geochemical reconstruction of pacific decadal variability from the eastern north pacific during the holocene determining climate variations over the holocene requires high resolution records with well developed age models a 40 m long marine sediment core raised from effingham inlet an anoxic fjord on the west coast of vancouver island british columbia canada yields such a record forty six 14c accelerator mass spectrometry ams dates determined from terrestrial plant material form the age model downcore sampling at both 5 cm 20 year and 1 5 cm 7 year resolution indicates that high frequency oceanographic variability has prevailed at this site over the last 10 000 years spectral analysis of wt opal a proxy for diatom productivity in the basin reveals the bidecadal and pentadecadal periods of the pacific decadal oscillation pdo north pacific index npi that are related to changes in the strength of the aleutian low coherence analysis between the effingham inlet data and 18o records from jellybean lake a high elevation site in southwest yukon indicates regional coherence at periods of 45 7

tidal correction of topex poseidon altimetry for seasonal sea surface elevation and current determination off the pacific coast of canada altimetry from the topex poseidon satellite is analyzed for the waters off british columbia canada tides are removed using harmonic constants from two coastal and two global models and the accuracy of this detiding is assessed by using these same models and one digital filter to remove the tide from the time series of three representative coastal tide gauges it is demonstrated that inaccurate m2 s2 and k1 tide removal from topex poseidon altimetry can introduce systematic biases to the calculation of seasonally averaged fields average summer and winter sea surface heights are calculated from the detided altimetry and estimates of their accuracy nearshore are computed using concurrent time series from 11 tide gauges finally these seasonal elevations are blended with those from the 11 tide gauges and the associated surface currents are calculated using a diagnostic finite element model these currents are compared with those calculated from historical conductivity and temperature versus depth measurements and those measured by historical near surface current meters

the generation of oceanic rhyolites by crystal fractionation the basalt rhyolite association at volcan alcedo galapagos archipelago

cross shore separation of adult and juvenile euphausiids in a shelf break alongshore current abstract euphausiids are an important component of the zooplankton in boundary current upwelling regions including the pacific northwest continental margin many aspects of euphausiid distribution and ecology in this region are well known however some features of their spatial and temporal distribution are less understood how and why euphausiids aggregate near the shelf break upwelling center how and why there is within an alongshore band of high abundance of all stages spatial segregation of adults and larvae why despite spatial association with upwelling euphausiid abundance off vancouver island is weakly or negatively correlated at interannual time scales with upwelling intensity to address these we made km resolution surveys of adult juvenile and larval euphausiid horizontal distributions water properties and currents across the vancouver island shelf break in mid to late spring of two successive years survey timing was before 1997 and after 1998 the spring transition to upwelling conditions and near the annual spring reproductive peak in both years early developmental stages occupied an alongshore band that was offset from the late juveniles and adults the direction of the offset differed between the two surveys early life history stages larvae and early juveniles were shoreward of adults in april 1997 downwelling conditions but seaward of adults in may 1998 upwelling conditions separation distance order 5 10 km was consistent with expected differences in cumulative wind driven and vertically sheared cross shore transport of surface dwelling larvae and early juveniles vs transport of diel migratory late juveniles and adults separation direction was consistent with recent history of winds and ekman transport shoreward during poleward winds and seaward into blue water and usually into a strong equatorward current during equatorward winds

large scale response to atmospheric forcing of shelf currents and coastal sea level off the west coast of north america may july 1981 and 1982 the response of alongshore currents v over the continental shelf and of coastal sea level along the pacific coast of north america to atmospheric forcing on large alongshore scales 100 2000 km during may july 1981 coastal ocean dynamics experiment code 1 and may july 1982 code 2 has been studied using sea level and wind measurements from coastal stations and buoys between 33 n and 48 n and using current measurements from five locations between 35 n and 48 n characteristics of the large scale response of v and to fluctuations in the alongshore component of the wind stress varied with latitude and with year in relation to variations in in 1981 large scale fluctuations were coherent within but not between separate domains north and south of 42 n in 1982 large scale coherent fluctuations were found only in a northern domain that extended much farther south to near 37 n accordingly in 1981 alongshore current v fluctuations from 39 n code were coherent with v from 35 n while in 1982 v fluctuations from 39 n were coherent with those north to 48 n in 1981 the northern domain fluctuations were forced by between 42 n and 45 n with southern domain forcing at 35 36 n in 1982 northern domain fluctuations were forced by over a region of much larger along shore extent 37 48 n high values of space lagged coherences between v and y y is the alongshore coordinate indicate that v at 39 n was strongly wind driven maximum squared coherences of v versus y are found with to the south by 100 300 km for low frequencies 0 23 cpd in 1981 0 14 cpd in 1982 and with from near local stations at higher indicating the importance of remote forcing at low frequencies and local forcing at high frequencies the response of v to y at 35 n and 43 n was more complicated but evidence for strong wind forcing is found in several frequency bands for v at 43 n during 1981 and 1982 and at 35 n during 1981 at 48 n v was forced in 1982 for 0 18 cpd by from locations 300 1400 km to the south

a model for estimating cross shore surface transport with application to the new jersey shelf 1 a one dimensional steady state numerical model is developed for estimating cross shore surface transport in shallow waters where the water depth is comparable to boundary layer thickness the model is used to solve a momentum equation which describes the cross shore balance to validate the model acoustic doppler current profiler adcp current data collected during an experiment off the new jersey shelf in the summer of 1996 are used to estimate the cross shore surface transport during that period and then compared with model predictions based on the local wind the success of the model in estimating the cross shore surface transport leads to an improved version of the conventional upwelling index i e the bakun index particularly for coastal areas with wide and shallow shelves such as the east coast of the united states finally the model because of its simplicity is well suited for operational applications where computational resources may be limited

influence of the pacific decadal oscillation el nino southern oscillation and solar forcing on climate and primary productivity changes in the northeast pacific evidence of 11 year schwabe solar sunspot cycles el nino southern oscillation enso and the pacific decadal oscillation pdo were detected in an annual record of diatomaceous laminated sediments from anoxic effingham inlet vancouver island british columbia radiometric dating and counting of annual varves dates the sediments from ad 1947e1993 intact sediment slabs were x rayed for sediment structure lamina thickness and composition based on gray scale and subsamples were examined for diatom abundances and for grain size wavelet analysis reveals the presence of w2e3 w4 5 w 7a ndw9e12 year cycles in the diatom record and an w11e13 year record in the sedimentary varve thickness record these cycle lengths suggest that both enso and the sunspot cycle had an influence on primary productivity and sedimentation patterns sediment grain size could not be correlated to the sunspot cycle although a peak in the grain size data centered around the mid1970s may be related to the 1976e1977 pacific climate shift which occurred when the pdo index shifted from negative cool conditions to positive warm conditions additional evidence of the pdo regime shift is found in wavelet and cross wavelet results for skeletonema costatum a weakly silicified variant of s costatum annual precipitation and april to june precipitation higher spring april may values of the north pacific high pressure index during sunspot minima suggest that during this time increased cloud cover and concomitant suppression of the aleutian low al pressure system led to strengthened coastal upwelling and enhanced diatom production earlier in the year these results suggest that the 11 year solar cycle amplified by cloud cover and upwelling changes as well as enso exert significant influence on marine primary productivity in the northeast pacific the expression of these cyclic phenomena in the sedimentary record were in turn modulated by the phase of pdo as indicated by the change in period of enso and suppression of the solar signal in the record after the 1976e1977 regime shift

a cyclonic eddy over the continental margin of vancouver island evidence for baroclinic instability abstract this paper describes the circulation water properties and energetics of an observed cyclonic eddy that formed over the continental margin of vancouver island between late july and early september 1980 the eddy was characterized by a depth scale of 1 km a radius of 50 km and a maximum near surface geostrophic flow of 50 cm s 1 within the middepth core of the eddy isopycnal surfaces were domed upward by 50 m and were comprised of relatively warm saline and low dissolved oxygen water that appeared to originate with the california undercurrent the eddy is shown to have been generated through dynamic instability of the seasonal mean flow along vancouver island the appearance in late july of the undercurrent over the slope may have been an important factor in the amplification of the mesoscale meander that eventually deformed into the eddy calculation of each of the terms in the integrated energy balance reveals that both barotropic and baroclinic instability contributed to the amplification

phase relationships of gabbro tonalite granite water at 15 kbar with applications to differentiation and anatexis phase relationships have been determined at 15 kbar with variable h 2o contents for three rocks a gabbro a tonalite and a muscovite granite representing the compositional trend of the calc alkaline rock series experiments were conducted in 0 5 in piston cylinder apparatus using ag pd or pt capsules the results obtained are acceptable representations of the phase relationships for elucidation of petrological processes selected runs with 5 h 2o were completed using au capsules to overcome the problem of iron loss up to the temperature limit of au for reliable electron microprobe analyses of glass garnet clinopyroxene amphibole and plagioclase no glasses could be analyzed in the gabbro the data provide k d values as a function of temperature for pairs of coexisting minerals and liquid the chemical variations are used to evaluate 1 the fractionation trends in hydrous magmas at 55 km in thickened continental crust or uppermost mantle and 2 the products of anatexis of the thickened crust at this depth fractionation of hydrous basalt or anatexis of gabbro and tonalite or their metamorphosed equivalents appears to produce liquids diverging from the calc alkaline trend anatexis of granite produces a liquid less siliceous than itself with some chemical characteristics of syenite

the role of a longshore pressure gradient in pacific northwest coastal dynamics abstract in this paper we demonstrate the importance of the seasonal barotropic longshore pressure gradient force to pacific northwest coastal dynamics values of the seasonal longshore pressure gradient corrected for gauge height relative to a level surface hickey and pola 1982 and for year to year variations enfield and alien 1980 were included in the two dimensional time dependent baroclinic finite difference model of hamilton and rattray 1978 as an external force observed wind stress stratification and bottom topography were included in the model and comparisons were made with current meter data in each of the three seasonal situations observed in the northwest pressure gradient force southward opposing local wind stress winter pressure gradient force northward opposing local wind stress summer and pressure gradient force and local wind stress both southward spring three important features of the seasonal circulation are shown to depend on the existence of the pressure gradient

large scale structure of the spring transition in the coastal ocean off western north america past measurements off the coast of central oregon and washington have shown that the rapid change from northward monthly mean winter winds to southward summer winds forces a spring transition of the coastal ocean sea levels and temperatures drop and mean surface currents shift from northward to southward current and water temperature data from 35 n to 48 n from 1981 and 1982 and sea level and wind stress data from 1971 1975 and 1980 1983 show the transition to have a large alongshore scale typically 500 to 2000 km the large scale wind stress appears to be the forcing mechanism at latitudes north of approximately 37 n south of 37 n sea level usually falls more gradually before the northern transition event both wind and sea level events generally progress from south to north over a 3 to 10 day period but this is not always true several aspects of the spring transition reflect coastal trapped wave dynamics previous studies at 45 n found persistent vertical shear of the southward summer current associated with a cross shelf density gradient during 1982 the shear and the density front develop over the shelf break immediately after the transition at 43 n and to the south but they are much less persistent than at 48 n the stronger winds between 38 n and 42 n and the narrower shelf result in an offshore displacement of the density front and vertical shear past the shelf break leaving the water over the shelf less stratified and more subject to barotropic reversals of the current than that farther north where the front stays closer to the coast

petrogenesis of basalt comendite and basalt pantellerite suites terceira azores and some implications for the origin of ocean island rhyolites petrogenetic modeling of the recent lava succession of santa barbara and pico alto volcanoes and associated basaltic lavas indicates that there are two discrete lava series present one erupted from the axial rift linking the two central volcanoes and one associated with monogenetic cones scattered around the flanks of santa barbara the felsic lavas of both volcanoes are peralkaline and appear to be derived from associated basalts by fractional crystallization of an assemblage including essential amphibole trace element abundances in the felsic lavas particularly those of sr and ree cannot be reconciled with an origin through partial melting of basaltic material at the base of the volcanic pile the difference between the comenditic and pantelleritic differentiation trends of santa barbara and pico alto is attributed primarily to fo2 control of the crystallizing assemblage probably related to thermal dissociation of magmatic water in the santa barbara magma chamber this effect may be augmented by minor differences in parent basaltic compositions the pico alto pantellerites being derived from the rift basalts whereas the santa barbara comendites are derived from the off rift basalts a compositional gap between 54 and 64 silica content in the lavas is not present if the suite is extended to include co magmatic hypabyssal xenoliths leading to the inference that the gap in this and other bimodal suites results solely from a relative inability of magma of intermediate composition to erupt

stratification and mean flow effects on diurnal tidal currents off vancouver island abstract a series of numerical experiments with a three dimensional baroclinic model were conducted to study the influences of density stratification and wind driven currents on the k1 tide over the continental shelf off vancouver island the region is one of anomalously large diurnal tidal currents due to the generation of coastally trapped waves at the entrance to juan de fuca strait model results are compared with data obtained from a number of moorings deployed over the shelf including a line extending for over 300 km in the alongshore direction the results show that inclusion of stratification significantly improves the representation of k1 currents in the model particularly with respect to the alongshore phase propagation of the clockwise and counterclockwise rotary components with homogeneous water the coastally trapped waves propagate relatively slowly and are dissipated before reaching brooks peninsula in contrast the ambient stratification permits coastally trapped motions to propagate

three dimensional model simulations of tides and buoyancy currents along the west coast of vancouver island a three dimensional finite element model is used to calculate the barotropic tides and seasonal buoyancy flows off the western and northern coasts of vancouver island the model buoyancy currents and the harmonics of eight tidal constituents are compared with those from previous models and those from tide gauge and current meter observations the rms differences between observed and calculated sea level tidal amplitudes are within 2 3 cm for all constituents whereas the rms differences between observed and calculated phases are with the exception of q1 within 3 58 the model currents are more accurate than those from previous models of particular interest are the diurnal continental shelf waves it is shown that these waves are generated through the conservation of potental vorticity arising when the strong diurnal tidal currents in juan de fuca strait encounter the abrupt topography near the entrance to the strait these waves do not appear to propagate beyond brooks peninsula a large promontory cutting across the continental shelf a power budget analysis reveals that the reason for this is not the blocking effect of the peninsula but rather there is little energy left in the waves when they reach that point this energy loss is primarily through frictional dissipation in a series of trapped eddies along the shelf break the location of these eddies varies with the forcing frequency and appears to be related to the spacing of canyons it is also demonstrated that the strong diurnal currents observed over the shallow banks in queen charlotte sound to the north of brooks peninsula do not arise from the oscillatory diurnal flows in queen charlotte strait unlike the case for juan de fuca strait the region offshore of queen charlotte strait does not support diurnal coastally trapped waves seasonal changes in the wavelengths of the vancouver island shelf waves are shown to arise through an advective interaction doppler shift with the buoyancy driven vancouver island coastal current and the wind driven shelf break current

the profile method of calculating the composition of solid in magma fractionation and its application to an alkaline volcano a new profile mass balance procedure is presented to calculate the chemical composition of solid precipitated during cooling and crystallization of many tholeiitic and alkaline magmas it is a variant of the earlier interval method maclean 2000 contrib mineral petrol 139 85 100 and is also based on chemical variation diagrams of lava sequences liquid profiles constructed with a quantitative monitor of fractionation derived from the residual enrichment of an incompatible trace high field strength element hfse in this new profile method the concentration of a component in solid is shown by mass transfer considerations to be a function of its mass on a liquid fractionation path profile and on a path profile of perfect incompatible enrichment the latter hypothetically contains all of the component hence subtraction of the amount contained in liquid will yield its mass in the solid the calculations are straightforward and adaptable to both equilibrium and fractional crystallization processes corrections to the fractionation monitor for measured d hfse s l solid liquid distribution coefficient estimates of trapped liquid in solid and other variables can be applied the method is illustrated with chemical data for a suite of alkaline volcanic rocks from mt erebus antarctica kyle et al 1992 j petrol 33 849 875 the lavas are silica undersaturated and range from nepheline bearing basanite to phonolite the solids correspond to those of ultrabasic rocks through most of fractionation and are more sio2 undersaturated than the lavas

volcanic sequence and alteration at the parys mountain volcanic hosted massive sulfide deposit wales united kingdom applications of immobile element lithogeochemistry lenses of massive zn pb cu sulfides at the parys mountain deposit in anglesey northwestern wales occur at and near the contact between ordovician shales and overlying rhyolites the rhyolites which have been dated as lower silurian parrish 1999 have a thickness of a few hundred meters and are overlain by lower silurian shales the rhyolites and shales strike northeasterly for 2 to 3 km and dip to the north minor basalts are present but there are no intermediate rocks cu bearing stockwork veins occur in the upper portion of the ordovician shales and cu bearing mineralization was mined from the lower silurian shales in the 18th century precambrian basement rocks are present to the south and north of parys mountain application of immobile element lithogeochemical techniques to 1 000 drill core and outcrop samples allows division of the rhyolites into five main chemical types a b c d1 and d2 the shales into three main types and the mafic rocks into two types the distribution of these units has been mapped across the property where individual volcanic chemical units have lateral continuity they are considered to represent singular geologic events and thus are time markers correlations based on volcanic facies alone are of limited use because a chemical unit can pass laterally through different volcanic facies whereas in strongly altered zones the original volcanic facies cannot be recognized at all the chemostratigraphic units on the other hand can be traced through even the most altered zones consequently they provide an improved means of correlating volcanic units on local to property scales the first volcanic rocks to accumulate above the ordovician shales were thin flows and volcaniclastic beds of rhyolite b and a laterally adjacent lens of largely massive rhyolite c the main massive sulfide lenses in the western part of the property are associated with these volcanic events these units were covered by thick flows of rhyolite a in the western part of the property rhyolites d and a are the main chemical types in the eastern part rhyolite d has two subtypes d1 is generally massive and flow banded whereas d2 is pyroclastic it is suggested that rhyolite d1 was erupted first followed by less fractionated rhyolite d2 which was the last volcanic event prior to the accumulation of the silurian shales the main vents for rhyolite a in the west and d in the east were separated by about 1 km the alteration minerals at parys mountain are sericite chlorite quartz pyrite and fe bearing carbonates mass changes calculated for the rhyolites and the shales show a general property scale increase in alteration in the downdip direction feo and mgo additions of up to 10 and 20 wt percent respectively are present in footwall shales up to 50 m below the massive sulfide lenses in areas where stockwork veins are present similar feo and mgo gains occur in rhyolites up to 50 m above the ore lenses in rhyolites with fe mg gains si and k have generally been lost in areas lateral to the massive sulfides shales and rhyolite b have gained large amounts of silica most parys mountain rhyolites have moderately high nb contents and slightly inclined rare earth element ree patterns whereas the basalts are enriched in the high field strength elements hfse including the light ree the primary geochemical features of the volcanic rocks together with regional geologic relationships in northwestern wales suggest that volcanism occurred during intraplate rifting of a small marine basin which was underlain by precambrian continental crust the small volumes of all rhyolite types and basalt at parys mountain suggest that they were derived from small discrete pods of magma which were tapped by basement faults most of the massive sulfides accumulated immediately before and during the first outpourings of rhyolitic lava

the fluctuating longshore pressure gradient on the pacific northwest shelf a dynamical analysis abstract the majority of papers on pacific northwest shelf dynamics have emphasized the relationship between longshore wind stress 3 and longshore velocity v however attempts to illustrate a balance of momentum in the longshore direction have not been encouraging 3 sol h where h is water depth has insufficient magnitude to balance the vertically averaged longshore acceleration vt at least during summer in this paper it is demonstrated that the missing momentum is provided by the longshore pressure gradient force py the pressure gradient was estimated using tide gauge and atmospheric pressure data at stations separated by roughly 400 km seasonal and long term means from hickey and pola and in some cases nonseasonal monthly anomalies from enfield and allen were added to the sum of the tide gauge and atmospheric pressure data to form time series of total subsurface pressure the pressure data were multiplied by an offshore deny factor to simulate coastal trapping the analysis was performed

observation and modeling of satellite sensed meanders and eddies off vancouver island abstract a long time series of satellite infrared images spanning the period 21 july 8 october 1980 reveals the evolution of long 160 km and short 80 km wavelength meanders of the california current system off vancouver island midway in the series strong interactions occurred between the two meander scales although the shorter meanders were initially more energetic they were eventually dominated by the longer meanders near the end of the time series detached mesoscale eddies were formed from the longer meanders current meter data from the period before meander growth clearly indicates the presence of a strong vertical shear near 150 m which consists of a southeastward surface current and a northwestward undercurrent it is argued in this paper that the observed shear flow is the energy source for the meanders and eddies seen in the satellite images a four layer quasi geostrophic model is used to represent the california current system off vancouver island the two upper layers represent the

the effect of trapped liquid crystallization on cumulus mineral compositions in layered intrusions a series of calculations have been carried out to evaluate the effect on cumulus mineral compositions of solidification of trapped intercumulus liquid in orthocumulates the calculation assumes local equilibrium between phases and that the system remains chemically closed during crystallization of the trapped liquid the latter assumption is held to be valid on a scale of tens to hundreds of centimeters it is not necessary to know the composition of the trapped liquid as the calculation only requires an estimate of feo content and trapping temperature the change in composition of a mineral from that of the initially precipitated cumulus crystals to the final composition after complete solidification is termed the trapped liquid shift its magnitude depends on the modal proportions of cumulus phases and the initial porosity and is only weakly dependent on initial phase compositions trapped liquid shifts are significant when compared with mineral composition changes occurring during fractional crystallization crystallization of 30 trapped liquid gives rise to shifts of up to 10 mol percent in mg number of olivine or pyroxene the size of the shift becomes greater when the initial cumulus assemblage has a lower total feo mgo content and vice versa as a result of the relationship between trapped liquid shift and cumulus mode mineral composition variations and trends may be generated in sequences of cumulates which originally had constant compositions of cumulus minerals for example in a cyclic unit grading from a pyroxenitic base to an anorthositic top crystallization of a uniform proportion of trapped liquid will result in an apparent iron enrichment trend from bottom to top of the cycle as has been observed in the upper critical zone of the bushveld complex

geochronological and geochemical constraints on genesis of the adakitic rocks in outang south tan lu fault belt northeastern yangtze block abstract the outang intrusion was newly found near the south tan lu fault belt stlf of the northeastern margin of yangtze block due to the excavating construction of the beijing shanghai high speed railway observations show that lithology of the outang intrusion is intermediate rock series mainly composed of monzodiorite and quartz monzonite major and trace elements zircon u pb dating and hf isotope were analyzed two ages of 124 6 2 9 ma mswd 0 60 n 29 and 129 2 4 1 ma mswd 1 5 n 21 are obtained showing that the regional igneous activity was in early cretaceous being consistent with the massive yanshanian magmatic events in eastern china the quartz monzonite was identified as a high mg adakitic rocks showing geochemical features of high si high k and low sr which indicates that the igneous genesis may be results of partial melting of the delaminated lower crust the negative e hf t values with much older t dm2 ages indicate that the original magma may derive from remelting of ancient continental crust a tectonic model has been proposed to account for the massive subduction of the pacific plate beneath eastern china in jurassic with effect of delamination and thinning from which we conjecture that the archean materials could compose the basement of the stlf caused by massive subduction of the pacific plate beneath the eastern china continent

mass change calculations in altered rock series a technique is presented whereby precursors of altered rocks in a fractionated rock series can be identified and changes in chemical components mass and volume accurately calculated the procedure utilizes elements with high degrees of immobility in hydrothermal and associated interactive water rock systems igneous rock series and sedimentary and metamorphic rocks with primary continuity of chemical composition are amenable to this treatment in the procedure for igneous rocks best fit fractionation lines are established for an immobile igneous compatible incompatible element pair the latter element functioning as the fractionation monitor alteration paths are linear and pass through the origin intersections of the fractionation and alteration lines yield the immobile element concentrations in the precursors to the altered rocks mobile components are determined from fractionation lines and monitor values total mass changes are proportional to the displacement of altered samples from the fractionation line masses of other elements in an altered sample reconstructed values are recalculated to the concentration of the monitor element in the precursor chemical changes are the differences between the calculated precursor compositions and the reconstructed altered rock compositions errors are mainly a function of the positioning of the fractionation lines

kiglapait mineralogy iii olivine compositions and rayleigh fractionation models olivints present throughout the layered cumulates of the kiglapait intrusion record extreme iron enrichment during fractional crystallization mn is less compatible than fe the exchange coefficient kd for mn fe ol liq has values near 0 95 but they drop to 0 7 near the lower one upper one boundary ca is depleted by more than a factor of 30 relative to experimental values at 5 kbar pressure attempts to find a sink for ca in the lower zone without invoking liquid as a reactant are unconvincing and questions of metastability arise cumulus olivines vary systematically to lower fo contents with stratigraphic height using equilibrium values for the exchange coefficient kd fe mg ol ljq j and the observed mode of olivine and residual porosity a rayleigh fractionation calculation reproduces the observed lower zone trend without recourse to multiple injections of magma an anomalously fe rich region above the main ore band in the upper zone ascribed to ponding of fe rich magma at the floor of the intrusion until later buoyant residual magma entrained the fe rich residua such fe rich ponds probably account for the abnormal fe enrichment shown by some other fenner trend layered intrusions summation over the observed crystal compositions yields values of xjug that do not represent the equilibrium liquid but that reduce to it by a simple multiplier p 0 78 this result means that if ko is known the high temperature liquidus olivine compositions can be retrieved or vice versa because the observed olivine compositions are supported by realistic forward models there is no need to invoke evolved boundary layer liquids to explain the in situ crystallization of kiglapait cumulates classical cumulate theory suffices

seasonal cycles of currents temperatures winds and sea level over the northeast pacific continental shelf 35 n to 48 n seasonal cycles of coastal wind stress adjusted sea level asl shelf currents and water temperatures off the west coast of north america 35 n to 48 n are estimated by fitting annual and semiannual harmonics to data from 1981 1983 longer records 9 34 years of monthly asl indicate that these two harmonics adequately represent the long term monthly average seasonal cycle and that the current measurement period is long enough to estimate the seasonal cycles we characterize the differences between fall winter and spring summer as follows for fall winter monthly mean winds north of 35 n are northward for 3 6 months longer in the north than in the south south of 35 n the mean winds are near zero or weakly southward monthly mean alongshore currents are northward over midshelf and shelf break at all locations sampled at depths of 35 m and deeper and are associated with high coastal sea levels and relatively warm water temperatures for spring summer monthly mean wind stresses are southward at all latitudes for 3 6 months longer in the south than in the north sea levels are low and water temperatures are relatively cool monthly mean currents at 35 m depth over the shelf are southward for 1 6 months longer at the shelf break than over midshelf and longer in the north than in the south while the deeper currents are less southward or northward the magnitudes of the seasonal cycles of all variables are maximum between approximately 38 n and 43 n generally decreasing slightly to the north and greatly to the south at each location the seasonal cycle of the alongshore current from 35 m depth at midshelf leads the sea level slightly and both lead the wind stress and temperatures by 1 2 months the seasonal cycles of all variables show a south to north progression south leads north by 1 2 months at 48 n annual mean currents at 50 m depth over the shelf break oppose the annual mean wind northward wind and southward current similarly at 35 n annual mean currents at 35 m depth over both midshelf and shelf break are opposed to the annual mean wind southward wind and northward current from 35 n to 43 n both summer and winter regimes are dominated by strongly fluctuating currents

remote alongshore winds drive variability of the california undercurrent off the british columbia washington coast the california undercurrent transports warm salty nutrient rich oxygen depleted water along the continental slope from the equatorial pacific to the aleutian islands we use multiyear acoustic doppler current profiler records collected simultaneously at two mooring sites off vancouver island to detail the regional structure of the undercurrent and to show that much of its variability is attributable to the passage of remotely forced coastal trapped waves we also document two subsurface currents missed by earlier current measurements the undercurrent becomes evident in spring intensifies through summer and fall and merges with the wind driven poleward surface flow in winter during intensification at the southern mooring site a1 the undercurrent shoals from 250 50 m in early summer to 150 50 m depth in late fall at the northern site bp2 225 km to the northwest of a1 the current is weaker and maintains a year round depth of 150 50 m temporal variability in the undercurrent velocity attains highest coherence with winds along the southern oregon northern california coast with peak coherence occurring for synoptic 10 40 day period alongshore winds off cape blanco in southern oregon the undercurrent lag of 3 2 days relative to the cape blanco winds at synoptic periods is consistent with low mode poleward propagating coastally trapped waves for periods 40 days the wind current coherence remains high for winds off the oregon california coast but lags are often negative indicating possible forcing by alongshore baroclinic pressure gradients at interannual time scales the undercurrent variations have links to climate scale processes in the equatorial pacific

crystallization and compositional convection in a porous medium with application to layered igneous intrusions growing crystals can provide a local source of buoyancy by depleting melt of certain chemical components and vigorous convective motions in the fluid can result we report a quantitative experimental study in which saturated aqueous solutions of cuso4 and na2so4 in porous media of either glass balls or cuso4 5h2o crystals were crystallized by cooling from below the crystals growing in the pore space released light chemically depleted solution which had the potential to convect out of the porous medium and be replaced by additional saturated solution from above we explore the physical and chemical effects of compositional convection during the complete solidification of the interstitial solution by varying the permeability of the porous medium the cooling rate and the initial composition of the solution this type of convection can form adcumulate rocks by enabling continuous circulation of melt from the main magma reservoir through the pores of a cumulus pile adcumulus growth can occur by this mechanism as long as the convective velocity in the porous medium is greater than the velocity of the solidification front we scale the experimental results to magmatic conditions and infer that this process should occur commonly in layered igneous intrusions when our porous media had a small permeability compositional convection enabled the adcumulate growth of a completely solid contact between melt and cumulate trapping of dynamically unstable melt beneath this impermeable layer of crystals also occurred in these experiments and may be important geologically small shallowly emplaced intrusions and the cumulate zones at the base of komatiites are probably cooled too rapidly for significant intercumulus convection to occur

petrogenesis of the flood basalts forming the northern kerguelen archipelago implications for the kerguelen plume the thick 20 km crust of the kerguelen archipelago formed as the tectonic setting of the kerguelen plume changed from an oceanic ridge centered location at 43 ma to its present location beneath the antarctic plate the uppermost crust is dominantly flood basalt with a thickness of up to 10 km inverse isochron 40ar 39ar ages for upper and lower lavas in a 630 m section of basalt flows from mont bureau are 30 4 and 29 0 ma re os isotopic systematics are consistent with this age most of the lavas in two stratigraphic sections mont bureau and mont rabouillere from the northern part of the archipelago have sr nd and pb isotopic characteristics similar to the youngest upper miocene to pleistocene lavas erupted in the southeast part of the archipelago i e initial 87sr 86sr 0 7050 143nd 144nd 10 mgo alkalic lavas in the southeast province of the archipelago in these northern sections it is confined to transitional lavas with

the seasonal alongshore pressure gradient on the west coast of the united states the long term mean steric height 0 500 dbar data of reid and mantyla 1976 are added to relative monthly mean adjusted sea level data to obtain a seasonal time series of quasi absolute large scale 300 km sea surface elevation along the west coast of the united states from 48 n to 33 n north of 38 n the elevation slope reverses sign seasonally so that the resulting pressure gradient force is southward from october to june and northward from july to september south of 38 n the pressure gradient force is northward except during january at all latitudes and during february in the interval from 38 n to 35 n maximum northward force occurs during august and september at all latitudes the relative contributions to sea level elevation slope by seasonal heating and cooling freshwater effluent effects the alongshore component of coastal wind stress and deep ocean currents are investigated both seasonal heating and cooling and freshwater contributions to large scale elevation slope are relatively insignificant 10 in every month at all latitudes wind stress forcing determined with the barotropic steady frictional model of csanady 1978 is significant north of point conception 35 n for both the long term mean slope and its seasonal oscillation remote contributions are particularly important in the pacific northwest south of san francisco 38 n empirical evidence suggests that deep ocean currents contribute significantly to coastal elevation slope in summer and fall and in the mean deep ocean currents may also affect elevation slope along the whole coast during spring causing elevated sea level toward the north

calculation of the composition of fractionated solid as deduced from chemical profiles in tholeiitic lava the composition of solid precipitated from cooling magma is calculated from chemical differentiation profiles and an incompatible element monitor of fractionation in a period of cooling magma evolves to a derivative liquid and a solid liquid compositions are obtained from the chemical profiles and the fractionation interval via the incompatible element and the rayleigh distillation equation the composition of the solid the only unknown can be calculated for both equilibrium and continuous fractionation models a sequence of low k tholeiitic laves basalt to rhyolite from an archean greenstone belt in northwestern quebec are used to describe the procedure chemical trends in the lava exhibit strong iron enrichment followed by depletion and evolution to rhyolite trends in the calculated solid are amplified relative to lava and bulk distribution coefficients normative minerals mg number and other parameters also show significant divergence oxidation state and amount of trapped liquid have important effects on solid composition solids have notably more basic chemical compositions than coexisting liquids and this produces a lag in differentiation indices between the two the high values of bulk distribution coefficients calculated for fe ti and p d 3 to 4 in late stages of fractionation make it possible to produce the extremely fe ti p rich solid fractions in layered igneous complexes from quartz normative liquids

trace element partitioning in pantellerites and trachytes abstract in order to investigate the effect of increasing melt peralkalinity on partitioning partition coefficients have been determined using neutron activation analyses of coexisting phenocrysts and glass of five samples from pantelleria spanning the range trachyte to pantellerite alkali feldspar partition coefficients for fe rb ba sr and eu vary with melt peralkalinity due to changes in melt polymerization and to the systematic increase in xor and decrease in xan of the feldspar in going from trachyte to pantellerite fe partition coefficients increase from 0 04 to 0 10 presumably because fe 3 increasingly substitutes in the feldspar tetrahedral site as melt activity of al declines and fe concentrations increase partition coefficients for trivalent light rees decrease and the partitioning pattern becomes flatter the most evolved samples having some of the lowest published values for feldspar the hundredfold decline in eu partition coefficients 2 5 to 0 024 and the decrease in the size of the positive partitioning anomaly are attributed to increasing eu3 eu2 in the melt as it becomes more peralkaline as well as to concomitant decrease in the ca content of feldspar as a result the behavior of eu during fractional crystallization of peralkaline suites is fundamentally different from that in metaluminous suites absolute abundances rise and the size of the negative eu anomaly changes little with fractionation beyond pantelleritic trachyte barium and strontium do not decline to extremely low concentrations in pantellerites as they do in highly evolved metaluminous rhyolites because the feldspar partition coefficients drop precipitously with peralkalinity similarly rb contents do not get large because the partition coefficient increases slightly 0 11 to 0 25 with peralkalinity and is sufficient to make rb only weakly incompatible in the feldspar dominated assemblage partition coefficients calculated for sr and ba from natural phenocryst matrix pairs can be gross over estimates in these feldspar rich felsic rocks if phenocrysts are zoned this effect is severe for assemblages with bulk distribution coefficients d greater than 4 even at very small crystal contents and for 4 d 2 it is significant if crystal contents exceed about 25 some of the very high values and much of the variability reported in the literature for ba and sr feldspar partition coefficients may be a result of this effect in contrast to feldspar partition coefficients for apatite and mafic phases change little with peralkalinity partition coefficients for rees and the compatible elements sc co and cr are all less than half those in fe rich clinopyroxene and olivine of similar composition in high silica rhyolite although absolute levels of partition coefficients are a function of melt polymerization the shapes of the ree partitioning patterns appear to be related to the composition of the clinopyroxene scandium is most strongly concentrated in clinopyroxene partition coefficient 27 60 having larger values in more fe rich compositions apatite shows a wide range in composition within the suite the concentrations of si fe rees and y increasing and mg ca and p decreasing in more evolved samples these trends however parallel those in coexisting glasses so that partition coefficients are essentially constant in peralkaline suites cs is the most incompatible of commonly analyzed elements but its great mobility during alteration and weathering limits its use as a differentiation index next in order of incompatibility are th u hf zr and ta which have small but finite values of d due to the partitioning of th and u into apatite 2 the accommodation of zr and hf by clinopyroxene 0 4 and titanomagnetite 0 2 and relatively high concentrations of ta in cossyrite and fe ti oxides the next most incompatible are the lightest and the heaviest rees and finally the middle trivalent rees and rb plots of pairs of relatively incompatible elements form straight line trends over large compositional ranges in peralkaline suites because the replacement of olivine titanomagnetite by cossyrite as the melt becomes more peralkaline causes little change in d the ree patterns of titanomagnetite and cossyrite are both approximately flat at values less than 0 1 and the relatively high titanomagnetite partition coefficients for ta 2 zr and hf when combined with the very low partition coefficients for these elements for olivine approximate the moderate partition coefficients for cossyrite

the near surface dynamics of coastal upwelling abstract an attempt is made to examine some observational and theoretical aspects of upper ocean dynamics in regions of strong coastal upwelling upper ocean is roughly defined as about the upper 10 30 m of the water column for most systems first the basic surface ekman and mixed layers are discussed including some of the modifications due to upwelling next coastal upwelling fronts and their associated circulation are treated finally areas of strongly three dimensional upwelling are classified and discussed horizontal advection of heat and momentum appear to be generally important for the near surface dynamics of coastal upwelling and these phenomena make realistic theoretical treatments especially difficult

a current velocity index of ocean variability we use daily time series of the longshore component of residual detided current velocity z t measured at several depths at a single location on the continental slope to construct a current velocity index i s z z of coastal ocean variability here z is depth t is time and sgn f f2 2 1 is a normalization factor constructed from the local coriolis parameter f a friction parameter and the standard deviation of the near surface current velocity where s is the fluctuation about the time series mean sgn f 1 for the northern hemisphere and 1 for the southern hemisphere the time series of vertical shear z z is derived from the velocity difference between simultaneous current meter records separated by a vertical distance z within the upper half of the water column the index characterizes low frequency baroclinic variability over the continental margin and is linked through use of the thermal wind relation to instability processes that effect the transfer of potential energy stored in the mean cross slope density field to the kinetic energy of mesoscale meanders and eddies for eastern boundary regions the index ranges from large positive values during summer upwelling conditions to large negative values during winter downwelling conditions the transition seasons spring and fall are characterized by i 0 we demonstrate use of the index by applying it to the continental margin of southwest vancouver island using current velocity data collected from october 1989 to march 1995 at depths of 35 100 175 and 400 m at a long term mooring site results enable us to specify the start and end times of the oceanic seasons and to quantify the summer upwelling and winter downwelling intensities for the region gaps in the current meter time series prompted us to examine records of coastal sea level sea surface temperature sea surface salinity and bakun upwelling index the wind driven cross shore component of surface ekman transport as possible surrogates for the velocity index none of these time series were acceptable although the bakun index is a logical substitute for the velocity index differences between the two indices are significant and suggest that current velocity data are needed for accurate delineation of seasonal oceanic variability along continental margins

changes in the onset and intensity of wind driven upwelling and downwelling along the north american pacific coast 1 the timing duration and intensity of wind driven upwelling and downwelling along the north american pacific coast play an integral role in coastal circulation and basinwide ecosystem composition it has been suggested that global warming will cause changes in these winds here we develop a new set of objective criteria to unambiguously determine the onset duration and intensity of upwelling and downwelling seasons due to local wind forcing we use these criteria to examine and better characterize temporal trends in wind driven coastal currents over the previous 60 years and relate them to global warming and large scale climate oscillations in the coastal ocean between northern california and vancouver island 37 n and 51 n we find an exceptionally variable onset of upwelling at all locations some significant temporal trends are found in summer onset and upwelling intensity time series near the juan de fuca strait and off the coast of oregon positive phases of the pacific decadal oscillation are correlated to later and shorter upwelling seasons with weaker upwelling warm phases of the el nino southern oscillation are associated with a later onset of summer upwelling south of oregon and with more intense downwelling throughout the study area our analysis identifies strong interannual to interdecadal variability and emphasizes the importance of time series length when isolating physical temporal trends influenced by large scale oscillatory behavior of the climate

remote forcing of subsurface currents and temperatures near the northern limit of the california current system local and remote wind forcing of upwelling along continental shelves of coastal upwelling regions play key roles in driving biogeochemical fluxes including vertical net fluxes of carbon and nutrients these fluxes are responsible for high primary productivity which in turn supports a lucrative fishery in these regions however the relative contributions of local versus remote wind forcing is not well quantified or understood we present results of coherence analyses between currents at a single mooring site 48 5 n 126 w in the northern portion of the california current system calcs from 1989 2008 and coincident time series of north america regional reanalysis narr 10 m wind stress within the calcs 36 54 n 120 132 w the two decade long current records from the three shallowest depths 35 100 and 175 m show a remote response to winds from as far south as 36 n in contrast only temperatures at the deepest depth 400 m show strong coherences with remote winds weaker local wind influence is observed in both the currents and 400 m temperatures but is mostly due to the large spatial coherence within the wind field itself lack of coherence between distal winds and the 400 m currents suggests that the temperature variations at that depth are driven by vertical motion resulting from poleward travelling coastal trapped waves ctws understanding the effects of remote forcing in coastal upwelling regions is necessary for determining the occurrence and timing of extreme conditions in coastal oceans and their subsequent impact on marine ecosystems this article is protected by copyright all rights reserved