a gulf stream model and an altimetry assimilation scheme a continuous data assimilation scheme and a multilayer primitive equation numerical model are described the model is an eddy resolving coastal ocean model that has been extended to include the gulf stream region it has complete thermohaline dynamics a bottom following sigma vertical coordinate system and a coastal following curvilinear orthogonal horizontal coordinate system calculated model fields are used to provide a model climatology and correlations between subsurface temperature and salinity anomalies and surface elevation anomalies an optimal interpolation method the surface to subsurface correlations and estimated model and data errors are the basis of the assimilation technique altimetry anomaly data extracted from the model calculations according to the geosat orbital schedule are used to test the assimilation scheme and to provide nowcasts and forecasts sensitivity studies are performed to test the effects of various parameters of the scheme it is found that the scheme is less efficient in the shallow continental shelf area than in the deeper regions of the model the results show significant nowcast skill with area averaged rms error for surface elevation and subsurface properties of about 40 50 of the corresponding error of the unassimilated case good forecast skill better than persistence is demonstrated for 10 20 days there is little skill after 30 40 days increasing the density of the satellite altimetry data especially by decreasing the separation distance between tracks should decrease the nowcast rms error to about 15 and improve the forecast

a comparison of geosat altimeter inferred currents and measured flow at 5400 m depth in the argentine basin abstract a comparison is made between an 11 month duration current meter record obtained near the bottom at 40 27 s 49 25 w in the mid argentine basin in water depth 5400 m and near surface flow inferred from geosat altimeter data the geosat has a repeat path time of 17 days and inferred near surface flow features with periods of 34 days or less should not be detectable thus the current meter record was filtered with a 34 day low pass filter since only fluctuating flows can be inferred with the geosat altimeter data the deep recorded mean current was added to the satellite inferred flow for comparison purposes the deep flow and the altimeter inferred near surface flow agree remarkably well suggesting that for time scales 34 days the flow was nearly barotropic in this region of the south atlantic

uncertainties in altimetry based velocity estimates 1 three methods to estimate ocean geostrophic surface currents from satellite altimetry measurements are evaluated for several single and multiple satellite configurations with specific emphasis on resulting uncertainties altimetric sea surface height measurements are simulated by sampling along satellite ground tracks the surface pressure output from the 1 10 north atlantic run of the los alamos parallel ocean program model and by subsequently adding realistic instrument and orbit errors the effects of both sampling and data errors on the velocity estimates are discussed the satellite orbit configurations considered represent current missions or candidates for future coordinated tandem missions data error budgets are based on those of existing missions and on estimates for new altimetric technology currently under development in midlatitude regions characterized by strong variability such as the gulf stream region velocities estimated at crossovers of interleaved tracks and along a virtual ground track between two parallel tracks with a 0 75 zonal offset are found to be comparable in accuracy and more accurate than velocities estimated from optimally interpolated sea surface height maps error variances as low as 15 25 of the local signal variance can be obtained from all three methods near the gulf stream core larger relative errors are found almost everywhere else with the exact details of the error in the two velocity components depending on data error orbit configuration latitude estimation method and smoothing several scientific applications of the configurations and methods are discussed including the estimation of reynolds stresses momentum fluxes velocity spectra and covariance functions accuracy and applicability suggest that the newly proposed parallel track configuration is a viable option for future tandem missions

the seasat altimeter data and its accuracy assessment the seasat satellite launched on june 27 1978 carried a radar altimeter designed to measure the altitude of the satellite above the ocean surface the surface wave height and the ocean surface backscatter coefficient from which wind speed can be inferred postlaunch engineering assessment indicated that the seasat altimeter met the performance specification for 10 cm precision noise in the altitude measurements however to determine the accuracy of this measurement as well as the accuracy of the wave height and wind speed measurements a significant calibration validation and model development effort was required this summary describes the instrument atmospheric and geophysical effects which influence the radar altimeter measurement accuracies and the attendant correction models adopted for the altimeter geophysical data record also summarized are the activities of the seasat altimeter precision orbit determination experiment team directed towards the validation and improvement of these models as well as the investigations required to assess the accuracy of the altimeter measurement and the computed satellite altitude ephemeris finally an accuracy assessment is made for the various altimeter measurement corrections which are included on the altimeter geophysical data record

typhoon induced ground deformation geodetic instruments now offer compelling sensitivity allowing to investigate how solid earth and surface processes interact by combining surface air pressure data nontidal sea level variations model and rainfall data we systematically analyze the volumetric deformation of the shallow crust at seven borehole strainmeters in taiwan induced by 31 tropical cyclones typhoons that made landfall to the island from 2004 to 2013 the typhoon s signature consists in a ground dilatation due to air pressure drop generally followed by a larger ground compression we show that this compression phase can be mostly explained by the mass loading of rainwater that falls on the ground and concentrates in the valleys towards the strainmeter sensitivity zone further our analysis shows that borehole strainmeters can help quantifying the amount of rainwater accumulating and flowing over a watershed during heavy rainfalls which is a useful constraint for building hydrological models

zonal penetration scale of model midlatitude jets abstract all available observations indicate that the most energetic time dependent currents are located in the vicinity of intense large scale oceanic current systems this characteristic is also a basic property of eddy resolving gyre scale numerical models an initial detailed intercomparison of two layer eddy resolving numerical experiments with observation focused on the largest scales of horizontal structure in patterns of abyssal eddy kinetic energy and on time scales the numerical experiments examined generally had relevant temporal and meridional scales but not necessarily realistic zonal scales the model eddy field did not penetrate as far from the western boundary as observed distributions by a factor of 2 to 3 the present study examines the physical processes that govern the model zonal penetration scale and suggests reasons for the previous discrepancy it is demonstrated that a subtle balance exists between the complex instability processes that tend to tear the jet apart restricting

sea surface height fluctuations observed simultaneously with inverted echo sounders and geosat time series of sea surface height anomaly as measured by inverted echo sounders with pressure gauges ies pgs and geosat altimetry are compared at six locations in the northwest atlantic near 40 n 55 w three ies pg sites lay along each of two adjacent geosat exact repeat mission ground tracks better agreement was found along the westernmost ground track pressure sensor noise is the probable source of the larger errors along the easternmost ground track the overall correlation is 0 78 along the westernmost ground track it is 0 91 decorrelation scales are about 100 km along track and about 5 days uncorrelated errors dominate but along the westernmost ground track ies pg derived sea surface height variability is systematically smaller than that derived from geosat data this factor determined by regression analysis is about 0 81 however a consistent adjustment of ies calibration removes the systematic discrepancy

eddy shedding and energy conversions in the east australian current 1 mesoscale variability and eddy shedding in the tasman sea particularly of the east australian current eac is studied through the analysis of remotely sensed observations and outputs from a global ocean model previous observations of the western boundary current separation from the coast showed strong variability at periods ranging between 90 and 140 days we show from satellite altimetric observations that rapid northward migration of the separation point of the eac follows the formation of large eddies at periods of 100 days after an eddy separation event the normally southward flowing current swiftly assumes a more zonal configuration near the separation latitude with a cyclonic circulation developing inshore the formation of large separation eddies is preceded by the southward propagation of sea level anomalies along the east australian continental slope from 25 s sea level anomalies grow as they travel south eventually being pinched off in the form of large anticyclones at 32 s in the current retroflection area energy conversion terms in a global ocean model and in altimetric data suggest both barotropic and baroclinic instability may account for the growth of these anomalies as they propagate south east of the main eac jet there is evidence that eddies may be feeding potential energy back to the mean flow

frontal signals east of iceland from the geosat altimeter frontal sea surface height signals were identified in the iceland faeroe region for height differences from the three sets of geosat tracks july may 1987 these signals were verified with in situ measurements and then combined with them for an improved and synoptic estimate of frontal location the data assimilation context made the weak signals quantitatively useful real time analysis of geosat data contributed to a frontal nowcast and forecast scheme

the effect of diagenesis and fluid migration on rare earth element distribution in pore fluids of the northern cascadia accretionary margin analytical challenges in obtaining high quality measurements of rare earth elements rees from small pore fluid volumes have limited the application of rees as deep fluid geochemical tracers using a recently developed analytical technique we analyzed rees from pore fluids collected from sites u1325 and u1329 drilled on the northern cascadia margin during the integrated ocean drilling program iodp expedition 311 to investigate the ree behavior during diagenesis and their utility as tracers of deep fluid migration these sites were selected because they represent contrasting settings on an accretionary margin a ponded basin at the toe of the margin and the landward tofino basin near the shelf s edge ree concentrations of pore fluid in the methanogenic zone at sites u1325 and u1329 correlate positively with concentrations of dissolved organic carbon doc and alkalinity fractionations across the ree series are driven by preferential complexation of the heavy rees simultaneous enrichment of diagenetic indicators doc and alkalinity and of rees in particular the heavy elements ho to lu suggests that the heavy rees are released during particulate organic carbon poc degradation and are subsequently chelated by doc ree concentrations are greater at site u1325 a site where shorter residence times of poc in sulfate bearing redox zones may enhance ree burial efficiency within sulfidic and methanogenic sediment zones where ree release ensues cross plots of la concentrations versus cl li and sr delineate a distinct field for the deep fluids z 75 mbsf at site u1329 and indicate the presence of a fluid not observed at the other sites drilled on the cascadia margin changes in ree patterns the presence of a positive eu anomaly and other available geochemical data for this site suggest a complex hydrology and possible interaction with the igneous crescent terrane located east of the drilled transect

observation of the circulation in the newfoundland basin in winter 1997 a hydrographic survey was performed in january february 1997 to document the winter circulation of the north atlantic current system in the newfoundland basin as part of the fronts and atlantic storm tracks experiment fastex eighty seven conductivity temperature depth ctd stations were occupied along a foursection trapezoid which spanned the northwest corner and the branching of the north atlantic current along 358w realistic sea surface temperature analyses were produced every 15 days using all available data collected in this area during the two months of the fastex experiment these maps were combined with sea level anomaly fields from the topex poseidon anders 2 satellites at the same time intervals to analyze the features of the main currents in the area and their evolution these combined analyses providing a coherent overview of the fronts and jets identified along the ship track and the ctd stations are further used to estimate their transports the general pattern is a 15 sv sv 106 m3 s21 transport by the north atlantic current at 478n 438w the existence of a recirculating gyre inside the northwest corner and a complex branching of the circulation associated with significant surface fronts the recirculating gyre forms a closed circulation in which a very deep warm eddy 100 km wide was sampled at the end of february its mixed layer was 800 m deep and its transport was 27 sv along 358w three fronts were identified between 458 and 528n the northern subarctic front the southern subarctic front and the mid atlantic front whose origins are precisely located the currents associated with these fronts transport 26 sv toward the east before crossing the mid atlantic ridge and supplying the eastern part of the north atlantic basin an important transport 14 sv was calculated near 46 8n 378w which mostly fed the current associated with the mid atlantic front

can meddies be detected by satellite altimetry geosat exact repeat mission altimeter data have been used to estimate the sea surface height anomaly relative to a 2 year mean reference surface in the eastern north atlantic ocean horizontal maps of the sea surface height anomaly for various periods were constructed by means of an objective analysis procedure the mean sea level was approximated by the dynamic topography from climatological hydrographic data results were compared to the dynamic topography calculated from hydrographic ground truth data sampled during march 1988 on an eddy resolving station network in the iberian basin despite the low signal to noise ratio of the altimeter data in this part of the ocean the agreement of the altimeter signal with hydrographic measurements is found to be significant individual cyclonic and anticyclonic eddies in the mediterranean outflow are identified in the altimetric maps the information visible in the sea surface height is significantly correlated with the dynamic topography of the layer 500 3000 dbar containing the core of the mediterranean outflow and maximum velocities of the baroclinic eddies the successive development of the identified eddies as studied from a sequence of sea surface height maps indicates a slight westward drift of the most pronounced feature with approximately 1 9 cm s propagation velocity the inferred path of that feature is consistent with additional information from moored current meter data

determination of oceanic dynamic barometer corrections to atmospheric excitation of earth rotation the excitation of earth s rotation by atmospheric pressure fluctuations on timescales from days to years is modified by the oceanic response to the pressure load that response has often been approximated as a static inverted barometer ib change in sea level but evidence from theory and both tide gauge and altimetric data suggests that the ib poorly models the sea level response at short periods static models also fail to account for the currents induced by the pressure loading the actual dynamic response of the oceans to barometric loads depends on frequency and on the spatial structure of the loading this work presents a green s function approach to determining the rotational effects of that oceanic response the green s functions characterize the rotational effects of the oceanic response to pressure loads described spatially by individual spherical harmonics for each harmonic of forcing they were computed at nine periods ranging from 4 days to 18 years and interpolated at intermediate periods computations were based on solutions to the author s dynamic spherical harmonic ocean tide model the effects on rotation of the dynamic barometer oceanic response are obtained by a convolution type combination of the green s functions with actual atmospheric pressure data results for data spanning the past decade will be illustrated using harmonically decomposed national center for environmental prediction ncep and european centre for medium range weather forecasts ecmwf pressure fields

integrated geophysical modelling of terranes and other structural features along the western canadian margin an integrated geophysical data set has been used to develop structural models across the continental margin west of vancouver island canada a modern accretionary complex underlies the continental slope and shelf and rests against and below the allochthonous crescent and pacific rim terranes these terranes in turn abut against the pre tertiary wrangellia terrane that constitutes most of the island gravity and magnetic anomaly data constrained by seismic reflection seismic refraction and other data were interpreted to determine the offshore positions of these terranes and related features iterative 2 5 dimensional forward models of anomaly profiles were stepped laterally along the margin to extend areal coverage over a 70 km wide swath oriented normal to the tectonic features an average model was then developed to represent this part of the margin the pacific rim terrane appears to be continuous and close to the coastline along the length of vancouver island consistent with emplacement by strike

on the slippage of deep drogued drifters deep drogued drifters are in use to measure the near surface geostrophic currents an attempt is made to study the slippage of these drifters due to wind and ekman currents the results are based on a data set from the unstratified north sea obtained in winter 1991 1992 where the currents were decomposed into ekman currents and barotropic currents the influence of these ekman currents on the drift performance of drifters drogued below the mixed layer in the barotropic current is determined by using quadratic drag laws in 90 of all cases 1540 data points the combined effect of wind drag and ekman currents on buoy and 100 m tether produces a slippage of less than 2 cm s drifters drogued within the mixed layer show less slippage due to the reduced drag on the tether but they are primarily designed to measure the actual near surface currents which are strongly dependent on the wind conditions it is concluded that deep drogued drifters are a reliable device to study weakly baroclinic geostrophic currents

reconstructing the ancestral yellowstone plume from accreted seamounts and its relationship to flat slab subduction recent geodynamic analyses have emphasized the relationship between modern flat slab subduction zones and the overriding of buoyant oceanic crust although most models for the evolution of the late mesozoic cenozoic laramide orogeny in the southwestern united states involve flat slab subduction the mechanisms proposed are controversial an examination of the geological evolution of the 60 50 ma crescent terrane of the coast ranges indicates that it was formed in a shallowing upward loihi type oceanic setting culminating in the eruption of subaerial lavas plate reconstructions indicate that the crescent terrane was emplaced into ca 20 ma crust and the presence of subaerial lavas implies an uplift due to the plume of ca 4 2 km which we use to calculate a minimum buoyancy flux of 1 1 mg s 1 similar to that of the modern yellowstone plume published paleomagnetic data indicate that the crescent terrane was formed at a paleolatitude similar to that of the yellowstone plume the crescent seamount was accreted within 5 my of the cessation of plume magmatism plate reconstructions indicate that it would have originated about 750 km to the west of the north american plate margin if it developed above a fixed yellowstone plume and are therefore consistent with the recorded very short interval between its formation and tectonic emplacement we interpret the crescent terrane as due to the ancestral yellowstone plume such a plume would have generated an elongate swell and related plateau that would have been overridden by the north american margin taken together the relationship between flat slab and overriding of oceanic plateau in laramide times would have been analogous to the relationship between modern andean flat slab subduction zones and the juan fernandez and nazca oceanic plateaus d 2003 elsevier science b v all rights reserved

geosat data assimilation with application to the eastern north atlantic abstract an attempt is made to determine the three dimensional ocean circulation from satellite altimeter measurements by assimilating geosat sea surface height data into an eddy resolving quasigeostrophic qg model of the eastern north atlantic ocean results are tested against independent information from hydrographic field observations and moored current meter data collected during the geosat erm the comparison supports the concept of inferring aspects of the three dimensional flow field from sea surface height observations by combining altimetric measurements with the dynamics of ocean circulation models a holland type qg model with open boundaries is set up on a 2000 km 2000 km domain of the eastern north atlantic between 25 and 45 n 32 and 8 w by using a simple nudging technique about two years of geosat altimeter data are assimilated into the model every five days as space time objective analyses on the model grid the error information resulting from the analysis is used during the assim

life history of a cyclonic ring detached from the kuroshio extension as seen by the geosat altimeter the sea surface dynamic topography ssdt sea surface height relative to the geoid is approximately estimated by combining the temporal fluctuation of ssdt determined from altimetry data with the climatological mean ssdt calculated from hydrographic data this approximated ssdt or composite ssdt is obtained in the area southeast of japan for the first year 1986 1987 of the geosat exact repeat mission variations in the kuroshio current system are well described by the composite ssdt in particular a complete life history of a cyclonic ring is observed for the first time in this region namely westward propagation of a southward meander of the kuroshio extension its pinching off to form a cyclonic ring the ring s westward movement its coalescence with the kuroshio and its eastward advection all available hydrographic data and cloud free satellite infrared images support the existence of this series of phenomena

physical oceanography of the azores front abstract there is a considerable body of evidence for the existence of a permanent front sw of the azores surveys in the summer of 1981 show the structure to penetrate to a depth of 2 000 m and suggest that its meandering is related to the alignment of the atlantis gt meteor seamount chain the total volume transport above 2 000 m is between 10 and 12 106 m3 s 1 towards the east the main water mass contrasts across the front are confined to the upper 400 m of the water column only a small change in mediterranean water strength was seen across the front satellite tracked drogued buoys seeded into the front showed surface speeds of up to 40 cm sec 1 and revealed the formation of a closed cold core eddy some 100 115 km in diameter which propagated westward at 2 2 km day 1 over a 200 day period sea surface temperature contrasts across the frontal boundary are small and together with frequent cloud cover prevent the detection of the front and associated eddies by satellite infra red imagery the front apparently marks the eastward extension of the southern branch of the gulf stream recirculation and the northern limit of the 18 c water mass eddies formed at the front could propagate westward into the interior of the sargasso sea but have not yet been observed to cross the mid atlantic ridge

accretion related metamorphism of the metchosin igneous complex southern vancouver island british columbia the metamorphic history of the volcanic sequence of the metchosin igneous complex mic an eocene ophiolite exposed on southern vancouver island british columbia canada was studied to examine the roles of seafloor and accretion related processes metamorphic facies in the volcanics vary from prehnite actinolite assemblages in the east to greenschist and amphibolite assemblages in the west in the east metamorphism is typified by chlorite prehnite epidote actinolite assemblages that fill vesicles and replace interstitial material plagioclase is variably albitized and clinopyroxene is relatively fresh in the west the common groundmass assemblage is amphibole epidote chlorite these assemblages and chlorite geothermometry show a regional east west gradient of 5 10 c km that is oblique to the volcanic stratigraphy the regional metamorphic facies distribution for the mic volcanics is not consistent with seafloor hydrothermal metamorphism documented for ocean crust from mid ocean ridges o

the time mean circulation in the agulhas region determined with the ensemble smoother the time mean circulation in the agulhas retroflection area is determined by combining topex poseidon data and a two layer quasi geostrophic model using the ensemble smoother by taking the time mean circulation as the unknown in the data assimilation procedure the time varying altimeter signal is used to constrain the time mean field the quasi geostrophic model is applied as a strong constraint with only the time mean circulation containing errors inspection of the posterior penalty function showed that the inversion was successful the errors in the time mean sea surface topography reduced from about 10 to about 3 cm a cyclonic recirculation cell over the agulhas plateau was found related to the northward meander of the agulhas return current another cyclonic recirculation cell was found west of africa probably related to the passage of anticyclonic agulhas rings south of it the new field is compared with advanced very high resolution radiometer infrared satellite data confirming the northward meander of the agulhas return current

verification of geosat sea surface topography in the gulf stream extension with surface drifting buoys and hydrographic measurements altimeter data from geosat have been analyzed in the gulf stream extension area horizontal maps of the sea surface height anomaly relative to an annual mean for various 17 day intervals were constructed using an objective mapping procedure the mean sea level was approximated by the dynamic topography from climatological hydrographic data geostrophic surface velocities derived from the composite maps mean plus anomaly are significantly correlated with surface drifter velocities observed during an oceanographie experiment in the spring of 1987 the drifter velocities contain much energy on scales less than 100 km which are not resolved in the altimetric maps it is shown that the composite sea surface height also agrees well with ground verification from hydrographic data along sections in a triangle between the azores newfoundland and bermuda except in regions of high mean gradients

eddy kinetic energy in the north atlantic from surface drifters one hundred ten satellite tracked freely drifting buoys measured velocities and trajectories of the near surface currents in the north atlantic mean velocity values and the velocity variance about the mean were calculated for different regions a horizontal map of eddy kinetic energy was prepared on a 2 2 grid between latitudes 20 and 55 n maximum eddy energy 3000 cm2 s 2 coincides with the high speed gulf stream jet where it begins large amplitude meanders near 37 n 67 w a tongue of high eddy energy coincides with the stream s path eastward and around the grand banks into the newfoundland basin where values of 1000 cm2 s 2 are found a weaker tongue extends eastward across the mid atlantic ridge near 45 n a second weak extension reaches southeastward from the stream and crosses the mid atlantic ridge between 30 and 35 n north and south of the stream eddy energy diminishes rapidly reaching an e folding at 300 km from the axis values of 200 cm2 s 2 were observed in the mid gyre region and 100 cm2 s 2 in the eastern north atlantic and north equatorial current although the gross distribution of eddy energy is similar to that determined from ship drift measurements there are significant differences eddy energy from drifters amounts to about twice the value measured by ship drift in the gulf stream and one half the ship drift values in the mid gyre it is suggested that these differences are due to the horizontal averaging of mesoscale motion and the errors in navigation both of which are problems with the ship drift technique

the branching of the gulf stream southeast of the grand banks during march april 1987 101 hydrographic stations were occupied on three sections spanning a triangle between the azores faial the southern tip of the grand banks of newfoundland and bermuda information on the near surface processes in the interior of the triangle were obtained from 32 satellite tracked buoys deployed during the cruise and a composite infrared image based on cloud free noaa 9 data during april 1987 the data were combined to analyze the eddy field and the branching of the gulf stream into the north atlantic current and the azores current calculations of mass transports through the legs of the triangle gave a total of 46 sv supplied by the gulf stream 31 sv of which left the area as the north atlantic current and westwind drift north of the azores the remaining 14 sv continued towards east southeast as the azores current and southern recirculation additional conductivity temperature depth stations from a cruise in april 1986 into the same area allowed also study of the large scale circulation within that triangle in deeper layers the azores current appears as a baroclinic stream which reaches down to approximately 1000 m intensive mixing was observed at the continental slope of newfoundland between water of the labrador current and the gulf stream mixed water owing to cabbeling and consecutive convective mixing this water penetrates down to 2000 m depth and creates horizontal density gradients to the surrounding gulf stream water which intensifies the north atlantic current this process is considered to be an important energy source for this current

mapping mesoscale variability of the azores current using topex poseidon and ers 1 altimetry together with hydrographic and lagrangian measurements the semaphore mesoscale air sea experiment was conducted in the azores madeira region from july to november 1993 topex poseidon tip and ers 1 were flying simultaneously at that time the main purposes of this paper are to evaluate the estimation of the oceanic mesoscale circulation from the two different sets of altimetric data tip and ers 1 and to compare the results with in situ measurements provided by the semaphore hydrographic surveys and smface drifters three expendable bathytermograph conductivity temperature depth surveys in a 500 km2 box and a set of 47 lagrangian surface drifters drogued at 150m comparisons are carried out through the maps obtained by objective analysis ti om the four data sets the mapping accuracy of tip ers i tip and ers 1 combined and in situ data is investigated as weii as the sensitivity of the mapping to the correlation functions used there is a good qualitative agreement between altimetric maps and corresponding drifter and hydrographic maps for the three hydrographic surveys correlations are about 0 8 and the regression fit is about 0 6 0 7 the lower values are clue to the smooth climatology used to reference the altimetric maps the correlation for time differences is better with regression lines not significantly different from i especiaily when ers 1 and tip are combined tip mapping is almost as good as ers 1 mapping which was rather unexpected since the ers 1 space time sampling is better suited for the mesoscale this may reflect the fact that the signal mapped by the hydrography and drifters does not contain the high frequency wavenumber components tip and ers 1 combined provide better results although the improvement is not as large as expected probaply for the same reason

metchosin igneous complex southern vancouver island ophiolite stratigraphy developed in an emergent island setting the metchosin igneous complex of southern vancouver island has three components gabbro stocks formerly sooke gabbro a newly recognized sheeted dike complex and a basaltic volcanic sequence formerly the metchosin volcanics the sheeted dikes occupy a position transitional between the gabbro stocks and submarine volcanics which they tie together in an ophiolitic pseudostratigraphy the submarine volcanics shoal upward and pass into subaerial sheet flows the complex formed in an area of regional extension as an emergent island