combined visual and quantitative techniques in the study of natural turbulent flows an important difficulty in understanding turbulence in natural flows is that one does not see what is being measured by devices recording velocity fluctuations this study shows how visualization of turbulent structures can be effectively implemented in natural river flows in order to match turbulent flow structures with their velocity signatures flow visualization is combined with high frequency 20 hz velocity measurements from electromagnetic current meters two fluvial environments are examined in a river confluence where the difference in turbidity provides a natural tracer very strong negative velocity fluctuations for the streamwise component are concomitant with an upwelling motion a video recording made from a bridge of the passage of turbulent structures delineated by turbid and clear water allowed us to relate the marked fluctuations in velocity to eddies of a duration of 1 2 s in the mixing layer in a gravel bed river we have examined patterns of eddy shedding in the lee of a pebble cluster these patterns were highlighted by dye milk injected in the separation zone downstream black and white images were obtained from an underwater lens linked to a video camera recorder we observed a complex dynamic characterized by two dominant patterns of eddy shedding one with a clear motion of eddies toward the water surface and another with a downward expansion toward the bed of the structures this pattern is related to the passage of intermittent wedges of low speed fluid separated by wedges of fast moving fluid

detection and reconstruction of large scale coherent flow structures in gravel bed rivers large scale flow structures lsfs in the streamwise direction are important features of gravel bed river flows because they may contribute to sediment transport and gas exchange in the present study these structures are detected using huang s empirical mode decomposition and reconstructed with phase averaging techniques based on a hilbert transform of the velocity signal the analysis is based on the fluctuating component of 15 quasi instantaneous velocity profiles measured with a three dimensional 3d acoustic doppler velocity profiler advp in an armoured gravel bed river with a low relative submergence of 2 9 ratio between flow depth and bed grain diameter lsfs were identified in most of the measured profiles and consistently showed similar features we were able to characterize the geometry of these large scale coherent structures the front has a vertical linear shift in the time domain and a vertical profile corresponding to a first quarter moon with the apex situated at z h approximate to 0 4 in the vertical the front scales with flow depth h and in the streamwise direction lsfs scale with three to seven times the mean flow depth on the bed the effect of lsfs is a periodic non linear variation of the friction velocity on average between 0 90 and 1 10 times the mean value a model for the friction velocity cycle resulting from lsfs oscillation is presented copyright c 2014 john wiley sons ltd

shear velocity estimates in rough bed open channel flow shear velocity u is an important parameter in geophysical flows in particular with respect to sediment transport dynamics in this study we investigate the feasibility of applying five standard methods the logarithmic mean velocity profile the reynolds stress profile the turbulent kinetic energy tke profile the wall similarity and spectral methods that were initially developed to estimate shear velocity in smooth bed flow to turbulent flow over a loose bed of coarse gravel d 50 15cm under sub threshold conditions the analysis is based on quasi instantaneous three dimensional 3d full depth velocity profiles with high spatial and temporal resolution that were measured with an acoustic doppler velocity profiler advp in an open channel the results of the analysis confirm the importance of detailed velocity profile measurements for the determination of shear velocity in rough bed flows results from all methods fall into a range of 20 variability and no systematic trend between methods was observed local and temporal variation in the loose bed roughness may contribute to the variability of the logarithmic profile method results estimates obtained from the tke and reynolds stress methods reasonably agree most results from the wall similarity method are within 10 of those obtained by the tke and reynolds stress methods the spectral method was difficult to use since the spectral energy of the vertical velocity component strongly increased with distance from the bed in the inner layer this made the choice of the reference level problematic mean shear stress for all experiments follows a quadratic relationship with the mean velocity in the flow the wall similarity method appears to be a promising tool for estimating shear velocity under rough bed flow conditions and in field studies where other methods may be difficult to apply this method allows for the determination of u from a single point measurement at one level in the intermediate range 036 copyright c 2013 john wiley sons ltd

lunar meteorites from oman abstract sixty named lunar meteorite stones representing about 24 falls have been found in oman in an area of 10 7 103 km2 in southern oman lunar meteorite areal densities average 1 g km 2 all lunar meteorites from oman are breccias although two are dominated by large igneous clasts a mare basalt and a crystalline impact melt breccia among the meteorites the range of compositions is large 9 32 al2o3 2 5 21 1 feo 0 3 38 g g 1 sm and 1 to 22 5 ng g 1 ir the proportion of nonmare lunar meteorites is higher among those from oman than those from antarctica or africa omani lunar meteorites extend the compositional range of lunar rocks as known from the apollo collection and from lunar meteorites from other continents some of the feldspathic meteorites are highly magnesian high mgo mgo feo compared with most similarly feldspathic apollo rocks two have greater concentrations of incompatible trace elements than all but a few apollo samples a few have moderately high abundances of siderophile elements from impacts of iron meteorites on the moon all lunar meteorites from oman are contaminated to various degrees with terrestrial na k p zn as se br sr sb ba u carbonates or sulfates the contamination is not so great however that it seriously compromises the scientific usefulness of the meteorites as samples from randomly distributed locations on the moon

role of near bed turbulence structure in bed load transport and bed form mechanics the interactions between turbulence events and sediment motions during bed load transport were studied by means of laser doppler velocimetry and high speed cinematography sweeps u 0 w 0 w 0 which contribute negatively to the bed shear stress and are relatively rare individually move as much sediment as sweeps of comparable magnitude and duration however and much more than bursts u 0 and inward interactions u 0 w 0 when the magnitude of the outward interactions increases relative to the other events therefore the sediment flux increases even though the bed shear stress decreases thus although bed shear stress can be used to estimate bed load transport by flows with well developed boundary layers in which the flow is steady and uniform and the turbulence statistics all scale with the shear velocity it is not accurate for flows with developing boundary layers such as those over sufficiently nonuniform topography or roughness in which significant spatial variations in the magnitudes and durations of the sweeps bursts outward interactions and inward interactions occur these variations produce significant peaks in bed load transport downstream of separation points thus supporting the hypothesis that flow separation plays a significant role in the development of bed forms

the petrology and geochemistry of miller range 05035 a new lunar gabbroic meteorite miller range mil 05035 is a lunar gabbroic meteorite the mineralogy fe mn ratios in olivine and pyroxene bulk rock chemical composition and the bulk oxygen isotope values 17o 2 86 2 97 and 18o 5 47 5 71 are similar to those of other mare basalts and are taken as supporting evidence for a lunar origin for this meteorite the sample is dominated by pyroxene grains 54 61 by area mode of thin section along with large plagioclase feldspar 25 36 by mode and accessory quartz ilmenite spinel apatite and troilite the bulk rock major element composition of mil 05035 indicates that the sample has a very low ti vlt to low ti lunar heritage we measure bulk tio2 to be 0 9 wt and has low bulk incompatible trace element ite concentrations akin to samples from the vlt mare basalt suite to account for these geochemical characteristics we hypothesize that mil 05035 s parental melt was derived from a mantle region dominated by early cumulates of the magma ocean comprised principally of olivine and orthopyroxene mil 05035 is likely launch paired with the asuka 881757 and yamato 793169 basaltic lunar meteorites and the basaltic regolith breccia met 01210 this group of meteorites y a m m therefore may be a part of a stratigraphic column consisting of an upper regolith environment underlain by a coarsening downwards basalt lava flow

correlative velocity fluctuations over a gravel river bed velocity fluctuations in a steep coarse bedded river were measured in flow depths ranging from 0 8 to 2 2 m with mean velocities at middepth from 1 1 to 3 1 m s 1 analyses of synchronous velocity records for two and three points in the vertical showed a broad range of high coherence for wave periods from 10 to 100 s centering around 10 30 s streamwise correlations over distances of 9 and 14 m showed convection velocities near mean velocity for the same wave periods the range of coherent wave periods was a small multiple of predicted boil periods correlative fluctuations in synchronous velocity records in the vertical direction suggested the blending of short pulses into longer wave periods the highest spectral densities were measured beyond the range of coherent wave periods and were probably induced by migration of low relief bed forms

the spatial characterization of turbulence around large roughness elements in a gravel bed river abstract this study characterizes the flow field above and around multiple instream submerged cobbles boulders and pebble clusters in order to obtain a better understanding of the hydrodynamics associated with large roughness elements lres in gravel bed rivers spatially distributed high frequency three dimensional velocity measurements were recorded in situ using acoustic doppler velocimeters at different flow stages the spatial distributions of turbulent kinetic energy ke longitudinal component integral timescales itsu and reynolds shear stresses were characterized and are presented for selected sites the longitudinal vertical reynolds shear stress increased with flow stage more strongly than the longitudinal lateral or lateral vertical reynolds shear stresses and dominate at the highest measured flows canonical redundancy analysis was used to relate lre morphometrics and mean flow conditions to the turbulence parameters estimated in the lre wakes i e ke itsu and reynolds shear stresses lre size and mean unobstructed velocity explained the highest proportion of the variance in the turbulent wake statistics multivariate regression models based on lre width mean unobstructed longitudinal velocity and flow depth are presented offering a tool to predict lre wake turbulence

flow turbulence over fixed and weakly mobile gravel beds characteristics of turbulence structure in quasi 2d flows with static and weakly mobile gravel beds are presented three sets of measurements with acoustic doppler velocimeters in an irrigation canal were used two with subcritical bed shear stress static beds and one with the bed shear stress o close to critical oc weakly mobile bed the analyses included vertical distributions of local mean velocities turbulence intensities turbulent shear stresses velocity auto and cross spectra the quadrant method and high order velocity moments a number of properties of turbulence intensities high order moments streamwise bursting parameters and velocity spectra appeared to be similar for all three flows but some properties were different the most important one was an observed reduction in the von karman constant for the flow with weakly mobile bed comparison of these results with other studies and analogies with drag reducing flows suggest that at o oc 1 the drag on the bed for a given granula

on large scale flow structures in a gravel bed river abstract previous studies have suggested the presence of large scale flow structures in gravel bed rivers these structures are pictured as intermittent high speed wedges separated by regions of lower velocity however the characteristics of these structures have not been examined in detail through either visualisation techniques or detailed field measurements this paper confirms the presence of large scale flow structures in gravel bed rivers pictures their sequence and patterns and characterises their mean and individual properties the analysis relies on a new technique for displaying velocity fluctuations in a space time matrix that allows one to see the structures as they pass an array of current meters streamwise and vertical velocities were measured simultaneously with an array of three electromagnetic current meters the sampling frequency was 20 hz five velocity profiles of up to 13 1 min series of measurements and one profile of three 20 min measurements were sampled these data suggest the presence of large wedges of faster fluid joined by regions of slower fluid space time correlation analysis confirmed the presence of vertical coherence of the flow the average angle of the front of the wedges is 36 although individual structures are variable in size and shape a new detection technique using all three velocity signals simultaneously showed that their average frequency is nine events per minute and their duration is more than 2 s the high speed wedges display a complex organisation and do not show a preferred sequence of events as was postulated by previous studies because of their duration and size these high speed wedges are likely to play a major role in bedload sediment transport

influence of coherent flow structures on the dynamics of suspended sediment transport in open channel flow the influence of suspended sediments on coherent flow structures has been studied by simultaneously measuring the longitudinal and vertical components of the instantaneous velocity vector and the instantaneous suspended particle concentration with an acoustic particle flux profiler the measurements were carried out in clear water and in particle laden open channel flows in both cases they clearly show the predominance of ejection and sweep phases that are part of a burst cycle the analysis further demonstrates the importance of the ejection and sweep phases in sediment resuspension and transport ejections pick up the sediment at the bed and carry it up through the water column close to the surface it is shown that ejections and sweeps are in near equality in the near bottom layer whereas ejections clearly dominate in the remaining water column the implications of these results for sediment transport dynamics are discussed

macroturbulent structure of open channel flow over gravel beds the turbulent structure of open channel flow over a mobile gravel bed was investigated in an 8 m long 0 3 m wide and 0 3 m deep tilting flume a flow visualization technique was used and complemented by measurements of flow velocity fluctuations near the bed the experiments reveal that turbulent flow consists of a sequence of large scale eddies with a vertical size close to the flow depth an average length equal to four to five depths and a width of about two depths the downstream motion of these eddies causes quasiperiodic fluctuations of the local flow velocity components the development of longitudinal troughs and ridges on the mobile bed and preferential transport of bed particles along troughs are related to the effect of the eddies the experimental results indicate that the depth scale eddies are an important turbulence mechanism contributing to sediment transport

origin of lunar meteorite alha 81005 clues from the presence of terrae clasts and a very low titanium mare basalt clast petrographic data and pyroxene compositions indicate that meteorite alha 81005 is a breccia from the terrae of the earth s moon thin section alha 81005 9 includes ferroan anorthositic clasts a lone clast of mg suite plutonic composition fragments which are intermediate in composition between ferroan anorthosite and mg suite plutonics and a clast of very low titanium mare basalt fragments of norite and harzburgite have mineral compositions like ferroan anorthosite and a clast of ferroan anorthosite has pyroxenes with lower molar mg mg fe than in known pristine rocks the mg suite protoliths for the clasts of intermediate composition are inferred to be magnesian troctolites spinel troctolites and feldspathic lherzolites although clasts of these lithologies are not present in alha 81005 9 mineral fragments from them are present a single basaltic clast is of mare origin based on the molar mg mg fe ratio and cr content of its pyroxenes the composition of its plagioclase and the molar ti ti cr ratios of its pyroxenes indicate that the clast is a fragment of very low titanium vlt mare basalt if this basalt is significantly younger than the last basin forming impact event 3 9 109 years ago its presence probably constrains the source crater for alha 81005 to be within a hundred kilometers of a vlt mare basalt flow

measurements of turbulence in the benthic boundary layer over a gravel bed it is now generally recognized that the mathematical description of sediment dynamics will be improved through an understanding of geophysical turbulence in this study therefore the turbulence characteristics of the benthic boundary layer over coarse sediments are examined as a step towards the realization of such a description examination of the turbulence has been conducted using spectral correlation quadrant and statistical analyses and a number of features have been identified mean eddy length scales obtained using spectral and autocorrelation techniques were found to be similar the interpretation of the duration and interval between the intermittent bursting events scaled using outer flow variables was found to be dependent upon the sampling interval autocorrelation analysis revealed a high correlation between bedload transport and the instantaneous horizontal flow component rather than instantaneous kinematic stress from the standpoint of developing prognostic transport models based on physically realistic benthic flow processes it is considered that turbulence measurements will lead to such formulation

timing and heat sources for the barrovian metamorphism scotland abstract new shrimp u pb zircon ages of 472 2 5 8 ma and 471 2 5 9 ma are presented for the age of peak metamorphism of barrovian migmatites 40 ar 39 ar ages for white mica from the barrovian metamorphic series are presented and are recalculated using recently proposed revisions to the 40 k decay constants to allow more precise and accurate comparison with u pb ages the 40 ar 39 ar ages are found to vary systematically with increasing metamorphic grade between c 465 ma for the biotite zone and c 461 ma for the sillimanite zone there is no evidence for any significant metamorphic heating during the first 15 myr of the grampian orogeny before c 473 ma or the final 4 myr after c 465 ma the barrovian metamorphism occurred over a period of 8 myr within the 27 myr grampian orogeny the barrovian metamorphism records punctuated heating was temporally and spatially associated with large scale bimodal magmatism and developed within crust that was not overthickened the temporally distinct nature of the barrovian metamorphic episode within the grampian orogeny and its heating pattern and tectonic context are not consistent with significant heat contribution from thermal equilibration of overthickened crust rather the barrovian metamorphism records a transient phase of crustal thermal disequilibrium during the grampian orogeny temporal and spatial association with grampian bimodal magmatism is consistent with production of the barrovian metamorphic series within the middle crust as the result of advection of heat from the lower crust and or mantle the barrovian metamorphic series the classic example of orogenic regional metamorphism did not form in response to crustal thickening and thermal relaxation but appears to record large scale contact metamorphism

petrography geochronology and source terrain characteristics of lunar meteorites dhofar 925 961 and sayh al uhaymir 449 abstract dhofar dho 925 961 and sayh al uhaymir sau 449 are brecciated lunar meteorites consisting of mineral fragments and clasts from a range of precursor lithologies including magnesian anorthositic gabbronorite granulites crystalline impact melt breccias clast bearing glassy impact melt breccias lithic fragmental breccias mare basalts and evolved silica rich rocks on the similarity of clast type and mineral chemistry the samples are likely grouped and were part of the same parent meteorite phosphate pb pb ages in impact melt breccias and matrix grains demonstrate that dho 961 records geological events spanning 500 ma between 4 35 and 3 89 ga these pb pb ages are similar to the ages of ancient intrusive magmatic samples and impact basin melt products collected on the lunar nearside by the apollo missions however the samples bulk rock composition is chemically distinct from these types of samples and it has been suggested that they may have originated from the farside south pole aitken impact basin i e jolliff et al 2008 we test this hypothesis and conclude that although it is possible that the samples may be from the south pole aitken basin there are other regions on the moon that may have also sourced these complex breccias

a concise compilation of petrologic information on possibly pristine nonmare moon rocks ansrn q cr to facilitate systematic study of the surviving compositionally pristine endogenously igneous rocks of the ancient lunar crust a compilation has been generated of all likely samples along with key information on the petrologic characteristics and chemistry of each sample the compilation includes 260 samples besides information related to the likelihood of each sample being truly pristine i e mainly its texture and siderophile element abundances information is compiled on mineral content listing major phases present as well as basic information on mineral compositions on size expressed as mass and on whether a reasonably comprehensive chemical analysis has been published the compilation also classifies the samples into seven categories of confidence in the pristine composition of the samples reflecting an estimation of the relative likelihood that each arguably pristine sample is in fact pristine for many purposes it is crucial to avoid inclusion of polymict rocks in a data base on petrologic diagrams such as a plot of average mg mg 100 x molar mg mg fe in a low ca mafic silicate vs average an content in plagioclase rocks in the top three categories of the confidence in pristine character appear distinctly bimodal in composition with roughly half belonging to a ferroan suite characterized by high an despite relatively low mg when samples of low to moderate pristine character are included the bimodality appears less distinct sample mass can also be important with a data base restricted to samples more massive than i g there is a clear distinction in feldspar content and bulk density between ferroan and nonferroan mgsuite rocks such that only the ferroan suite rocks are likely to have formed as flotation cumulates with a data base including smaller samples the same basic pattern is seen but only in a blurred form as the two rock types show considerable overlap in their modal feldspar contents

flow over rough mobile beds friction factor and vertical distribution of the longitudinal mean velocity 1 the main objective of the present study is to identify the impacts of bed mobility on the vertical profile of the mean longitudinal velocity and on resistance in flows over water worked beds of poorly sorted mixtures of sand and gravel water worked beds with sediment transport are explicitly distinguished from immobile beds with imposed sediment feed flows with different equilibrium sediment transport rates are generated in a laboratory flume the initial bed mixtures featured combinations of sand and gravel modes data collection included instantaneous velocities measured with laser doppler annemometry wall similarity in the sense of townsend 1976 is assumed the parameters of the formulae are discussed within three scenarios comprising different definitions ofu and ks combined with different conceptions of the von karman constant flow independent or flow dependent it is shown that the parameters of the formulae that express the velocity profile vary with the shields number and with the initial bed composition the variation is independent of the adopted scenario except in what concerns the formulation of hydraulic smoothening in the presence of sand sizes which depends on the definition of ks

basaltic fragments in lunar feldspathic meteorites connecting sample analyses to orbital remote sensing abstract the feldspathic lunar meteorites contain rare fragments of crystalline basalts we analyzed 16 basalt fragments from four feldspathic lunar meteorites allan hills alha 81005 macalpine hills mac 88104 88105 queen alexandra range que 93069 miller range mil 07006 and utilized literature data for another dhofar dho 1180 we compositionally classify basalt fragments according to their magma s estimated tio2 contents which we derive for crystalline basalts from pyroxene tio2 and the mineral melt ti distribution coefficient overall most of the basalt fragments are low ti basalts 1 6 tio2 with a significant proportion of very low ti basalts 10 tio2 and 6 10 tio2 respectively this distribution of basalt tio2 abundances is nearly identical to that obtained from orbital remote sensing of the moon both uv vis from clementine and gamma ray from lunar prospector however the distribution of tio2 abundances is unlike those of the apollo and luna returned samples we observe a paucity of high ti basalts the compositional types of basalt differs from meteorite to meteorite which implies that all basalt subtypes are not randomly distributed on the moon i e the basalt fragments in each meteorite probably represent basalts in the neighborhood of the meteorite launch site these differences in basalt chemistry and classifications may be useful in identifying the source regions of some feldspathic meteorites some of the basalt fragments probably originate from ancient cryptomaria and so may hold clues to the petrogenesis of the moon s oldest volcanism

sensitivity of bed shear stress estimated from vertical velocity profiles the problem of sampling resolution bed shear stress in open channel flows is often estimated from the logarithmic vertical velocity profile however most measuring devices used in the field do not allow for flow velocity to be measured very close to the bed the lack of near bed measurements is a critical loss of information which may affect bed shear stress estimates detailed velocity profiles obtained from a field acoustic doppler velocimeter over three different bed roughnesses clearly show that the inclusion of near bed points is critical for the estimation of bed shear stress in a shallow river environment moreover the results indicate that using the full flow depth instead of the bottom 20 per cent of the profile generates an underestimation of the shear stress when flow is uniform 1998 john wiley sons ltd

magnesian anorthositic granulites in lunar meteorites allan hills a81005 and dhofar 309 geochemistry and global significance abstract fragments of magnesian anorthositic granulite are found in the lunar highlands meteorites allan hills alh a81005 and dhofar dho 309 five analyzed clasts of meteoritic magnesian anorthositic granulite have mg molar mg mg fe 81 87 feo 5 wt al2o3 22 wt rare earth elements abundances 0 5 2 ci except eu 10 ci and low ni and co in a non chondritic ratio the clasts have nearly identical chemical compositions even though their host meteorites formed at different places on the moon these magnesian anorthositic granulites are distinct from other highlands materials in their unique combination of mineral proportions mg ree abundances and patterns ti sm ratio and sc sm ratio their mg is too high for a close relationship to ferroan anorthosites or to have formed as flotation cumulates from the lunar magma ocean compositions of these magnesian anorthositic granulites cannot be modeled as mixtures of or fractionates from known lunar rocks however compositions of lunar highlands meteorites can be represented as mixtures of magnesian anorthositic granulite ferroan anorthosite mare basalt and kreep meteoritic magnesian anorthositic granulite is a good candidate for the magnesian highlands component inferred from apollo highland impactites magnesian feldspathic and ree poor bulk compositions of meteorite magnesian anorthositic granulites are comparable to those inferred for parts of the lunar farside the feldspathic highlands terrane 4 5 wt feo 28 wt al2o3 and th 1 ppm thus magnesian anorthositic granulite may be a widespread and abundant component of the lunar highlands

1 min in the life of a river selecting the optimal record length for the measurement of turbulence in fluvial boundary layers in the analysis of instantaneous velocity measurements it is important to consider carefully the properties of the instruments as well as the sampling frequency and the record length although several studies have examined the influence of instrument settings on velocity measurements in rivers little information is available on the effects of the record length on these measurements and on the turbulence parameters that can be extracted from the time series decisions on the record length are often made ad hoc here we quantify the effects of the sampling period on the precision of turbulence statistics e g mean standard deviation skewness reynolds stress quadrant analysis obtained from velocity measurements in fluvial turbulent boundary layers a bootstrapping method is used to determine the standard errors s e of turbulence statistics from 19 time series the time series were sampled in three gravel bed rivers using both electromagnetic current meters ecm and acoustic doppler velocimeters adv the record lengths ranged between 20 and 60 min the sampling frequencies were 20 and 25 hz for the ecms and advs respectively we show that for most turbulence statistics the optimal record length minimum sampling effort to achieve low standard errors ranges between 60 and 90 s we discuss the implication of these record lengths for standard errors estimates and variance losses

size shape and dynamics of large scale turbulent flow structures in a gravel bed river in this paper we present a detailed investigation of the size scale and dynamics of macro turbulent flow structures in gravel bed rivers we used an array of seven electromagnetic current meters with high resolution in both space and time to measure the streamwise velocity fluctuations in a gravel bed river the array was deployed successively in various configurations in order to quantify the vertical lateral and longitudinal extent of the flow structures and to estimate their advecting velocities to depict the spatial and temporal properties of the flow structures we used space time velocity matrices space time correlation analysis and coherent structure detection schemes the results show that the large scale turbulent flow structures in a gravel bed river occupy the entire depth of the flow and that they are elongated and narrow the length of the structures is 3 to 5 times the flow depth while the width is between 0 5 and 1 times flow depth in spite of the high roughness of the bed these values are similar to those reported in the literature for laboratory experiments on large scale turbulent flow structures the dynamics of the large scale turbulent flow structures investigated using flow visualization highlight the interactions between the outer flow region and the near bed region our evidence suggests that large scale flow incursions trigger ejections in the near bed region that can develop into megabursts that can reach the water surface

the hadley apennine kreep basalt igneous province abstract we have studied 27 kreep basalt fragments in six thin sections of samples collected from four apollo 15 stations based on local geology and regional remote sensing data these samples represent kreep basalt lava flows that lie beneath the younger local apollo 15 mare basalts and under other mare flows north of the apollo 15 site some of these rocks were deposited at the site as ejecta from the large craters aristillus and autolycus kreep basalts in this igneous province have a volume of 103 2 104 km3 mineral and bulk compositional data indicate that the erupted magmas had mg 100 molar mg mg fe up to 73 corresponding to orthopyroxene rich interior source regions with mg up to 90 minor element variations in the parent magmas of the kreep basalts inferred from compositions of the most magnesian pyroxene and most calcic plagioclase in each sample indicate small but significant differences in the concentrations of minor elements and mg reflecting variations in the composition of lower crustal or mantle source regions and or different amounts of partial melting of those source regions

fe mn systematics of type iia chondrules in unequilibrated co cr and ordinary chondrites we have examined fe mn systematics of 34 type iia chondrules in eight highly unequilibrated co cr and ordinary chondrites using new data from this study and prior studies from our laboratory olivine grains from type iia chondrules in co chondrites and unequilibrated ordinary chondrites uoc have significantly different fe mn ratios with mean molar fe mn 99 and 44 respectively olivine analyses from both these chondrite groups show well defined trends in mn versus fe afu and molar fe mn versus fe mg diagrams in general type iia chondrules in cr chondrites have properties intermediate between those in uoc and co chondrites in most uoc and cr type iia chondrules the fe mn ratio of olivine decreases during crystallization whereas in co chondrites the fe mn ratio does not appear to change it is difficult to interpret the observed fe mn trends in terms of differing moderately volatile element depletions inherited from precursor materials instead we suggest that significant differences in the abundances of silicates and sulfides metals in the precursor material as well as open system behavior during chondrule formation were responsible for establishing the different fe mn trends using fe mn mg systematics we are able to identify relict grains in type iia chondrules which could be derived from previous generations of chondrules including chondrules from other chondrite groups and possibly chondritic reservoirs that have not been sampled previously