aligned buoyant highs across trench deformation clustered volcanoes and deep earthquakes are not aligned with plate tectonic theory abstract bathymetry shows the regional interaction of aseismic buoyant highs in northern pacific subduction zones seamounts ridges and fractures on the seaward side of the trench are associated with events that do not support the accepted plate tectonics paradigm including an altered slab dip angle benioff zone and the clustered volcanoes and earthquakes within the convergent margin most of the examples in this study show a reduction in the number of total earthquakes but an increase in the deeper earthquakes an abnormal amount of across trench deformation and a larger amount of volcanism on the active arc than if no bouyant highs existed in the subduction zone the connections between the seaward highs and the landward clustered highs are the transverse faults which widen by turbidite scour as they age forearc canyons are the modern day bathymetdc expression of these faults all of the parameters introduced disagree with the plate tectonic hypothesis making an alternate explanation for the genesis necessary that explanation falls into the realm of the surge tectonic hypothesis which can explain by fluid mechanics and eastward flow each of the introduced parameters

shelf cross shore flows under storm driven conditions role of stratification shoreline orientation and bathymetry abstractnumerical simulations are used to study the response of long bay south carolina a typical coastal embayment with curved coastline located on the south atlantic bight to realistic climat

deep seismic crustal structure beneath the bonin trough abstract the bonin trough and the bonin ridge are located in the fore arc region of the southern bonin arc system such a conspicuous trough ridge formation along an arc cannot be recognized in other trench island arc systems the southern bonin arc is characterized by other several unique geological and geophysical features the tectonics controlling their formation and evolution has attracted interest of many earth scientists but has not been understood well in 1987 we made a seismic refraction experiment across the bonin trough to clarify the structure of the crust and the upper mantle of this area which has not been known well to date high quality seismic data of airgun shooting and of explosive sources were acquired by ocean bottom seismograph and hydrophone obsh systems a detailed seismic velocity structure model was obtained by modeling of the observed travel times and amplitudes using a two dimensional ray tracing technique the structure is considerably variable across the bonin trough especially in the sedimentary layers in spite of its flat sea floor topography thinning of the upper crust is recognized in the trough suggesting that the bonin trough was formed by rifting of the island arc crust uplifting of the crust and the uppermost mantle beneath the bonin ridge is required in our structure model the depth to the moho boundary decreases from 18 km beneath the shichito ridge to 14 km beneath the bonin ridge this is in good agreement with the crustal structure expected from large positive gravity anomaly observed over the bonin ridge

tectonic and geomorphic interpretation of the ogasawara plateau region by multi beam based 3d methods abstract three dimensional views in this case of a subduction complex including the ogasawara plateau significantly enhance the geomorphic interpretation small scale features such as fracturing are apparent in some views and hidden in others so there is merit to producing more than one view this method shows a marked improvement over the use of two dimensional map views coloring or models because the user has less to carry and computer generated products take less time to construct

moored wind temperature and current observations made during coastal ocean dynamics experiments 1 and 2 over the northern california continental shelf and upper slope moored observations of winds currents and temperature made over the northern california shelf and upper slope during the 1981 and 1982 upwelling seasons as part of the coastal ocean dynamics experiment code are described in both field experiments code 1 and code 2 the onset of the upwelling season is triggered by the strengthening of the north pacific high off northern california and signalled by the presence of water colder than 9 c near the bottom over the shelf vertical temperature stratification over the shelf is reduced during active upwelling local winds and subtidal currents over the shelf are strongly polarized in the alongshelf direction and the mean wind stress is directed equatorward response of alongshelf currents to wind forcing is similar at all depths over the shelf the response of the cross shelf current is more complex in the surface layer offshelf flow is significantly and positively correlated with the upwelling favorable alongshelf wind stress beneath this layer a weak return flow exists the thickness of the upper mixed layer varies greatly reaching 60 m during upwelling events thus direct wind forcing affects a substantial fraction of the water over the shelf low frequency wind stress current and temperature fields are adequately described by a few energetic empirical orthogonal functions with simple spatial structure the most energetic mode typically accounts for 75 or more of the variance of wind stress and temperature over the middle and inner shelf the most energetic current mode accounts for 90 or more of the variance is dominated by he alongshelf component and veers to the left with depth the low frequency alongshelf flow fluctuations are quasi barotropic with some vertical shear but no reversal with depth vertical shear in alongshelf current and the cross shelf density gradient obey the thermal wind relation the simple structure of the subdiurnal currents allow estimation of the alongshelf volume transport between the 60 and 130 m isobaths through three cross shelf transects in code 2 volume transport over the shelf is often nearly two dimensional but occasional large differences indicate significant mass exchange between the shelf and the adjacent upper slope correlation of low frequency currents and alongshelf wind stress shows the response of alongshelf current to be maximum near the surface and near midshelf where a 15 cm 1 alongshelf flow lags a 1 dyn cm 2 alongshelf wind stress by the order of 10 hours currents over the upper slope are not significantly correlated with local wind alongshelf transport over the shelf is highly correlated with local wind stress explaining 80 of the variance in the low frequency transport during code 2 volume transport is best correlated with wind stress approximately 30 km to the south winds in the code area during spring and summer are characterized by strong and persistent upwelling favorable winds interrupted by shorter periods of weak winds regression analysis indicates that in the absence of wind a poleward barotropic current jet exists over the shelf with a maximum amplitude over the inner shelf in the code area an upwelling favorable wind counters this jet over the shelf so that the alongshore flow is everywhere equator ward during strong wind events since the maximum response to wind forcing is found at midshelf and near surface the mean current over the upwelling season is strongly sheared in both the vertical and cross shelf directions mean flow over the outer shelf is surface intensified and is directed offshelf and equatorward while the deeper flow at midshelf and through most of the water column over the inner shelf is directed poleward

a modeling study of the formation maintenance and relaxation of upwelling circulation on the northeastern south china sea shelf abstract we investigated persistent summer upwelling circulation in response to upwelling and downwelling favorable winds in the northeastern south china sea nscs we used a validated three dimensional ocean circulation model that was forced by realistic atmospheric fluxes and downscaled coupling of real time lateral fluxes we found that upwelling in the nscs was formed and maintained by the presence of an intensified westward along isobath pressure gradient force pgfm and bottom frictional effect that led to cross isobath currents over the unique nscs widened shelf the upwelling favorable pgfm and the frictional effect arose from the interaction between the eastward shelf current and the shelf topography these intrinsic upwelling dynamics in the nscs were largely sustained during episodic downwelling winds in the upwelling season because the retreat of the eastward shelf current from pre existing upwelling was significantly slowed by the unique widened shelf topography furthermore the upwelling dynamics could also be maintained and even developed during downwelling favorable winds when the eastward shelf current was sustained by the pumping of downstream outflow

new results and implications for lunar crustal iron distribution using sensor data fusion techniques remote measurements of the moon have provided iron maps and thus essential constraints for models of lunar crustal formation and mare basalt petrogenesis a bulk crustal iron map was produced for the equatorial region from apollo gamma ray agr spectrometer measurements and a global iron variation map from recent clementine spectral reflectance csr measurements both iron maps show bimodal distribution but have significantly different peak values and variations in this paper csr data have been recalibrated to pyroxene in lunar landing site soils a residual iron map is derived from the difference between agr bulk and recalibrated csr pyroxene iron abundances the most likely interpretation is that the residual represents ferrous iron in olivine this residual iron is anticorrelated to basin age with older basins containing less olivine suggesting segregation of basin basalt sources from a progressively fractionating underlying source region at the time of basin formation results presented here provide a quantitative basis for 1 establishing the relationship between direct geochemical gamma ray x ray and mineralogical near ir remote sensing data sets using sensor data fusion techniques to allow 2 simultaneous determination of elemental and mineralogical component distribution on remote targets and 3 meaningful interpretation of orbital and ground based spectral reflectance measurements when calibrated data from the lunar prospector mission are available mapping of bulk crustal iron and iron bearing soil components will be possible for the entire moon similar analyses for data from the near earth asteroid rendezvous near mission to asteroid 433 eros will constrain models of asteroid formation

the lunar regolith chemistry mineralogy and petrology the lunar regolith a several meter thick layer of unconsolidated debris forms the interface between the moon and its space environment the regolith forms from lithic sources by the destructional processes of comminution and the constructional processes of agglutinate formation in this manner a steady state soil can develop and will remain in a type of dynamic equilibrium until the system is disturbed by burial or mixing with new soil mixing takes place mainly on a local scale vertically through meters and horizontally over several kilometers lateral transport is a relatively inefficient process and therefore most of the lunar soil components were derived locally there is no evidence for preferential transport of the finer soil fractions relative to the coarser fractions the truly exotic derived at distances of tens of kilometers component is generally in low abundance 1 therefore remotely sensed data should provide a reasonably accurate picture of bedrock geology the chemical composition of the regolith varies with grain size the 10 m fraction is chemically fractionated from the bulk soil in most cases the 10 m fraction is enriched in al2o3 cao na2o k2o light rare earth elements and th and depleted in mgo feo mno and sc these systematics are largely a result of simple comminution with feldspar and friable mesostasis from local source rocks concentrating in the finest fraction there is evidence that agglutinate glass forms preferentially by fusion of the finest soil fractions therefore agglutinate glass like the 10 m soil fraction appears to be fractionated from bulk soil compositions highland soils are distinct from mare soils both chemically and petrologically soil samples collected near mare highland contacts are mixtures of the two lithologies mineral chemical systematics of monomineralic fragments in the lunar soil provide important clues to soil provenance they can in some cases sort out the highland mare contributions and in special cases can even further pinpoint a lithic source in theory lunar regolith cores can serve as solar probes recording the sun s activity over billions of years in practice this has generally not been the case the formation and evolution of most cores is still poorly understood for most we have not established how they formed for example how many depositional and erosional events were involved what the time span involved in the accretion of the sampled soil column was and how long that soil column has remained in situ without this information it is difficult if not impossible to read the sun s record more interdisciplinary studies on cores must be carried out before they can be used as solar probes

dynamics of wind driven upwelling off the northeastern coast of hainan island both observational and reanalysis sea surface temperature data reveal that upwelling occurs frequently off the northeastern coast of hainan island downstream of the change in topography off tongluo cape which cannot be attributed to the along shelf wind alone to identify dynamics of the upwelling we conduct a numerical experiment using an idealized topography that is simplified from the actual topography off the eastern and northeastern coasts of hainan island the result indicates that the upwelling downstream of the change in topography is associated with onshore cross isobath transport analysis of the vertically integrated momentum balance shows that the upwelling linked onshore transport is primarily intensified by the along isobath barotropic pressure gradient force pgt but is weakened by the along isobath baroclinic pressure gradient force pgc the along isobath pgt is linked to the advection of relative vorticity the bottom stress curl and the gradient of momentum flux in vorticity equation on the other hand the pgc related process is diagnosed by potential vorticity pv balance similar to the negative pv term from wind stress the negative pv terms of the joint effect of baroclinicity and relief and the baroclinic bottom pressure torque weaken the upwelling linked onshore transport downstream of the change in topography the onshore transport is enhanced by the positive pv from bottom stress in addition the cross isobath forces play an important role in upwelling intensification in the shallow nearshore region

comparative geochemistry of apollo 16 surface soils and samples from cores 64002 and 60002 through 60007 new data are presented for the concentrations of 23 to 27 elements in nine apollo 16 surface soil samples two subsplits each of 12 splits of core 60002 7 and one subsplit each of 10 splits of drive tube 64002 the surface soils are generally similar to other surface soils collected at their respective stations all ten 64002 samples are similar to each other and to the station 4 surface soils and distinctly different from soils at other stations high iron concentrations previously reported for these same subsplits of 60002 7 result primarily from meteoritic metal one sample from each core is contaminated by stainless steel the recently proposed ferroan anorthositic norites are required to explain the soil compositions a yet uncharacterized component with high concentrations of na sr and eu is also needed

variability of circulation induced by the separation of gaspe current in baie des chaleurs canada observational studies the observed variability of summer circulation in the baie des chaleurs bdc canada is found to be largely controlled by the intrusion separation processes of a coastal jet gaspe current gc at the bay entrance an analysis of hydrographic and current meter data showed that the mean counter wind cyclonic circulation in the bdc from spring to the beginning of the cooling season in 1991 was ascribed to the westward intrusion of the gc the forcing mechanism of the gc on the bdc was determined by the characteristics of the coastal jet separation under the intrusion regime the gc entered into the bdc along the north coast of the bay suppressed the local wind driven eastward currents and formed a cyclonic circulation in the bay under the separation regime gc mainly passed across the entrance of the bdc with the formation of an anticyclonic recirculation at the lee of the jet near the bay entrance and a weaker cyclonic circulation in the bay dynamics of the boundary current separation is utilized to reason the observed variability of flow field in the bdc

seasonal circulation over the catalan inner shelf northwest mediterranean sea 1 this study characterizes the seasonal cycle of the catalan inner shelf circulation using observations and complementary numerical results the relation between seasonal circulation and forcing mechanisms is explored through the depth averaged momentum balance for the period between may 2010 and april 2011 when velocity observations were partially available the monthly mean along shelf flow is mainly controlled by the along shelf pressure gradient and by surface and bottom stresses during summer fall and winter the along shelf momentum balance is dominated by the barotropic pressure gradient and local winds during spring both wind stress and pressure gradient act in the same direction and are compensated by bottom stress in the cross shelf direction the dominant forces are in geostrophic balance consistent with dynamic altimetry data

rootless serpentinite seamount on the southern izu bonin forearc implications for basal erosion at convergent plate margins we use multichannel seismic reflection mcs and gravity data from the southern izu bonin convergent plate margin to test for tectonic erosion the hahajima seamount is a serpentinite seamount on the izu bonin forearc this serpentinite body likely originated from the mantle wedge beneath the izu bonin arc but it subsequently detached mcs data and gravity modeling demonstrate that the ogasawara plateau on the incoming pacific plate has been partly subducted beneath the hahajima seamount our analysis indicates that the hahajima seamount is a rootless serpentinite seamount and the root of the serpentinite body was eroded during subduction of the western edge of the ogasawara plateau structural features of the hahajima seamount the ogasawara plateau and the philippine sea plate suggest that tectonic erosion particularly basal erosion has been occurring throughout this area

processes of seamount subduction in the mariana and izu bonin trenches abstract morphology of oceanic plate seamounts near the mariana and izu bonin trenches in the western pacific indicates that the response of these seamounts to subduction related tectonic processes is a function of two factors seamount size and the degree of fracturing of the surrounding sea floor as the oceanic plate bends prior to subduction seamounts smaller than about 40 km in diameter are fractured on the same scale as or to a greater degree than the surrounding sea floor larger seamounts 40 100 km in diameter show less evidence of fracturing prior to subduction since there is no evidence of accretion of large amounts of plate material onto the mariana fore arc it is probable that plate seamounts are subducted at least partially intact the subduction of plate seamounts beneath the mariana arc may be responsible for some areas of uplift on the outer mariana fore arc broad areas of uplift on the mariana and bonin fore arcs are associated in some cases with apparent subduction of ridges of large greater than 100 km diameter seamounts the large seamounts at the western end of the michelson ridge appear to be breaking up into a series of blocks separated by en echelon fractures that are oriented oblique to the trench axis and lie in line with the convergence direction of the pacific plate such large seamounts may interrupt normal subduction processes this suggestion is consistent with the occurrence of gaps in benioff zone seismicity where chains of such large seamounts abut the trenches it appears likely that these large seamounts are also eventually subducted although they may first undergo significant fracturing and reorientation

upwelling induced by the frictional stress curl and vertical squeezing of the vortex tube over a submerged valley in the east china sea we conducted a process oriented modeling study to investigate the characteristics and dynamics of the prominent upwelling over a vast submerged valley in the east china sea ecs the valley is inversely funnel shaped with the west bank and the east bank oriented in the north south direction a cross bank upward transport occurred along the west bank it intensified northward and peaked around the head of the valley an along bank southward pressure gradient force pgf formed the cross bank geostrophic transport for the upwelling over the valley the pgf reached its maxima at the head of the valley our momentum and vorticity dynamic analyses revealed that a bottom stress curl mainly contributed the pgf along the west bank at the same time both the bottom stress curl and the nonlinear vorticity advection contributed to the pgf around the head the bottom stress curl was due to the bottom shear vorticity of the coastal current and the curvature vorticity around the head the nonlinear vorticity advection formed because of the vertical squeezing of vortex tube as the current flowed over the valley the nonlinearity mainly affected the pgf around the head whereas the bottom stress curl contributed to the pgf over the entire valley the ratio of the nonlinear to frictional contributions to the pgf increased as the coastal current intensified our study demonstrates that the pgf that drives the upwelling over the valley is the combined result of the nonlinearity due to vertical squeezing of vortex tube and bottom frictional effects

andean tectonics as a consequence of sea floor spreading abstract the evolution of sea floor spreading directions and rates in the southeast pacific shows a close relationship with the andean structural directions and the plutonic episodicity as well as the succession of short compressive orogenic phases alternating with relatively longer periods of extension the orogenic periods coincided with the beginning of periods of relatively higher rates of plate convergence immediately after periods of relative quiescence with the following periodicity 110 85 76 70 63 60 49 45 35 33 16 13 7 m y the presence of oceanic structures as aseismic ridges or fracture zones produces weak benioff zones shallow and poorly defined without a corresponding active volcanism on the other hand ancient continental structures such as the precambrian paleozoic orogenic belts have active volcanism and neat deep and well developed benioff zones

ancient multiring basins on the moon revealed by clementine laser altimetry analysis of laser altimetry data from clementine has confirmed and extended our knowledge of nearly obliterated multiring basins on the moon these basins were formed during the early bombardment phase of lunar history have been filled to varying degrees by mare lavas and regional ejecta blankets and have been degraded by the superposition of large impact craters the mendel rydberg basin a degraded three ring feature over 600 kilometers in diameter on the lunar western limb is about 6 kilometers deep from rim to floor only slightly less deep than the nearby younger and much better preserved orientale basin 8 kilometers deep the south pole aitken basin the oldest discernible impact feature on the moon is revealed as a basin 2500 kilometers in diameter with an average depth of more than 13 kilometers rim crest to floor this feature is the largest deepest impact crater yet discovered in the solar system several additional depressions seen in the data may represent previously unmapped ancient impact basins

petrologic comparisons of cayley and descartes on the basis of apollo 16 soils from stations 4 and 11 petrologic aspects of the cayley and descartes formations are reviewed in the light of new data on apollo 16 soils specific comparison of the modal abundances of lithic fragments in drive tube sample 64001 2 from the slopes of stone mountain station 4 and in soil 67941 from the north ray crater rim station 11 shows that melt rocks especially poikilitic rocks are more abundant at station 4 than at station 11 the reverse is true for fragmental breccias such lithologic differences suggest that stations 4 and 11 do not belong to the same geologic formation metamorphosed breccias are pervasive in both the formations and may represent a local component that has been reworked and diluted as fresh materials were added lithologic compositions inferred from the study of soil samples are different from lithologic compositions inferred from the study of rake samples or breccia clasts this difference may be related to a mixing of material of different grain size distributions the petrology of soils at the apollo 16 site may not accurately reflect original material associated with either the descartes or the cayley formation because of extensive mixing with local material

provenance analysis of muddy sandstones abstract a new approach to determine the precursor grains of detrital and diagenetic clay in sandstones requires a reiterative use of optical microscopy and electron beam microanalysis excluding muddy sandstone successions from analysis of the siliciclastic fill of a basin may lead to incomplete if not erroneous provenance interpretation because of biased samping of the sediments to minimize problems inherent in muddy sandstones we have combined a two tier optical modal analysis with energy dispersive x ray analysis edxa to identify precursors of clay this is a new method of point counting and estimating the mineral compositions of muddy sandstones because we apply the principle of identifying the mineral under the cross hair albeit on a micron scale we call this the new or modified g zzi dickinson method calculations of mass balance type using the results of this new method may be performed to reconstruct the original composition of the parental detrital material we have used muddy siliciclastic rocks outcrop and core samples of siltstones and sandstones from the oligocene intra arc medicine lodge beds of southwestern montana usa for this study eocene volcanic rocks of the challis region and thrusts that have transported pre cenozoic sedimentary and metasedimentary rocks in this region were the sources of the siliciclastic sediments results of modal analysis by the standard gazzi dickinson method and by the new modified gazzi dickinson method using both optical and edxa on a micron scale plot in different clusters in a qfl diagram our results show that the standard gazzi dickinson method is not truly independent of grain size even in the context of provenance analysis on the other hand the modified version has the promise of achievi g truly mineralogical modal petrologic analysis of detrital rocks of any grain size

subsurface recirculation and larval retention in the lee of a small headland a variation on the upwelling shadow theme 1 the interaction of alongshore coastal currents with large headlands has been shown to increase the retention of planktonic organisms through the formation of headland eddies or upwelling shadows in their lee this study investigates the circulation within bodega bay in the lee of a small headland in an upwelling region and the potential for retention of plankton during the upwelling season of 2004 time series of temperature and velocity were recorded throughout bodega bay conductivity temperature depth ctd surveys were conducted and surface drifters were released during upwelling downwelling and relaxation conditions postlarval settlement was monitored daily over two periods coinciding with ctd surveys under strong upwelling favorable conditions wind driven surface currents were equatorward both offshore and throughout the bay however there was significant current shear along the eastern shore of the bay where cold bottom waters move poleward counter to the direction of the wind driven surface flow during downwelling and relaxation conditions flow was poleward throughout the water column along the eastern shore of the bay postlarvae settled during all wind conditions but greatest settlement was observed at the onset of upwelling favorable conditions while no typical upwelling shadow is evident in the lee of the bodega headland subsurface recirculation driven by the alongshore flow past bodega head may facilitate the retention of plankton in the bay previous studies have generally focused on large headlands however it is likely that other small embayments in the lee of small headlands may also provide retention opportunities for planktonic organisms in upwelling regions

numerical model simulations of continental shelf flows off northern california abstract the three dimensional circulation on the continental shelf off northern california in the wind events and shelf transport west experiment region during summer 2001 is studied using the primitive equation regional ocean modeling system roms the simulations are performed with realistic topography and initial stratification in a limited area domain with a high resolution grid forcing consists of measured wind stress and heat flux values obtained from a west surface buoy the general response shows a southward coastal upwelling jet of up to 1 m s 1 and a weakening or reversal of currents inshore of the jet when upwelling winds relax model results are compared to west moored velocity and temperature measurements at five locations to codar surface current observations between pt reyes and bodega bay and to hydrographic measurements along shipboard survey lines the model performs reasonably well with the highest depth averaged velocity correlation 0 81 at the inshore mooring 40 m water depth and lowest correlation 0 68 at the mid depth mooring 90 m depth the model shows generally stronger velocities than those observed especially at the inshore moorings and a lack in complete reversal of southward velocities observed when upwelling winds relax the comparison of surface velocities with codar measurements shows good agreement of the mean and the dominant mode of variability the hydrography compares closely at the southern and northern edges of the survey region correlation coefficients between 0 90 and 0 97 with weaker correlations at the three interior survey lines correlation coefficients between 0 44 and 0 76 mean model fields over the summer upwelling period show slight coastal jet separation off pt arena and significant separation off pt reyes the cape regions also experience relatively strong bottom velocities and nonlinearity in the surface flow across shelf velocity sections examined along the shelf reveal a double jet structure that appears just north of bodega bay and shows the offshore jet strengthening to the south we examine the dynamics during an upwelling and subsequent relaxation event in may 2001 in which the west measurements show evidence of a strong flow response the alongshelf variability in the upwelling and relaxation response introduced by pt reyes is evident analysis of term balances from the depth averaged momentum equations helps to clarify the event dynamics in different regions over the shelf a clear pattern in the nonlinear advection term is due to the spatial acceleration of the southward jet around the capes of pt arena and pt reyes during upwelling results from a three dimensional lagrangian analysis of water parcel displacement show significant southward displacement in the coastal jet region including a strong signal from the double jet alongshelf variability in parcel displacements and upwelling source waters due to the presence of pt arena and pt reyes is also apparent from the lagrangian fields a cyclonic eddy like recirculation feature offshore of pt arena prior to the upwelling event causes large patches of onshore displaced parcels additionally across shelf variability in the response of water parcels along the d line includes decreased vertical displacement and increased alongshelf displacement in the offshore direction

subinertial currents on the southern califoinia shelf abstract subinertial currents on the southern california shelf are investigated using observations from a current meter array deployed near san diego during the summer fall and winter of 1978 79 this region is characterized by weak winds order 1 2 m s 1 and thus other driving mechanisms for the subinertial currents may be important a simplified depth averaged longshore momentum equation consisting of a balance between current accelerations the adjusted sea level asl gradient and the wind and bottom stress is examined the asl gradient is estimated using sea level and atmospheric pressure observations separated by 350 km a linear parameterization of the bottom stress is used with a drag coefficient of 5 10 4 m s 1 during fall and winter the first order balance of terms in the longshore momentum equation over the inner shelf 15 m depth is between the wind and bottom stress over the outer shelf 60 m the primary balance is between the asl gradient and the bottom stress at midshelf 30 m bo

poleward propagating subinertial alongshore surface currents off the u s west coast 1 the network comprising 61 high frequency radar systems along the u s west coast uswc provides a unique high resolution and broad scale view of ocean surface circulation subinertial alongshore surface currents show poleward propagating signals with phase speeds of o 10 and o 100 300 km d 1 that are consistent with historical in situ observations off the uswc and that can be possibly interpreted as coastally trapped waves ctws the propagating signals in the slow mode are partly observed in southern california which may result from scattering and reflection of higher mode ctws due to curvature of shoreline and bathymetry near point conception california on the other hand considering the order of the phase speed in the slow mode the poleward propagating signals may be attributed to alongshore advection or pressure driven flows a statistical regression of coastal winds at national data buoy center buoys on the observed surface currents partitions locally and remotely wind forced components isolates footprints of the equatorward propagating storm events in winter off the uswc and shows the poleward propagating signals year round

structure of the collision zone between bougainville guyot and the accretionary wedge of the new hebrides island arc southwest pacific multichannel seismic reflection data show the structure that develops within an island arc guyot collision zone the bougainville guyot fills the new hebrides trench stands about 3 km above the abyssal ocean plain and is capped by a broad platform that is underlain by a parallel bedded sequence probably lagoon and reef rocks a thick debris apron made up of unconsolidated sediment underlies the unsubducted part of the lower guyot flank and possibly the subducted flank as well the contact zone between the arc and the north and east sides of the guyot is marked by discontinuous antiforms that include reflective thrust faulted rocks that may have been derived from the guyot the extent of collision deformation to the arc and guyot depends in part on the contrast in compressibility and viscosity between these features we propose that the high drag subcircular guyot evolves during collision into a more streamlined shape streamlining may be achieved by processes like 1 bulk deformation of the guyot by thrust faulting and sediment compaction 2 ripping away of projecting parts of the guyot and blunting sharp edges tectonic erosion like that formed by the limestone cap and 3 formation of a boundary layer between the guyot and the arc that is made up of water rich mobilized units of soft sediment we draw an analogy between some features of glacial origin and the subducted part of a guyot if the bulk of the guyot is low strength especially in view of the thick debris apron then the guyot may behave like till that was overridden by a glacier and forms a drumlin an elongated blunt faced streamlined feature thrust faults evident in the guyot may indicate deformation that leads toward a streamlined shape and not necessarily to accretion of guyot rocks

multi beam surveys of the michelson ridge guyots subduction or obduction abstract this is the first graphic presentation of the michelson ridge in its entirety from a total coverage multi beam survey the ridge splits the izu and bonin trenches is comprised of four guyots and is anomalous to the strike of all other ridges heretofore discovered in the pacific ocean the ridge is obducting offscraping onto the philippine plate instead of subducting

coulomb wedge model applied to the subduction of seamounts in the japan trench results from the french japanese kaiko exploration program of the japan trench and complementary data are used to propose a model of subduction of seamounts examples in two seamount chains one at the junction between the japan and kuril trenches and the other in the southern part of the japan trench off inubo cape illustrate the stages of subduction the japan trench margin evolved as a homogeneous wedge of deformable noncohesive coulomb material during seamount subduction this is illustrated by the subduction of the daiichi kashima seamount in the southern japan trench our model predicts that the first consequence of seamount subduction is a compressive thickening of the toe of the wedge above the advancing flank of the seamount because of the oversteepening of the rigid base of the wedge this agrees with our observations in the daiichi kashima area this thickening shifts landward across the wedge with the advancing flank of the seamount erosion dominates the wedge above the trailing flank of the seamount because of the corresponding understeepening of the rigid base of the wedge a reentrant of the toe of the wedge is thus created it is largest when the oceanic flank of the seamount coincides with the base of the landward slope at this time the trench axis will probably have an abnormally large amount of sediments as illustrated at the junction between the japan and kuril trenches after the subduction of the seamount the edge of the wedge should progressively move back to its initial location frontal accretion is absent or very limited

x ray digital imaging petrography of lunar mare soils modal analyses of minerals and glasses it is essential that accurate modal i e volume percentages of the various mineral and glass phases in lunar soils be used for addressing and resolving the effects of space weathering upon reflectance spectra as well as for their calibration such data are also required for evaluating the resource potential of lunar minerals for use at a lunar base however these data are largely lacking particle counting information for lunar soils originally obtained to study formational processes does not provide these necessary data including the percentages of minerals locked in multi phase lithic fragments and fused soil particles such as agglutinates we have developed a technique for modal analyses sensu stricto of lunar soils using digital imaging of x ray maps obtained with an energy dispersive spectrometer mounted on an electron microprobe a suite of nine soils 90 to 150 micrometers size fraction from the apollo 11 12 15 and 17 mare sites was used for this study this is the first collection of such modal data on soils from all apollo mare sites the abundances of free mineral fragments in the mare soils are greater for immature and submature soils than for mature soils largely because of the formation of agglutinitic glass as maturity progresses in considerations of resource utilization at a lunar base the best lunar soils to use for mineral beneficiation i e most free mineral fragments have maturities near the immature submature boundary is feo approximately or 30 not the mature soils with their complications due to extensive agglutination the particle data obtained from the nine mare soils confirm the generalizations for lunar soils predicted by l a taylor and d s mckay 1992 lunar planet sci conf 23rd pp 1411 1412 abstract

the relative importance of wind strength and along shelf bathymetric variations on the separation of a coastal upwelling jet abstract a high resolution numerical model with idealized topography is used to investigate the degree to which a coastal upwelling jet separates from the shelf as it flows around a submarine bank depending on the wind strength and the horizontal scale of the bank experiments were run using several wind forcing magnitudes and submarine banks with different geometries so as to explore a wide range of the flow strength as measured by the rossby number ro and the ratio of the squares of the internal rossby radius of deformation and curvature of the topography as denoted by the burger number bu the intensity of the jet separation is strongly dependent on both parameters with maximum separation with increasing ro and bu close to 1 when large amounts of upwelled water are exported toward deeper waters for small bu separation is minimal and independent of ro for high ro the degree of separation decreases at large bu since the bank acts only as a small perturbation to the flow term balances in the a

observations of divergence and upwelling around point loma california 1 historical records of near surface water temperatures in the southern californian bight often show a preferential cooling in the lee of headlands such as point dume palos verdes and point loma at times this cooler water is associated with an increase in chlorophyll a as is evident in satellite images of ocean color from the region here we combine hydrographic data from a 1 day cruise aboard the rv roger revelle a precursor to the 0304 california cooperative oceanic fisheries investigations calcofi cruise with high frequency hf radar codar measurements satellite images and long term thermistor records of near surface temperature to identify a small scale isolated upwelling in the lee of point loma 32 5 n associated with the more saline water downstream of the headland are higher nutrient concentrations an increase in chlorophyll a concentration and a bloom of chain forming diatoms indicative of a mature upwelling system it is suggested that this upwelling is not primarily due to local or remote wind forcing but rather to the divergence of the prevailing southerly flow as it passes the point loma headland time series of surface vorticity calculated from hf radar measurements of sea surface velocity show that as the flow separates from the headland relative vorticity increases offshore of the cape inshore the time series of divergence convergence shows a tendency toward divergence at the surface indicating a preferential upwelling which appears to raise the thermocline thus resulting in a flux of cold nutrient rich water to the surface in the presence of high nutrients and light photosynthetic organisms bloom in these upwelled waters as they are advected away from the headland and offshore by the prevailing surface currents

on the transport of buoyant coastal plumes abstract the role of discharge conditions and shelf geometry on the transport of coastal plumes is studied with a fully nonlinear primitive equation hydrodynamic model the physical setting is an estuarine channel with a small discharge rossby number by simulating different discharge magnitudes buoyant plumes are shown to be succinctly described by a simple coastal front model three results emerge from the model analysis first the plume transport is given by t 0 g ph2 2f where 0 is a parameter dependent on the ratio of the front and the plume widths g p is the plume reduced gravity h is the plume maximum depth and f is the coriolis parameter second this model links the plume transport directly to upstream river conditions with t qr where qr is the river outflow and is a parameter that relates to entrainment the geometry of the plume front and shelf slope and the fraction of freshwater carried downshelf third these equations reduce to analytic results previously established for

mapping the feo and tio2 content of the lunar surface with multispectral imagery the derivation of quantitative elemental concentrations from multispectral imaging of the moon has long been a goal of lunar remote sensing concentration maps at the spatial resolutions available from the recent clementine mission would provide a revolutionary new tool for understanding the origin and evolution of the lunar crust lucey et al 1995 presented a method for extracting the concentration of fe from multispectral imaging of the moon this paper examines and quantifies important aspects ofthat technique left unexamined by lucey et al which had the potential to severely limit its utility these aspects include the effects of maturity grain size mineralogy shading due to topography and the presence of glass we also present a new algorithm for derivation of tio2 from multispectral imaging of both mare and highland units we find that both techniques are only weakly sensitive to maturity and that they have about 1 wt accuracy based on examination of the spectral properties and compositions of resolved lunar sampling stations presented by blewett et al 1997 we also discuss these findings in the context of two contrasting views of the effect of composition on lunar spectral properties presented by pieters and coworkers and hapke and coworkers we find the view of hapke and coworkers to be more consistent with our observations using a global mosaic of clementine multispectral data and these element derivation algorithms we find that the global modal abundance of feo is 4 5 wt 1 wt and the global modal abundance of tio2 is 0 45 wt 1 wt

was the laramide orogeny related to subduction of an oceanic plateau numerous models have been presented to explain the late cretaceous early cenozoic laramide orogeny which affected the foreland region of the western cordillera within the us1 the most attractive models invoke low angle subduction2 4 which can develop for various reasons5 6 evidence from south america indicates that one such reason may be the subduction of buoyant ocean floor we here extend the low angle subduction models by attributing the shallowing of the subduction angle during the laramide orogeny to subduction of a large oceanic plateau of anomalously thick and buoyant oceanic crust pacific plate history indicates that a twin to the hess rise may represent the oceanic plateau that triggered laramide events

alongshore momentum balance analysis on a cuspate foreland 1 nearshore measurements of waves and currents off cape hatteras north carolina u s a are used to investigate depth averaged subtidal circulation and alongshore momentum balances in the surf and inner shelf region around a cuspate foreland data were collected on both sides of the cape representing shorefaces with contrasting shoreline orientation north south vs northwest southeast subjected to the same wind forcing in the nearshore the subtidal flow is aligned with the local coastline orientation while at the cape point the flow is along the existing submerged shoal suggesting that cape associated shoals may act as an extension of the coastline alongshore momentum balance analysis incorporating wave current interaction by including vortex and stokes coriolis forces reveals that in deep waters surface and bottom stress are almost in balance in shallower waters the balance is complex as nonlinear advection and vortex force become important furthermore linearized momentum balance analysis suggests that the vortex force can be of the same order as wind and wave forcing farther southwest of cape hatteras point wind and wave forcing alone fail to fully explain subtidal flow variability and it is shown that alongshore pressure gradient as a response to the wind forcing can close the momentum balance adjacent tide gauge data suggest that the magnitude of pressure gradient depends on the relative orientation of local coastline to the wind vector and in a depth averaged sense the pressure gradient generation due to change in coastline orientation even at km length scale is analogous to the effect of alongshore variable winds on a straight coastline

mixing levels the apennine front soil component and compositional trends in the apollo 15 soils variations in concentrations of lithophile elements in samples of apollo 15 soil can be explained in terms of only four chemical components three components are represented by extrusive rock types found at the apollo 15 site mare basalt kreep basalt and the pyroclastic green glass associated with breccia 15426 the fourth component the highlands component can be represented by soil from the apennine front particularly the soil obtained from the 55 57 cm depth interval of station 2 core 15007 8 among samples of apennine front soil this one appears to be the least contaminated by mare materials and may be our most typical sample of the apennine front highlands although soil fron the apennine front is itself a complex mixture of many types of highlands rocks it behaves as a single component with respect to mixing with the other three rock type components the various subcomponents of the apennine front soil e g melt rock and anorthositic norite that have been used in some mixing models are not required as discrete components in order to explain the compositional variation among samples of apollo 15 soil most of this compositional variation results from mare highlands mixing i e apennine front soil with mare basalt kreep basalt which probably derives from local possibly unexposed sources is also a variable component of the soil and is most prevalent in the soil from stations lm 6 and 9

wind relaxation and a coastal buoyant plume north of pt conception ca observations simulations and scalings in upwelling regions wind relaxations lead to poleward propagating warm water plumes that are important to coastal ecosystems the coastal ocean response to wind relaxation around pt conception ca is simulated with a regional ocean model roms forced by realistic surface and lateral boundary conditions including tidal processes the model reproduces well the statistics of observed subtidal water column temperature and velocity at both outer and inner shelf mooring locations throughout the study a poleward propagating plume of southern california bight water that increases shelf water temperatures by 5 c is also reproduced modeled plume propagation speed spatial scales and flow structure are consistent with a theoretical scaling for coastal buoyant plumes with both surface trapped and slope controlled dynamics plume momentum balances are distinct between the offshore 30 m depth region where the plume is surface trapped and onshore of the 30 m isobath within 5 km from shore where the plume water mass extends to the bottom and is slope controlled in the onshore region bottom stress is important in the alongshore momentum equation and generates vertical vorticity that is an order of magnitude larger than the vorticity in the plume core numerical experiments without tidal forcing show that modeled surface temperatures are biased 0 5 c high potentially affecting plume propagation distance and persistence

modal mineralogic distribution in the regolith at apollo landing sites we have reduced published petrographic data on 90 surface soils from apollo sample return sites in terms of olivine pyroxene plagioclase and opaques mostly ilmenite for a best estimate to do so we have recast the best estimates of modal mineralogy of mare and highland lithic fragments to add to the monomineralic population of soils we have assumed that agglutinates and regolith breccias mimic those of local soils we have thus arrived at a working summary of mineral distribution in areas traversed by apollo astronauts in addition we have proportioned these averages to geologic units in the premission maps to estimate the average mineral composition of areas up to 30 km 30 km around the landing sites the calibration and testing of remote sensing signals for planetary exploration depend largely on the ground truth provided by lunar samples chemical compositions and the modal distribution of petrologic constituents of most lunar soils are known these can be grouped spatially to represent areas that coincide with pixels of remote sensing observations and measurements signals from certain petrographic constituents such as lithic fragments breccias and agglutinates however are understandably ambiguous petrologic inference from remote sensing signals would be facilitated if petrographic data from actual samples were to be reduced and expressed as sums of single phases occurring in each pixel of observation

ogasawara plateau multi beam sonar bathymetry and possible tectonic implications the ogasawara plateau bathymetry in the northwest pacific ocean is presented by u s naval oceanographic office multi beam sonar data the plateau is significant in that it separates the izu and bonin trenches and may be obducted onto the overriding plate and or jamming the subduction zone the high resolution bathymetry suggests morphologic evidence of faulting within and possible uplifting on the approximately 20 000 km 2 features

seasonal variability and coastal upwelling near cape santa marta brazil 1 the santa marta grande cape csm area a relatively steep and narrow continental shelf off southeast brazil is under the influence of the brazil current and intense seasonal variations of the wind field that affect the composition of water masses and their circulation hydrographic data satellite derived wind stress and numerical simulations are used to characterize the seasonal and shorter period variability of the oceanographic conditions off csm in the area between 27 s and 30 s the study is focused on the upwelling episodes and the dynamical mechanisms associated with these events field data and numerical results indicate significant seasonal changes in the oceanographic structure the water mass composition and the dynamical balance during fall and winter when southwesterly winds prevail and the frequency of meteorological frontal systems increases the region is characterized by waters of continental origin the plata plume water ppw during spring and summer deeper waters reach the surface layer due to the action of northeasterly winds coastal upwelling events are revealed by surface temperature minima observed south of csm synoptic data show that these events occur in pulses associated with changes in the wind direction analysis of the numerical results shows that this particular location of the upwelling band results from the synergy between shelf break upwelling and the regional shelf circulation induced by the northeasterly winds both of which are modulated by changes in the coastline orientation and shelf width

mineralogy of the lunar crust results from clementine received 1997 december 5 accepted in revised form 1998 september 15 abstract the central peaks of 109 impact craters across the moon are examined with clementine ultraviolet visible uvvis camera multispectral data the craters range in diameter from 40 to 180 km and are believed to have exhumed material from 5 30 km beneath the surface to form the peaks including both upper and lower crustal rocks depending on whether craters have impacted into highlands or basins representative five color spectra from spectrally and spatially distinct areas within the peaks are classified using spectral parameters including key ratio which is related to mafic mineral abundance and spectral curvature linked to absorption band shape which distinguishes between low and high ca pyroxene and olivine the spectral parameters are correlated to mineralogical abundances related in turn to highland plutonic rock compositions the derived rock compositions for the various central peaks are presented in a global map from these results it is evident that the lunar crust is compositionally diverse both globally and at local 100 m scales found within individual sets of central peaks although the central peaks compositions imply a crust that is generally consistent with previous models of crustal structure they also indicate a more anorthositic crust than generally assumed with a bulk plagioclase content of 8 1 evolving from pure anorthosite near the surface towards more mafic low ca pyroxene rich compositions with depth comparable to anorthositic norite evidence for mafic plutons occurs in both highlands and basins and represent all mafic highland rock types however the lower crust is more compositionally diverse than the highlands with both a greater range of rock types and more diversity within individual sets of central peaks

global distribution of seamounts from seasat profiles bathymetrie profiles and contour charts have been used to study the distribution of seamounts in the deep ocean basins but only a small fraction of the seafloor has been sampled by ships at the present exploration rate it will take several centuries to map significant portions of the seafloor topography satellite altimetry which maps the topography of the equipotential sea surface is a promising tool for studying the gravity fields of seamounts because all ocean basins can be sampled in a couple of years using a model of a gaussian shaped seamount loading a thin elastic lithosphere we develop a new technique for measuring basic characteristics of a seamount from a single satellite altimeter profile the model predicts that the seamount diameter is equal to the peak to trough distance along the vertical deflection profile and that the overall diameter of the signature reveals the age of the lithosphere when the seamount formed moreover the model suggests that these two measurements are relatively insensitive to the cross track location of the seamount we confirm these model predictions using seasat altimeter profiles crossing 14 well surveyed seamounts in the pacific we then apply the measurement technique to 26 106 million kilometers of seasat profiles resulting in a new global set of seamount locations approximately one quarter of the seamounts identified in seasat profiles were previously uncharted modeling suggests that there is no direct relationship between the size of a seamount and its signature in the geoid therefore the set of locations is not a straightforward sampling of the total seamount population but is weighted toward seamounts which are poorly compensated a preliminary analysis indicates considerable variations in population density and type across the oceans most notable among them are the absence of seamounts in the atlantic variations in population density across large age offset fracture zones in the pacific the prevalence of small signatures in the indian ocean and the existence of linear trends in the large seamounts of the west pacific

relaxation from upwelling in the coastal ocean dynamics experiment a relaxation of the upwelling system on the northern california shelf occurs when upwelling favorable winds decay or reverse observations from the coastal ocean dynamics experiment are used to investigate this process with emphasis on the near surface temperature evolution models of relaxation warming are tested for the surface layer 0 30 m over midshelf with the result that the surface heat flux and poleward alongshelf advection can account for the observed temperature behavior onshore advection of the upwelled isopycnal field is a relatively unimportant contribution the warming patterns that are observed and which provide the gradients for the advective process have wedgelike shapes warmest inshore and in the south of the experimental area these patterns appear to be related to a topographic influence of point reyes possibly through the generation of gradients in the wind field remote advection of warm water from as far south as san francisco occasionally occurs as well the nature of the relaxation mechanism has general implications a new warm saline nutrient rich water mass may be formed in the surface layer since the warming processes are not the reverse of the cooling an important asymmetry is present it causes time variable upwelling to generate conditions very different from steady upwelling a new upwelling front is created during each event with upwelled water seaward of it and reversed alongshelf flow contributes to the warming and exchange mechanisms the system cannot be described or understood without the irreversible processes during upwelling and relaxation or without a mixed layer

a modeling study of shelf circulation off northern california in the region of the coastal ocean dynamics experiment 2 simulations and comparisons with observations 1 this is the second part of a modeling study of wind forced flow on the continental shelf off northern california in the region 37 40 n of the coastal ocean dynamics experiment code gan and allen 2002 analyzed the shelf flow response to idealized wind stress forcing in a process oriented study the study here applies forcing from observed winds and heat flux for april may 1982 and compares the model results with moored current and temperature measurements the princeton ocean model pom is used in a three dimensional limited area domain with a high resolution curvilinear grid approximately 1 km horizontal spacing 60 vertical levels and realistic coastline and bottom topography the objectives of the study are to simulate the response of the shelf circulation field to time varying observed wind stress and heat flux to compare model results with oceanographic observations to establish confidence in the model and to subsequently analyze the model fields and the model dynamical balances to help understand the behavior of the observed flow the model variables show overall good agreement with corresponding observations similar to the conclusions by gan and allen 2002 it is found that the alongshore variability of upwelling is mainly controlled by the interaction of the wind forced shelf flow with the coastline and bottom topography different dynamical regimes in the regions north and south of the coastal capes formed by pt reyes and pt arena and in the more uniform region between these capes are identified and investigated the results demonstrate that the coastal capes play a dominant role in causing alongshore variability of the upwelling flow including the setup of an alongshore pressure gradient that forces northward currents during relaxation of southward upwelling favorable winds an analysis of the balance of terms in the equation for potential temperature indicates that across shore temperature advection is the major contributor to the cooling of coastal water during upwelling with a larger magnitude to the south of the capes to the north of the capes however alongshore temperature advection is the dominant contributor to the colder water near the coast

compositional variation in apollo 16 impact melt breccias and inferences for the geology and bombardment history of the central highlands of the moon abstract high precision data for the concentrations of a number of lithophile and siderophile elements were obtained on multiple subsamples from 109 impact melt rocks and breccias mostly crystalline from the apollo 16 site compositions of nearly all apollo 16 melt rocks fall on one of two trends of increasing sm concentration with increasing sc concentration the eastern trend lower sm sc mg fe and sm yb ratios consists of compositional groups 3 and 4 of previous classification schemes these melt rocks are feldspathic poor in incompatible and siderophile elements and appear to have provenance in the descartes formation to the east of the site the western trend higher sm sc mg fe and sm yb ratios consists of compositional groups 1 and 2 these relatively mafic kreep bearing breccias are a major component 35 of the cayley plains west of the site and are unusual compared to otherwise similar melt breccias from other sites in having high concentrations of fe ni metal 1 2 the metal is the carrier of the low ir au 0 3 chondritic siderophile element signature that is characteristic of the apollo 16 site four compositionally distinct groups 1m 1f 2db and 2nr of western trend melt breccias occur that are each represented by at least six samples compositional group 1 of previous classification schemes the poikilitic or lkfm melt breccias can be subdivided into two groups group 1m represented by six samples including 60315 is characterized by lower al2o3 concentrations higher mgo and alkali concentrations and higher mg fe and cr sc ratios than group 1f represented by fifteen samples including 65015 group 1m also has siderophile element concentrations averaging about twice those of group 1f and ir au and ir ni ratios that are even lower than those of other western trend melt rocks ir au 0 24 0 03 ci normalized at the mafic extreme of group 2 vha melt breccias the melt lithology occurring as clasts in feldspathic fragmental breccias from north ray crater group 2nr is compositionally distinct from the melt lithology of dimict breccias from the cayley plains group 2db in having higher concentrations of sc cr and heavy rare earth elements and lower concentrations of siderophile elements the distinct siderophile element signature high absolute abundances low ir au ratio suggest that the four groups of mafic melt breccia are all somehow related ratios of some lithophile elements also suggest that they are more closely related to each other than they are to melt breccias from other apollo sites however none of the breccia compositions can be related to any of the others by any simple process of igneous fractionation or mixing involving common lunar materials thus the origin of the four groups of mafic melt breccia is enigmatic if they were produced in only one or two impacts then a mechanism exists for generating regimes of impact melt breccia in a single impact that are substantially different from each other in composition for various reasons including the problem of delivering large volumes of four different types of melt to the apollo 16 site it is unlikely that any of these breccias were produced in basin forming impacts if they were produced in as many as four crater forming impacts then the unusual siderophile element signature is difficult to explain possible explanations are 1 1 the four groups of melt breccia all contain metal from a single earlier impact 2 2 they were each formed by related metal rich meteoroids or 3 3 some common postimpact process has resulted in metal of similar composition in each of four melt pools within a compositional group most intrasample and intersample variation in lithophile element concentrations is caused by differences among samples in the proportion of a component of normative anorthosite or noritic anorthosite in most cases this compositional variation probably reflects variation in clast abundance for group 2db and probably 2nr differences in abundance of a component of ferroan anorthosite estimated al2o3 32 accounts for the compositional variation for groups 1m and 1f the anorthositic component is more mafic estimated al2o3 26 some group 2 samples may be related by a troctolitic component of varying abundance

a sharper view of impact craters from clementine data the ultraviolet visible camera on the clementine spacecraft obtained high spatial resolution images of the moon in five spectral channels impact craters mapped with these multispectral images show a scale of lithologic diversity that varies with crater size and target stratigraphy prominent lithologic variations feldspathic versus basaltic occur within the south wall of copernicus 93 kilometers in diameter on the scale of 1 to 2 kilometers lithologic diversity at tycho 85 kilometers in diameter is less apparent at this scale although the impact melt of these two large craters is remarkably similar in this spectral range the lunar surface within and around the smaller crater giordano bruno 22 kilometers in diameter is largely dominated by the mixing of freshly excavated material with surrounding older soils derived from a generally similar feldspathic lithology

a modeling study of shelf circulation off northern california in the region of the coastal ocean dynamics experiment response to relaxation of upwelling winds 1 a two part modeling study of the wind forced flow on the continental shelf off northern california in the region 37 40 n of the coastal ocean dynamics experiment code is pursued this paper involves a process oriented study with idealized wind stress forcing gan and allen 2002 involves forcing with observed winds and heat flux for april may 1982 and comparison of model results with code observations a characteristic but previously unexplained response observed during code following the weakening or relaxation of southward upwelling favorable winds is the time dependent development of northward currents over the inner shelf next to the coast the presence of northward winds is not necessary for this occurrence the objective in this paper is to investigate the dynamics of the shelf flow response to upwelling wind relaxation events under idealized conditions in the basic case experiment a spatially uniform upwelling favorable southward wind stress of 0 1 pa is applied to the ocean initially at rest the stress is held constant for 10 days and then decreased linearly to zero over 3 days in response to the southward wind stress southward alongshore currents develop on the shelf accompanied by upwelling of cold dense water near the coast considerable spatial variability in the shelf flow clearly related to the alongshore variations in coastline and bottom topography is found the alongshore currents tend to separate from the coast south of capes and the coldest surface water is found at those locations as the winds decrease northward currents similar to those observed develop on the inner shelf next to the coast at many alongshore locations examination of the alongshore momentum balances shows that the northward currents are forced by a northward pressure gradient force associated with negative alongshore pressure gradients these pressure gradients are set up by the interaction of the wind forced flow with the alongshore variations in shelf topography in general negative alongshore pressure gradients intensified off pt reyes and pt arena by the gradient wind balance are found south of capes the negative pressure gradients geostrophically balance onshore flow at depth and upwelling is strengthened in these locations north of capes positive pressure gradients that are primarily in balance with nonlinear advective effects are found after the winds cease the forced across shelf circulation weakens and the resulting unbalanced negative pressure gradients south of the capes accelerate the alongshore currents northward processes with similar dynamics are found embedded in the more complex coastal ocean response to observed time varying winds by gan and allen 2002

clementine uvvis multispectral data and the apollo 17 landing site what can we tell and how well multispectral data obtained by the clementine mission are correlated to compositional and petrographic information for individual sample stations at the apollo 17 landing site the soils contain a variety of fe2 bearing phases in different proportions including low and high ca pyroxene olivine ilmenite and glass in the mare soils ilmenite carries a substantial proportion of the fe2 and in all soils glasses particularly agglutinates carry nearly as much or more fe2 as the silicates using an empirical calibration concentrations of feo and tio2 estimated from the ultraviolet visible uvvis data correlate well with measured compositions of surface soils yielding correlation coefficients of 0 94 and 0 95 respectively the ferrous absorption however is weak in the mostly submature to mature apollo 17 soils thus spectral curvature is useful only for investigating the mafic silicate mineralogy around fresh craters and deposits the effects of local topography cause significant variations in feo and tio2 derived from clementine uvvis data but do not impair first order geologic interpretations parameters derived from the uvvis data allow quantification of the composition and nature of the soils and by inference underlying rock formations and are consistent with the known geologic character of the landing site the highland regions along this part of the serenitatis rim are relatively feo rich partly as a result of abundant mafic impact melt breccia and partly from the addition of basaltic material in the form of impact debris and pyroclastic deposits at high elevations massif soils are rich in a mafic melt breccia component although slopes and areas mixed by small craters reveal a mixture of melt breccia and older highland material of anorthositic norite composition soils developed on hummocky deposits that postdate the massifs such as the sculptured hills have a similar range of compositions as the massifs elevated plains northeast of the sculptured hills are more mafic than the known impact melt breccias suggesting that they may also contain an older volcanic component sources of low ti basalt or very low ti basalt though not present in the immediate vicinity of the landing site occur east and northeast of taurus littrow valley and are readily identified using the uvvis data

abundance and distribution of iron on the moon the abundance and distribution of iron on the moon is derived from a near global data set from clementine the determined iron content of the lunar highlands crust 3 percent iron by weight supports the hypothesis that much of the lunar crust was derived from a magma ocean the iron content of lower crustal material exposed by the south pole aitken impact basin on the lunar farside is higher 7 to 8 percent by weight and consistent with a basaltic composition this composition supports earlier evidence that the lunar crust becomes more mafic with depth the data also suggest that the bulk composition of the moon differs from that of the earth9s mantle this difference excludes models for lunar origin that require the earth and moon to have the same compositions such as fission and coaccretion and favors giant impact and capture

dynamics of wind driven upwelling and relaxation between monterey bay and point arena local regional and gyre scale controls 1 in north and central california equatorward winds drive equatorward flows and the upwelling of cold dense water over the shelf during the midspring and summer upwelling season when the winds temporarily weaken the upwelling flows between point reyes and point arena relax becoming strongly poleward over the shelf analytical and numerical models are used to describe the effect of alongshore variability of winds bathymetry and basin scale pressure gradients on the strength of upwelling and its relaxation alongshore winds weaken to the south of point reyes and the shelf becomes narrower from point reyes to monterey bay both of these lead to reduced upwelling at and to the north of point reyes causing an alongshore gradient of temperature and density on the shelf these alongshore gradients lead to an along isobath pressure gradient over the shelf that drive the relaxation flows a simple analytical model is used to explain the dynamics magnitude and structure of the relaxation flows the modeling also suggests that the depth of origin of the upwelled waters and thus their temperature is controlled by the along isobath pressure gradient that exists over the continental slope this along slope pressure gradient is also responsible for the california undercurrent in this region this pressure gradient is not generated in a model of the californian coast extending from 32 n to 42 n and integrated for several months suggesting it is caused by dynamics whose spatial or temporal scales are larger than the californian coast and or longer than several months

subducting seamounts and deformation of overriding forearc wedges around japan abstract two subducting seamounts under inner trench slopes have been identified around japan on the basis of magnetic anomalies morphology and geological structure the first one is located under the foot of the inner trench slope at the junction between the japan trench and the kuril trench another one occurs beneath the slope slightly seaward of the tosabae the basement high at the trench slope break along the nankai trough off shikoku the magnetic anomalies of seamount origin are accompanied by the characteristic morphology of a forearc wedge i e a swell landward and a depression seaward the seamounts beneath the inner trench slopes have preserved magnetization showing reasonably consistent directions which suggests that the subducting seamounts have kept roughly their original shapes the morphology of the forearc wedge can be explained by a subducting seamount on the oceanic crust pushing the forearc material forward and upward deformation of the forearc wedge by the subducting seamount extends to the forearc basin the seamounts are stronger and less deformable than the inner slope material and are not offscraped onto inner trench slopes two other examples of deformed inner trench slopes around japan which can be explained by subduction of topographic highs are presented one example is a depression on the foot of the inner trench slope northeast of the junction between the kyushu palau ridge and the nankai trough another one is an area of complex morphology of the inner trench slope along the japan trench around the daiichi kashima seamount

cross shore variation of wind driven flows on the inner shelf in long bay south carolina united states and exceeded 0 1 n m 2 vertical mixing occurred the two layered flow pattern disappeared and currents were directed alongshore with the wind at all sites and throughout the water column in the fall near bed flows close to the shore water depth 7 m were often reduced compared to or opposed those measured farther offshore under southwestward winds a simplified analysis of the depth averaged alongshore momentum balance illustrates that the alongshore pressure gradient approached or exceeded the magnitude of the alongshore wind stress at the same time that the nearshore alongshore current opposed the wind stress and alongshore currents farther offshore in addition the analysis suggests that the wind stress is reduced closer to shore so that the alongshore pressure gradient is large enough to drive the flow against the wind

surface circulation in the gulf of california in summer from surface drifters and satellite images 2004 2006 surface drifters released in the gulf of california between june 2004 and august 2006 are used to describe the surface circulation in late spring and summer in the june to september mean there was a poleward coastal current on the shelf and slope of the mainland side of the gulf with mean speed 0 3 m s it reached the northern gulf and joined the cyclonic circulation typical of this zone in summer in the western half of the southern gulf the drifters presented recirculating currents that are due to mesoscale eddies that appear to dominate the surface circulation in summer in june 2004 the coastal current presented an enhancement event with mean speed around 0 60 m s and maximum 0 80 m s it took 20 days for a particular drifter to travel the 1000 km from the gulf entrance to the head this strengthening of the coastal current was apparent in chlorophyll a and sst satellite images the drifters following closely the intrusion of warm chlorophyll poor surface water from outside the gulf the drifters and the satellite images suggest that the current enhancement event lasted less than a month this mesoscale event was linked with a mesoscale remote forcing in the tropical pacific coast and with a mesoscale local forcing of the wind these events seem to occur every year and are probably important in carrying organisms and properties from the entrance to the whole length of the gulf

optical effects of space weathering the role of the finest fraction the optical properties of lunar softs are different than those of rocks from which they are derived as a consequence of lunar space weathering soils are darker and exhibit a distinctive red sloped continuum and weaker mineral absorption bands the accumulation of dark glass welded aggregates agglutinates has been thought to account for these optical effects of space weathering on lunar soils spectroscopic analyses of agglutinate separates and size fractions for a suite of lunar softs presented here indicate that the agglutinate paradigm is insufficient to fully account for lunar optical alteration it is the finest fraction of lunar soils 25 gm which constitute 25 wt that dominates the optical properties of the bulk soil unlike size fractions of most silicates for which the finest fraction is the brightest the lunar soil size fractions all have comparable albedos in the short wavelength visible in the near infrared however it is the finest fraction that exhibits the steep red continuum and weak absorption bands the properties of the finest fraction cannot be duplicated by preparing a fine fraction by grinding larger agglutinate rich soil particles these results suggest space weathering on airless bodies is dominated by surface correlated processes perhaps associated with the development of fine grained fe o on or near the surface of grains and the accumulation of the larger agglutinates is not necessarily required to account for lunar optical alteration

transport and retention in an upwelling region the role of across shelf structure abstract the paradox of upwelling is the relationship between strong wind forcing nutrient enrichment and shelf productivity here we investigate how across shelf structure in velocity and hydrography plays a role in the retention inshore and export offshore of particles such as nutrients plankton and larvae we examine the spatial structure of the coastal currents during wind driven upwelling and relaxation on the northern californian shelf the field work was conducted as part of the wind events and shelf transport west project a 5 year nsf coop funded study of the role of wind driven transport in shelf productivity off bodega bay northern california from 2000 to 2003 we combine shipboard velocity profiles adcp and water properties from hydrographic surveys during the upwelling season to examine the mean across shelf structure of the hydrography and velocity fields during three contrasting upwelling seasons and throughout the upwelling relaxation cycle we also present results from two winter seasons that serve as contrast to the upwelling seasons during all three upwelling seasons clear spatial structure is evident in velocity and hydrography across the shelf exemplified by current reversals inshore and the presence of a persistent upwelling jet at the shelf break this jet feature changes in structure and distance from the coast under different wind forcing regimes the jet also changes from the north of our region where it is a single narrow jet adjacent to the coast and to the south of our region where it broadens and at times two jets become evident we present observations of the california under current which was observed at the outer edge of our domain during all three upwelling seasons the observed across shelf structure could aid both in the retention of plankton inshore during periods of upwelling followed by relaxation and in the export of plankton offshore in the upwelling jet

quantitative mineralogical characterization of lunar high ti mare basalts and soils for oxygen production efficient lunar resource utilization requires accurate and quantitative evaluation of mineral and glass abundances distribution and extraction feasibility especially for ilmenite with this in mind true modal analyses were performed on high ti mare basalts and soils with x ray backscattered electron signal digital imaging techniques and these data indicate that 1 ilmenite concentrations are similar for basalts and immature submature soils with similar tio2 content 2 ilmenite liberation of crushed mare basalts and immature submature mare soils are comparable i e both contain similar amounts of free ilmenite and 3 because of impact melting and agglutination of primary minerals mature mare soils contain less ilmenite both free and attached modal analyses of magnetic separates of high ti mare basalts and soils show that 1 ilmenite was concentrated by a factor of 3 3 and 2 soil ilmenite was concentrated to factors of 1 7 2 3 the lower soil ilmenite separation efficiency is attributed to fe bearing agglutinitic glass and amorphous rinds adhered to soil particles mass yields of magnetically generated feedstocks were generally less than 5 wt in most cases calculation of oxygen yield as released by hydrogen gas reduction of ilmenite show that 1 beneficiated basalt will provide the most oxygen 8 10 because of higher ilmenite concentration 2 reduction of raw immature submature mare soils and basalts will produce similar amounts of lunar liquid oxygen llox 2 1 3 1 and 3 raw fe rich pyroclastic soil 74220 will provide more oxygen 5 4 than beneficiated high ti mare soils and half that of beneficiated high ti mare basalts high ti mare soils are attractive resources for lunar liquid oxygen llox production because of their unconsolidated nature high ilmenite abundance and widespread occurrence energy intensive excavation and comminution likely prohibits the basalt mining during early lunar occupation orange soils are important resources for llox and various volatile elements but slower reaction kinetics and glass sintering pose potential difficulties for large scale operations

three dimensional secondary surface geomorphology of submarine landslides on northwest pacific plate guyots abstract slump and debris slides form on seamounts as they grow age and are transported across the sea floor slump scars evident as amphitheater headwalls are a good morphological indicator where a landslide has occurred radical changes in the lower flank slope angles are also good indicators debris flows can be surmised by hummocky topography with the larger blocks being nearer the main edifice a cursory inspection of the pacific plate from younger to older shows 1 the hawaiian emperor ridge from loihi to suiko at 65 ma where the lower flank slopes increase with age 2 mammerickx seamount in the mapmakers on 140 ma crust out of the fractured region still showing moats and having no sign of landslides 3 castor and pollux guyots of the michelson ridge on 150 ma crust where the debris field size is added to or overprinted by later volcanics to 4 hunk jennings and jaybee guyots in the marcus wake seamounts on 160 ma crust where later fracture zone formation may have helped form landslides none of the older seamounts have been dated three dimensional views aid in the location and description of landslides

global petrologic variations on the moon a ternary diagram approach ltrbil kreep rich rocks 5j portions of the east limb and 4 highlands have considerable amounts of a mafic chondritic th ti component like mare basalt whose occurrences coincide with mapped concentrations of light plains that display dark halo craters the presence of this component supports the hypothesis that mare volcanism had occurred within this highland region before the end of final heavy bombardment

subtidal inner shelf currents off cartagena de indias caribbean coast of colombia 1 seasonal trends in inner shelf subtidal circulation off the coast of cartagena de indias colombia are examined through the analysis of current profiles hydrographic meteorological and satellite data collected from 1999 to 2002 during the dry season december april the water column is well mixed and along shelf currents flow southwestward following the steady trade winds in the rainy season may november the water column experiences continuous events of stratification and the along shelf currents flow northeastward opposing the weak southwestward winds in the dry season the along shelf circulation is mostly driven by wind forcing while in the rainy season the circulation is set by an alongshore baroclinic pressure gradient in the cross shelf direction upwelling conditions are observed most of the year and geostrophic balance conditions are found

clementine images of the lunar sample return stations refinement of feo and tio2 mapping techniques clementine uvvis images of the lunar sample return sites have been processed and used to produce refined calibrations for the iron and titanium determination algorithms of lucey et al 1995 1996 the high spatial resolution of the clementine data permits individual sampling stations to be resolved at the apollo 15 16 and 17 landing sites we find an excellent linear correlation between the spectral fe and ti parameters and the average feo and tio 2 contents of soils sampled at each site or station this correlation demonstrates that these techniques can confidently be applied to other areas of the moon the luna 24 site does not fit the ti relation found for other sites suggesting that either its sample is nonrepresentative or the reported landing coordinates are incorrect

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

wind relaxations and poleward flow events in a coastal upwelling system on the central california coast 1 when upwelling favorable winds weaken or relax in coastal upwelling systems prevailing equatorward currents often weaken and then reverse to form propagating poleward currents here the statistics of wind relaxations and poleward flow events along the south central california coast are derived using meteorological and oceanographic times series during 2000 2006 over the 7 year record 169 wind relaxations were observed about 1 every 2 weeks and 127 of these were followed by poleward flow events thermistor moorings and current profilers along the 15 m isobath at alegria point arguello point purisima and point sal recorded the poleward flows the poleward flows propagate northward at 10 30 km d 1 and appear as sequential temperature increases at the moorings wind relaxations occur throughout the year but are most frequent in september and least frequent in april when upwelling winds are strong and persistent poleward flows follow wind relaxations frequently during may through november and rarely in december and january sea level differences between santa monica and port san luis california decreased as winds relaxed consistent with forcing by alongshore pressure gradients temperature distributions at point arguello point purisima and point sal were skewed toward higher values because of the poleward flows the alongshore distance traveled by the poleward flows increased with duration of the wind relaxations and magnitudes of alongshore temperature and sea level differences prior to the relaxations

mesoscale surveys over the shelf and slope in the upwelling region near point arena california repeated mesoscale surveys of a 40 km wide 100 km long coastal region near point arena california were conducted during the upwelling season april august in 1981 and 1982 each survey included conventional conductivity temperature depth casts at standard locations over the continental shelf and slope between 38 n and 39 10 n and continuous operation of a doppler acoustic log to obtain velocity profiles in the 20 to 150 m depth range synoptic surveys covered the entire grid in 2 3 days winds were strongly favorable for upwelling during the three 1981 surveys and were weak or variable during the three 1982 surveys surface temperature and salinity fields reflect the influence of both the seasonal winds and day to day variations in the wind persistently low surface salinities offshore reflect the general southward advection of subarctic waters and sporadic low salinities over the inner shelf reflect north ward advection of local runoff through an intermittent narrow countercurrent along the coast circulation patterns during all but one of the surveys were very complex and included meandering equatorward flow cyclonic and anticyclonic eddies and inshore countercurrents the simple two dimensional equatorward baroclinic coastal jet usually associated with coastal upwelling was observed during only one of our surveys overall average fields are relatively simple they show broad equatorward surface flow a very weak inshore countercurrent and a definite poleward undercurrent at the shelf break average temperature salinity and density fields are generally congruent with the average flow pattern average isotherms and isohalines are not strictly parallel to the coastline south of the coastline bend at point arena they diverge gradually from the coast comparison of average sections calculated from 10 matched pairs of central and arena lines separated by 50 km shows there are systematic differences between them warmer fresher waters lie nearer shore and in shallower water off point arena than on the central line this suggests that the surface waters flowing past point arena have sufficient southward momentum to cross isobaths comparison of average velocity sections on these two lines shows some differences in structure since the variability is large these may not be significant comparison of the measured and geostrophic average shears suggests there is a significant ageostrophic component in the upper layers above 40 m it may be the signature of an average wind driven ekman spiral

copernicus crater central peak lunar mountain of unique composition olivine is identified as the major mafic mineral in a central peak of copernicus crater information on the mineral assemblages of such unsampled lunar surface material is provided by near infrared reflectance spectra 0 7 to 2 5 micrometers obtained with earth based telescopes the composition of the deep seated material comprising the copernicus central peak is unique among measured areas other lunar terra areas and the wall of copernicus exhibit spectral characteristics of mineral assemblages comparable to the feldspathic breccias returned by the apollo missions with low calcium orthopyroxene being the major mafic mineral

a new solution of a nonlinear model of upwelling abstract a two dimensional frictionless nonlinear model of coastal upwelling is reexamined the model has been solved previously at steady state and as an initial value problem the previous solution to the initial value problem is inconsistent with the steady state solution a new solution to the spinup problem is presented that approaches the existing steady state solution in the new solution a surface equatorward jet develops more rapidly than a poleward undercurrent but the surface jet is of limited strength so that the undercurrent velocity eventually surpasses that of the surface flow consideration of dimensional scales implies that the magnitude of the wind stress determines how quickly steady state is approached but does not affect the steady state fields exact solutions found with an arbitrary alongshore pressure gradient imply that there is no poleward flow without a poleward pressure gradient