geochronology of early to middle paleozoic tectonic development in the southwest newfoundland gander zone southwest newfoundland s gander zone was once considered part of the collided eastern margin of an early paleozoic iapetus ocean distinguished from the rest of the gander zone by the extensive exposure of a polydeformed amphibolite to greenschist facies sequence considered devonian in age overlying presumed precambrian basement it was later found that truly devonian strata were confined to the cape ray fault system the local northwestern boundary of the zone u pb zircon isotopic ages of 452 13 51 ma and 458 22 29 ma on metavolcanic rocks in the upper part of the sequence southeast of the fault system indicate that ordovician and possibly older rocks underlie the gander zone itself a temporal framework for the three main stages of regional deformation corresponding to pre metamorphic recumbent folding d 1 and transpression d 2 and d 3 is presented using u pb and 40 ar 39 ar dates of granitoid and metamorphic rocks d 1 is bracketed as late o

winter cascading of cold water in lake geneva 1 during the winters of 1998 and 1999 observations were made of the cascading of cold water from the nearshore shallow shelf zones and down the sloping sides of lake geneva cascading starts on the average 10 hours after the onset of surface cooling the draining cold water descends like a gravity current and the downslope speed of the head of these slugs of cold water u has a mean value of 5 2 cm s 1 with slugs persisting on the average for 8 hours when the monin obukov length scale at the water surface l is negative implying convection occurs and d over bar lg 1 where d is the mean shelf depth the nondimensionalized speed of the front of slugs u b 1 3 is found to be 1 3 0 4 where b is the surface buoyancy flux integrated over the time period from one slug to the next each slug is unsteady the head being followed by several fronts in which the temperature of the current decreases and its thickness increases these fronts travel faster than the mean flow by a factor of r 1 38 0 3 dynamical similarities are found with roll waves observed in turbulent open channel flows the circulation induced by the cascade is found to give a positive skewness to the time derivatives of near surface temperature in shallow waters in contrast with negative values close to the slope the volume of cold water carried by a slug increases with downslope distance as a consequence of turbulent entrainment and the contribution of convectively unstable plumes from the surface the average volume carried by the slug across the 21 m depth contour is about 1 9 times the volume of water in shallower water i e that on the shelf between shore and a depth of 21 m implying that cascading is an efficient means of flushing shelf water integrated around the lake the mean total volume flux amounts to 11 5 the average winter river inflow

the provenance of granite boulders in conglomerates of the northern and central belts of the southern uplands of scotland rb sr whole rock isochrons from several suites of granite boulders which occur in ordovician and silurian conglomerates in the southern uplands of scotland yield ages of around 1200 ma 600 to 700 ma and 470 to 490 ma the plutonic and tectonic history recorded by these clasts corresponds more closely with that of nw newfoundland than with that of scotland the petrography of the clasts can also be matched with exposed granite plutons in newfoundland since the conglomerates were derived from the nw it is concluded that the southern uplands lay to the se of newfoundland a total of 1500 km strike slip displacement occurred between the caradoc and the early devonian consistent with oblique subduction of the iapetus ocean below the north american continental margin

collision along an irregular margin a regional plate tectonic interpretation of the canadian appalachians discussion stockmal et al recently presented a simple three dimensional plate tectonic model by which they attempted to explain the pre carboniferous evolution of the northern appalachians this model which in part follows the basic principles of the two stage collision model of colman sadd 1982 is mainiy based on the results of a marine seismic profile across northem newfoundland and on large scale geometrical considerations such models are useful because they provide geologists with a framework that can be tested against field data however in this case the existing geological data base in our opinion is incompatible with the model we will discuss the inconsistencies and present an altemative model the main thesis of the stockmal et al model is that the taconian and acadian orogenies are explained in terms of continuous southeastward subduction of iapetus oceanic lithosphere during the collision between the taconic magmatic arc and the irregular margin of north america the benioff zone clogged first in newfoundland and then in mainland canada the continuing convergence between the taconic arc and north america in newfoundland was then achieved by delamination of lithospheric mantle while b subduction continued between the taconic arc and north america in mainland canada evidence in support of this model includes the 300 400 km right hand offset of equivalent tectono stratigraphic zones between newfoundland and mainland canada and a difference in style and vergence of the acadian structures in newfoundland and new brunswick the idea of a diachronous collision is not a new one but the sense of diachronism remains unresolved see e g dallmey er 1977 clague et al 1981 lux 1986 considered the allochthonous ophiolites in the humber zone and argued in favour of a north to south diachronism his conclusion is consistent with the fact that the oldest fossil dated autochthonous flysch is younger in quebec than in newfoundland since there is no overstepping autochthonous cover in quebec stockmal et al argue that the timing of the final emplacement of the allochthons and the closure of iapetus is not well constrained there and they explain the acadian orogeny in mainiand canada as

the thermal bar a simple theoretical model of the thermal bar is derived on the basis of heat budget equations for the following three zones of a wedge shaped water basin warmed from above i stably stratified shallow warm water zone ii vicinity of the bar iii convectively mixed deep cold zone in contrast to the traditional approach advective warming of the vicinity of the bar and associated facilitating of the thermal bar propagation are taken into account theoretical predictions are compared with the data of lacustrine and laboratory measurements taken from current literature new laboratory experiments have been carried out to examine the laminar regime of the thermal bar

underwater sounds recorded from migrating bowhead whales balaena mysticetus in 1979 bowhead whale sounds were recorded from sonobuoys in the course of conducting aerial surveys of the beaufort sea during spring and fall migrations in 1979 sounds were recorded over 28 day spring and 12 day fall investigations most bowhead sounds in both spring and fall samples were low frequency below 800 hz moans of two classes simple and complex repetitive moan sequences were found in the spring sample and are regarded as simple songs no such repetitive sequences were found in fall recordings high frequency to 4 khz trumpeting calls were recorded in the fall no particular behavior nor environmental condition could be associated with bowhead sound production

blue and fin whale call source levels and propagation range in the southern ocean blue balaenoptera musculus and fin whales b physalus produce high intensity low frequency calls which probably function for communication during mating and feeding the source levels of blue and fin whale calls off the western antarctic peninsula were calculated using recordings made with calibrated bottom moored hydrophones blue whales were located up to a range of 200km using hyperbolic localization and time difference of arrival the distance to fin whales estimated using multipath arrivals of their calls was up to 56km the error in range measurements was 3 8km using hyperbolic localization and 3 4km using multipath arrivals both species produced high intensity calls the average blue whale call source level was 189 3db re 1 pa 1m over 25 29hz and the average fin whale call source level was 189 4db re 1 pa 1m over 15 28hz blue and fin whale populations in the southern ocean have remained at low numbers for decades since they became protected using source level and detection range from

devonian extension in northwestern newfoundland 40ar 39ar and u pb data from the ming s bight area baie verte peninsula abstract the ming s bight group of northwestern newfoundland an outlier of humber zone continental margin rocks is entirely surrounded by ophiolitic rocks of the dunnage zone structures in the ming s bight group and adjacent units record three main phases of deformation the earliest structures relate to silurian sinistral transpression previously documented in the region two later phases of extensional deformation produced a series of dextral oblique normal shear zones and faults that now separate the ming s bight group in the footwall from ophiolitic and granitoid rocks in the hangingwall 40ar 39ar and u pb data constrain the times of oblique normal shear and cooling metagabbro in the point rousse ophiolite complex which lies in the hangingwall preserves disturbed ordovician hornblende 40ar 39ar ages whereas adjacent shear zones record devonian ages hornblendes in pacquet harbour group amphibolites within extensional shear zones mainly record 40ar 39ar ages of 390 380 ma synkinematic titanite

a model of the thermal bar circulation in a long basin a thermal bar is defined here as a zone of descending water at or near the fresh water temperature of maximum density in the present study we model physical properties such as velocity temperature turbulent fluxes time of onset and migration speed of the thermal bar in an idealized basin unlike models using prescribed eddy viscosity and diffusivity coefficients our model uses a second order turbulence closure scheme to model mixing due to turbulence the only inputs in the calculation are the surface wind the surface heat flux and the initial state of the fluid numerical simulations of the resulting circulation are presented for flow in a long rotating basin under prescribed surface heat and wind conditions the results show the influence of the relative magnitudes of mechanical and thermal forcing on the circulation a comparison with field observations shows reasonable agreement between computed and measured bar migration speeds the time necessary for the formation of the bar is computed and is found to depend on the surface forcing

lead isotopic compositions of the western dharwar craton southern india evidence for distinct middle archean terranes in a late archean craton abstract lead and sr isotopic compositions of whole rocks and feldspar separates from several fielddefined suites of rocks from the western dharwar craton of southern india elucidate a complex history of the area the evolution of the craton earlier than 3 0 ga is difficult to determine because of thermal and metasomatic overprinting at 3 0 ga many whole rocks were completely reset then but feldspar separates preserve some of the earlier history apparently a series of terranes evolved from the mantle over the period 3 4 to 3 0 ga to form the western dharwar craton in each case metamorphism and anatexis of older terranes accompanied extraction of juvenile material from the mantle the oldest gneisses 3 4 ga had radiogenic pb and sr isotopic compositions when they formed and were derived from older crustal protoliths that were plausibly accreted to the crust at or even before 3 8 ga the old gneisses were greatly depleted in rb probably at 3 4 ga when the protoliths of younger magmatic rocks may have separated from the mantle younger gneisses apparently formed from these mafic intermediate protoliths in the age range of 3 2 to 3 0ga the 3 0 ga event in the central part of the craton was accompanied by intrusion of small diapiric trondhjemites formed by melting of older crust and penecontemporaneous metasomatism of country rocks by hydrous fluids carrying u and other lithophilic elements the resultant deep crust was greatly depleted in heat producing elements and the craton has been inactive since 3 0 ga except for production of minor granites from depleted source regions at 2 5 2 6 ga the lack of activity at 2 5 ga contrasts strongly with extensive magmatism and metamorphism in surrounding areas that had not undergone depletion at 3 0 ga lower crustal depletion also has caused present day reduced heat flow to be very low

ranging bowhead whale calls in a shallow water dispersive waveguide this paper presents the performance of three methods for estimating the range of broadband 50 500 hz bowhead whale calls in a nominally 55 m deep waveguide conventional mode filtering cmf synthetic time reversal str and triangulation the first two methods use a linear vertical array to exploit dispersive propagation effects in the underwater sound channel the triangulation technique used here while requiring no knowledge about the propagation environment relies on a distributed array of directional autonomous seafloor acoustics recorders dasars arranged in triangular grid with 7 km spacing this study uses simulations and acoustic data collected in 2010 from coastal waters near kaktovik alaska at that time a 12 element vertical array spanning the bottom 63 of the water column was deployed alongside a distributed array of seven dasars the estimated call location to array ranges determined from cmf and str are compared with dasar triangulation results for 19 whale calls the vertical array ranging results are generally within 10 of the dasar results with the str results providing slightly better agreement the results also indicate that the vertical array can range calls over larger ranges and with greater precision than the particular distributed array discussed here whenever the call locations are beyond the distributed array boundaries

bowhead whale localization using asynchronous hydrophones in the chukchi sea this paper estimates bowhead whale locations and uncertainties from bayesian inversion of modally dispersed calls recorded on asynchronous recorders in the chukchi sea alaska bowhead calls were recorded on a cluster of seven asynchronous ocean bottom hydrophones that were separated by 0 5 7 5 km a warping time frequency analysis is used to extract relative mode arrival times as a function of frequency for nine frequency modulated whale calls that dispersed in the shallow water environment each call was recorded on multiple hydrophones and the mode arrival times are inverted for the whale location in the horizontal plane source instantaneous frequency if water sound speed profile subbottom layering and geoacoustic parameters relative recorder clock drifts and residual error standard deviation all with estimated uncertainties a simulation study shows that accurate prior environmental knowledge is not required for accurate localization joint inversion of multiple recorded calls is shown to substantially reduce localization source if and relative clock drift uncertainties whale location uncertainties are estimated between 30 and 160 m and clock drift uncertainty is estimated between 3 and 26 ms the clock synchronization provided by the inversion is sufficient for localizing other types of marine mammal calls using simpler time difference of arrival methods

synthesis of palaeozoic deformational events and terrane accretion in the canadian appalachians plate tectonic theory predicts that most deformation is associated with subduction and terrane accretion with some deformation associated with transform transcurrent movements deformation associated with subduction varies between two end members 1 where the tectonic regime is dominated by subduction of oceanic lithosphere containing small terranes a narrow surface zone of accretionary deformation along the subduction zone starts diachronously on the subducting plate at the trench as material is transferred from the subducting plate to the over riding plate and 2 where continent continent collision is occurring a wide surface zone of accretionary deformation starts synchronously or with limited diachronism palaeozoic deformational events in the canadian appalachians correspond to narrow diachronous events in the ordovician and silurian whereas devonian carboniferous and permian deformational events are widespread and broadly synchronous along the western side of the canadian appalachians the taconian deformational event starts diachronously throughout the ordovician and corresponds to the north north west accretion of the notre dame ascot weedon st victor and various ophiolitic massifs volcanic arc and peri arc terranes over cratonic north america within the eastern half of the central mobile belt the late cambrian early ordovician penobscotian deformational event corresponds to the south easterly accretion of the exploits subzone various volcanic are and peri arc terranes over the gander zone continental rise in the centre of the orogen the late ordovician silurian beothukan deformational event corresponds to the south easterly accretion of the notre dame over the exploits gander subzones along the south eastern side of the central mobile belt the silurian ganderian deformational event corresponds to the north north east sinistral transcurrent accretion of the avalon composite terrane microcontinent over the gander exploits zones along the south eastern half of the orogen the late silurian middle devonian acadian deformation event corresponds to the westerly accretion of the meguma terrane intradeep or continental rise over the avalon composite terrane affecting the entire orogen the late devonian carboniferous and permian acadian alleghanian deformational events correspond to the east west convergence between laurentia and gondwana continent continent collision

calibration and comparison of the acoustic location methods used during the spring migration of the bowhead whale balaena mysticetus off pt barrow alaska 1984 1993 between 1984 and 1993 visual and acoustic methods were combined to census the bering chukchi beaufort bowhead whale balaena mysticetus population passive acoustic location was based on arrival time differences of transient bowhead sounds detected on sparse arrays of three to five hydrophones distributed over distances of 1 5 4 5 km along the ice edge arrival time differences were calculated from either digital cross correlation of spectrograms old method or digital cross correlation of time waveforms new method acoustic calibration was conducted in situ in 1985 at five sites with visual site position determined by triangulation using two theodolites the discrepancy between visual and acoustic locations was 1 5 of visual range and less than 0 7 of visual bearing for either method comparison of calibration results indicates that the new method yielded slightly more precise and accurate positions than the old method comparison of 217 bowhead whale call locations from both acoustic methods s

a displaced and metamorphosed peralkaline granite related to the late proterozoic labrador and gardar suites the doolough granite of county mayo northwest ireland the chemically and lithologically distinct doolough granite from the annagh division in northwest county mayo ireland includes part of the northwesternmost exposures of precambrian basement in europe the doolough granite is similar to precambrian granitic intrusions found in labrador and southwest greenland although its age of emplacement at u pb in zircon is slightly younger than the canadian intrusions a reconstruction of the pre iapetus disposition of the eastern laurentian margin suggests that the doolough granite was probably emplaced at a location sufficiently close to both southwest greenland and labrador for it to have formed part of the same magmatic province during a period of restricted crustal extension that preceded the grenville event

the northwest portion of the gander zone a geophysical interpretation geophysical data from the northwestern portion of the gander zone of newfoundland are used to test existing geological models and to propose amended ones for the upper crustal structure of the regi

investigation of the spring thermal regime in lake ladoga using field and satellite data we use a combination of field and satellite data to investigate the thermal regime in lake ladoga in spring 1992 the analysis concentrates mainly on the temperature structure in the convectively mixed region and the dynamics of a special thermo hydrodynamic phenomenon called thermal bar a zone of descending water with the temperature of maximum density equal to 4 c a theoretical model of the temperature distribution in the convectively mixed region temperatures 4 c and the thermal bar progression is also applied and compared with satellite data the study shows that the temperature offshore the 4 c isotherm in the convectively mixed region of the lake is almost depth constant because of strong convective mixing and that the horizontal heat flux seems to be of minor importance in this region the comparison between predictions from the simple theoretical model describing the temperature evolution and movement of the thermal bar with observations showed a fairly good agreement however calculations of the change of heat content in water columns along sections indicate heat transport from the nearshore stably stratified region toward the 4 c isotherm which will affect the movement of the thermal bar this effect has been incorporated in an improved model of the thermal bar progression a better agreement between predictions and observations was also obtained with this model

upwelling of deep water during thermal stratification onset a major mechanism of vertical transport in small temperate lakes in spring using airborne thermal infrared imaging and horizontally resolved in situ temperature monitoring at the lake surface we estimated strength and duration of regular wind driven upwelling of dense deep water to the lake surface in two small in terms of rossby radius temperate lakes during the initial phase of summer thermal stratification the onset and duration of the upwelling events correlated well with the balance between stratification in terms of schmidt stability and wind forcing as expressed by lake and wedderburn numbers the period of regular upwelling appearances lasted 7 15 days identified by schmidt stabilities around 30 j m 2 and lake numbers between 0 and 1 and resulted in persistent temperature gradients of up to 2 c across the lake surface our results suggest that spring upwelling should inevitably take place in all freshwater temperate lakes with mean temperatures crossing the maximum density value of freshwater on annual cycle whereas duration and intensity of the upwelling would vary depending on lake morphometry and weather conditions our results suggest major contribution of upwelling in nutrient supply to the upper waters oxygenation of the deep water column and air lake gas exchange in particular the release of the sediment produced methane into the atmosphere

geochronology of the baie verte peninsula newfoundland implications for the tectonic evolution of the humber and dunnage zones of the appalachian orogen u pb analyses of zircon from the burlington granodiorite suggest intrusion at c 460 465 ma hornblende and biotite from central portions of the pluton record markedly younger sup 40 ar sup 39 ar plateau dates 410 420 ma which are interpreted to date contact metamorphic effects associated with the widespread emplacement of silurian devonian igneous suites northern portions of the burlington granodiorite are polydeformed and regionally metamorphosed hornblende and biotite from this terrane yield sup 40 ar sup 39 ar plateau ages of 345 350 ma u pb analyses of zircon from the dunamagon granite indicate emplacement at c 440 460 ma thereby providing an upper limit for tectonic juxtapositioning of the humber and dunnage zones along the baie verte line similar ages are also recorded by hornblende and biotite throughout northerly portions of the mings bight humber zone and pacquet harbour dunnage zone groups these results indicate that the tectonic evolution of the baie verte line as polygenetic and involved 1 regionally significant tectonothermal activity prior to the middle ordovician and 2 middle to late paleozoic tectonothermal activity centered along easterly segments of the baie verte line the regional metamorphism associated with this orogenic activity altered primary u pb and rb sr isotopic systems within various igneous suites exposed in northeastern portions ofmore the burlington peninsula which may explain some inconsistent geochronological results previously obtained 54 references 6 figures 5 tables less

range estimation of bowhead whale balaena mysticetus calls in the arctic using a single hydrophone bowhead whales generate low frequency calls in shallow water arctic environments whose dispersive propagation characteristics are well modeled by normal mode theory as each mode propagates with a different group speed a call s range can be inferred by the relative time frequency dispersion of the modal arrivals traditionally at close ranges modal arrivals are separated using synchronized hydrophone arrays here a nonlinear signal processing method called warping is used to filter the modes on just a single hydrophone the filtering works even at relatively short source ranges where distinct modal arrivals are not separable in a conventional spectrogram however this warping technique is limited to signals with monotonically increasing or decreasing frequency modulations a relatively common situation for bowhead calls once modal arrivals have been separated the source range can be estimated using conventional modal dispersion techniques with the original source signal structure being recovered as a by product twelve bowhead whale vocalizations recorded near kaktovik alaska in 2010 with signal to noise ratios between 6 and 23 db are analyzed and the resulting single receiver range estimates are consistent with those obtained independently via triangulation from widely distributed vector sensor arrays geoacoustic inversions for each call are necessary in order to obtain the correct ranges

bowhead whale localization using time difference of arrival data from asynchronous recorders this paper estimates bowhead whale locations and uncertainties using nonlinear bayesian inversion of the time difference of arrival tdoa of low frequency whale calls recorded on onmi directional asynchronous recorders in the shallow waters of the northeastern chukchi sea alaska a y shaped cluster of seven autonomous ocean bottom hydrophones separated by 0 5 9 2 km was deployed for several months over which time their clocks drifted out of synchronization hundreds of recorded whale calls are manually associated between recorders the tdoa between hydrophone pairs are calculated from filtered waveform cross correlations and depend on the whale locations hydrophone locations relative recorder clock offsets and effective waveguide sound speed a nonlinear bayesian inversion estimates all of these parameters and their uncertainties as well as data error statistics the problem is highly nonlinear and a linearized inversion did not produce physically realistic results whale location uncertainties fro

localization of marine mammals near hawaii using an acoustic propagation model humpback whale songs were recorded on six widely spaced receivers of the pacific missile range facility pmrf hydrophone network near hawaii during march of 2001 these recordings were used to test a new approach to localizing the whales that exploits the time difference of arrival time lag of their calls as measured between receiver pairs in the pmrf network the usual technique for estimating source position uses the intersection of hyperbolic curves of constant time lag but a drawback of this approach is its assumption of a constant wave speed and straight line propagation to associate acoustic travel time with range in contrast to hyperbolic fixing the algorithm described here uses an acoustic propagation model to account for waveguide and multipath effects when estimating travel time from hypothesized source positions a comparison between predicted and measured time lags forms an ambiguity surface or visual representation of the most probable whale position in a horizontal plane around the array this is an important benefit because it allows for automated peak extraction to provide a location estimate examples of whale localizations using real and simulated data in algorithms of increasing complexity are provided

geochronology of the baie verte peninsula newfoundland implications for the tectonic evolution of the humber and dunnage zones of the appalachian orogen a discussion

recognition of extraneous argon components through incremental release 40ar39ar analysis of biotite and hornblende across the grenvillian metamorphic gradient in southwestern labrador 40ar39ar incremental release ages have been determined for 15 hornblende and 20 biotite concentrates separated from rocks collected across the garnet and kyanite zones of grenvillian metamorphism in southwestern labrador most hornblende spectra from the kyanite zone are slightly discordant with low temperature increments yielding ages older than the ca 1000 ma date suggested for culmination of grenvillian metamorphism in the area however all the hornblende concentrates record well defined plateau ages these range from 968 to 905 ma across the kyanite zone and date times of diachronous post metamorphic cooling the discordant spectra are interpreted to result from low temperature liberation of excess 40ar components from grain margins two hornblende concentrates from the garnet zone display very discordant spectra total gas ages of 2100 and 3017 ma in which incremental dates systematically decrease during analysis this pattern of discordance suggests that excess argon components are inhomogeneously distributed throughout these hornblende grains most biotites from the garnet and kyanite zones record total gas or plateau ages in excess of 1000 ma 2066 857 ma reflecting the widespread presence of excess argon components because most of the 40ar39ar age spectra are internally concordant the ratios of excess 40ar relative to radiogenic 40ar must have been uniform in the various gas fractions liberated from each sample this is also reflected in the inability of isotope correlation diagrams to differentiate between excess radiogenic and atmospheric argon components the biotite total gas or plateau dates show marked local variation this is interpreted to indicate that the biotite grains were in contact with a post metamorphic intergranular vapor phase that was characterized by large and variable 40ar36ar ratios such ratios most likely resulted from widespread diffusion of the argon liberated from adjacent archean basement gneisses during the grenvillian metamorphic overprint

directional frequency and recording difar sensors in seafloor recorders to locate calling bowhead whales during their fall migration bowhead whales balaena mysticetus migrate west during fall 10 75 km off the north coast of alaska passing the petroleum developments around prudhoe bay oil production operations on an artificial island 5 km offshore create sounds heard by some whales as part of an effort to assess whether migrating whales deflect farther offshore at times with high industrial noise an acoustical approach was selected for localizing calling whales the technique incorporated difar directional frequency and recording sonobuoy techniques an array of 11 dasars directional autonomous seafloor acoustic recorders was built and installed with unit to unit separation of 5 km when two or more dasars detected the same call the whale location was determined from the bearing intersections this article describes the acoustic methods used to determine the locations of the calling bowhead whales and shows the types and precision of the data acquired calibration transmissions at gps measured times and locations provided measures of the individual dasar clock drift and directional orientation the standard error of the bearing measurements at distances of 3 4 km was 1 35 after corrections for gain imbalance in the two directional sensors during 23 days in 2002 10 587 bowhead calls were detected and 8383 were localized

geochemical and geological evidence bearing on the origin of the bay of islands and coastal complex ophiolites of western newfoundland abstract suggestions that ophiolitic rocks of the bay of islands complex boic and coastal complex cc of southwestern newfoundland were formed at a seafloor spreading center are supported by 1 1 whole rock trace and major element data from diabases and basalts 2 2 spinel mineral chemistry from ultramafic rocks 3 3 the internal geology of the ophiolite terranes and 4 4 regional geologic and tectonic constraints in the western newfoundland appalachians diabase and basalt samples from the boic and the northern cc massifs are tholeiitic and geochemically indistinguishable from present day mid ocean ridge basalts morbs many diabases from the lewis hills massif the southernmost part of the cc are also identical to morbs but there is also an unusual suite of diabases from the lewis hills that is unlike any other suite yet reported from a variety of tectonic settings including island arcs ocean islands or spreading centers this suite is interpreted to have been produced by unusual magma generation processes in the deep structural levels of an oceanic ridge ridge transform fault approximately 90 of spinels from ultramafic rocks in the boic and cc have cr cr al ratios that are less that 0 60 comparable to those values reported from ultramafic rocks of the present day ocean basins these geochemical constraints in combination with previously described geological relationships within the ophiolite terranes and regional tectonic relationships in the western newfoundland appalachians suggest that the boic and cc ophiolites formed within a main ocean basin i e the early paleozoic iapetus ocean along a seafloor spreading center and ridge ridge transform fault respectively there is little evidence to suggest formation in either an island arc or back arc basin tectonic setting as such the boic and cc ophiolites are probably well suited for detailed petrologic structural and geophysical studies to determine the processes involved in the generation and evolution of contemporary oceanic crust and upper mantle

sound source localization technique using a seismic streamer and its extension for whale localization during seismic surveys marine seismic surveys are under increasing scrutiny because of concern that they may disturb or otherwise harm marine mammals and impede their communications most of the energy from seismic surveys is low frequency so concerns are particularly focused on baleen whales extensive mitigation efforts accompany seismic surveys including visual and acoustic monitoring but the possibility remains that not all animals in an area can be observed and located one potential way to improve mitigation efforts is to utilize the seismic hydrophone streamer to detect and locate calling baleen whales this study describes a method to localize low frequency sound sources with data recoded by a streamer beamforming is used to estimate the angle of arriving energy relative to sub arrays of the streamer which constrains the horizontal propagation velocity to each sub array for a given trial location a grid search method is then used to minimize the time residual for relative arrival times along the streamer estimated by cross correlation results from both simulation and experiment are shown and data from the marine mammal observers and the passive acoustic monitoring conducted simultaneously with the seismic survey are used to verify the analysis

circulation and turbulent exchange characteristics during the thermal bar in lake ontario we made observations from vertical moorings of thermistors and current meters in lake ontario to study the spring thermal bar circulation its effect in inhibiting the horizontal mixing and spatial and temporal variability of vertical mixing during this period thermal bar progression rates were compared with two analytical models both produced overestimates during the early part of the thermal bar and underestimates during the late spring in a zone between the shore and the thermal bar currents were influenced by the local wind stress and flowed in a counterclockwise direction the mean cross shore flows in the nearshore zone were reduced during the thermal bar period the alongshore horizontal exchange coefficients were higher than cross shore exchange coefficients during the thermal bar period the magnitude of both alongshore and cross shore exchange coefficients decreased when the bar was still within middepth 40 m when it was further offshore the thermal bar did not have any significant effect on alongshore exchange coefficients but cross shore exchanges decreased marginally the vertical exchange coefficients were high in the water column because of convective mixing during the thermal bar period during the evolution of spring thermal bar the vertical mixing decreased considerably in the nearshore regions under stable stratification whereas the high vertical mixing levels continued in the offshore region for a longer period

tracking fin whale calls offshore the galicia margin north east atlantic ocean data recorded during a temporary deployment of ocean bottom seismometers obss are used in this study to monitor the presence of fin whales around the array in the summer of 2003 ten obss were placed 250 km from the nw coast of iberia in the galicia margin ne atlantic ocean for a period of one month the recorded data set provided a large variety of signals including fin whale vocalizations identified by their specific acoustic signature the use of a dense array of seafloor receivers allowed investigation into the locations and tracks of the signal generating whales using a seismological hypocentral location code individual pulses of different sequences have been chosen to study such tracks problems related to the correct identification of pulses discrimination between direct and multiple arrivals and the presence of more than one individual have been considered prior to location fin calls were concentrated in the last two weeks of the deployment and the locations were spread around the area covered by the array these results illustrate that besides its classical seismological aim deployment of semipermanent seafloor seismic arrays can also provide valuable data for marine mammal behavior studies