land sea interaction and morphogenesis of coastal foredunes a modeling case study from the southern baltic sea coast abstract coastal foredunes are developed as a result of the interplay of multi scale land sea processes basic driving mechanisms of coastal foredune morphogenesis as well as natural processes and factors involved in shaping the foredune geometry are quantitatively studied in this paper by a numerical model aeolian sediment transport and vegetation growth on the subaerial part of a beach is simulated by a cellular automata ca approach while the sediment budget in the subaqueous zone serving as a sediment source sink for the foredune ridges is estimated in a process based model the coupled model is applied to a 1 km long section of a barrier coast swina gate in the southern baltic sea for a 61 year 1951 2012 hindcast of its foredune development general consistency is shown between the observational data and simulation results indicating that the formation of an established coastal foredune results from a balance between wind wave impacts and vegetation growth driven by an effective onshore wind and a boundary sediment supply small scale dunes develop on the backshore and migrate landward they are then trapped in a narrow strip characterized by a large density gradient of vegetation cover which separates the hydrodynamically active zone and the vegetated zone continuous accumulation of sediment in this strip induces the development of a foredune ridge according to the simulations the formation of an established coastal foredune has to meet three preconditions 1 an effective onshore aeolian transport 2 a net onshore or lateral sediment supply and 3 a climate favoring vegetation growth the formation of a new foredune ridge in front of an already existing foredune is determined by a combination of the sediment supply rate the extreme wind wave event frequency and the vegetation growth rate simulation results demonstrate a remarkable variability in foredune development even along a small 1 km coast section implying that the medium to long term land sea interaction and foredune morphogenesis is quite sensitive to boundary conditions and various processes acting on multi temporal and spatial scales

al rich objects in ordinary chondrites related origin of carbonaceous and ordinary chondrites and their constituents ca al rich inclusions cais common constituents of carbonaceous chondrites have been studied extensively because they contain refractory high temperature minerals suggesting that they formed at high temperatures during the early history of the solar system few cais have previously been discovered in ordinary chondrites here we describe 169 al rich objects arbitrarily defined as having 10 wt al2o3 from 24 types 3 and 4 ordinary chondrites five regolith breccias containing unequilibrated material the unique meteorite kakangari and a few types 5 and 6 ordinary chondrites based on shape and texture we divide al rich objects into chondrules round with igneous textures irregularly shaped inclusions similar to type f and spinel rich complex cais and fragments probably fragments of al rich chondrules and inclusions for descriptive purposes we further subdivide al rich chondrules into compositional subgroups although they are entirely transitional conclusions 1 a al rich chondrules and irregularly shaped inclusions and fragments are wide spread albeit rare constituents of ordinary chondrites and are similar to cais except the coarse grained ones in carbonaceous chondrites thus providing strong support for a related origin of ordinary and carbonaceous chondrites and their constituents 2 b al rich chondrules formed as independent freely floating molten droplets and cooled rather rapidly 3 c al rich chondrules like the common mg fe rich chondrules formed by melting of millimeter to submillimeter sized dust balls in the case of al rich chondrules the dust balls consisted largely of mixtures of variable amounts of at least two solid precursor materials one refractory rich and the other volatile rich phases which we interpret as unmelted relicts in some of these objects support this model 4 d the wide ranges in bulk compositions of al rich chondrules from refractory rich to volatile rich ones yet complete transition between them and the existence of chondrules transitional in composition between the al rich and common mg fe rich chondrules of ordinary chondrites suggest that all chondrules formed by related processes differences in bulk composition result from mixing of different proportions of refractory volatile and mg fe rich and other solid precursor materials into dust balls which were then melted 5 e most irregularly shaped inclusions show no indication of a once molten origin secondary alteration has probably changed the original mineral assemblage mainly volatile rich materials entered the refractory objects as a gas reacted with the constituents and produced secondary phases rims probably formed both by decomposition and reaction with solar gas as well as by accretion 6 f coarse grained inclusions as found in allende were not observed in ordinary chondrites

al rich chondrules from the ybbsitz h4 chondrite evidence for formation by collision and splashing three al rich chondrules al2o3 10 wt from the h4 chondrite ybbsitz were chemically and mineralogically studied all three clearly crystallized from molten droplets as individual objects they consist predominantly of olivine spinel and a feldspar rich mesostasis the three al rich chondrules have high concentrations of incompatible elements the rare earth element patterns are fractionated with enrichment of light rare earths and a strong positive eu anomaly this type of fractionated refractory element pattern is indicative of igneous processes ca al rich inclusions from carbonaceous chondrites also show high enrichments in refractory elements their patterns are however either flat or fractionated according to variable volatilities of refractory elements in the solar nebula e g yb anomaly the high level of refractory siderophiles observed in ca al rich inclusions from carbonaceous chondrites is not found in the al rich chondrules we therefore conclude that the al rich ybbsitz chondrules formed by different processes than the ca al rich inclusions from carbonaceous chondrites melting of inhomogeneous precursors generally assumed for the formation of ferromagnesian chondrules is also unlikely to produce such extreme compositions the possibility that metamorphism is the cause of the high content of incompatible elements can be excluded we therefore propose a new model for the formation of the al rich chondrules they may have formed by collisions of partly molten ferromagnesian chondrules with other objects chondrules during this process al rich melt fractions residual liquids may be ejected and form independent al rich chondrules this model explains the high enrichment and the fractionated patterns of incompatible elements in al rich chondrules as well as their generally much smaller sizes compared with ferromagnesian chondrules the eu anomaly is probably due to diffusive exchange of eu between matrix and the al rich chondrules eu is decoupled from the other ree in many ferromagnesian chondrules of equilibrated ordinary chondrites including three ferromagnesian chondrules from ybbsitz analyzed in this study

origin of chondrule rims and interchondrule matrices in unequilibrated ordinary chondrites optical microscopy electron probe microanalysis scanning electron microscopy and analytical transmission electron microscopy were used to study the interchondrule matrix and opaque chondrule rims in bishunpur krymka semarkona chainpur all ll3 tieschitz and sharps both h3 the size distribution of grains in matrix in bishunpur obeys a power law rims around chondrules tend to be finer grained than matrix and may be layered all rims and matrices studied contain clasts of forsteritic olivine and low ca pyroxene in bishunpur the clasts may be cemented by amorphous glue rich in normative albite and partly altered to smectite rims in krymka sharps chainpur and tieschitz have a densely packed olivine groundmass with a grain size of about 0 1 m in krymka groundmass olivine is fo20 30 and forms interlocking dendrites various fe oxides are present in rims and matrices grain size distribution and chemical data indicate that clastic olivines and pyroxenes are derived from chondrules from analyses matrices rims in the ll group apparently are enriched in a feldspathic component tieschitz rims are slightly enriched but here the feldspathic component is present as white matrix sharps rims are not enriched in a feldspathic component opaque interchondrule matrices and chondrule rims probably formed from the products of fragmentation of chondrules partly induced by contraction of protopyroxene on inversion to clinopyroxene fragmented silica rich chondrule mesostases reacted with fe oxides and na to form the groundmass of fayalitic olivine and feldspathic glue a low temperature nebular or pre solar component is limited to 3 vol of each meteorite so equilibrium condensate was not the carrier of volatiles such as tl and bi

mass flux and undertow in a surf zone abstract the mass of water carried shoreward by the breaking waves in a surf zone will in a two dimensional situation be compensated by a seaward return flow the undertow it is shown that the undertow is driven by the local difference between radiation stress and the set up pressure gradient which only balance each other in average over the depth turbulent shear stresses are required to maintain a steady situation comparison with measurements confirms the theoretical results

oxygen isotope studies of achondrites abstract oxygen isotope abundances provide a powerful tool for recognizing genetic relationships among meteorites among the differentiated achondrites three isotopic groups are recognized l snc mars 2 earth and moon and 3 hed howardites eucrites diogenites the hed group also contains the mesosiderites main group pallasites and silicates from iiiab irons the angrites may be marginally resolvable from the hed group within each of these groups internal geologic processes give rise to isotopic variations along a slope 1 2 fractionation line as is well known for terrestrial materials variations of 17o from one planet to another are inherited from the inhomogeneities in the solar nebula as illustrated by the isotopic compositions of chondrites and their constituents among the undifferentiated achondrites five isotopic groups are found 1 aubrites 2 winonaites and iab iiicd irons 3 brachinites 4 acapulcoites and lodranites and 5 ureilites the isotopic compositions of aubrites coincide with the earth and moon and also with the enstatite chondrites these bodies apparently were derived from a common reservoir the isotopic composition of which was established at the chondrule scale by nebular processes isotopic similarities between chondrites and achondrites are seen only for the following instances 1 enstatite chondrites and aubrites 2 h chondrites and he irons and 3 l or ll chondrites and iva irons the isotopic data also support the following genetic associations 1 winonaites and iab iiicd irons 2 acapulcoites and lodranites and 3 ureilites and dark inclusions of c3 chondrites an attempt to reconcile the whole planet isotopic compositions of earth mars and the eucrite parent body with mixing models of their chemical compositions failed it is not possible to satisfy both the chemical and isotopic compositions of the terrestrial planets using known primitive solar system components

mineralogy of fine grained material in the krymka ll3 1 chondrite two dark lithic fragments and matrix of the krymka ll3 1 chondrite were mineralogically and chemically studied in detail these objects are characterised by the following chemical and mineralogical characteristics which distinguish them from the host chondrite krymka 1 bulk chemical analyses revealed low totals systematically lower than 94 wt due to high porosity 2 enrichment in feo and depletion in s mgo and sio2 due to a high abundance of fe rich silicates and low sulfide abundance 3 fine grained almost chondrule free texture with predominance of a porous cryptocrystalline groundmass and fine grains 4 occurrence of a small amount of once molten material microchondrules enclosed in fine grained materials 5 occurrence of accretionary features especially unique accretionary spherules 6 high abundance of small calcium aluminium rich inclusions cais in one of the fine grained fragments it is suggested that the abundance of cais in this fragment is one of the highest ever found in an ordinary chondrite accretionary fine grained spherules within one of the fragments bear fundamental information about the initial stages of accretion as well as on the evolution of the clast its incorporation and history within the bulk rock of krymka the differences in porosity bulk composition and mineralogy of cores and rims of the fine grained spherulitic objects allow us to speculate on the following processes 1 low velocity accretion of tiny silicate grains onto the surface of coarse metal or silicate grains in a dusty region of the nebula is the beginning of the formation of accretionary porous fluffy silicate spherules 2 within a dusty environment with decreasing silicate metal sulfide ratio the porous spherules collected abundant metal and sulfide particles together with silicate dust which formed an accretionary rim variations of the silicate sulfide metal ratio in the dusty nebular environment result in the formation of multi layered rims on the surface of the silicate rich spherules 3 soft accretion and lithification of rimmed fluffy spherules fine grained silicate rich dust metal sulfide particles cais silicate rich microchondrules and coarse silicate grains and fragments followed 4 after low temperature processing of the primary accretionary rock collisional fragmentation occurred the fragments were subsequently coated by fine grained material which was highly oxidized and depleted in sulfides 5 in a final stage this accretionary dusty rock was incorporated as a fragment within the krymka host

revised model calculations for the thermal histories of ordinary chondrite parent bodies recent measurements of ordinary chondrite physical and thermal properties along with new geothermometry studies have provided the necessary parameters for updating a previously proposed model miyamoto et al 1981 for the thermal evolution and internal structure of ordinary chondrite parent bodies model calculations assumed a heat source term derived from the decay of 26al justification is provided differences from the previous model include varying the thermal diffusivity parameter with increasing temperature and decreasing porosity using variable physical and thermal parameters to provide end member models and incorporating a shortened thermal history of 60 ma obtained from new pb pb chronology of phosphates rather than 100 ma times of isotopic closure in chondrite phosphates overlap the thermal model estimates and postmetamorphic cooling rates from the model approximately coincide in both trend and magnitude with metallographic and fission track cooling rate data model calculations attempt to match peak metamorphic conditions in the central portions of these bodies and yield accretion ages between 1 4 to 3 1 ma after calcium aluminum inclusion cai formation model calculations also predict that both the h and the l chondrite parent asteroids consisted of 80 equilibrated and 20 unequilibrated chondritic material and that their original radii ranged from 80 to 95 km

the halite bearing zag and monahans 1998 meteorite breccias shock metamorphism thermal metamorphism and aqueous alteration on the h chondrite parent body zag and monahans 1998 are h chondrite regolith breccias comprised mainly of light colored metamorphosed clasts dark clasts that exhibit extensive silicate darkening and a halite bearing clastic matrix these meteorites reflect a complex set of modification processes that occurred on the h chondrite parent body the light colored clasts are thermally metamorphosed h5 and h6 rocks that were fragmented and deposited in the regolith the dark clasts formed from light colored clasts during shock events that melted and mobilized a significant fraction of their metallic fe ni and troilite grains the clastic matrices of these meteorites are rich in solar wind gases parent body water was required to cause leaching of chondritic minerals and chondrule glass the fluids became enriched in na k cl br al ca mg and fe evaporation of the fluids caused them to become brines as halides and alkalies became supersaturated grains of halite and in the case of monahans 1998 halite with sylvite inclusions precipitated at low temperatures 100 c in the porous regolith in both meteorites fluid inclusions were trapped inside the halite crystals primary fluid inclusions were trapped in the growing crystals secondary inclusions formed subsequently from fluid trapped within healed fractures

reclassification of villalbeto de la pena occurrence of a winonaite related fragment in a hydrothermally metamorphosed polymict l chondritic breccia na meteorite clearly bears consequences for the previous classification of the rock the oxygen isotope data clearly show that an exotic eye catching black and plagioclase maskelynite rich clast is not of l chondrite heritage villalbeto de la pe is consequently reclassified as a polymict chondritic breccia the oxygen isotope data of the clast are more closely related to data for the winonaite tierra blanca and the anomalous silicate bearing iron meteorite lew 86211 than to the ordinary chondrite groups the ree pattern of the bulk inclusion indicates genetic similarities to those of differentiated rocks and their minerals e g lunar anorthosites eucritic and winonaitic plagioclases and points to an igneous origin the an content of the plagioclase within the inclusion is increasing from the fragment host meteorite boundary approximately an10 toward the interior of the clast approximately an52 this is accompanied by a successive compositionally controlled transformation of plagioclase into maskelynite by shock as found for plagioclase compositions of individual spinels enclosed in plagioclase maskelynite also vary from the border toward the interior of the inclusion in addition huge variations in oxygen isotope composition were found correlating with distance into the object the chemical and isotopical profiles observed in the fragment indicate postaccretionary metamorphism under the presence of a volatile phase

bleached chondrules evidence for widespread aqueous processes on the parent asteroids of ordinary chondrites we present the first detailed study of a population of texturally distinct chondrules previously described by kurat 1969 christophe michel levy 1976 and skinner et al 1989 that are sharply depleted in alkalis and al in their outer portions these bleached chondrules which are exclusively radial pyroxene and cryptocrystalline in texture have porous outer zones where mesostasis has been lost bleached chondrules are present in all type 3 ordinary chondrites and are present in lower abundances in types 4 6 they are most abundant in the l and ll groups apparently less common in h chondrites and absent in enstatite chondrites we used x ray mapping and traditional electron microprobe techniques to characterize bleached chondrules in a cross section of ordinary chondrites we studied bleached chondrules from semarkona by ion microprobe for trace elements and h isotopes and by transmission electron microscopy chondrule bleaching was the result of low temperature alteration by aqueous fluids flowing through finegrained chondrite matrix prior to thermal metamorphism during aqueous alteration interstitial glass dissolved and was partially replaced by phyllosilicates troilite was altered to pentlandite but pyroxene was completely unaffected calcium rich zones formed at the inner margins of the bleached zones either as the result of the early stages of metamorphism or because of fluid chondrule reaction the mineralogy of bleached chondrules is extremely sensitive to thermal metamorphism in type 3 ordinary chondrites and bleached zones provide a favorable location for the growth of metamorphic minerals in higher petrologic types the ubiquitous presence of bleached chondrules in ordinary chondrites implies that they all experienced aqueous alteration early in their asteroidal histories but there is no relationship between the degree of alteration and metamorphic grade a correlation between the oxidation state of chondrite groups and their degree of aqueous alteration is consistent with the source of water being either accreted ices or water released during oxidation of organic matter ordinary chondrites were probably open systems after accretion and aqueous fluids may have carried volatile elements with them during dehydration individual radial pyroxene and cryptocrystalline chondrules were certainly open systems in all chondrites that experienced aqueous alteration leading to bleaching

evolution of the winonaite parent body clues from silicate mineral trace element distributions we have measured the trace element compositions of individual plagioclase pyroxene and olivine grains in 6 different winonaites that span the range of textures and mineralogies observed in these meteorites textural evidence in these meteorites including the presence of a plagioclase clinopyroxene rich lithology and coarse grained olivine lithologies suggests that they may have experienced some silicate partial melting however trace element distributions in these lithologies do not show any clear signatures for such an event pyroxene trace element compositions do exhibit systematic trends with abundances generally lowest in pontlyfni and highest in winona the fact that the same trends are present for both incompatible and compatible trace elements suggests however that the systematics are more likely the result of equilibration of minerals with initially heterogeneous and distinct compositions rather than partial melting of a compositionally homogeneous precursor the winonaites have experienced brecciation and mixing of lithologies followed by varying degrees of thermal metamorphism on their parent body these factors probably account for the variable bulk rare earth element ree patterns noted for these meteorites and may have led to re equilibration of trace elements in different lithologies

exposure history of the regolithic chondrite fayetteville ii solar gas free light inclusions abstract noble gases and cosmic ray tracks were determined on light solar gas free inclusions of the solar gas rich h4 chondrite fayetteville 10 be 26 a1 major and trace element concentrations as well as oxygen isotope ratios complete the data set one exceptional inclusion is an l chondrite xenolith identified by its oxygen isotope signature and the concentration of metallic fe ni oxidized fe of this inclusion equilibrated with the host early in the history of fayetteville s parent body track density variations indicate that the majority of fayetteville s inclusions were irradiated as pebbles in the parent body by solar flare particles for about 10 4 10 6 years the l chondritic inclusion contains an unequivocal excess of gcr produced he and ne relative to the remaining inclusions this clast as well as two more solar gas free samples suffered a gcr exposure on the parent body lasting some 10 million years or longer this exposure is comparable in length to the residence times of solar gas rich matrix samples in the gcr active zone of the fayetteville parent regolith probably the other inclusions also were irradiated by gcr during at least several million years prior to the separation of the meteoroid from the parent body

examination of reference concentration under waves and currents on the inner shelf 1 we examine reference concentration using three different data sets of near bed suspended sediment concentration observed under combined waves and currents the data include observations made at 15 and 20 m depth off dounreay scotland uk and observations obtained at 13 m depth off duck north carolina usa these data accommodate different dynamic conditions from wave dominated conditions at dounreay to wind driven current dominated conditions at duck and sediment properties median size of bed sediment ranging from 120 to 350 m near bed concentration profiles to elevations of about 80 cm were obtained using acoustic backscatter sensors with 1 cm resolution the reference concentrations cr at 1 cm were then evaluated by regressing the observed suspended sediment concentrations against a rouse type model bed shear stresses associated with each estimate of cr were estimated using the wave current interaction model of grant and madsen existing equations for reference concentration based on shear stress alone fail to accommodate all cr estimates from different environments we introduce a new empirical relationship between cr and the product of shields and inverse rouse numbers these dimensionless parameters represent the ratio of bed shear stress and submerged particle weight and the ratio of shear velocity and particle settling velocity respectively the new formula adjusts the amount of mobile sediment at the bed related to the shields number to that available for suspension at the reference height related to the inverse rouse number the new formula for reference concentration accommodates observations from different environments suggesting that it may have wide applicability on sandy inner shelves

storm driven bottom sediment transport on a high energy narrow shelf nw iberia and development of mud depocenters bottom sediment transport on the nw iberian shelf was monitored during a downwelling storm in september 2014 collected data was analyzed and fed into a 3d coastal ocean model to understand storm driven sediment transport on the shelf and its impact on mid shelf mud depocenters mdcs a significantly enhanced level of bottom sediment resuspension nearly two orders of magnitude higher than that in the pre storm period was recorded at the mooring site field data analysis reveals that it was induced by a short lasting strong bottom current in combination with enhanced wave current interaction simulation results indicate that this strong current was part of a coastal jet resulted from downwelling an across shelf horizontal density gradient as high as 0 32 g m4 occurred at the interface between the downwelling and the bottom waters forming a remarkable front due to buoyancy effect the downwelling water was mostly confined to the coast with a depth limit of 80 m in the south and 120 m in the north of the region resulting in a northward directed coastal jet simulation results suggest that during the storm local near bottom sediment suspensions with concentrations on the order of 10 kg m3 would be triggered by wave current interaction and flow convergence associated with the front direct impact on the development of mdcs by transport and deposition of concentrated sediment suspensions is indicated by model results the seaward limit of the front coincided with the shoreward edge of the mdc nucleus suggesting the front as a primary control on the deposition of fine grained sediment this article is protected by copyright all rights reserved

early solar system hydrothermal activity in chondritic asteroids on 1 10 year timescales chondritic meteorites are considered the most primitive remnants of planetesimals from the early solar system as undifferentiated objects they also display widespread evidence of water rock interaction on the parent body understanding this history has implications for the formation of planetary bodies the delivery of water to the inner solar system and the formation of prebiotic molecules the timescales of water rock reactions in these early objects however are largely unknown here we report evidence for short lived water rock reactions in the highly metamorphosed ordinary chondrite breccia villalbeto de la pena l6 an exotic clast d 2cm has coexisting variations in feldspar composition and oxygen isotope ratios that can only result from hydrothermal conditions the profiles were modeled at t 800 c and p h2o 1 bar using modified grain boundary diffusion parameters for oxygen self diffusion and reaction rates of nasica 1al 1 exchange in a fumarole the geochemical data are consistent with hydrothermal activity on the parent body lasting only 1 10 y this result has wide ranging implications for the geological history of chondritic asteroids

the effect of sea breeze on beach morphology surf zone hydrodynamics and sediment resuspension abstract beach morphodynamic processes were investigated over part of a sea breeze cycle on a microtidal low wave energy sandy beach in southwestern australia prior to the onset of the sea breeze offshore winds with speeds less than 5 m s prevailed during the sea breeze alongshore winds with speeds higher than 10 m s were experienced the sea breeze induced pronounced changes to the nearshore morphodynamics which were similar to that of a storm event 1 root mean square wave height increased from 0 3 to 0 5 m 2 zero upcrossing wave period decreased from 8 to 4 s 3 mean cross shore flows reached velocities of 0 2 m s directed offshore and 4 the longshore current increased in strength from 0 05 to 1 0 m s before the sea breeze sediment resuspension typically occurred during isolated high wave events associated with the passage of wave groups flux coupling between the wave oscillatory currents and the suspended sediment jaffe b e sternberg r w sallenger a h 1984 the role of suspended sediment in shore normal beach profile changes proc 19th int conf coastal engineering asce pp 1983 1996 induced net onshore suspended sediment transport resulting in beachface accretion and a steepening of the foreshore profile in contrast during the sea breeze sediment resuspension was almost continuous the suspended sediment load increased six fold and as a consequence the longshore suspended sediment transport rate increased by a factor of 100 during the sea breeze cross shore transport was directed offshore and primarily associated with mean offshore flows this resulted in erosion of the beachface and deposition in the surf zone and consequently a flattening of the beach profile the suspended sediment load was strongly related to the shields parameter defined for the combined action of waves and currents investigation of the suspended sediment profiles indicated that the degree of vertical mixing parameterised by the sediment diffusion coefficient increased with distance from the bed in addition the sediment diffusion coefficient exhibited a large temporal variation ranging between 0 005 and 0 018 m2 s the variability in the sediment diffusion coefficient is possibly due to changes in the sea bed morphology

shock metamorphism of ordinary chondrites a revised petrographic classification of progressive stages of shock metamorphism of ordinary chondrites is proposed six stages of shock s1 to s6 are defined based on shock effects in olivine and plagioclase as recognized by thin section microscopy the characteristic shock effects of each shock stage are s1 unshocked sharp optical extinction of olivine s2 very weakly shocked undulatory extinction of olivine s3 weakly shocked planar fractures in olivine s4 moderately shocked mosaicism in olivine s5 strongly shocked isotropization of plagioclase maskelynite and planar deformation features in olivine and s6 very strongly shocked recrystallization of olivine sometimes combined with phase transformations ringwoodite and or phases produced by dissociation reactions s6 effects are always restricted to regions adjacent to melted portions of a sample which is otherwise only strongly shocked in stages s3 to s6 localized melting results from stress and temperature peaks which locally deviate from the equilibration shock pressure due to differences in shock impedance these melting effects are a opaque melt veins shock veins b melt pockets with interconnecting melt veins c melt dikes and d troilite metal deposits in fractures based on a critical evaluation of data from shock recovery experiments a shock pressure calibration for the six shock stages is proposed which defines the s1 s2 s2 s3 s3 s4 s4 s5 and s5 s6 transitions at 5 5 10 15 20 30 35 and 45 55 gpa respectively whole rock melting and formation of impact melt rocks or melt breccias occurs at about 75 90 gpa the symbol for the shock stage may be used in combination with the symbol for the petrologic type to abbreviate the complete classification of a chondrite e g h5 s3 we propose this new shock classification and pressure calibration system to replace previous systems which are out of date with respect to the pressure calibration nominally restricted to l chondrites and based on incomplete and in part illdefined sets of shock effects we have classified seventy six ordinary chondrites using the new classification system and conclude the following 1 1 shock effects and the sequence of progressively increasing degrees of shock metamorphism are very similar in h l and ll groups differences in the frequency distribution of shock stages are relatively minor e g l chondrites appear to have the largest fraction with stages s5 and s6 this suggests that the collisional histories of the h l and ll parent bodies were similar 2 2 petrologic type 3 chondrites are deficient in stages s4 to s6 and with increasing petrologic type the frequency of stages s4 to s6 increases we suggest that the more porous and volatile rich type 3 chondrites are subject to melting at a lower shock pressure than the nonporous chondrites of higher petrologic type volatiles trapped in pores cause shock induced dispersal of the shocked and melted material into small particles which are not expected to survive as meteorites 3 3 stage s3 is the most abundant in nearly all petrologic types 4 4 at shock pressures in excess of about 35 gpa s5 and s6 4he and 40ar are almost completely lost pressures below 10 gpa s1 and s2 do not cause noble gas losses

late accretion and lithification of chondritic parent bodies mg isotope studies on fragments from primitive chondrites and chondritic breccias recent results of isotopic dating studies 182hf 182w 26al 26mg and the increasing number of observed igneous and metamorphosed fragments in primitive chondrites provide strong evidence that accretion of differentiated planetesimals predates that of primitive chondrite parent bodies the primitive chondrites adrar 003 and acfer 094 contain some unusual fragments that seem to have undergone recrystallization magnesium isotope analyses reveal no detectable radiogenic 26mg in any of the studied fragments the possibility that evidence for 26al was destroyed by parent body metamorphism after formation is not likely because several other constituents of these chondrites do not show any metamorphic features since final accretion of a planetesimal must have occurred after formation of its youngest components formation of these parent bodies must thus have been relatively late i e after most 26al had decayed al mg isotope data for some igneous textured clasts granitoids and andesitic fragments within the two chondrite regolith breccias adzhi bogdo and study butte reveal also no evidence for radiogenic 26mg as calculated from the upper limits the formation of these igneous clasts the incorporation into the parent body regolith and the lithification must have occurred at least 3 8 myr andesite in study butte and 4 7 myr granitoids in adzhi bogdo after calciumaluminum rich inclusions cai formation the absence of 26mg excess in the igneous inclusions does not exclude 26al from being a heat source for planetary melting in large early formed planetesimals cooling below the closure temperature of the al mg system may be too late for any evidence for live 26al in the form of 26mg excess to be preserved thus growing evidence exists that chondritic meteorites represent the products of a complex multi stage history of accretion parent body modification disruption and re accretion

observations and 3d hydrodynamics based modeling of decadal scale shoreline change along the outer banks north carolina abstract long term decadal scale shoreline change is an important parameter for quantifying the stability of coastal systems the decadal scale coastal change is controlled by processes that occur on short time scales such as storms and long term processes such as prevailing waves the ability to predict decadal scale shoreline change is not well established and the fundamental physical processes controlling this change are not well understood here we investigate the processes that create large scale long term shoreline change along the outer banks of north carolina an uninterrupted 60 km stretch of coastline using both observations and a numerical modeling approach shoreline positions for a 24 yr period were derived from aerial photographs of the outer banks analysis of the shoreline position data showed that although variable the shoreline eroded an average of 1 5 m yr throughout this period the modeling approach uses a three dimensional hydrodynamics based numerical model coupled to a spectral wave model and simulates the full 24 yr time period on a spatial grid running on a short second scale time step to compute the sediment transport patterns the observations and the model results show similar magnitudes o 105 m3 yr and patterns of alongshore sediment fluxes both the observed and the modeled alongshore sediment transport rates have more rapid changes at the north of our section due to continuously curving coastline and possible effects of alongshore variations in shelf bathymetry the southern section with a relatively uniform orientation on the other hand has less rapid transport rate changes alongshore gradients of the modeled sediment fluxes are translated into shoreline change rates that have agreement in some locations but vary in others differences between observations and model results are potentially influenced by geologic framework processes not included in the model both the observations and the model results show higher rates of erosion 1 m yr averaged over the northern half of the section as compared to the southern half where the observed and modeled averaged net shoreline changes are smaller

oxygen isotope studies of ordinary chondrites several stages in the evolution of ordinary chondritic meteorites are recorded in the oxygen isotopic composition of the meteorites and their separable components chondrules fragments clasts and matrix the whole rock isotopic compositions reflect the iron group of the meteorite h l or ll isotopic uniformity of h3 to h6 and l3 to l6 are consistent with closed system metamorphism within each parent body ll3 chondrites differ slightly from ll4 to ll6 implying a small degree of opensystem aqueous alteration and carbon reduction on the scale of individual chondrules the meteorites are isotopically heterogeneous allowing recognition of the solar nebular processes of chondrule formation chondrules for all classes of ordinary chondrites are derived from a common population which was separate from the population of chondrules in carbonaceous or enstatite chondrites chondrules define an isotopic mixing line dominated by exchange between 16o rich and 16o poor reservoirs the oxygen isotopic compositions of chondrites serve as fingerprints for identification of genetic association with other meteorite types achondrites and iron and for recognition of source materials in meteoritic breccias

a coupled modeling scheme for longshore sediment transport of wave dominated coasts a case study from the southern baltic sea abstract a modeling scheme based on dynamic coupling of a high resolution 1d cross shore model to a 2dh area model is developed to calculate the total longshore sediment transport lst rate in wave dominated coasts the purpose of this coupling strategy aims at resolving the lst with a high resolution both temporally and spatially inside the surf zone and with a coarser spatial resolution seaward of the surf zone the 2dh area model operates on a fixed pre designed regional grid parent grid and the 1d cross shore model is dynamically coupled to the boundary of the parent grid with a time varying domain starting from the first wave breaking point and ending at the maximum wave set up point the time varying domain is generated in the 1d model by resolving the landward wave propagation from the offshore conditions provided by the 2dh area model at every time step with a high resolution cell size the 1d model resolves the wave propagation processes and resulting lst along the profile the coupled model is applied to study the lst in the pomeranian bight at the southern baltic sea simulation results are compared with three other different hierarchical modeling methods from empirical formulas such as cerc and kamphuis to a 2dh area simulation the comparative study indicates that the dynamically coupled model can be a reliable tool in practical applications especially for the areas where hydrodynamics is controlled by complex bathymetry e g multiple longshore bars or morphologically induced circulation patterns

shock metamorphism and petrography of the shergotty achondrite the shergotty subsamples 1 and 12 consist of augite and pigeonite 67 5 maskelynite 24 ilmenite and titanomagnetite 2 pyrrhotite 0 4 whitlockite 1 8 apatite 0 1 quartz 0 5 baddeleyite trace fayalite 0 4 mesostasis 3 and shock induced local polymineralic melt products 0 6 the overall modal composition is similar to other shergotty samples except for the rather high whitlockite content the shock effects observed in the mineral constituents include mosaicism deformation bands planar fractures and mechanical twin lamellae in clinopyroxene isotropization of plagioclase with very rare remnants of birefringence planar deformation structures mosaicism and strongly reduced birefringence in quartz mechanical twinning of ilmenite localized in situ melting of neighbouring minerals at the contact of low and high density phases based on the refractive index of maskelynite average 1 5467 with average an content of 49 and the degree of isotropization of the plagioclase an equilibrium shock pressure of 29 1 gpa is derived the inferred post shock temperature is 200 20 c no heating event could have exceeded 400 c duke 1968 local stress and temperature concentrations reach 60 80 gpa and 1600 2000 c the observed shock effects can be explained by a single shock event a second weaker shock event as found by others appears to be highly improbable equilibrium shock pressures and post shock temperatures for the other known shergottites are 31 2 gpa and 220 50 c zagami 43 2 gpa and 400 800 c alha 77005 the pressure estimate for eeta 79001 by lambert 1985 is confirmed 34 1 gpa the post shock temperature is 250 50 c the abundance and textural setting of localized melt products in these meteorites confirm increasing shock pressures in the sequence shergotty zagami eeta 79001 alha 77005 undoubtedly the melts could have been formed by the same single shock which produced the equilibrium shock effects e g maskelynitization in these meteorites the shock induced particle velocities inferred from hugoniot data of basalts are in the 1 5 2 0 km s range for the parental rocks of the shergottites ejection velocities are therefore in the order of 3 4 km s special ejection mechanisms are required in order to exceed the escape velocity of a planet like mars without producing higher degrees of shock e g melting than those observed in the shergottites

lithification of gas rich chondrite regolith breccias by grain boundary and localized shock melting we studied the fine grained matrices 150 m of 14 gas rich ordinary chondrite regolith breccias in an attempt to decipher the nature of the lithification process that converted loose regolith material into consolidated breccias we find that there is a continuous gradation in matrix textures from nearly completely clastic class a to highly cemented class c breccias in which the remaining clasts are completely surrounded by interstitial shock melted material we conclude that this interstitial material formed by shock melting in the porous regolith in general the abundances of solar wind implanted 4he and 20ne are inversely correlated with the abundance of interstitial shock melted feldspathic material chondrites with the highest abundance of interstitial melted material class c experienced the highest shock pressures and temperatures and suffered the most extensive degassing it is this interstitial feldspathic melt that lithifies and cements the breccias together those breccias with very little interstitial melt class a are the most porous and least consolidated

cross shore distribution of longshore sediment transport comparison between predictive formulas and field measurements abstract the skill of six well known formulas developed for calculating the longshore sediment transport rate was evaluated in the present study formulas proposed by bijker bijker e w 1967 some considerations about scales for coastal models with movable bed delft hydraulics laboratory publication 50 delft the netherlands journal of the waterways harbors and coastal engineering division 97 4 1971 687 engelund hansen engelund f hansen e 1967 a monograph on sediment transport in alluvial streams teknisk forlag copenhagen denmark ackers white journal of hydraulics division 99 1 1973 2041 bailard inman journal of geophysical research 86 c3 1981 2035 van rijn journal of hydraulic division 110 10 1984 1431 110 11 1984 1613 110 12 1984 1733 and watanabe watanabe a 1992 total rate and distribution of longshore sand transport proceedings of the 23rd coastal engineering conference asce 2528 2541 were investigated because they are commonly employed in engineering studies to calculate the time averaged net sediment transport rate in the surf zone the predictive capability of these six formulas was examined by comparison to detailed high quality data on hydrodynamics and sediment transport from duck nc collected during the duck85 superduck and sandyduck field data collection projects measured hydrodynamics were employed as much as possible to reduce uncertainties in the calculations and all formulas were applied with standard coefficient values without calibration to the data sets overall the van rijn formula was found to yield the most reliable predictions over the range of swell and storm conditions covered by the field data set the engelund hansen formula worked reasonably well although with large scatter for the storm cases whereas the bailard inman formula systematically overestimated the swell cases and underestimated the storm cases the formulas by watanabe and ackers white produced satisfactory results for most cases although the former overestimated the transport rates for swell cases and the latter yielded considerable scatter for storm cases finally the bijker formula systematically overestimated the transport rates for all cases it should be pointed out that the coefficient values in most of the employed formulas were based primarily on data from the laboratory or from the river environment thus re calibration of the coefficient values by reference to field data from the surf zone is expected to improve their predictive capability although the limited amount of high quality field data available at present makes it difficult to obtain values that would be applicable to a wide range of wave and beach conditions

meteorites from mongolia the mineralogy and composition of six mongolian meteorites were studied in some detail previously only limited information existed about these rocks and some were still unclassified the six meteorites include three ordinary chondrites and three irons the ordinary chondrite adzhi bogdo stone is a regolith breccia ll3 6 containing various types of clasts some of foreign origin embedded within a fine grained clastic matrix tugalin bulen h6 and noyan bogdo l6 meteorites are typical well metamorphosed ordinary chondrites adzhi bogdo iron has to be regarded as an ia iron meteorite like campo del cielo or canyon diablo although the sample studied had been heated to about 900 c 950 c some time in the past thus eradicating all original structural elements manlai is structurally closely related to the iic iron meteorites but based on its chemistry which does not fit into this group it is suggested that manlai is an anomalous iron meteorite the third iron sargiin gobi is certainly a normal member of the ia iron meteorites the concentrations and isotopic compositions of he ne and ar were measured for all meteorites and their gas retention ages and exposure ages are discussed

asteroid 2008 tc 3 almahata sitta a spectacular breccia containing many different ureilitic and chondritic lithologies abstract asteroid 2008 tc3 impacted earth in northern sudan on october 7 2008 the meteorite named almahata sitta was classified as a polymict ureilite in this study 40 small pieces from different fragments collected in the almahata sitta strewn field were investigated and a large number of different lithologies were found some of these fragments are ureilitic in origin whereas others are clearly chondritic as all are relatively fresh w0 w0 1 and as short lived cosmogenic radioisotopes were detected within two of the chondritic fragments there is strong evidence that most if not all belong to the almahata sitta meteorite fall the fragments can roughly be subdivided into achondritic ureilitic 23 samples and chondritic lithologies 17 samples among the ureilitic rocks are at least 10 different lithologies a similar number of different chondritic lithologies also exist most chondritic fragments belong to at least seven different e chondrite rock types eh3 el3 4 el6 el breccias several different types of el and eh impact melt rocks and impact melt breccias some of the latter are shock darkened in addition two h group ordinary chondrite lithologies were identified and one sample of a chondrite type that is so far unique the latter has some affinities to r chondrites oxygen isotope compositions of 14 fragments provide further fundamental information on the lithological heterogeneity of the almahata sitta meteorite based on the findings presented in this study the reflectance spectrum of asteroid 2008 tc3 has to be evaluated in a new light

hammadah al hamra 193 the first amphibole bearing winonaite the hammadah al hamra 193 winonaite was found in the libyan desert in 1996 unlike most winonaites with fine to medium grained equigranular textures it consists predominantly of very large up to 5 mm optically continuous orthopyroxene grains enclosing smaller grains of olivine and plagioclase it also contains large up to 2 mm poikilitic grains of amphibole enclosing clinopyroxene plagioclase olivine and occasionally orthopyroxene which occur interstitial to the large orthopyroxene grains the amphibole is identified as fluoro edenite and textures indicate that it replaces clinopyroxene via a reaction in which diopside olivine and plagioclase form fluoro edenite trace element data are consistent with the formation of fluoro edenite from clinopyroxene and plagioclase fluoro edenite has a ree pattern similar to that of clinopyroxene but has elevated abundances of na k and ba elements typically enriched in plagioclase the source of the f is uncertain but may be apatite which is fluor apatite in this meteorite the presence of fluoro edenite in hah 193 a meteorite that experienced extensive thermal metamorphism indicates a significant stability field for this rare mineral

on the speed of the eddy driven jet and the width of the hadley cell in the southern hemisphere a strong correlation between the speed of the eddy driven jet and the width of the hadley cell is found to exist in the southern hemisphere both in reanalysis data and in twenty first century integrations from the intergovernmental panel on climate change ipcc fifth assessment report multimodel archive analysis of the space time spectra of eddy momentum flux reveals that variations in eddy driven jet speed are related to changes in the mean phase speed of midlatitude eddies an increase in eddy phase speeds induces a poleward shift of the critical latitudes and a poleward expansion of the region of subtropical wave breaking the associated changes in eddy momentum flux convergence are balanced by anomalous meridional winds consistent with a wider hadley cell at the same time faster eddies are also associated with a strengthened polewardeddymomentumflux sustainingastronger westerlyjet in midlatitudes the proposedmechanismis consistent with the seasonal dependence of the interannual variability of the hadley cell width and appears to explain at least part of the projected twenty first century trends one of the most salient features of earth s general circulation is the presence of hadley cells hcs in the tropical belts of both hemispheres associated with their large scale motions are some of the main characteristics of tropical and subtropical climates the intertropical convergence zone in the rising branch and the subtropical dry zones in the descending branches e g hartmann 1994 studying the factors determining the meridional extent of these overturning circulations is therefore essential to understand the spatial distribution of tropical and subtropical climates and its changes the role of the hcs is particularly crucial in the context of climate change and the observed widening of the atmospheric circulation observations show a poleward shift of the eddy driven jets and an expansion of the hcs in recent decades particularly in the southern hemisphere hu and fu 2007 johanson and fu 2009 lu et al 2009 and the role of radiative forcings induced by greenhouse gases and stratospheric ozone has been shown to be crucial in this context polvani et al 2011b

on the origin of shocked and unshocked cm clasts in h chondrite regolith breccias cm chondrite clasts that have experienced different degrees of aqueous alteration occur in h chondrite and hed meteorite breccias many clasts are fragments of essentially unshocked cm projectiles that accreted at low relative velocities to the regoliths of these parent bodies a few clasts were heated and dehydrated upon impact these objects most likely accreted at higher relative velocities we examined three clasts and explored alternative scenarios for their formation in the first scenario we assumed that the h and hed parent bodies had diameters of a few hundred kilometers so that their high escape velocities would effectively prevent soft landings of small cm projectiles this would imply that weakly shocked cm clasts formed on asteroidal fragments family members associated with the h and hed parent bodies in the second scenario we assumed that weakly shocked cm clasts were spall products ejected at low velocities from larger cm projectiles when they slammed into the h and hed parent bodies in both cases if most cm clasts turn out to have ancient ages e g 3 4 4 1 ga a plausible source for their progenitors would be outer main belt objects some which may have been dynamically implanted 3 9 ga ago by the events described in the so called nice model on the other hand if most cm clasts have recent ages 200 ma a plausible source location for their parent body would be the inner main belt between 2 1 2 2 au in that case the possible source of the cm clasts progenitors parent fragments would be the breakup 160 ma ago of the parent body 170 km in diameter of the baptistina asteroid family baf

a simple method to determine breaker height and depth for different deepwater wave height length ratios and sea floor slopes existing easily applicable methods to calculate the depth and height of breaking waves are hampered by two obstacles first the breaker depth is usually required to compute its height and vice versa second the equations take into account either the deepwater height to wavelength ratio or the sea floor slope but not both a simple iterative procedure is therefore proposed which incorporates both elements for fully developed waves breaking over a nearly horizontal bottom the breaker height and depth are also direct functions of the deepwater wavelength

characterising the relaxation distance of nearshore submarine morphology a southern baltic sea case study abstract a method for defining the length of coast with alongshore uniformity of nearshore submarine morphology is required in many shore normal nearshore profile modelling approaches here we introduce a new variable the relaxation distance to describe the alongshore spacing between two adjacent shore normal profiles characterised by distinct morphologies within this distance alongshore morphological changes are too small to distinguish so the nearshore submarine morphology is regarded as uniform along the coast we apply a semi variogram approach which expresses decreased spatial correlation of the nearshore submarine morphology with alongshore distance to quantify relaxation distances we apply this morphological variable to analyse 225 measured shore normal submarine profiles at 500 m intervals in three distinct sites of the tideless wave dominated southern baltic coast swina eba and hel the relaxation distances of these three sites are approximately 4500 m 3000 m and 2200 m of the three sites swina has the smoothest nearshore submarine morphology and the weakest wave energy the relaxation distances of different quasi straight segments at each site appear similar but those at different sites decrease with enlarged morphological perturbations which are residuals resulting from detrending the shore normal profiles the standard deviations of these morphological perturbations are correlated with the incidence wave angles and wave energy we also found that large perturbations such as longshore bars and channels have a significant impact on the estimation of underwater volume using shore normal profile trends therefore relaxation distance can indicate morphological smoothness the length of shore parallel uniform nearshore submarine morphology and the impact of local processes on submarine morphology

the origin of chromitic chondrules and the volatility of cr under a range of nebular conditions abstract we characterize ten chromitic chondrules two spinelian chondrules and one spinel bearing chondrule and summarize data for 120 chromitic inclusions discovered in an extensive survey of ordinary chondrites compositional and petrographic evidence suggests that chromitic chondrules and inclusions are closely related thecr cr al ratios in the spinel of these objects range from 0 5 to 0 9 and bulk al 2 o 3 contents are uniformly high 10 wt except for one with 8 wt no other elements having comparable solar abundances are so strongly enriched and alkali feldspar and merrillite are more common than in normal chondrules the cr mg ratios in chromitic chondrules are 180 750 the ratios in the bulk chondrite with the possible exception of magnetic clumping of chromite in the presolar cloud mechanical processes cannot account for this enrichment examination of nebular equilibrium processes shows that 50 condensation temperatures of cr atph 2 ph 2 o of 1500 are several tens of degrees below those of mg as mg 2 sio 4 the condensation of cr is primarily as mgcr 2 o 4 dissolved in mgal 2 o 4 at nebular pressures of 10 4 atm or below atph 2 10 3 atm condensation as cr in fe ni is favored making the nebula much more oxidizing reduces the difference in condensation temperatures but mg remains more refractory we conclude that nebular equilibrium processes are not responsible for the enhanced cr mg ratios we propose that both cr and al became enriched in residues formed by incomplete evaporation of presolar lumps we suggest that spinels remained as solid phases when the bulk of the silicates were incorporated into the evaporating melt vaporization of al and cr were inhibited by the slow kinetics of diffusion subsequent melting and crystallization of these residues fractionated cr from al the resulting materials constituted major components in the precursors of chromitic chondrules our model implies that chromitic chondrules and inclusions preserve the cr isotopic record of presolar sources

a multi scale hybrid long term morphodynamic model for wave dominated coasts abstract process based modules based on conservative equations to solve the transport of waves currents and sub aqueous sediment and behavior oriented modules based on empirical descriptions of cliff erosion bed load and terrestrial aeolian sand transport are coupled with up scaling measures and stability maintaining approaches in a parallel code to simulate decadal to millennial scale morphological evolution of wave dominated coasts an application to the southern baltic sea for a hindcast of holocene morphogenesis of the darss zingst peninsula demonstrates the robustness of the model the model is then used to investigate the morphogenesis and evolution of spits in an idealized fetch limited sandy coastal environment evolution of the spit system can be categorized into three periods according to the simulation results in the early period all initial coastline perturbations are amplified due to the high angle wave effects size competition between adjacent spits starts afterwards interaction between adjacent spits dominates the middle period smaller spits tend to retrogress due to unbalanced sediment budget and this sediment loss feeds further growth of their larger neighbors the retrograded spits are either smoothed or evolve into barrier lagoons and relatively stable large scale spits originating from larger spits are developed in the late period low frequency storms impinging from a regular high angle onto the coastline facilitate the development of spits in the early period but become a hindering factor afterwards terrestrial aeolian transport not only plays a key role in stabilizing the spits but is also revealed as an important factor for long term coastline erosion

surf zone longshore currents and random waves field data and models abstract analytic and numerical models for longshore currents generated by obliquely incident random waves am compared with field observations five days of observations were selected during which the waves were narrow banded in both frequency and direction in keeping with model assumptions the extensive measurements included radiation stress and wave directional spectra in 9 m depth and a closely spaced array of current and pressure sensors on a line perpendicular to shore the longshore current models are based on balancing the gradient of the radiation stress with the alongshore bed shear and reynold s stresses assuming stationary wave conditions and straight and parallel bottom contours the spatial variation of wave height required to determine the gradient of the radiation stress is modeled using linear random wave theory given hrms in 9 m depth the model predicts hrms at shoreward locations with an average error of less than 9 using a nonlinear bottom shear stress formulation and the meas

the villalbeto de la pena meteorite fall i fireball energy meteorite recovery strewn field and petrography an impressive daylight fireball was observed from spain portugal and the south of france at 16h46m45s utc on january 4 2004 the meteoroid penetrated into the atmosphere generating shock waves that reached the ground and produced audible booms the associated airwave was recorded at a seismic station located 90 km north of the fireball trajectory in spain and at an infrasound station in france located 750 km north east of the fireball the absolute magnitude of the bolide has been determined to be 18 1 from a casual video record the energy released in the atmosphere determined from photometric seismic and infrasound data was about 0 02 kilotons kt a massive fragmentation occurred at a height of 28 0 2 km resulting in a meteorite strewn field of 20 6 km the first meteorite specimen was found on january 11 2004 near the village of villalbeto de la pena in northern palencia spain to date about 4 6 kg of meteorite mass have been recovered during several recovery campaigns the meteorite is a moderately shocked s4 l6 ordinary chondrite with a cosmic ray exposure age of 48 5 ma radioisotope analysis shows that the original body had a mass of 760 150 kg which is in agreement with the estimated mass obtained from photometric and seismic measurements

deterministic coastal morphological and sediment transport modeling a review and discussion 1 modern coastal ocean modeling systems are now capable of numerically simulating a variety of coastal and estuarine problems and can thus provide useful information for managing coastal zones here we review state of the art eulerian implementations of bottom up sediment transport and morphological change in coastal ocean hydrodynamic models in order to investigate the fate of suspended sediment in coastal and estuarine waters as well as the evolution of sea or river beds sediment dynamics need to be represented at a scale relevant to the numerical discretized solution and significant effort is devoted to parameterize sediment processes we discuss boundary layer hydrodynamics and the computation of the bed shear stress we also focus on approaches used to represent near bed processes such as bed load transport and sediment erosion and deposition sediment diffusivities settling velocities and cohesive processes such as flocculation all have an impact on suspended sediment throughout the water column we then describe the implementation of process parameterizations in coastal hydrodynamic models explicitly reviewing five widely used systems the approaches implemented in these coastal models may present distinct strengths and shortcomings with regard to some important issues for coastal zones both numerical and physical while these detailed limitations need to be considered as part of model assessment more general issues also hinder present state of the art models in particular sediment transport is inherently highly empirical which is further compounded by issues arising from turbulence closure schemes we conclude by suggesting some possible directions toward improving sediment dynamics understanding and coastal scale predictive ability

mineral chemistry and the petrogenesis of eucrites ii cumulate eucrites abstract we carried out an ion microprobe study of rees and other selected trace and minor element concentrations in orthopyroxene augite lamellae and plagioclase of two cumulate eucrites moama and moore county in order to reevaluate the relationships between cumulate and noncumulate eucrites and among cumulate eucrites pyroxene and plagioclase in these two meteorites are more homogeneous in major minor and trace elements than in noncumulate eucrites and trace and minor element concentrations in moore county are higher than in moama although subsolidus equilibration erased and original igneous zoning it did not affect the ree patterns of these minerals both pigeonite and plagioclase of moama and moore county have higher lree hree ratios than those phases in noncumulate eucrites this indicates that cumulate eucrites derived from melts with fractionated ree patterns and thus are not related to noncumulate eucrites in addition the inconsistency between degrees of fractional crystallization deduced from major and trace elements and the differences of lree hree ratios recorded in pigeonite and plagioclase also suggest that moama and moore county did not form in the same fractional crystallization sequence this study confirms earlier observations and conclusions of ma and schmitt 1979 and poses problems for prevalent models

one dimensional modelling of individual waves and wave induced longshore currents in the surf zone a probabilistic model wavis model was developed to describe the propagation and transformation of individual waves wave by wave approach the individual waves shoal until an empirical criterion for breaking is satisfied wave height decay after breaking is modelled by using an energy dissipation method wave induced set up and set down and breaking associated longshore currents are also modelled laboratory and field data were used to calibrate and verify the model the model was calibrated by adjusting the wave breaking coefficient as a function of local wave steepness and bottom slope to obtain optimum agreement between measured and computed wave height four tests carried out in the large delta flume of delft hydraulics were considered generally the measured h13 wave heights are reasonably well represented by the model in all zones from deep water to the shallow surf zone the fraction of breaking waves was reasonably well represented by the model in the upsloping zones of the bottom profile verification of the model results with respect to wave induced longshore current velocities was not extensive because of a lack of data in case of a barred profile the measured longshore velocities showed a relatively uniform distribution in the trough zone between the bar crest and the shoreline which could to some extent be modelled by including space averaging of the radiation force gradient horizontal mixing and longshore water surface gradients related to variations in set up in case of a monotonically upsloping profile the cross shore distribution of the longshore current velocities is reasonably well represented

examination of the influence of several factors on longshore current computation with random waves abstract influence of various factors affecting the longshore currents induced by obliquely incident random waves is examined through numerical calculation seven numerical models for random wave breaking process are found to yield large differences in the wave heights in the surf zone and longshore current velocities the turbulent eddy viscosity formulation by larson and kraus larson m and kraus n c 1991 numerical model of longshore current for bar and trough beaches j waterway port coastal and ocean eng asce 117 4 pp 326 347 functions almost equal to that by battjes battjes j a 1975 modeling of turbulence in the surf zone proc symp modeling techniques pp 1050 1061 but the formulation by longuet higgins longuet higgins m s 1970 longshore current generated by obliquely incident sea waves 1 and 2 j geophys res 75 33 pp 6779 6801 produces excessive diffusion of longshore currents into the offshore zone the generation and decay process of the surface roller is indispensable in the longshore current analysis the random wave transformation model called pegbis parabolic equation with gradational breaker index for spectral waves by goda goda y 2004 a 2 d random wave transformation model with gradational breaker index coastal engineering journal jsce and world scientific 46 1 pp 1 38 produced good agreement with several laboratory and field data of longshore currents

the semarkona meteorite first recorded occurrence of smectite in an ordinary chondrite and its implications abstract semarkona is an unshocked unequilibrated ordinary chondrite much of the interchondrule matrix and the mesostases of some chondrules and clasts have been hydrothermally altered analyses of altered materials and opaque matrix are presented ca and fe have been redistributed from primary anhydrous phases into calcite and na fe smectite respectively in semarkona the process possibly requires open system behavior inconsistent with the conventional view of metamorphism of the ordinary chondrites the low petrologic type previously assigned to semarkona is the result of retrograde metamorphism under aqueous conditions of a higher temperature mineral assemblage semarkona and possibly bishunpur should be assigned to petrologic type 2

a numerical approach for approximating the historical morphology of wave dominated coasts a case study of the pomeranian bight southern baltic sea abstract comparison between historical maps from the 1900s 1980s and a modern map from the 2000s of the pomeranian bight at the southern baltic sea indicates that a major part of the coastline has been suffering continuous erosion this also holds for a major part of other coasts on a global scale quantifying coastal geomorphological changes on a decadal to centennial temporal scale thus needs to be intensified for coastal protection activities and integrated coastal zone management this study applies an estimation of sediment mass balance including the investigation of sediment source to sink transport in the case of absent historical survey data a numerical approach namely the dynamic equilibrium shore model desm is developed to approximate the historical morphology and to estimate sediment budget of wave dominated coasts based on the information of historical coastline configuration derived from maps a high resolution modern digital elevation model dem and relative sea level change the basic concept of the model is a dynamic equilibrium of the coastal cross shore profiles adapting to sediment mass balancing of a semi enclosed coastal area in which the unknown parameters of the cross shore profile shapes are calculated by numerical iterations the model is applied at the pomeranian bight in order to validate its capability in reflecting the pattern of bed level change and estimating sediment mass volume two tests of the model are conducted in approximating historical dems in 1980s and ca 1900 the changes of approximated dems from past to present are then respectively compared with the ones derived from a nautical sea chart in 1980s and the ones produced by a complex morphodynamic model that uses the approximated dem at ca 1900 as a starting point to hindcast the coastal morphological evolution of the research area the deposition erosion patterns along the coastline are consistent in both comparisons the pre conditions and limitations of the model are discussed in detail the model proposed here can serve as a useful tool for coastal morphological studies and potential applications for the future projection of coastal morphogenesis