nature and distribution of deep crustal reservoirs in the southwestern part of the baltic shield evidence from nd sr and pb isotope data on late sveconorwegian granites late sveconorwegian postorogenic granites c 1 0 0 93 ga make up a voluminous and widespread suite of intrusions across south norway from radiogenic isotope data three groups of late sveconorwegian granites can be distinguished 1 granite with more than 150 ppm sr 87 rb 86 sr 87 sr 86 sr 0 93 ga nd 87 rb 86 sr 5 87 sr 86 sr 0 93 ga 0 710 and e nd 87 sr 86 sr 0 93 ga nd 0 granite plutons belonging to group 1 normal sr concentration granite occur all over south norway and include the largest batholiths ostfold fla herefoss granite plutons of group 2 low sr concentration granites are restricted to north central telemark rjukan rift and are associated with c 1 5 ga rjukan group rhyolite group 3 is represented by one intrusion only but still suggests input of mantle derived magma or the presence of young mantle derived rocks in the deep crust in the region at c 0 93 ga the group 1 granites are similar in sr and nd characteristics to some of the older 1 05 ga sveconorwegian granitic intrusions augen gneisses in the region in terms of radiogenic isotope systematics but pb isotopes suggest that the magmas did not form by simple remelting of augen gneiss the nd sr and pb isotopic systematics of the late sveconorwegian granites indicate mixing between a depleted mantle derived component and two or more major components with an extended crustal history one of the crustal end members is present throughout south norway and has an isotopic signature similar to older granitic rocks of the trans scandinavian igneous belt tib the other crustal end member is indistinguishable from rjukan group rhyolites and slightly younger intrusions associated with these and is restricted to areas within the mid proterozoic rjukan rift the available data suggest that the deep continental crust of south norway both east and west of the permian oslo rift is an integral part of the baltic shield with a common history back to 1 7 1 9 ga that is to the end of the svecofennian orogeny and the tib magmatism

derivation of the 1 0 0 9 ga ferro potassic a type granitoids of southern norway by extreme differentiation from basic magmas major and trace elements sr and nd isotopic data as well as mineral compositions are presented for a selection of the 1 0 0 9 ferro potassic a type granitoids bessefjellet rustfjellet verhuskjerringi valle holum svofjell handeland tveit aseral lyngdal gabbronorites that occur close to the mandal ustaoset line mul of southern norway these hornblende biotite granitoids hbg define an extensive differentiation trend ranging from gabbronorites 50 wt sio 2 to granites 77 wt sio2 this trend is interpreted as resulting from extreme fractional crystallization of several basaltic magma batches with similar major and trace elements compositions at 930 ma the hbg suite displays a narrower range in isr 0 7027 0 7056 than in end t 1 97 down to 4 90 suggesting some assimilation of a rb depleted lower crust afc process or and source variability an age of 929 47 ma is given by a rb sr isochron on the holum granite sri 0 7046 0 0006 mswd 1 7 geothermobarometers indicate a low pressure of emplacement 1 3 2 7 kbar and an oxygen fugacity close to nno high liquidus temperatures are given by the apatite saturation thermometer 1005 1054 c and are in agreement with results from other studies the basaltic parent magmas of the hbg suite are partial melts of an hydrous mafic potassic source lying either in the lithospheric upper mantle or in the mafic lower crust derived from it this contrasts with the 930 ma anorthosite mangerite charnockite suite amc suite of the rogaland province for which a depleted lower crustal anhydrous gabbronoritic source has been indicated the present data imply the penecontemporaneous melting of two contrasting sources in southern norway the source duality could result from an increasing degree of metamorphism amphibolite to granulite from east to west an horizontal stratification of the lower crust or from the stratification of the lithosphere melting of the lower crust or upper mantle it may also indicate that the amc and hbg suites formed in two distinct crustal segments the linear alignment of the hbg suite along the mandal ustaoset shear zone suggests that a linear uprise of the asthenosphere following a lithospheric delamination under this structure could be the vector of the mantle heat 2003 elsevier science b v all rights reserved

sedimentary recycling in arc magmas geochemical and u pb hf o constraints on the mesoproterozoic suldal arc sw norway the hardangervidda rogaland block within southwest norway is host to 1 52 to 1 48 ga continental building and variable reworking during the 1 1 to 0 9 ga sveconorwegian orogeny due to the lack of geochronological and geochemical data the timing and tectonic setting of early mesoproterozoic magmatism has long been ambiguous this paper presents zircon u pb hf o isotope data combined with whole rock geochemistry to address the age and petrogenesis of basement units within the suldal region located in the centre of the hardangervidda rogaland block the basement comprises variably deformed grey gneisses and granitoids that petrologically and geochemically resemble mature volcanic arc lithologies u pb ages confirm that magmatism occurred from 1 521 to 1 485 ma and conspicuously lack any xenocrystic inheritance of distinctly older crust hafnium isotope data range from ehf initial 1 to 11 suggesting a rather juvenile magmatic source but with possible involvement of late palaeoproterozoic crust oxygen isotope data range from mantle like 18o 5 to elevated 10 suggesting involvement of low temperature altered material e g supracrustal rocks in the magma source the hf o isotope array is compatible with mixing between mantle derived material with young low temperature altered material oceanic crust sediments and older low temperature altered material continent derived sediments this combined with a lack of xenoliths and xenocrysts exposed older crust afc trends and s type geochemistry all point to mixing within a deep crustal magma generation zone a proposed model comprises accretion of altered oceanic crust and the overlying sediments to a pre existing continental margin underthrusting to the magma generation zone and remobilisation during arc magmatism the geodynamic setting for this arc magmatism is comparable with that seen in the phanerozoic e g the sierra nevada and coast range batholiths with compositions in the suldal sector reaching those of average upper continental crust as within these younger examples factors that drive magmatism towards the composition of the average continental crust include the addition of sedimentary material to magma source regions and delamination of cumulate material underthrusting of sedimentary materials and their subsequent involvement in arc magmatism is perhaps a more widespread mechanism involved in continental growth than is currently recognised finally the suldal arc magmatism represents a significant juvenile crustal addition to sw fennoscandia

significance of some geotechnical properties of continental slope and rise sediments off northeast newfoundland shear strength measurements carried out on the 0 20 cm interval of continental slope and continental rise surficial sediments yielded mean values per station that ranged from 3 7 to 8 9 kpa the factors controlling the bathymetric variation of sediment shear strength appear to be sediment texture which is controlled locally by sediment spillover on the upper slope increased deposition of fines silt and clay sized particles from suspension and greater bioturbation activity on the middle slope and bottom current sediment reworking on the base of slope and upper rise sediments deposited on the downslope side of the present presumed location of the western boundary undercurrent wbu axis have comparatively high shear strength gradients that appear to denote the increased proportion of fine sediment deposition during early to middle holocene time when the wbu axis may have been located further upslope than at present

petrology and geochemistry of the lyngdal granodiorite southern norway and the role of fractional crystallisation in the genesis of proterozoic ferro potassic a type granites abstract in south western norway the sveconorwegian orogenic thickening 1024 970 ma is followed by an important post collisional magmatism 950 930 ma divided in two suites vander auwera et al 2003 the anorthosite mangerite charnockite suite amc suite and the hornblende biotite granitoids suite hbg suite the hbg suite displays a continuous trend from gabbronorites to granites this paper presents the petrography and geochemistry major and trace elements sr nd isotopes of the lyngdal granodiorite and associated massifs tranevag and red granite massifs which belong to the hbg suite although being very close to the anorthosite massifs mafic microgranular enclaves mme resulting from magma mingling can be abundant and probably correspond to the parent magma of the studied plutons the lyngdal granodiorite and associated massifs are subalkaline metaluminous a type granitoids with high feo t feo t mgo ratio and k 2 o content forming a ferro potassic a type continuous trend from quartz monzodiorite to granite 56 72 wt sio 2 in harker diagrams the lyngdal tranevag plutons share the proterozoic rapakivi granites trend that they extend to lower sio 2 content major and trace element modelling as well as sr nd isotopes show that fractional crystallisation without assimilation is the differentiation process for lyngdal tranevag fractionating minerals are clinopyroxene hornblende plagioclase oxides biotite apatite zircon and allanite the red granite 71 75 wt sio 2 does not belong to this trend probably due to a different initial magma composition this study shows that ferro potassic a type granitoids can be derived by fractional crystallisation from mafic magmas

smos sea surface salinity signals of tropical instability waves sea surface salinity sss measurements from the soil moisture and ocean salinity smos mission provide an unprecedented opportunity to observe the salinity structure of tropical instability waves tiws from space especially during the intense 2010 la nina condition in the eastern equatorial pacific ocean smos sss signals correlate well and have similar amplitude to 1 m salinity from the tropical atmosphere ocean tao array at six locations with strong tiw signals at these locations the linear negative relationships between smos sss and ostia sst signals vary from 0 20 c 1 to 0 25 c 1 which are comparable to the ones obtained from tao from june to december 2010 the largest tiw signals and meridional gradients of both sss and sst appear around 2 n west of 100 w they shift southward and cross the equator at 90 w in addition to the large negative correlation band around 2 n a band of negative correlations between sss and sst signals also exists around 8 n west of 110 w for the 33 day signals the peak amplitude of the 33 day smos sss signals west of 135 w is reduced by 40 with respect to values east of 135 w while the reduction for sst is much lower 20 the amplitudes and longitudinal extents of tiw signals and the dominant westward propagation speed of 17 day tiws as detected by smos and aquarius at the equator decrease from 2010 to 2013 associated with the transition from a strong la nina to non la nina conditions

sveconorwegian massif type anorthosites and related granitoids result from post collisional melting of a continental arc root article i nfo two magmatic suites were emplaced during the post collisional evolution of the sveconorwegian orogeny an anorthosite mangerite charnockite suite amc suite and an hornblende and biotite bearing granitoids suite hbg suite the amc suite is exclusively located in the westernmost and warmest part of the orogen in granulite facies gneisses whereas the hbg suite intruded in the rest of the orogen but not in the granulite domain new u pb zircon geochronological data confirm previous age determinations 970 932 ma hbg suite and 933 916 ma amc suite the mafic facies of the two post collisional magmatic suites have similar geochemical compositions but the hbg differentiation trend displays higher cao sr u and th as well as lower k2o and feot mgo than the amc differentiation trend the hbg suite is hydrous and has a broadly higher fo2 whereas the amc suite is anhydrous the inferred parent magmas of both suites have overlapping initial sr nd and pb isotopic compositions with increasing differentiation the two trends point towards two different crustal contaminants together with the recent recognition of a major crustal shear zone located just east of the amc suite this difference suggests that the suites were emplaced in two different lithotectonic units using published experimental constraints and geochemical modeling we suggest that the mafic facies of both suites were produced by partial melting of lower crustal sources which were previously underplated probably during the evolution of a long lasting convergent margin later these lower crustal sources were modified by the regional granulite facies metamorphism 1 035 to 0 97 ga prevailing in the westernmost part of the orogen thus producing an anhydrous lower crustal source for the amc suite accordingly we conclude that the sveconorwegian massif type anorthosites result from partial melting of the continental arc root this process if accepted for other amcg anorthosite mangerite charnockite granite complexes was possible in the proterozoic because of a sufficiently high temperature but not in the archean because in subduction zones the main transfer to the crust was then felsic tonalites granodiorites and not basaltic we thus further suggest that the onset of massif type anorthosites at the beginning of the proterozoic may mark the time when plate tectonics began to operate in a similar way as today

an analysis of tropical instability waves in a numerical model of the pacific ocean 2 generation and energetics of the waves this work was supported by the department of com merce noaa under grant na56gp0026 one of the au thors sm was partially supported by a nasa global change fellowship ngt 30288 another author ab was supported by a ucar postdoctoral fellowship

a census of tehuantepec and papagayo eddies in the northeastern tropical pacific 1 we use a 12 year 1992 2004 time series of satellite altimetry to characterize long lived wind generated anticyclonic eddies originating in the gulfs of tehuantepec and papagayo in the northeastern tropical pacific a total of 42 tehuantepec and 26 papagayo eddies were observed eddy merging usually of a tehuantepec papagayo pair was observed on 16 occasions on average the eddy season began in late october and lasted approximately 250 days until early july with 3 5 tehuantepec and 2 2 papagayo eddies formed each year minimum average eddy lifespan was 143 days and 84 days for tehuantepec and papagayo eddies respectively there was considerable interannual variability in eddy activity with greater fewer number of eddies more intense weaker eddies and a longer shorter eddy season during el nino la nina years eddy intensification was consistently observed at the east pacific rise

the sveconorwegian orogeny reamalgamation of the fragmented southwestern margin of fennoscandia abstract the sveconorwegian orogeny encompasses magmatic metamorphic and deformational events between ca 1140 and 920 ma at the southwestern margin of fennoscandia in recent years the tectonic setting of this nearly 200 myr long evolution has been debated with some workers arguing for collision with an unknown continent off the present day southwest coast of norway and others advocating accretionary processes inboard of an active margin recently it has been suggested that orogeny may have been gravity driven by delamination and foundering of heavy subcontinental lithospheric mantle in an intraplate setting in some ways similar to proposed sagduction processes in the archaean resolving the tectonic setting of the sveconorwegian orogen has implications for correlation with other orogens and rodinia supercontinent reconstructions and for assessments of the evolution of plate tectonics on earth from the archaean to the present here we present new mapping and geochronological data from the bamble and telemark lithotectonic units in the central and western sveconorwegian orogen the former representing a critical region separating western parts of the orogen that underwent long lived high to ultrahigh temperature metamorphism and magmatism from parts closer to the orogenic foreland that underwent episodic high pressure events the data show that the units constituting the sveconorwegian orogen most likely formed at the southwestern margin of fennoscandia between ca 1800 and 1480 ma followed by fragmentation during widespread extension between ca 1340 and 1100 ma marked by bimodal magmatism and sedimentation a summary of sveconorwegian magmatic metamorphic and depositional events in the different units shows disparate histories prior to their assembly with adjacent units the most likely interpretation of this record seems to be that episodic sveconorwegian metamorphic and deformational events in the central and eastern parts of the orogen represent accretion and assembly of these units this process most likely took place behind an active margin to the southwest that sustained mafic underplating in the proximal back arc resulting in high to ultrahigh temperature metamorphism in the western parts in this interpretation all features of the sveconorwegian orogen are readily explained by modern style plate tectonic processes and hypotheses involving some form of vertical intraplate tectonics are not supported

peraluminous i type granites abstract s type granites always contain more al than the amounts of na ca and k in the rock required to form feldspars primarily owing to their derivation from source components that had previously been weathered those rocks are therefore always saturated in al or peraluminous many i type granites are also peraluminous despite i type source rocks typically not being saturated in al it has previously been suggested that this may result from the fractional crystallisation of amphibole however data from compositionally zoned high temperature plutons in the lachlan fold belt show that it is difficult to generate large quantities of peraluminous melt by removal of amphibole most of the i type granites 95 in the lachlan fold belt formed at lower temperatures and almost half of those rocks for which bulk chemical compositions are available are peraluminous among these granites there are 98 separate suites for which there are chemical data for two or more samples with 47 suites that include both metaluminous more mafic and peraluminous more felsic compositions the origin of those peraluminous compositions is fundamental to any understanding of i type granite petrogenesis in this region compositional variations caused by the assimilation or by partial melting of supracrustal rocks are very small as the isotopic variations within these rocks are dominantly between different suites not within suites the partial melting of more mafic source rocks rather than the fractional crystallisation of more mafic magmas is favoured for the origin of these rocks partial melting is the most likely process involved in the petrogenesis of felsic granites where broadly granodioritic monzogranitic batholiths are associated with lesser amounts of tonalite and very minor amounts of mafic rock experimental studies have shown that the melts generated by the partial melting of basaltic to andesitic rocks under crustal conditions are mostly peraluminous during the dehydrational melting of i type granite source rocks at pressures below the garnet stability field biotite and amphibole melt incongruently to yield pyroxenes the excess al is incorporated into the felsic liquid resulting in the generation of peraluminous melts in this instance the excess al in felsic i type granites is a function of the melting process and unrelated to the bulk composition of the source the observed gradation from peraluminous felsic granites to metaluminous compositions in less felsic rocks in largely isotopically closed systems could happen in two ways at higher temperatures of partial melting ca and other components of clinopyroxene could dissolve in the melt with the melt eventually becoming metaluminous alternatively minerals residual from partial melting dominantly pyroxenes and plagioclase could be incorporated in suspension in the melt so that the resulting bulk magma is metaluminous examples of these two extremes and of intermediate cases are well developed among the granites of southeastern australia

satellite observations of mesoscale eddies in the gulfs of tehuantepec and papagayo eastern tropical pacific seawifs high resolution ocean color images and avhrr sea surface temperature were obtained for the period from november 1998 to march 1999 generation of mesoscale eddies was observed for the region between the gulf of tehuantepec and the gulf of papagayo tropical pacific ocean eighteen eddies with diameters ranging between 100 and 450 kmwere identified 14 originated in the gulf of tehuantepec and m ost were cyclonic our results show that the frequency of cyclonic eddy formation is higher than it has been reported and their lifetime can be longer using both ocean color images and daily temporal resolution instead of sea surface temperature alone improved our ability to identify and follow the propagation of these eddies the generation and fate of smaller cyclonic eddies around the periphery of the anticyclonic eddy indicate the importance of the onshore offshore exchange of energy and biological material which has not been considered previously three anticyclonic eddies were generated in the gulf of papagayo these eddies have a common origin and they travel along the main flux of the costa rica coastal current crcc which later turns offshore and joins the north equatorial current this behavior can be seen clearly on seawifs images and suggests that the crcc influences eddy propagation time series of chlorophyll a concentration and sst were obtained fromtwo points at tehuantepec and two at papagayo cross correlation analysis confirms an inverse relationship between these variables showing that a decrease in sst is followed by an increase in chlorophyll a concentration values indicating high growth and primary production rates r 2004 elsevier ltd all rights reserved

origin of the rhyolitic rocks of the taupo volcanic zone new zealand abstract major element rb sr ba cr and v analyses as well as 13 new rare earth element ree analyses are presented for the greywacke basement surrounding the taupo volcanic zone tvz on this basis the basement rocks are divided into a western basement of approximately andesitic composition 62 sio2 and an eastern basement of approximately granodiorite composition 75 sio2 these analyses 5 new ree analyses for the rhyolites and published data for the volcanic rocks of tvz are used to investigate the petrogenesis of rhyolitic rocks in the area least squares mixing calculations for major elements show that 88 fractional crystallisation of high alumina basalt produces a liquid of rhyolitic bulk composition but rayleigh fractionation models show that the trace element concentrations of the rhyolites are inconsistent with basalt fractionation 57 fractionation of the assemblage plagioclase 35 6 orthopyroxene 9 7 clinopyroxene 7 8 ilmenite 0 6 and magnetite 3 4 from a plagioclase pyroxene andesite can produce liquids of rhyolitic bulk composition ree concentrations produced by this model are consistent with those observed in the rhyolites but predicted ba and rb values are lower and v concentrations are higher than those in the rhyolites andesite fractionation also produces an unrealistic fractionation of the cr v ratio a non modal melting model involving 35 melting of a granulitic assemblage plagioclase quartz clinopyroxene orthopyroxene biotite magnetite cordierite with a bulk composition equivalent to the western basement can reproduce the ree pattern of the rhyolites as well as the concentrations of rb and ba sr values remain anomalously high but the cr v ratio does not indicate fractionation absolute values of cr and v are within the uncertainties of published crystal liquid partition coefficients the rhyolites have relatively flat ree patterns la yb 7 5 as do the greywackes la yb 8 2 so it is therefore unlikely that the rhyolites equilibrated with a garnet or amphibole bearing assemblage

a linear relationship between enso intensity and tropical instability wave activity in the eastern pacific ocean the interannual variations of tropical instability waves tiws in the eastern pacific ocean and their relationships with enso intensity are studied using a 28 year long coupled atmosphere ocean general circulation model cgcm simulation the activity of tiws is measured by the root mean square value of the 50 day high pass filtered sea surface temperature sst perturbations produced in the simulation the cgcm realistically produces two branches of large tiw activity near the equator one at 2 n and the other at 2 s it is found that along both branches there are linear relationships between the year to year variations of tiw activity and those of enso intensity tiw activity is enhanced or reduced in proportion to the nino3 sst anomalies with larger activity in la nina years and smaller activity in el nino years it is found that enso modulates tiw activity in both branches primarily by changing the latitudinal sst gradient associated with the sst front immediately north of the equator weaker correlations are found between the year to year variations of tiw activity and those of the ocean current shears between the south equatorial current and the equatorial undercurrent or the north equatorial countercurrent this cgcm study suggests that the baroclinic instability associated with the northern sst front is a major generation mechanism for both the northern and southern tiw branches in the eastern pacific ocean

pyroxene megacrysts in proterozoic anorthosites implications for tectonic setting magma source and magmatic processes at the moho abstract proterozoic anorthosites from the 1630 1650 ma mealy mountains intrusive suite grenville province canada the 1289 1363 ma nain plutonic suite nain churchill provinces canada and the 920 949 ma rogaland anorthosite province sveconorwegian province norway all entrain comagmatic cumulate high alumina orthopyroxene megacrysts haoms the orthopyroxene megacrysts range in size from 0 2 to 1 m and all contain exsolution lamellae of plagioclase that indicate the incorporation of an excess ca al component inherited from the host magma at pressures in excess of 10 kbar at or near moho depths 30 40 km suites of haoms from each intrusion display a large range in 147sm 144nd 0 10 to 0 34 making them amenable for precise age dating with the sm nd system sm nd isochrons for haoms give ages of 1765 12 ma mealy mountains 1041 17 ma rogaland and 1444 100 ma nain all of them older by about 80 to 120 m y than the respective 1630 1650 920 949 and 1289 1363 ma crystallization ages of their host anorthosites internal mineral sm nd isochrons between plagioclase exsolution lamellae and the orthopyroxene host for haoms from the rogaland and nain complexes yield ages of 968 43 and 1347 6 ma respectively identical within error to the ages of the anorthosites themselves this age concordance establishes that decompression exsolution in the haom was coincident with magmatic emplacement of the anorthosites 100 m y after haoms crystallization at the moho correspondence of pb isotope ages 206pb 204pb vs 207pb 204pb with sm nd ages and other strong lines of evidence indicate that the older megacryst ages represent true crystallization ages and not the effects of time integrated mixing processes in the magmas nd isotopic evolution curves afc mixing calculations and the age relations between the hoams and their anorthosite hosts show that the haoms are much less contaminated with crustal components and are an older part of the same magmatic system from which the anorthosites are derived modeling of these anorthositic magmas with melts indicates that their ultramafic cumulates would have sunk in the magma and been sequestered at the moho where they may have sunk deeper into the mantle resulting in large scale compositional differentiation the haoms thus represent a rare example of part of a cumulate assemblage that was carried to the upper crust during anorthosite emplacement and together with the anorthosites illustrate the dramatic influence that magma ponding and differentiation at the moho has on residual magmas traveling towards the surface the new geochronologic and isotopic data indicate that the magmas were derived by melting of the mantle forming magmatic systems that could have been long lived e g 80 100 m y a geologic setting that would fit these temporal constraints is a long lived andean type margin

the effect of tropical instability waves on co2 species distributions along the equator in the eastern equatorial pacific during the 1992 enso event tropical instability waves have been shown to have a major impact on the variability of temperature and nutrients along the equatorial wave guide in order to assess the impact of these features on carbon species distributions during an enso event sea surface temperature salinity sigma t nitrate co sub 2 fugacity total inorganic carbon total alkalinity and ph along the equator were measured from 130 degrees w to 100 degrees w during 8 15 may 1992 concurrent moored measurements of surface currents and temperature were also made at 0 degrees 110 degrees w results indicate that tropical instability waves with periods of 15 to 20 days and zonal wavelengths of 700 800 km controlled the observed spatial variability of the co sub 2 species nitrate and hydrographic parameters at the equator 37 refs 3 figs

deep sea sedimentary processes off newfoundland an overview a combination of long range sidescan sonar airgun seismic reflection and high resolution echo sounder data has allowed an overview of the different sedimentary processes along the southeast canad

the influence of nonlinear mesoscale eddies on near surface oceanic chlorophyll oceanic rossby waves have been widely invoked as a mechanism for large scale variability of chlorophyll chl observed from satellites high resolution satellite altimeter measurements have recently revealed that sea surface height ssh features previously interpreted as linear rossby waves are nonlinear mesoscale coherent structures referred to here as eddies we analyze 10 years of measurements of these ssh fields and concurrent satellite measurements of upper ocean chl to show that these eddies exert a strong influence on the chl field thus requiring reassessment of the mechanism for the observed covariability of ssh and chl on time scales longer than 2 to 3 weeks the dominant mechanism is shown to be eddy induced horizontal advection of chl by the rotational velocities of the eddies

the petrogenesis of massif anorthosites a nd and sr isotopic investigation of the proterozoic of rogaland vest agder sw norway sm nd and rb sr isotopic analyses of charnockitic migmatite augen gneiss anorthosite leuconorite and two acid plutons from the rogaland and vest agder districts of southwest norway constrain their crustal residence ages origin and evolution the charnockitic migmatites which are a major component of the metamorphic basement complex represent the oldest and largest episode of accretion in which new crust was derived 1 5 1 9 ga ago from a mantle source of depleted nd isotopic composition the basement complex was intruded by a number of large anorthositic to granitic plutons during and after the sveconorwegian orogenic period samples from the ca 1050 ma old synorogenic haland anorthosite leuconorite massif exhibit substantial variation of initial nd of 2 1 to 4 4 at an anorthosite locality and 0 5 to 2 3 at a leuconorite locality but display significant variation of initial 87sr 86sr ratio only between the localities anorthosite mean 0 70369 leuconorite mean 0 70560 a model is proposed whereby the anorthosite and leuconorite were derived by major crustal contamination of and fractional crystallization from a picritic magma derived from isotopically depleted mantle two younger acid intrusions the 950 ma old lyngdal granodiorite and the 930 ma old farsund charnockite both have initial sr and nd isotope ratios consistent with massive contamination of depleted mantle derived magma by old continental crustal material

coupled ocean atmospheric waves on the equatorial front striking 20 30 day sea surface temperature waves observed along the equatorial front in the later half of the year are generally believed to be of an oceanic origin here we report the detection of atmospheric waves that are unambiguously tied to these oceanic waves using new satellite measurements of surface winds a general circulation model simulation reveals that these atmospheric waves have a shallow vertical structure trapped in the planetary boundary layer pbl unlike el nino southern oscillation where changes in deep convection are the cause of anomalous winds vertical wave motion penetrates well above the pbl and is likely to impact the distribution and transport of climatically important gas species such as ozone and dimethyl sulfide

aquarius reveals salinity structure of tropical instability waves 1 sea surface salinity sss measurements from the aquarius sac d satellite during september december 2011 provide the first satellite observations of the salinity structure of tropical instability waves tiws in the pacific the related sss anomaly has a magnitude of approximately 0 5 psu different from sea surface temperature sst and sea surface height anomaly ssha where tiw related propagating signals are stronger a few degrees away from the equator the sss signature of tiws is largest near the equator in the eastern equatorial pacific where salty south pacific water meets the fresher inter tropical convergence zone water the dominant westward propagation speed of sss near the equator is approximately 1 m s this is twice as fast as the 0 5 m s tiw speed widely reported in the literature typically from sst and ssha away from the equator this difference is attributed to the more dominant 17 day tiws near the equator that have a 1 m s dominant phase speed and the stronger 33 day tiws away from the equator that have a 0 5 m s dominant phase speed the results demonstrate the important value of aquarius in studying tiws

geographical variability of the first baroclinic rossby radius of deformation global 1 83 18 climatologies of the first baroclinic gravity wave phase speed c1 and the rossby radius of deformation l1 are computed from climatological average temperature and salinity profiles these new atlases are compared with previously published 5 83 58 coarse resolution maps of l1 for the northern hemisphere and the south atlantic and with a 1 83 18 fine resolution map of c1 for the tropical pacific it is concluded that the methods used in these earlier estimates yield values that are biased systematically low by 5 15 owing to seemingly minor computational errors geographical variations in the new high resolution maps of c1 and l1 are discussed in terms of a wkb approximation that elucidates the effects of earth rotation stratification and water depth on these quantities it is shown that the effects of temporal variations of the stratification can be neglected in the estimation of c1 and l1 at any particular location in the world ocean this is rationalized from consideration of the wkb approximation

partial melting of apatite bearing charnockite granulite and diorite melt compositions restite mineralogy and petrologic implications melting experiments p 6 9 kbar t 850 950 c nno 02 hm were done on mafic to felsic charnockites a dioritic gneiss and a felsic garnet granulite all common rock types in the grenville basement of eastern north america a graphite bearing granulite gneiss did not melt water h2o 0 60 to 2 0 wt is bound in low grade retrograde metamorphic minerals and is consumed during the earliest stages of melting most melts are water undersaturated melt compositions range from metaluminous silicic granodiorite diorite starting composition to peraluminous or weakly metaluminous granites all others in general liquids become more feldspathic less silicic and less peraluminous and are enriched in feo mgo and tio2 with increasing temperature residual feldspar mineralogy controls the cao k2o and na2o contents of the partial melts and the behavior of these elements can be used particularly if the degree of source melting can be ascertained to infer some aspects of the feldspar mineralogy of the source k feldspar a common restite phase in the charnockite and granulite but not the diorite should control the behavior of ba and possibly eu in these systems and yield signatures of these elements that can distinguish source regions and in some cases bulk versus melt assimilation apatite a common restite phase is enriched in rare earth elements ree especially middle ree retention of apatite in the restite will result in steep light ree enriched patterns for melts derived from the diorite and charnockites

a comparison of shear strength in calcareous and siliciclastic marine sediments abstract more than 2000 measurements of shear strength versus depth in fine grained marine sediments were collected from the literature and our own experiments in order to study the relationship between carbonate content and strength behavior of marine sediments depositional environments include slope rise and abyssal plain with most data originating from the slopes the depth range is restricted to 6 m subbottom depth in order to minimize diagenetic effects contour plots of shear strength versus depth for calcareous and siliciclastic sediments clearly reveal different trends whereas shear strength in siliciclastic sediments shows low variability and increases only gradually with depth the shear strength in the calcareous population is highly variable and increases rapidly with depth the difference in strength behavior of the two sediment groups has implications for the stability of submarine slopes previous research has shown that carbonate sediments build up steeper and more variable slopes than siliciclastic sediments this difference in slope angle can be explained at least in part by the higher internal strength of the carbonate sediments

the origin of granite the role and source of water in the evolution of granitic magmas temperature and water content are the two most important parameters in the formation of granitic magmas evidence from volcanic and plutonic lithologies suggests that water contents of 2 to 4 wt are present in most silicic magmas calculations based on the stability of biotite yield water fugacities within the melt phase from about 500 to 2 000 bars although these calculations determine the log f h 2 o and the effective uncertainty of 0 5 log units yields a large absolute uncertainty comparison with crystallization experiments demonstrates that less than 2 water would require significant percentages of crystallization at temperatures above 900 c with liquidus temperatures about 1000 c water contents greatly in excess of 4 wt would mean that the magma would become vapor saturated at high pressures and would tend to crystallize during ascent to a fine grained granite before reaching shallow depths the main sources of water for magma generation are the dehydration of hydrous silicates within the crust and volatiles transported into the crust from subducted oceanic crust and upper mantle in the form of hydrous basalts and andesites dehydration reactions of muscovite biotite and horn blende are of particular significance anatectic granites may be partially classified in terms of the probable dehydration reaction responsible for their generation melts generated from muscovite dehydration are relatively cool peraluminous in composition high in k na ratio and generally high in initial 87 sr 86 sr and delta 18 o biotite generated melts tend to be higher in temperatures peraluminous to meta aluminous in composition moderately high in k na ratio and relatively high in strontium and oxygen ratios both types may contain metasedimentary enclaves granitoids generated by hornblende dehydration would be much higher in initial temperature peralka line to meta aluminous in composition and lower in k na ratio and in general would have lower strontium and oxygen ratios volatiles deposited in hydrothermally altered oceanic crust and upper mantle will be released during subduction in the form of hydrous basalts and andesites these melts are important energy transfer mechanisms to drive anatexis within the crust if these melts encounter a silicic magma chamber when intruding the crust they will be trapped below the lower density granitic melt while partially quenching against the cooler melt they may release volatiles and heat which will aid in the melting process granites generated in this way will vary in their geochemical properties depending on the relative importance of crustal versus mantle magma systems in general they will have moderate to high initial temperatures be meta aluminous in composition be variable but somewhat low in k na ratio and have lower initial strontium and delta 18 o ratios than will melts derived completely from the crust the fact that most terrestrial spreading centers are subaqueous thus may aid in the formation of a thick granitic continental crust

local and remote atmospheric response to tropical instability waves a global view from space a la nina took place in the equatorial pacific in 1999 and strong tropical instability waves tiws developed causing large meanders of a sea surface temperature sst front between the equator and 3 n high resolution satellite measurements are used to describe the variability of sst surface wind velocity column integrated water vapor cloud liquid water and precipitation associated with these strong tiws in 1999 coherent ocean atmosphere patterns emerge in both the pacific and atlantic revealing rich regional characteristics in the far eastern pacific southeasterly trades strengthen weaken over positive negative sst anomalies apparently due to enhanced reduced mixing with high speed winds aloft in the central pacific we find evidence that sst induced sea level pressure changes also contribute substantially to wind fluctuations similar sst wind covariability also exists in the southern hemisphere along 2 s but the wind variability induced by unit sst anomaly is much larger than that north of the equator in the central pacific where the equatorial front is broad the northern sst pattern has a large meridional scale and reaches as far north as 6 n further to the north in the intertropical convergence zone itcz where local sst anomalies are small significant variability is found in clouds and precipitation which is further correlated with surface wind convergence in the atlantic tiw signals in sst are strongly trapped near the equator but they induce significant remote response in the itcz which takes a more southern position than its pacific counterpart and thus more susceptible to tiw influence

spatio temporal variability of the equatorial front in the eastern tropical pacific from remote sensing salinity data 2010 2015 abstract in the eastern pacific the equatorial front ef separates the relatively cold and salty equatorial surface water to the south from the relatively warm and fresh surface tropical water to the north although previous studies have succinctly described the main ef characteristics little is known about its spatial pattern and temporal variability beyond seasonal scale in this study we used 5 years of remote sensing sea surface salinity sss data acquired by smos in a synoptic and continuous manner to describe the spatio temporal variability of the haline ef hef after validating the sss satellite dataset with concomitant in situ data we developed an algorithm based on maximum sss gradients to automatically identify the hef position on every smos sss map this algorithm applied to the 4 day resolution smos sss product allows us to investigate the spatio temporal variability of the hef between 2010 and 2015 seasonally west of the galapagos islands the hef is centered at 2 n and shows relatively weak meridional displacements in contrast east of the galapagos archipelago the hef varies on average between 4 s in spring and 2 n in autumn at intraseasonal scales the hef shows meridional fluctuations of 1 25 around its average position these intraseasonal fluctuations are partly related to kelvin waves which was more noticeable since 2014 over the 5 year studied period the hef position showed a northward trend of 0 3 0 4 latitudinal degrees per year between 2010 and 2015 however the relatively short time series does not permit to investigate whether this low frequency trend is due to long term variability or interdecadal fluctuations

intraseasonal variability of surface salinity in the eastern tropical pacific associated with mesoscale eddies strong variability in sea surface salinity sss in the eastern tropical pacific etpac on intraseasonal to interannual timescales was studied using data from the soil moisture and ocean salinity soil moisture active passive and aquarius satellite missions a zonal wave number frequency spectral analysis of sss reveals a dominant timescale of 50 180days and spatial scale of 8 degrees 20 degrees of longitude with a distinct seasonal cycle and interannual variability this intraseasonal sss signal is detailed in the study of 19 individual etpac eddies over 2010 2016 identified by their sea level anomalies propagating westward at a speed of about 17cm s etpac eddies trap and advect water in their core westward up to 40 degrees of longitude away from the coast the sss signatures of these eddies with an average anomaly of 0 5 pss magnitude difference from ambient values enable the study of their dynamics and the mixing of their core waters with the surroundings three categories of eddies were identified according to the location where they were first tracked 1 in the gulf of tehuantepec 2 in the gulf of papagayo and 3 in the open ocean near 100 degrees w 12 degrees n they all traveled westward near 10 degrees n latitude category 3 is of particular interest as eddies seeded in the gulf of tehuantepec grew substantially in the vicinity of the clipperton fracture zone rise and in a region where the mean zonal currents have anticyclonic shear the evolution of the sss signature associated with the eddies indicates the importance of mixing to their dissipation

interaction of the western boundary undercurrent with the continental margin off newfoundland sedimentation on the newfoundland rise is strongly influenced by the western boundary undercurrent wbu the upper rise 2600 2800 m is swept by a rapid 8 5 cm sec 1 south flowing core of the wbu which has generated a sandy contourite facies characterized by coarse gravelly sandy sediments current induced bedforms such as scour moats lineations and lee drifts ferro manganese stained gravel clasts a high proportion of broken foraminiferal tests and a diagnostic benthic foraminiferal assemblage the overlying nepheloid layer when compared to adjacent waters is thickest 800 m most sediment laden 80 g 1 1 contains the highest proportion of terrigenous sediment and exhibits the best developed bottom mixed layer 15 m thick comparisons with earlier data from the same area imply the dimensions and sediment load of the nepheloid layer vary with time empirical considerations based on near bottom current meter records from labrador and newfoundland suggest the wbu is capable of transporting bedload with threshold friction velocities u of around 0 87 1 14 cm sec 1 for between 1 and 15 of the time the prevailing transport direction is southwards along the rise but this may be punctuated periodically by brief incursions to the north the erosional regime of the upper rise is bordered by a regime of fine grained deposition typified by muddy contourites both the lower slope and lower rise are mantled by bioturbated muds the former zone having terrigenous mud and the latter biogenic calcareous mud the accompanying nepheloid layer is thin biogenic rich and devoid of an identifiable mixed layer

experimental determination of trace element partitioning between pargasite and a synthetic hydrous andesitic melt in order to more fully establish a basis for quantifying the role of amphibole in trace element fractionation processes we have measured pargasite silicate melt partitioning of a variety of trace elements rb ba nb ta hf zr ce nd sm yb including the first published values for u th and pb experiments conducted at 1000 c and 1 5 gpa yielded large crystals free of compositional zoning partition coefficients were found to be constant at total concentrations ranging from 1 to 100 ppm indicating henry s law is oparative over this interval comparison of partition coefficients measured in this study with previous determinations yields good agreement for similar compositions at comparable pressure and temperature the compatibility of u th and pb in amphibole decreases in the order pb th u partial melting or fractional crystallization of amphibole bearing assemblages will therefore result in the generation of excesses in238u activity relative to230th similar in magnitude to that produced by clinopyroxene the compatibility of pb in amphibole relative to u or th indicates that melt generation in the presence of residual amphibole will result in the long term enrichment in pb relative to u or th in the residue this process is therefore incapable of producing the depletion in pb relative to u or th inferred from the pb isotopic composition of morb and oib comparison of partition coefficients measured in this study with previous values for clinopyroxene allows some distinction to be made between expected trace element fractionations produced during dry cpx present and wet cpx amphibole present melting rb ba nb and ta are dramatically less compatible in clinopyroxene than in amphibole whereas th u hf and zr have similar compatibilities in both phases interelement fractionations such as dnb dba are also different for clinopyroxene and amphibole changes in certain ratios such as ba nb ba th and nb th within comagmatic suites may therefore offer a means to discern the loss of amphibole from the melting assemblage elastic strain theory is applied to the partitioning data after the approaches of beattie and blundy and wood and is used to predict amphibole melt partition coefficients at conditions of p t and composition other than those employed in this study given values of dca dti and dk from previous partitioning studies this approach yields amphibole melt trace element partition coefficients that reproduce measured values from the literature to within 40 45 this degree of reproducibility is considered reasonable given that model parameters are derived from partitioning relations involving iron and potassium free amphibole

the three dimensional structure of an upper ocean vortex in the tropical pacific ocean in the equatorial pacific ocean easterly trade winds and the earth s rotation combine to drive surface currents away from the equator thereby causing cold nutrient rich subsurface water to upwell the front1 that forms between this upwelled water and warmer waters north of the equator is sometimes visible as a spectacular line in the sea 2 between 2 and 6 n westward propagating cusp shaped disturbances observed along this front3 have been attributed to the effect of dynamical instabilities in the system of zonal equatorial currents4 11but the connection between these phenomena remains unclear here we report extensive measurements from shipboard sensors satellite and drifting buoys which reveal the three dimensional structure of an anticyclonic eddy or vortex 500 km in diameter and centred at 4 n we suggest that cusp shaped disturbances of the front are caused by trains of large amplitude vortices which are driven by instability of the mean zonal shear we show that these vortices not only play an important role in the meridional transport of heat salt and momentum but are also associated with regions of intense horizontal convergence along the front where dramatic concentrations of marine life are observed

metamorphic overprinting of smnd isotopic systems in volcanic rocks the telemark supergroup southern norway abstract the telemark supergroup of southern norway consists of a series of metamorphosed mesoproterozoic volcanics and sediments the volcanic pile records three metamorphic events a pervasive regional greenschist facies event ca 1050 ma starmer 1993 a more localised early pre regional metamorphism burial type event and a late thermal metamorphism related to granite intrusion ca 900 ma priem et al 1973 in the present study major and trace element data are employed to illustrate the influence of these metamorphic events on apparent initial nd isotopic compositions in metamorphosed volcanics in the case of the basaltic volcanics burial and thermal metamorphism caused substantial fractionation of the ree and alteration of nd isotopic compositions by interaction with open system fluids such that spurious ages might result from age calculations using the nd isotopic data during the regional metamorphism element mobility was limited to the lile rb sr k and ba the ree were not fractionated and the original nd isotopic signatures were preserved the regional metamorphic effects on the acid volcanics are related to the degree of matrix recrystallisation since this matrix contains a large fraction of the ree where groundmass recrystallisation was limited the original nd isotopic signatures were retained but where the groundmass has been extensively recrystallised the ree have been fractionated resulting in a sm nd isochron age menuge 1985 ca 300 ma younger than the u pb zircon age dahlgren et al 1990 the results of this study emphasise the importance of distinguishing the nature of metamorphic fluid rock reactions the potential for ree mobility during low grade metamorphism and the need for careful selection and geochemical screening of samples for nd isotopic studies in metamorphosed volcanic terrains

east pacific ocean eddies and their relationship to subseasonal variability in central american wind jets subseasonal variability in sea surface height ssh over the east pacific warm pool off central america is investigated using satellite observations and an eddy resolving ocean general circulation model ssh variability is organized into two southwest tilted bands on the northwest flank of the tehuantepec and papagayo wind jets and collocated with the thermocline troughs eddy like features of wavelength similar to 600 km propagate southwestward along the high variance bands at a speed of 9 13 cm s wind fluctuations are important for eddy formation in the gulf of tehuantepec with a recurring interval of 40 90 days when forced by satellite wind observations the model reproduces the two high variance bands and the phase propagation of the tehuantepec eddies our observational analysis and model simulation suggest the following evolution of the tehuantepec eddies on the subseasonal timescale in response to the gap wind intensification a coastal anticyclonic eddy forms on the northwest flank of the wind jet and strengthens as it propagates offshore in the following two to three weeks an energetics analysis based on the model simulation indicates that besides wind work barotropic and baroclinic instabilities of the mean flow are important for the eddy growth both observational and model results suggest a re intensification of the anticyclonic eddy in response to the subsequent wind jet event off papagayo ocean eddy formation is not well correlated with local wind jet variability in both the gulfs of tehuantepec and papagayo subseasonal ssh variability is preferentially excited on the northwest flank of the wind jet factors for this asymmetry about the wind jet axis as well as the origins of wind jet variability are discussed

tectonomagmatic evolution of the sveconorwegian orogen recorded in the chemical and isotopic compositions of 1070 920 ma granitoids abstract the sveconorwegian province in southern norway and sweden hosts at least four granitoid suites representing apparently continuous magmatism at the sw margin of the fennoscandian shield between 1070 and 920 ma this study presents a compilation of published and new zircon la icp ms u pb geochronology whole rock and zircon geochemistry and sm nd isotope data for the granitoid suites and demonstrates the granitoids ability to record changes in the tectonomagmatic evolution of this orogenic province the sirdal magmatic belt smb ca 1070 1010 ma represents the earliest magmatism west in the province followed by two hornblende biotite granitoid suites hbg ca 1000 920 ma and the fla iddefjord bohus suite fib ca 925 ma in central and eastern parts of the province respectively the smb and the hbg bodies located outside of the smb referred to as hbgout are chemically similar whereas the hbg bodies located in the same region as the smb referred to as hbgin are more ferroan enriched in incompatible elements and have higher zircon saturation temperatures isotopically the smb and both hbg suites fall on an evolutionary trend from widespread 1 5 ga crust in the region suggesting this was the dominant crustal contribution to magmatism the fib suite is more peraluminous rich in inherited zircon and has isotopic compositions suggesting a more evolved source than both the hbg suites and the smb trace element modelling shows that the smb and hbgout suites could have formed by 50 partial melting of 1 5 ga crust whereas 5 10 remelting of the dehydrated and depleted smb residue accounts for the geochemical composition of the hbgin suite the available data suggest a scenario where the 1 5 ga lower crust underwent melting due to long lived mafic underplating giving rise to the smb suite after ca 1000 ma regional scale extension may have led to more widespread mafic underplating causing remelting of the residue following smb melt extraction forming the hbgin suite with lower crustal melting farther east forming the hbgout suite changes in melt composition over this 150 myr time interval may thus be ascribed to an evolving melt source rather than fundamental changes in tectonic regime deep continental subduction at ca 990 ma east in the orogen provided an isotopically evolved crustal source for the fib suite the data underline the difference in tectonic processes across the orogen with long lived high temperatures in the western and central parts and colder high pressure events in the eastern parts of the orogen

u pb geochronology of the syn orogenic knaben molybdenum deposits sveconorwegian orogen norway paired isotope dilution thermal ionization mass spectrometry id tims and secondary ion mass spectrometry sims zircon u pb data elucidate geochronological relations in the historically important knaben molybdenum mining district sveconorwegian orogen south norway this polyphase district provided c 8 5 mt of ore with a grade of 0 2 it consists of mineralized quartz veins silica rich gneiss pegmatites and aplites associated with a heterogeneous locally sulphide bearing amphibolites facies gneiss called knaben gneiss and hosted in a regional scale monotonous commonly weakly foliated granitic gneiss an augen gneiss at the knaben i deposit yields a 1257 6 ma magmatic zircon age dating the pre sveconorwegian protolith of the knaben gneiss mineralized and non mineralized granitic gneiss samples at the knaben ii and kvina deposits contain some 1488 1164 ma inherited zircon and yield consistent intrusion ages of 1032 4 1034 6 and 1036 6 ma this age links magmatism in the district to the regional 1050 1020 ma sirdal i type granite suite corresponding to voluminous crustal melting during the sveconorwegian orogeny a high u low th u zircon rim is present in all samples it defines several age clusters between 1039 6 and 1009 7 ma peaking at c 1016 ma and overlapping with a monazite age of 1013 5 ma the rim records protracted hydrothermal activity which started during the main magmatic event and outlasted it this process was coeval with regional high grade sveconorwegian metamorphism molybdenum deposition probably started during this event when silica rich mineralizing fluids or hydrous magmas were released from granite magma batches an analogy between the knaben district and shallow short lived porphyry mo deposits is inappropriate

sea level variability in the eastern tropical pacific as observed by topex and tropical ocean global atmosphere tropical atmosphere ocean experiment sea surface height measurements from the topex altimeter and dynamic height from tropical ocean global atmosphere tropical atmosphere ocean toga tao moorings are used to explore sea level variability in the northeastern tropical pacific ocean after the annual harmonic is removed there are two distinct bands of variability one band is centered at 5 n to 7 n and extends from 165 w to 110 w and the other band is centered at 10 n to 12 n and extends from 120 w to the coast of central america the correspondence between the two independent observation data sets at 5 n is excellent with correlations of about 90 the variability at 5 7 n is identified as instability waves formed just south of the north equatorial countercurrent during the months of july through march wave amplitudes are largest in the range of longitudes 160 140 w where they can exceed 10 cm the waves disappear when the equatorial current system weakens during the months of march through may the variability at 11 n in 1993 has the form of anticyclonic eddies these eddies propagate westward at a speed of about 17 cm s 1 consistent with the dispersion characteristics of free rossby waves the eddies are shown to have their origin near the coast of central america during northern fall and winter their formation seems to result from intense wind bursts across the gulfs of tehuantepec and papagayo which generate strong anticyclonic ocean eddies the disappearance of the eddies in the summer of 1993 coincides with the seasonal intensification of equatorial currents thus the variability at 11 n has very little overlap in time with the variability at 5 n

constraints on melting and magma production in the crust major intrusions of granitic rocks are found in several tectonic settings and in all cases crustal melts may contribute to the volumes of granitic magma high grade metamorphism and partial melting of the crust take place predominantly under fluid absent conditions we present a model for calculating the amounts of melt that may be formed by fluid absent breakdown of micas and amphiboles in common crustal rock types pelitic quartzofeldspathic intermediate and mafic melt proportions depend mainly on the kind of source rock the pressure at which melting takes place the temperature and the hydrous mineral h2o content of the source as a consequence of the pressure dependence of water solubility in silicate melts any given source rock will produce more melt by a given fluid absent reaction at lower pressure at a given pressure higher temperature reactions can produce more melt from a given source rock based on a survey of the compositions of common rock types we show that the amounts of melt can vary from 50vol thus crustal rocks vary widely in their fertility as magma sources depending on the types and amounts of hydrous phases they contain in general muscovite breakdown in pelites will yield only small quantities of melt and lead to migmatite formation biotite breakdown in pelites occurs at higher temperature and because most high grade pelites below granulite grade are biotite rich can yield up to about 50 vol of granitoid melt rocks of intermediate composition and hornblende rich mafic rocks are potentially highly fertile magma sources also provided that the high temperatures necessary for biotite and hornblende breakdown are realized pyroxene rich mafic rocks and quartzofeldspathic rocks are much less potentially fertile data suggest that mechanisms exist for the efficient segregation of melt and restite in systems with 30and probably 20vol melt the pressure temperature history of a region can greatly influence crustal source fertility through its control over the occurrence of subsolidus dehydration and melting equilibria

eddy energetics in the upper equatorial pacific during the hawaii to tahiti shuttle experiment abstract eddy energetics in the central equatorial pacific ocean is examined using acoustic doppler current profiler velocities and ctd densities collected during the hawaii to tahiti shuttle experiment in 1979 80 three distinct sources of eddy energy are identified with varying degrees of statistical reliability and are interpreted as evidence for three separate instabilities of the mean flow field an instability at and just north of the equator occurs primarily in boreal summer and fall it arises from the cyclonic shear between the equatorial undercurrent and the south equatorial current sec north of the equator the instability is present only when and where both currents are well developed and there is little involvement of the shear between the sec and the north equatorial countercurrent necc the instability is characterized by local maxima in zonal and meridional eddy velocity variance strong u v reynolds stress and large mean flow to eddy kinetic energy conversion despite seasonal va

tropical instability waves at 0 n 23 w in the atlantic a case study using pilot research moored array in the tropical atlantic pirata mooring data temperature salinity velocity and wind from a mooring at 0 n 23 w are used along with satellite data for sea surface temperature and sea level to examine the contribution of tropical instability waves tiws to the energy and heat balance of the equatorial atlantic mixed layer the tiws appear as periodic 20 30 day fluctuations of currents temperature and salinity which intensify beginning in june and peak in late boreal summer the intensification occurs in phase with strengthening of the southeasterly trade winds and the seasonal appearance of the equatorial tongue of cold mixed layer temperatures in 2002 these waves which warm the mixed layer by 0 35 c during summer months are maintained by both barotropic and baroclinic conversions that are of comparable size salinity fluctuations previously neglected increase the magnitude of baroclinic energy conversion

geochronology of high pressure mafic granulite dykes in sw sweden tracking the p t t path of metamorphism using hf isotopes in zircon and baddeleyite although the u pb zircon chronometer has been widely used for dating metamorphism in moderate to high grade rocks it is generally difficult to link the u pb age of zircon to specific metamorphic reactions in this study the initial hf isotopic composition of secondary zircon is compared with the evolution of hf isotopic composition of the bulk sample back projected from the measured value through time this approach may enhance the interpretation of radiometric ages performed on metamorphic mineral assemblages here u pb sm nd and lu hf geochronology and thermobarometry have been integrated and applied to two metamorphosed diabase dykes in the sveconorwegian orogen sw sweden the dykes are located 5 km east of the nne trending gota alv deformation zone in the idefjorden terrane and trend parallel to this zone the lunden dyke is recrystallized into a coronitic granulite facies assemblage u pb isotopic analyses of baddeleyite in this dyke indicate an emplacement age of 1300 ma thermobarometric techniques applied to garnet and omphacitic clinopyroxene coronas indicate high pressure metamorphism at c 15 kbar and c 740 c growth of polycrystalline zircon at the expense of baddeleyite occurred at 1046 6 ma identical hf isotopic composition of polycrystalline zircon and baddeleyite shows that the baddeleyite to zircon transition took place before hf equilibration among the other metamorphic minerals and hence the c 1046 ma age of polycrystalline zircon sets an upper age limit of metamorphism of this sample the haregarden dyke is recrystallized into a granoblastic transitional upper amphibolite to granulite facies assemblage the estimated p t conditions are c 10 kbar and c 700 c analyses of small 30 m clear and round zircon in this sample yield a concordia u pb age of 1026 4 ma which is indistinguishable from the lu hf and sm nd mineral isochron ages of 1027 9 ma and 1022 34 ma this type of secondary zircon plots at the lower end of the lu hf isochron and indicates simultaneous growth with garnet at c 1026 ma a time when hf isotopic equilibrium among minerals must have been reached

characteristics of wind generated rings in the eastern tropical pacific ocean eddies are generated in the eastern tropical pacific 3 s 23 n 75 105 w by winds blowing through central american mountain passes from the atlantic we used coastal zone color scanner czcs and advanced very high resolution radiometer avhrr satellite imagery complemented with monthly in situ sea surface temperature and wind series from the comprehensive ocean atmosphere data set coads to study these eddies and their effect on pigment concentrations in the region pigment values in the gulf of tehuantepec generally reach higher values in november march before those in the gulf of papagayo the eddies generated in the gulf of tehuantepec are associated with passages of cold fronts across the gulf of mexico from the north while the eddies off papagayo and panama are associated with increases in trade wind intensity czcs images showed larger numbers of eddies per season than have been previously reported on the basis of in situ and avhrr observations or numerical simulations we counted 13 eddies in 1979 1980 8 in 1984 1985 and 6 in 1985 1986 the eddies transfer both energy and biological constituents from the continental margin to the offshore tropical pacific the eddies frequently moved distances in excess of 1500 km from their point of origin both anticyclonic and cyclonic eddies are generated but in general there are more anticyclones anticyclonic eddies generally moved to the southwest some cyclonic eddies moved to the south and southeast along the central american coast and appeared to be trapped by the cyclonic costa rica thermal dome eddies traveled at speeds varying between 9 and 21 cm s 1 and had diameters of 100 500 km phytoplankton concentrations associated with the eddies varied from 2 to 10 mg m 3 within 70 km of the coast to 1 mg m 3 up to 600 km of the coast between late april and october fewer eddies were observed and phytoplankton concentrations were lower 0 25 mg m 3 and more uniform over the region

observations of the dispersion characteristics and meridional sea level structure of equatorial waves in the pacific ocean spectral techniques applied to altimetry data are used to examine the dispersion relation and meridional sea level structure of wavelike variability with periods of about 20 to 200 days in the equatorial pacific ocean zonal wavenumber frequency power spectra of sea surface height when averaged over about 7 s 7 n exhibit spectral peaks near the theoretical dispersion curves of first baroclinic mode equatorial kelvin and rossby waves there are distinct statistically significant ridges of power near the first and second meridional mode rossby wave dispersion curves sea level variability near the theoretical kelvin wave and first meridional mode rossby wave dispersion curves is dominantly but not perfectly symmetric about the equator while variability near the theoretical second meridional mode rossby wave dispersion curve is dominantly antisymmetric these results are qualitatively consistent with expectations from classical or shear modified theories of equatorial waves the meridional structures of these modes resemble the meridional modes of equatorial wave theory but there are some robust features of the meridional profiles that were not anticipated the meridional sea level structure in the intraseasonal kelvin wave band closely resembles the theoretically expected gaussian profile but sea level variability coherent with that at the equator is detected as far away as 11 75 s possibly as a result of the forced nature of these kelvin waves both first and second meridional mode rossby waves have larger amplitude in the northern hemisphere the meridional sea level structure of tropical instability waves closely resembles that predicted by lyman et al using a model linearized about a realistic equatorial zonal current system

petrogenesis of archaean trondhjemites tonalites and granodiorites from eastern finland major and trace element geochemistry

trace element indicators of crystal accumulation in silicic igneous rocks abstract if fractional crystallization coupled with some crustal assimilation afc is the dominant process for generating evolved magmas in the earth s crust large quantities of igneous cumulates must be present in the rock record however despite some reported occurrences intermediate to silicic rocks characterized by an unambiguous crystal accumulation signature have remained elusive the signature is expected to be subtle in viscous silicic magmas and sensitive criteria need to be developed to test whether these cumulates are truly rare or simply difficult to discern we propose models that use specific trace element concentrations and ratios zr ba eu eu and zr hf within a well constrained framework for the physical extraction of liquid from crystals mostly occurring between 50 and 70 vol crystals to identify silicic cumulates the results of these models indicate that crystal accumulation or melt extraction has occurred in multiple natural examples around the world both in plutonic and volcanic realms however these examples were selected because they represent conditions that are most favorable high amount of melt extraction well constrained initial liquid compositions for unambiguously identifying cumulate residue in many cases we show that the trace element signature for crystal accumulation will remain largely concealed in addition the different liquid lines of descent related to the various tectonic settings on earth dry reduced in hot spots divergent margins and wetter more oxidizing in arc environments will lead to different trace element evolution and each criterion must be applied on a case by case basis despite these limitations the undeniable but subtle presence of silicic cumulates in the mid to upper crust lends support to the idea that igneous differentiation is dominantly driven by melt extraction from partially crystalline reservoirs

biogeomorphological implications of microscale interactions between sediment geotechnics and marine benthos a review abstract at the foundations of biogeomorphological processes in the sea lie interactions between the activities of marine benthic animals and the geotechnical properties of their sedimentary environments the potential significance of these interactions which take place at a microscale level of millimetres to metres for the large scale geomorphology of the seabed has rarely been appreciated in the context of this review large scale is defined as greater than 50 m to hundreds of kilometres the present review addresses this link drawing examples from a wide range of marine environments including estuaries the intertidal zone continental shelves and slopes and the deep sea it firstly considers sediment stabilisation slope failure sediment mixing biodeposition sediment compaction and hydrodynamic effects this is followed by a consideration of two extremes of the ecological pyramid the effects of marine meiofauna and marine vertebrates the final section draws attention to the central role of faunal mucus and extracellular polymeric material ecpm in many of the microscale interactions that we describe the implications of these microscale biological processes and features are discussed in terms of their influence on and control of the large scale geomorphology of the seabed

mesoscale variability in the northeastern tropical pacific forcing mechanisms and eddy properties 1 the generation mechanisms and properties of the mesoscale eddies in the northeastern tropical pacific netp are studied using a series of numerical solutions and satellite observations the spatial and temporal resolution of mountain wind jets over the gulfs of tehuantepec and papagayo are essential for an accurate modeling of the regional mesoscale variability three previously proposed eddy generation mechanisms are the local transient wind forcing the combined low frequency wind and boundary forcing and the remote equatorial kelvin wave forcing in our model the transient wind forcing was represented by wind fields with synoptic variability and the remote equatorial kelvin wave forcing by 5 day open boundary conditions with interannual variability solutions with and without high frequency forcings are contrasted to evaluate the contributions of the three mechanisms the combined low frequency wind and boundary forcing is the primary eddy forcing mechanism in the netp in the tehuantepec region the high frequency wind forcing contributes more to the mesoscale variability than the remote equatorial kelvin wave forcing while in the papagayo region their contributions are comparable eddies in the tehuantepec and papagayo regions are larger in both amplitude and size and are more likely to deflect equatorward than eddies in the rest of the netp the maximum temperature anomaly of eddies is at around 50 m depth eddies with lifetimes 6 weeks are more likely anticyclonic while eddies with lifetimes 6 weeks are more likely cyclonic the anticyclone dominance for large amplitude long lived eddies is the combined consequence of wind driven asymmetric dipole spin up and the evolutionary fragility of large amplitude cyclones

signature of mesoscale eddies in satellite sea surface salinity data a persistent signature of coherent mesoscale eddies in sea surface salinity sss is revealed by analyzing the relationship between satellite sss and sea surface height ssh variability in an eddy following reference frame our analysis focuses on mid ocean eddies in two representative regions the southern indian ocean and the north atlantic subtropical gyre the resulting composite averages reveal a clear signature of mesoscale eddies in satellite sss with typical sss anomalies of 0 03 0 05 psu the spatial structure of eddy induced sss perturbations can be characterized as a superposition of a dipole structure arising from horizontal advection of the background sss gradient by eddy velocity field and a monopole structure related to the eddy core the observed relationships between sss and ssh anomalies are used to provide a regional assessment of the role of mesoscale eddies in the ocean freshwater transport in the north atlantic subtropical gyre this article is protected by copyright all rights reserved

grain scale variations in trace element composition of fluid altered zircon acasta gneiss complex northwestern canada sem back scattered electron images of zircon separates from a 2 9 ga granitic dyke from the acasta gneiss complex slave province reveal primary igneous oscillatory zoning which is transgressively overprinted by irregular alteration domains electron microprobe analyses show that altered zircon domains are depleted in zr and si relative to unaltered zircon while retaining a constant zr si ratio sims trace element analyses indicate that lree are preferentially enriched in the altered domains altered zircon contains elevated concentrations of ba up to 580 ppm ca up to 2 weight of the element and common pb 50 ppb the presence of lree ca ba and common pb in the zircons is interpreted to be the result of secondary alteration by an aqueous fluid and not by primary incorporation during crystallization we propose that the alteration related elements are located in amorphous zircon domains

emplacement of polygeneration pegmatites in relation to sveco norwegian contractional tectonics examples from southern norway abstract recent studies have demonstrated that there is a strong link between sites of concentrated magmatism and crustal deformation zones magmatism is often described as being syn kinematic where one or more increments of intrusion punctuate deformation with successive generations of injections being progressively deformed pegmatite formation in the mesoproterozoic of south norway has been considered as post kinematic in nature relative to sveconorwegian grenvillian deformation 1 13 ga to 0 85 ga during accretion of the sw margin of baltica this paper presents structural observations from mapping of some pegmatites in the bamble terrane of south norway demonstrating that the pegmatites are structurally related to sveconorwegian fold geometries associated with peak metamorphism at approximately 1 14 ga and are kinematically related to overthrust geometries associated with the initial overthrusting phase of the porsgrunn kristiansand fault when the bamble terrane docked with the underlying telemark terrane local fold geometries suggest a strain regime where the maximum contractional axis is sub horizontal and oriented nw se consistent with the regional kinematics the pegmatites display a systematic deformation pattern consistent with deformation in the isoclinal fold limbs pegmatites are also deformed into asymmetric antiformal folds above reverse shear structures and are also cut by these structures thus showing a thrust geometry the undeformed pegmatites are emplaced in sub horizontal fractures and suggests sub horizontal contractional axis related to overthrusting which is identical to the strain regime of the folding the evidence suggests that the pegmatites are syn tectonic and were injected into reverse shear related fractures deformation was progressive and incremental with longer periods of ductile deformation at low strain rate punctuated by shorter periods of fracturing and pegmatite injection at high strain rate this work therefore implies an intimate spatial and temporal relationship between deformation and magmatism during crustal accretion on the western margin of fennoscandia

radiogenic isotope systematics of the herefoss granite south norway an indicator of sveconorwegian grenvillian crustal evolution in the baltic shield abstract a new pb pb mineral isochron dates the crystallization of the herefoss granite south norway to 926 8 ma confirming earlier rb sr evidence of a late sveconorwegian grenvillian age initial sr and nd isotopic compositions recalculated to esr 926 ma 40 end 926 ma 3 2 to 0 8 indicate that the magma has originated from a mixture of two distinct source components 1 a crustal component which has resided in a moderately lile enriched reservoir f rb 7 to 8 238 u 204 pb 17 22 since 1 6 1 9 ga this crustal component is clearly distinct from the extremely lile enriched metasedimentary country rocks of the granite f rb 21 238 u 204 pb 24 2 a mantle derived component e nd 4 6 to 5 9 e sr 12 to 9 238 u 204 pb 7 96 younger than 1 5 ga the ranges of initial sr nd and pb composition observed in the intrusion indicate that the magma was isotopically heterogeneous at the time of emplacement and that the crustal contribution amounted to 35 55 by the end of the sveconorwegian orogeny the southwestern part of the baltic shield had acquired a compositionally layered structure where an uppermost zone of the crust with extreme lile enrichment was underlain by a heterogeneous layer consisting of rocks with normal upper crustal degree of lile enrichment and mafic intrusions younger than 1 5 ga there is no evidence of involvement of lile depleted deep continental crust source material in the petrogenesis of the herefoss granite rejuvenation of the lower crust by injection of mantle derived magmas underplating has been an important process in the evolution of the southwestern part of the baltic shield the absence of a young mantle derived component from 1 12 ga charnockitic intrusions in the bamble sector and from the 989 ma grimstad granite suggests that this process may have been contemporaneous with late sveconorwegian mafic magmatism in the rogaland vest agder sector further to the west

tropical instability wave kinematics observations from the tropical instability wave experiment the kinematics of planetary waves originating from instability of the nearsurface equatorial currents are reported on using velocity measurements from an array of acoustic doppler current profilers deployed in the equatorial pacific during the tropical instability wave experiment a distinctive wave season was observed from august to december 1990 with wave energy confined primarily above the core of the equatorial undercurrent particle motions in the horizontal plane are described by eccentric ellipses oriented toward the north but tilting into the cyclonic shear of the south equatorial current the tilt is maximum near the surface just north of the equator and decreases to the south and with depth the distribution of wave variance is narrowband in both frequency and zonal wavenumber with central period zonal wavelength and westward directed phase propagation estimated to be 500 hours 1060 km and 59 cm s 1 respectively neither the meridional nor the vertical wavenumber component is statistically different from zero these results generally agree with previous findings on tropical instability waves from the atlantic and pacific oceans and in the undersampled arena of geophysical measurements they provide an example where statistical inference is supported by an ensemble of independent measurements

partial melting in amphibolites in a deep section of the sveconorwegian orogen sw sweden garnet amphibolite metataxites at the steningekusten nature reserve in southwestern sweden contain tonalitic patches and veins whole rock chemistry suggests that the protoliths were mafic igneous rocks with alkaline affinities orthopyroxene megacrysts are present in leucosome in parts of these garnet amphibolites but absent in others orthopyroxene megacrysts were formed by vapor absent melting initiated by incongruent melting of biotite followed by the breakdown of hornblende the net reaction was bt hbl pi qtz opx melt cpx gt melting occurred at pressures of approximately 1 gpa and temperatures which probably exceeded 800 degrees c pyroxenes are surrounded by hornblende quartz symplectites and hornblende in these coronas has distinctly lower concentrations of na k and ti than that in adjacent mesosorne the hornblende rims formed upon cooling and reaction with crystallizing melt this created a barrier to further reaction thus preserving the orthopyroxene megacrysts garnet amphibolite metatexites lacking pyroxene megacrysts have features characteristic of vapor present melting including lack of peritectic phases predicted by vapor absent melting reactions larger amounts of leucosome 14 versus 7 and less distinct melanosomes the variation in these migmatites reflects open system behavior either on a regional scale with the migration of aqueous fluids into the amphibolites or on a local scale with the migration of melt within the amphibolites zircons from all units have cl dark core domains that are dated at 1415 1390 ma the core zones are cut and overgrown by cl dark and cl bright rims that are dated at 975 965 ma the zircon rims are thin in the mesosome but are thicker in the leucosome suggesting that they formed during migmatization new growth of zircon associated with migmatization at ca 970 ma corresponds to the timing of crustal scale partial melting in the deep regions of the sveconorwegian orogen synchronous with east west extension and the intrusion of mafic dykes if partial melting was driven by an influx of aqueous fluids they were probably derived from a relatively cool source region which would indicate tectonic juxtaposition of hotter and cooler terranes c 2015 elsevier b v all rights reserved less

modulation of the ganges brahmaputra river plume by the indian ocean dipole and eddies inferred from satellite observations the bay of bengal receives large amounts of freshwater from the ganga brahmaputra gb river during the summer monsoon the resulting upper ocean freshening influences seasonal rainfall cyclones and biological productivity sparse in situ observations and previous modeling studies suggest that the east india coastal current eicc transports these freshwaters southward after the monsoon as an approximately 200 km wide 2 000 km long river in the sea along the east indian coast sea surface salinity sss from the soil moisture active passive smap satellite provides unprecedented views of this peculiar feature from intraseasonal to interannual timescales smap sss has a 0 83 correlation and 0 49 rms difference to 0 5 m in situ measurements smap and in stu data both indicate a sss standard deviation of 0 7 to 1 away from the coast that rises to 2 pss within 100 km of the coast providing a very favorable signal to noise ratio in coastal areas smap also captures the strong northern bob postmonsoon cross shore sss contrasts 10 pss measured along ship transects smap data are also consistent with previous modeling results that suggested a modulation of the eicc gb plume southward extent by the indian ocean dipole iod remote forcing associated with the negative indian ocean dipole in the fall of 2016 indeed caused a stronger eicc and river in the sea that extended by approximately 800 km further south than that in 2015 positive iod year the combination of smap and altimeter data shows eddies stirring the freshwater plume away from the coast

micro scale geotechnical variability in continental slope and abyssal sediments influenced by the oxygen minimum zone in the arabian sea abstract we describe a new micro scale method of measuring the penetration resistance of the surficial layers of slope and abyssal plain sediments within and below the omz on the oman continental slope the micro scale load resistance penetrometer mlrp continuously measures the penetration resistance q of a cylindrical probe driven at constant velocity into cores of sediment recovered by sub coring box core samples measurements are recorded at 0 8 mm depth intervals into the sediment by an automated data acquisition system these provide continuous depth profiles of penetration resistance q and its variability qr in surficial sediments 0 100 mm the results represent the first published application of this technique to slope and abyssal plain sediments the q data divide the stations into shallow omz somz stations 391 854 m deep omz domz stations 987 1285 m and abyssal non omz anomz stations 3392 3396 m one station 688 m was anomalous penetration resistance q was positively related to shear strength and inversely related to water content but not to bioturbation measured as burrow numbers relaxation and pull out data were obtained from three stations three patterns of qr were observed consisting of well confined data data containing large negative and positive spikes and data showing a progressive down core increase in spikes four additional measures of q variability were defined which show statistically significant relationships with burrow numbers an increase in bioturbation estimated by burrow numbers is associated with a decrease in micro scale variability in q this is related to the activity of burrowing macrofauna our results are discussed in the context of biogeotechnical modifications of sedimentary environments

observations of 20 day period meridional current oscillations in the upper ocean along the pacific equator abstract prominent oscillations of the meridional current with a mean period of approximately 20 days have been observed in the upper ocean over several years from may 1979 to october 1985 using moored current measurements along the pacific equator at 95 110 124 140 w and 152 w as well as off but near the equator at 110 and 140 w the fluctuations are relatively narrowband 0 005 cpd in frequency a 95 statistically significant peak in power spectra of meridional current occurred at 110 124 and 140 w but not at 95 and 152 w where the spectral peaks were smaller the dominant wave period decreased by about 4 from 110 to 140 w maximum amplitude was measured at 124 w the amplitude above 80 m was maximum at the equator and decreased poleward from the equator at 15 m the annual averaged root mean square amplitude was about 20 5 cm s 1 and individual peak to trough values reached 150 cm s 1 the wave amplitude decreased with depth and the wave was essentially confined to the upper 80 m

zircon as a metamorphic timekeeper a case study from the caledonides of central norway abstract during metamorphism inherited or detrital zircon grains commonly serve as a template onto which new generations of metamorphic zircon precipitates charting successive episodes in the thermal history of rocks in addition chemical modification of pre metamorphic zircon can leave an imprint in the u pb systematics we present a case study from a sample of migmatitic amphibole biotite gneiss from central norway that contains zircon grains that chart much of the history of an entire orogenic episode not only through generation of new zircon but also resetting of the u pb system via radiogenic pb loss the investigated gneiss from the helgeland nappe complex within the uppermost allochthon of the scandinavian caledonides records a prolonged metamorphic evolution phase equilibria modelling implies peak metamorphic conditions of 7 5 8 0 kbar and 650 675 c consistent with low degree partial melting and the presence of small volumes of leucosome laser ablation split stream analysis that simultaneously measures u pb ree and lu hf in the same volume of zircon yields a range of analyses that spread along concordia a zircon population between 485 and 443 ma is characterized by faded and blurred oscillatory zoned domains that have gained nonformula elements these analyses are interpreted to indicate the presence of reactive solutions during this time period that led to leaching and mobility of pb another texturally distinct zircon component yields an age of 478 4 ma has typical igneous ree zircon profiles and records low apparent alpha doses interpreted to reflect new zircon growth during migmitization a further population of zircon rims and discrete grains yields an age of 453 2 ma interpreted as a later episode of zircon growth during high grade metamorphism a final set of zircon overgrowths yield an age of 439 3 ma also interpreted to reflect new metamorphic growth many zircon growth phases in this rock have similar ree patterns implying broadly isochemical metamorphism consistent with the evidence for only limited partial melting furthermore the hf isotopic signature in the analyzed zircon grains suggests that there was no release of radiogenic hf during metamorphism the metamorphic zircon in the studied rock records several episodes of growth and or alteration over a period of 40 ma that was related to protracted destruction of the iapetus ocean in the context of regional data the new results suggest that the helgeland nappe complex which is generally considered to be exotic to baltica underwent geographically widespread long lived ordovician high temperature metamorphism this record of metamorphism is distinct from that recorded by tectonostratigraphically lower units which are conventionally regarded to have been derived from baltica the results shed light on the assembly of the scandinavian caledonides and show that zircon from individual samples may be used to unravel complex orogenic histories

oceanic and atmospheric anomalies of tropical instability waves tropical instability waves tiws are detected in remotely sensed sea surface height ssh temperature sst and wind records of the eastern equatorial pacific analyses of tiw anomaly relationships reveal strong dynamical influence of tiws within approximately 5 of the equator the first influence is advective heat flux the primary forcing of tiw sst anomalies is advection of the meridional temperature gradient by tiw currents the second influence is modification of the wind stress and ekman pumping fields by tiw surface ocean currents by affecting surface stress and hence roughness tiw currents in this low wind region introduce a significant bias in scatterometer vector wind measurement this bias is evident in both nscat and quikscat winds the difference between wind measurements from tao moorings and scatterometers is phase locked with tiw sst oscillations these results have important implications for scatterometry and for understanding tropical dynamics thermodynamics and biogeochemistry

heat flow measurements in late palaeoproterozoic to permian geological provinces in south and central norway and a new heat flow map of fennoscandia and the norwegian greenland sea abstract new heat flow determinations from 9 sites in south and central norway situated in late palaeoproterozoic to permian geological provinces show that topographically and palaeoclimatically corrected surface heat flow generally varies between 50 and 60 mw m 2 the palaeoclimatic corrections are significant typically constituting 10 20 of the final heat flow values higher heat flow was encountered at 3 sites however only at the fredrikstad site situated in the high heat producing iddefjord granite could this elevated heat flow be related to high heat production a compilation of new and previously published heat flow data from norway show that on the scale of major geological provinces heat flow varies significantly and is generally overlapping the lowest heat flow values ca 30 mw m 2 come from the early palaeoproterozoic karasjok kautokeino greenstone belt and the early neoproterozoic egersund anorthosite complex both of which are dominated by low heat producing rocks the highest heat flow values ca 60 80 mw m 2 come from early neoproterozoic high heat producing post orogenic granites in south norway these geological provinces display relatively little variation in lithology and heat production which allows such relationships to be made in general however significant lithological variation within geological provinces makes relationships between heat flow and geological factors such as tectonometamorphic age lithology and heat production on a country scale obscure at best in contrast a compilation of almost 1000 heat flow measurements from fennoscandia and the norwegian greenland sea shows a distinct correlation between heat flow and tectonic age the archaean provinces in ne fennoscandia karelia display low heat flow of ca 35 40 mw m 2 increasing gradually to ca 50 55 mw m 2 southwestwards in palaeoproterozoic and mesoproterozoic provinces the transscandinavian igneous belt which consists largely of relatively high heat producing granites breaks this trend with a heat flow of ca 60 65 mw m 2 on the norwegian continental margin the heat flow is rather constant at ca 60 mw m 2 and the oceanic crust shows an exponential increase in heat flow from ca 60 mw m 2 near the continent ocean boundary oceanic crust ca 55 million years old to 200 mw m 2 near the mid atlantic spreading ridge similar to heat flow determined from oceanic crust elsewhere as well as to theoretical models of oceanic heat flow although a number of factors may render individual heat flow measurements uncertain the abundance of available data obtained by different methods and the clear correlation between heat flow and geology provide confidence as to the significance of these heat flow values

satellite observations of the wind jets off the pacific coast of central america part ii regional relationships and dynamical considerations abstract satellite estimates of winds at 10 m above the sea surface by the nasa scatterometer nscat during the 9 month period october 1996 june 1997 are analyzed to investigate the correlations between the three major wind jets along the pacific coast of central america and their relationships to the wind and pressure fields in the inter american seas and eastern tropical pacific comparisons with sea level pressure confirm the conventional view that tehuantepec wind variations are driven by pressure variations in the gulf of mexico associated with north american cold air outbreaks the three jets sometimes developed sequentially from north to south statistically however the papagayo and panama jets were poorly correlated with variations of the tehuantepec jet over the nscat observational period the papagayo and panama jets were significantly correlated with each other and were coupled to coherent variations of the trade winds extending from the caribbean sea to the eastern tropical pacific the det