dominate hawaiian volcanism from inception until the postcaldera collapse alkalic stage

morphology and structure of loihi seamount based on seabeam sonar mapping loihi seamount has been mapped using seabeam multibeam sonar and the resulting data have been processed to produce bathymetric maps with a 10 m contour interval and shaded relief perspective images analysis of morphological and structural data recorded in the maps and images indicates that constructional volcanism on loihi has been localized predominantly along its southern and northern rift zones and that these rifts have been active since early in the seamount s history the distinct asymmetry between loihi s eastern and western slopes the eastern slopes are steeper is attributed to mass wasting of large sections of the volcano s west flank two large amphitheater valleys on the seamount s west flank are believed to have resulted from repeated mass wasting events triggered by earthquakes associated with an early rift zone whose core now lies buried beneath the block feature present on loihi s southwest flank the prominent kink in the present south rift zone of loihi may represent a fundamental readjustment of along rift magma conduits that was caused by gravitational slumping on the southwest flank of the volcano lava cones and constructional volcanic ridges are present along the rims of summit pit craters and form a continuous chain of volcanic constructs around the periphery of the summit platform the concentric arrangement of young eruptive vents pn loihi s summit may be caused by ring dikes the morphology and structural interrelationships of pit craters on loihi s summit suggest that the southeastern pit is the youngest the formation of a summit platform on loihi may have been caused by repeated collapse of pit craters and the southward migration of primary magma conduits that underlie the pits this model predicts a north to south age progression for volcanism on loihi s summit

geochemistry of diverse basalt types from loihi seamount hawaii petrogenetic implications the wide variety of basalt types tholeiitic to basanite dredged from loihi seamount have minor and trace element abundances that are characteristic of subaerial hawaiian basalts thereby confirming that loihi seamount is a manifestation of the hawaiian hot spot within the loihi sample suite there are well defined positive correlations among abundances of highly incompatible elements p k rb ba nb light ree and ta and moderately incompatible elements sr ti zr and hf and between mgo ni and cr however within the loihi suite abundance ratios of geochemically similar elements zr hf nb ta and la ce vary by factors of 1 2 1 5 and abundance ratios of highly incompatible elements such as p ce p th k rb ba th and la nb vary by factors of 1 2 2 5 these abundance ratios are not readily changed by different degrees of fractionation and melting therefore we conclude that these samples are not genetically related by different degrees of melting of a compositionally homogeneous source on the basis of k p k ti p ce zr nb th p and la sm abundance ratios the twelve samples studied in detail can be divided into six geochemical groups samples within each group are similar in 87sr 86sr 1 and intra group compositional variations may reflect low pressure fractionation and different degrees of melting in addition crossing chondrite normalized ree patterns within the alkalic basalt groups reflect equilibration of the magmas with garnet in ratio ratio plots involving abundance ratios of highly incompatible elements e g la p nb p k p rb p ba p and th p the geochemical groups define linear arrays suggestive of mixing however these data combined with the isotopic data are not consistent with two component mixing

a simple model of the response of the atlantic to the north atlantic oscillation the response of an idealized atlantic ocean to wind and thermohaline forcing associated with the north atlantic oscillation nao is investigated both analytically and numerically in the framework of a reducedgravity model the nao related wind forcing is found to drive a time dependent leaky gyre circulation that integrates basinwide stochastic wind ekman pumping and initiates low frequency variability along the western boundary thisissubsequentlycommunicated togetherwith the stochasticvariability induced bythermohaline forcing at high latitudes to the remainder of the atlantic via boundary and rossby waves at low frequencies the basinwide ocean heat content changes owing to nao wind forcing and thermohaline forcing are found to oppose each other the model further suggests that the recently reported opposing changes of the meridional overturning circulation in the atlantic subtropical and subpolar gyres between 1950 70 and 1980 2000 may be a generic feature caused by interplay between the nao wind and thermohaline forcing

constraining mid to late holocene relative sea level change in the southern equatorial pacific ocean relative to the society islands french polynesia precisely quantifying the current climate related sea level change requires accurate knowledge of long term geological processes known as glacial isostatic adjustments gia although the major postglacial melting phase is likely to have ended 6 4 ka bp before present gia is still significantly affecting the present day vertical position of the mean sea surface and the sea bottom here we present empirical rsl relative sea level data based on u th dated fossil corals from reef platforms of the society islands french polynesia together with the corresponding gia modeling fossil coral data constrain the timing and amplitude of rsl variations after the holocene sea level maximum hslm upon correction for isostatic island subsidence we find that local rsl was at least 1 5 0 4 m higher than present at 5 4 ka later minor amplitude variations occurred until 2 ka when the rsl started dropping to its present position with a rate of 0 4 mm yr the data match with predicted rsl curves based on global ice sheet chronologies confirming the role of gia induced ocean siphoning effect throughout the mid to late holocene a long lasting late holocene highstand superimposed with second order amplitudinal fluctuations as seen from our data suggest that the theoretical predicted timing of rsl change can still be refined pending future calibration

the manihiki plateau a key to missing hotspot tracks a neogene magmatic reactivation of the manihiki plateau a large igneous province lip in the central pacific is studied using seismic reflection data igneous diapirs have been identified exclusively within a narrow wnw ese striking corridor in the southern high plateau hp which is parallel to the neogene pacific plate motion and overlaps with an extrapolation of the society islands hotspot path the igneous diapirs are characterized by a narrow width 5 km penetration of the neogene sediments and they become progressively younger towards the east 23 10 ma the magmatic source appears to be of small lateral extent which leads to the conclusion that the diapirs represent neogene hotspot volcanism within a lip and thus may be an older previously unknown extension of the society islands hotspot track 4 5 ma comparing hotspot volcanism within oceanic and continental lithosphere we further conclude that hotspot volcanism within lip crust has similarities to tectonically faulted continental crust

origin of the annual to decadal peaks of variability in the response of simple ocean models to stochastic forcing abstract the response of the ocean to stochastic forcings is studied in a closed basin using a simple one dimensional analytical model the focus is on the mechanisms that determine the time scales of the response and their possible links with free basin modes the response may be described as a forced solution plus propagating solutions whose spatial pattern does not depend on the forcing the propagating solutions are of two types the first ones propagate eastward and are strongly damped so that their influence remains limited to the western boundary layer the others are damped long rossby waves that propagate westward and whose amplitude depends on the spatial extension and the frequency of the forcing the amplitude increases if the frequency of the forcing is close to the frequency of the basin modes but the spatial pattern differs from that of the latter higher frequencies are favored if the zonal extension of the forcing is reduced the response of a 1 5 layer reduced gravity ocean model force

geochemistry and sedimentology of a facies transition from microbanded to granular iron formation in the early proterozoic transvaal supergroup south africa abstract a transition from microbanded kuruman to granular griquatown iron formation is described in terms of sedimentological petrographic and geochemical characteristics major minor trace and rare earth elements as well as whole rock carbon and oxygen isotopic compositions transitions between microbanded and granular iron formation are uncommon in the global stratigraphic record with microbanding absent from most known granular iron formations the kuruman griquatown transition zone differs from other granular iron formation sequences in being non oolitic i e peloidal and magnetite rich instead of hematite rich it is concluded that the coarsening upward microbanded granular iron formation units in the kuruman griquatown sequence represent upward shallowing storm dominated deposits that is primary microbanded relatively deep water fair weather deposits having been intermittently reworked by storm wave action form wavy sharp based graded and poorly sorted irregular interbeds of granular iron formation this is in contrast to typical hematitic oolitic iron formation units which represent true shoal deposits geochemical results strongly support the storm reworking hypothesis microbanded and granular iron formation beds have similar ree patterns with negative ce anomalies and depletion in light ree reflecting deposits in a marine setting below the zone of shallow surface water positive eu anomalies in the ree patterns suggest admixture of a hydrothermal component of the ocean water carbonates in the iron formation are depleted in 13c indicating involvement of organic matter during diagenetic alteration of the iron formations there are also indications that total dissolved carbon dioxide in deeper water was more depleted in 13c than in shallower water deposition of the iron formations was sporadically interrupted by influx of tuffaceous material now represented by centimeter thick shard and lapilli bearing stilpnomelane lutite beds these beds differ chemically from the iron formations in being enriched in elements such as al sc y zr nb hf ta th u and the lanthanides and displaying ree patterns with strong negative eu and slight positive ce anomalies the composition of the parent magma of the volcanics remains uncertain because of probable post depositional alteration of the volcanic glass however it was most probably of intermediate to acidic composition as concluded from the widespread distribution of the ash beds typical of plinian type deposits chemical variations in the minor trace and ree compositions of the iron formations are closely correlated with the amounts of admixed volcanic ash material most of the iron formations appear chemically very uncontaminated being highly depleted in all minor trace and ree and organic carbon contents the iron formations were therefore most probably deposited as a chemical precipitate on a submerged shallow cratonic platform with volcanic ash as the only exogenic material sporadically reaching the depository

petrology of basalts from loihi seamount hawaii abstract loihi seamount is the southeasternmost active volcano of the emperor hawaii linear volcanic chain it comprises a spectrum of basalt compositional varieties including basanite alkali basalt transitional basalt and tholeiite samples from four dredge collections made on scripps institution of oceanography benthic expedition in october 1982 are tholeiite the samples include highly vesicular olivine rich basalt and dense glass rich pillow fragments containing olivine and augite phenocrysts both quartz normative and olivine normative tholeiites are present minor and trace element data indicate relatively high abundances of low partition coefficient elements e g ti k p rb ba zr and suggest that the samples were derived by relatively small to moderate extent of partial melting of an undepleted mantle source olivine composition mgo cr and ni abundances and mg mg fe are typical of moderately fractionated to relatively unfractionated primary magmas the variations in chemistry between samples cannot be adequately explained by low pressure fractional crystallization but can be satisfied by minor variations in extent of melting if a homogeneous source is postulated alternatively a heterogeneous source with variable abundances of certain trace elements or mixing of liquids may have been involved data for 3 he 4 he presented in a separate paper implies a mantle plume origin for the helium composition of the loihi samples there is little variation in the helium isotope ratio for samples having different compositions and textures the helium data are not distinctive enough to unequivocally separate the magma sources for the tholeiitic rocks from the other rock types such as loihi alkalic basalts and the whole source region for loihi may have a nearly uniform helium compositions even though other element abundances may be variable complex petrologic processes including variable melting fractional crystallization and magma mixing may have blurred original helium isotopic signatures

global teleconnections of meridional overturning circulation anomalies there is a wide range of evidence from both models and palaeoclimatic data that indicates the possibility of abrupt changes in the oceanic meridional overturning circulation moc however much of our dynamical understanding of the moc comes from steady state models that rely upon the assumption of thermodynamic equilibrium and are therefore only valid on millennial time scales here a dynamical model for the global teleconnections of moc anomalies on annual to multidecadal time scales is developed it is based on a linear theory for the propagation of zonally integrated meridional transport anomalies in a reduced gravity ocean and allows for multiple ocean basins connected by a circumpolar channel to the south the theory demonstrates that the equator acts as a low pass filter to moc anomalies as a consequence moc anomalies on decadal and shorter time scales are confined to the hemispheric basin in which they are generated and have little impact on the remainder of the global ocean the linear theory is compared with the results of a global nonlinear numerical integration which it reproduces to a good approximation

sedimentary manganese metallogenesis in response to the evolution of the earth system abstract the concentration of manganese in solution and its precipitation in inorganic systems are primarily redox controlled guided by several earth processes most of which were tectonically induced the early archean atmosphere hydrosphere system was extremely o2 deficient thus the very high mantle heat flux producing superplumes severe outgassing and high temperature hydrothermal activity introduced substantial mn2 in anoxic oceans but prevented its precipitation during the late archean centered at ca 2 75 ga the introduction of photosystem ii and decrease of the oxygen sinks led to a limited buildup of surface o2 content locally initiating modest deposition of manganese in shallow basin margin oxygenated niches e g deposits in india and brazil rapid burial of organic matter decline of reduced gases from a progressively oxygenated mantle and a net increase in photosynthetic oxygen marked the archean proterozoic transition concurrently a massive drawdown of atmospheric co2 owing to increased weathering rates on the tectonically expanded freeboard of the assembled supercontinents caused paleoproterozoic glaciations 2 45 2 22 ga the spectacular sedimentary manganese deposits at ca 2 4 ga of transvaal supergroup south africa were formed by oxidation of hydrothermally derived mn2 transferred from a stratified ocean to the continental shelf by transgression episodes of increased burial rate of organic matter during ca 2 4 and 2 06 ga are correlatable to ocean stratification and further rise of oxygen in the atmosphere black shale hosted mn carbonate deposits in the birimian sequence ca 2 3 2 0 ga west africa its equivalents in south america and those in the francevillian sequence ca 2 2 2 1 ga gabon are correlatable to this period tectonically forced doming up attenuation and substantial increase in freeboard areas prompted increased silicate weathering and atmospheric co2 drawdown causing glaciation on the neoproterozoic rodinia supercontinent tectonic rifting and mantle outgassing led to deglaciation dissolved mn2 and fe2 concentrated earlier in highly saline stagnant seawater below the ice cover were exported to shallow shelves by transgression during deglaciation during the sturtian glacial interglacial event ca 750 700 ma interstratified mn oxide and bif deposits of damara sequence namibia was formed the varangian marinoan ca 600 ma cryogenic event produced mn oxide and bif deposits at urucum jacadigo group brazil the datangpo interglacial sequence south china liantuo nantuo varangian event contains black shale hosted mn carbonate deposits the early paleozoic witnessed several glacioeustatic sea level changes producing small mn carbonate deposits of tiantaishan early cambrian and taojiang mid ordovician in black shale sequences china and the major mn oxide carbonate deposits of karadzhal type central kazakhstan late devonian the mesozoic period of intense plate movements and volcanism produced greenhouse climate and stratified oceans during the early jurassic oae organic rich sediments host many mn carbonate deposits in europe e g urkut hungary in black shale sequences the late jurassic giant mn carbonate deposit at molango mexico was also genetically related to sea level change mn carbonates were always derived from mn oxyhydroxides during early diagenesis large mn oxide deposits of cretaceous age at groote eylandt australia and imini tasdremt morocco were also formed during transgression regression in greenhouse climate the early oligocene giant mn oxide carbonate deposit of chiatura georgia and nikopol ukraine were developed in a similar situation thereafter manganese sedimentation was entirely shifted to the deep seafloor and since ca 15 ma b p was climatically controlled glaciation deglaciation assisted by oxygenated polar bottom currents aabw nadw the changes in climate and the sea level were mainly tectonically forced

seismic detection of underwater volcanism the example of french polynesia we present a review of the principal methods used for the seismic detection and identification of active underwater volcanism based on our experience in french polynesia in particular we descrobe the 5 year activity in the tahiti mehetia area during which more than 32000 earthquakes were detected by the polynesian network we discuss the use of the following three types of seismic waves conventional mostly body waves seismic tremor andt waves propagated in the low velocity acoustic channel of the ocean for each of these waves we discuss the principal characteristics of the signals their spectral content the type of information they provide on the activity of the volcano and the various limitations faced by their use in detection or monitoring of underwater volcanic edifices we present a review of the principal swarms monitored by the polynesian network and discuss their characterization as either volcanic or tectonic

a volcanic exhalative origin for the world s largest kalahari manganese field a discussion of the paper by d h cornell and s s schutte

multidimensional classification of magma types for altered igneous rocks and application to their tectonomagmatic discrimination and igneous provenance of siliciclastic sediments abstract a new multidimensional scheme consistent with the international union of geological sciences iugs is proposed for the classification of igneous rocks in terms of four magma types ultrabasic basic intermediate and acid our procedure is based on an extensive database of major element composition of a total of 33 868 relatively fresh rock samples having a multinormal distribution initial database with 37 215 samples multinormally distributed database in terms of log ratios of samples was ascertained by a new computer program domudaf in which the discordancy test was applied at the 99 9 confidence level isometric log ratio ilr transformation was used to provide overall percent correct classification of 88 7 75 8 88 0 and 80 9 for ultrabasic basic intermediate and acid rocks respectively given the known mathematical and uncertainty propagation properties this transformation could be adopted for routine applications the incorrect classification was mainly for the neighbour magma types e g basic for ultrabasic and vice versa some of these misclassifications do not have any effect on multidimensional tectonic discrimination for an efficient application of this multidimensional scheme a new computer program magclamsys ilr magclamsys magma classification major element based system was written which is available for on line processing on http tlaloc ier unam mx index html this classification scheme was tested from newly compiled data for relatively fresh neogene igneous rocks and was found to be consistent with the conventional iugs procedure the new scheme was successfully applied to inter laboratory data for three geochemical reference materials basalts jb 1 and jb 1a and andesite ja 3 from japan and showed that the inferred magma types are consistent with the rock name basic for basalts jb 1 and jb 1a and intermediate for andesite ja 3 the scheme was also successfully applied to five case studies of older archaean to mesozoic igneous rocks similar or more reliable results were obtained from existing tectonomagmatic discrimination diagrams when used in conjunction with the new computer program as compared to the iugs scheme the application to three case studies of igneous provenance of sedimentary rocks was demonstrated as a novel approach finally we show that the new scheme is more robust for post emplacement compositional changes than the conventional iugs procedure

long rossby wave basin crossing time and the resonance of low frequency basin modes the ability of long wave low frequency basin modes to be resonantly excited depends on the efficiency with which energy fluxed onto the western boundary can be transmitted back to the eastern boundary this efficiency is greatly reduced for basins in which the long rossby wave basin crossing time is latitude dependent in the singular case where the basin crossing time is independent of latitude the amplitude of resonantly excited long wave basin modes grows without bound except for the effects of friction the speed of long rossby waves is independent of latitude for quasigeostrophic dynamics and the rectangular basin geometry often used for theoretical studies of the wind driven ocean circulation is such a singular case for quasigeostrophic dynamics for more realistic basin geometries where only a fraction of the energy incident on the western boundary can be transmitted back to the eastern boundary the modes have a finite decay rate that in the limit of weak friction is independent of the choice of frictional parameters explicit eigenmode computations for a basin geometry similar to the north pacific but closed along the equator yield basin modes sufficiently weakly damped that they could be resonantly excited

a theory for the surface atlantic response to thermohaline variability abstract the response of the upper warm limb of the thermohaline circulation in the north atlantic to a rapid change in deep water formation at high latitudes is investigated using a reduced gravity ocean model changes in deep water formation rate initiate kelvin waves that propagate along the western boundary to the equator on a timescale of months the response in the north atlantic is therefore rapid the southern hemisphere response is much slower limited by a mechanism here termed the ldquo uatorial buffer since to leading order the flow is in geostrophic balance the pressure anomaly decreases in magnitude as the kelvin wave moves equatorward where the coriolis parameter is lower together with the lack of sustained pressure gradients along the eastern boundary this limits the size of the pressure field response in the southern hemisphere interior adjustment is by the westward propagation of rossby waves but only a small fraction of the change in thermohaline circulation strength is commun

spectral characteristics of the response of the meridional overturning circulation to deep water formation abstract the response of the upper limb of the meridional overturning circulation to the variability of deep water formation is investigated analytically with a linear reduced gravity model in basins of simple geometry the spectral characteristics of the model response are first derived by prescribing white noise fluctuations in the meridional transport at the northern boundary although low frequency basin modes are solutions to the eigenproblem they are too dissipative to be significantly excited by the boundary forcing and the thermocline depth response has a red spectrum with no prevailing time scale other than that of a high frequency equatorial mode only flattening at the millennial time scale because of vertical diffusivity the meridional transport is asymmetric about the equator because the northern part of the basin is directly influenced by the boundary forcing while the southern part is mostly set in motion by long rossby waves this results in the equator acting as a low pass filter for

physicochemical environments for the formation of quartz free manganese oxide ores from the early proterozoic hotazel formation kalahari manganese field south africa physicochemical environments for the formation of quartz free manganese oxide ores from the hotazel formation of the kalahari manganese field northern cape province south africa are discussed quantitatively on the basis of the phase relations in the system mn fe si o and qualitatively in the system ca mn fe si o the phase relations involve major oxide minerals of the ores namely braunite braunite ii hausmannite bixbyite jacobsite and hematite and were constructed under quartz deficient conditions using existing and estimated thermody namic data and mineral assemblages from the ores standard enthalpy delta hm 0 sub f 298 and gibbs free energy delta g 0 sub f 298 values of braunite are estimated to be 1 011 9 or 5 and 937 3 or 5 kcal mole respectively on the basis of published experimental data and predicted entropy and heat capacity the low grade diagenetic to very low grade metamorphic mamatwan type ores consisting mainly of braunite hausmannite jacobsite hematite kutnohorite and calcite are altered by hydrothermal solutions into the high grade high temperature wessels type ores consisting of braunite ii bixbyite hausmannite hematite calcite and andradite with trace amounts of braunite the peak temperature of formation of the high grade ores appears not to have exceeded about 300 degrees to 400 degrees c the ores are oxidized from oxygen fugacity levels defined by the assemblage hausmannite jacobsite hematite to that defined by the assemblage bixbyite hausmannite with increasing temperature under hydrothermal quartz deficient conditions the stability of braunite is enlarged to higher temperatures with increasing silica activity a sub sio sub 2 aq because braunite is much less abundant in the high grade wessels type ore than in the low grade mamatwan type ore the maximum a sub sio sub 2 aq in the solutions could be estimated at 10 super 4 to 10 super 3 at 300 degrees to 400 degrees c from the stable assemblage bixbyite hausmannite braunite kutnohorite and to some extent calcite was a major source of ca reacting with silica released from braunite to form braunite ii and andradite

a perspective on the future of physical oceanography the ocean flows because it is forced by winds tides and exchanges of heat and freshwater with the overlying atmosphere and cryosphere to achieve a state where the defining properties of the ocean such as its energy and momentum do not continuously increase some form of dissipation or damping is required to balance the forcing the ocean circulation is thought to be forced primarily at the large scales characteristic of ocean basins yet to be damped at much smaller scales down to those of centimetre sized turbulence for decades physical oceanographers have sought to comprehend the fundamentals of this fractal puzzle how the ocean circulation is driven how it is damped and how ocean dynamics connects the very different scales of forcing and dissipation while in the last two decades significant advances have taken place on all these three fronts the thrust of progress has been in understanding the driving mechanisms of ocean circulation and the ocean s ensuing dynamical response with issues surrounding dissipation receiving comparatively little attention this choice of research priorities stems not only from logistical and technological difficulties in observing and modelling the physical processes responsible for damping the circulation but also from the untested assumption that the evolution of the ocean s state over time scales of concern to humankind is largely independent of dissipative processes in this article i illustrate some of the key advances in our understanding of ocean circulation that have been achieved in the last 20 years and based on a range of evidence contend that the field will soon reach a stage in which uncertainties surrounding the arrest of ocean circulation will pose the main challenge to further progress it is argued that the role of the circulation in the coupled climate system will stand as a further focal point of major advances in understanding within the next two decades supported by the drive of physical oceanography towards a more operational enterprise by contextual factors the basic elements that a strategy for the future must have to foster progress in these two areas are discussed with an overarching emphasis on the promotion of curiosity driven fundamental research against opposing external pressures and on the importance of upholding fundamental research as the apex of education in the field

guyots of the mid emperor chain mapped with multibeam sonar abstract bathymetry of seven of the middle emperor chain guyots from u s naval oceanographic office multibeam narrow beam swath mapping surveys is presented these data are contoured at a 100 fm interval using different theories on formation juxtaposed with the accurate bathymetry of this chain tectonic possibilities are shown for changes in plate direction and conduit activity fluctuations the range for one complete pulse of this activity is shown to be 280 nm 518 km for the emperor chain

volcano tectonic and geochemical evolution of an oceanic intra plate volcano tahiti nui french polynesia abstract geological mapping accurate k ar dating and geochemical analyses of lavas allow a detailed reconstruction of the geological history of tahiti nui island french polynesia the exposed volcanic activity is first characterized by the construction of a main shield from 1 4 ma to 870 ka with a maximum aerial eruptive rate around 2 km3 kyr lavas from this early building stage are alkaline slightly silica undersaturated with 87sr 86sr and 143nd 144nd compositions rather constant and close to the enriched mantle ii type vent locations were first concentrated along a main e w rift zone which was responsible for the lateral collapse of the northern and southern flanks of the main shield around 0 87 ma ago the subsequent activity was first restricted to the northern depression corresponding to an eruptive rate of about 5 km3 kyr in the period 850 760 ka significant variations in la sm 87sr 86sr and 143nd 144nd occur in lavas erupted immediately after the main northern landslide indicating a sudden increase in the extent of partial melting likely caused by the decompression subsequent to collapse however the later activity declined and the lavas exhibit a gradual change toward strongly silica undersaturated basanites likely indicating a decreasing extent of partial melting of the upper mantle the evolution of radiogenic isotope ratios over time indicates a change in the source toward more depleted compositions until around 500 ka post erosion volcanic activity following an apparent hiatus of 240 kyr exhibits similar major and trace element and isotope compositions the volcano structural and geochemical evolution of tahiti nui and the overall alkaline character of the lavas from other eruptive complexes of the society alignment suggest a relative weakness low temperature and low eruptive rate of the society plume compared to the hawaiian hot spot

heaving modes in the world oceans part of climate changes on decadal time scales can be interpreted as the result of adiabatic motions associated with the adjustment of wind driven circulation i e the heaving of the isopycnal surfaces heat content changes in the ocean including hiatus of global surface temperature and other phenomena can be interpreted in terms of heaving associated with adjustment of wind driven circulation induced by decadal variability of wind a simple reduced gravity model is used to examine the consequence of adiabatic adjustment of the wind driven circulation decadal changes in wind stress forcing can induce three dimensional redistribution of warm water in the upper ocean in particular wind stress change can generate baroclinic modes of heat content anomaly in the vertical direction in fact changes in stratification observed in the ocean may be induced by wind stress change at local or in the remote parts of the world oceans intensification of the equatorial easterly can induce cooling in the upper layer and warming in the subsurface layer the combination of this kind of heat content anomaly with the general trend of warming of the whole water column under the increasing greenhouse effect may offer an explanation for the hiatus of global surface temperature and the accelerating subsurface warming over the past 10 15 years furthermore the meridional transport of warm water in the upper ocean can lead to sizeable transient meridional overturning circulation poleward heat flux and vertical heat flux thus heaving plays a key role in the oceanic circulation and climate