siderophile trace elements in alh84001 other snc meteorites and eucrites evidence of heterogeneity possibly time linked in the mantle of mars we report neutron activation analyses including radiochemical determination of trace siderophile elements au ge ir ni os and re for three snc martian meteorites and os and re results for numerous eucrites ratios such as ga al in the snc orthopyroxenite alh84001 confirm its martian affinity its many distinctive characteristics most notably its near primordial age notwithstanding to the list of alh84001 s idiosyncrasies can now be added extraordinarily low concentrations of au ni and especially re 17 pg g for a martian meteorite we consider several possible origins for the anomalously low re content in alh84001 including metasomatism or alteration the pyroxene cumulate nature of this rock probably does not account for its low re content other snc meteorites are also cumulates an examination of re nd variations among terrestrial basalts and komatiites suggests that re is compatible with mantle minerals in general and only incompatible with olivine however olivine dominates the mantle residuum especially during komatiite genesis our preferred model is that the alh84001 parent melt formed in a mantle source region that was far more re depleted and or at a substantially lower oxygen fugacity than the sources of the young snc meteorites such a contrast is consistent with models that replenish siderophile elements in planetary mantles by gradual admixture of late accreting matter and similarly derive most planetary water which serves as an oxidant very late in accretion according to this model alh84001 formed before the siderophile rich matter and water had been mixed well into the martian interior possibly the martian mantle never became generally as re rich and or oxidized as the source region s of the younger sncs

apollo 16 regolith breccias characterization and evidence for early formation in the mega regolith all of the apollo 16 regolith breccias 8 specimens have been characterized in terms of their petrography grain size distribution porosity major and trace element composition noble gas contents and ferromagnetie resonance properties these breccias vary signkqcantly with respect to their density and porosity with the more dense breccias showing significant shock damage the regolith breccias resemble the soils in grain size distribution and in the relative proportions of major petrological components except agglutinates many of the breecias are compositionally different from the apollo 16 soils in that they lack an important marie component present in the soils although some groupings occur the petrologic and chemical compositions of the regolith breedas do not correlate with the station location of the samples all but one of the breceias show some evidence of irradiation at the lunar surface solar gases measurable fmr agglutinates and analyses made on grain size separates from two disaggregated breedas indicate that this irradiation occurred before compaction when the breccia material was finely disseminated on the surface however the concentrations of surface irradiation parameters solar gases fmr agglutinates for most breedas are far less than seen in any lunar soils or in regolith breccias from other apollo missions several breedas also contain unusually high trapped 4oar 36ar ratios of 8 12 and a significant fission xe component in excess of that expected from in situ production these observations suggest that the surface irradiation of these breedas occurred as early as 4 x 109 years ago we conclude that most of the apollo 16 regolith breedas were not formed from any known apollo 16 soil they appear to be well comminuted material that contains ancient regolith developed during the late stage heavy bombardment of the moon when large impacts were much more common relative to small impacts so that regoliths did not have time to significantly mature before being diluted by fresh ejecta and buffed this ancient megaregolith is significantly different from more recent lunar regolith but may be similar to asteroidal regoliths from which some brecciated meteorites have formed

near bed mass flux profiles in aeolian sand transport high resolution measurements in a wind tunnel vertical profiles of the streamwise mass flux of blown sand in the near bed 17 mm region are analysed from high resolution measurements made using an optical sensor in a wind tunnel this analysis is complemented by detailed measurements of mass flux and mean velocity profiles throughout the boundary layer depth 0 17 m using passive chambered sand traps of small dimensions and armoured thermal anemometers respectively the data permit a preliminary analysis of the relations between the observed forms of the profiles of near bed fluid stress and horizontal mass flux within a carefully conditioned boundary layer profiles of mass flux density are found to be characterized by three regions of differing gradient with transitions at about 2 mm and 19 mm above the bed the exponential decay of mass flux with height is confirmed for elevations above 19 mm and when plotted as a function of u 2 g a parameter of mean vertical trajectory height in saltation the gradient of mass flux in this region scales with the wake corrected friction velocity u where u 0 30 m s 1 a separate near bed region of more intense transport below 19 mm is identified which carries 80 per cent of the total mass flux this region is evident in some previous field and wind tunnel data but not in profiles simulated by numerical models ventilated passive sand traps underestimate mass flux in this region by 37 per cent at slow or moderate wind speeds a third significant region below 2 mm is observed these regions are likely to be related to grain populations in successive saltation low energy ejections and intermittent bed contact respectively optical measurements reveal locally high grain concentrations at some elevations below 5 mm these heights scale with transport rate mass flux gradient and wind speed copyright 1999 john wiley sons ltd

the early geological history of the moon inferred from ancient lunar meteorite miller range 13317 abstract miller range mil 13317 is a heterogeneous basalt bearing lunar regolith breccia that provides insights into the early magmatic history of the moon mil 13317 is formed from a mixture of

reconstructing the vertical distribution of the aeolian saltation mass flux based on the probability distribution of lift off velocity the probability distribution of lift off velocity of the saltating grains is a bridge to linking microscopic and macroscopic research of aeolian sand transport the lift off parameters of saltating grains i e the horizontal and vertical lift off velocities resultant lift off velocity and lift off angle in a wind tunnel are measured by using a phase doppler particle analyzer pdpa the experimental results show that the probability distribution of horizontal lift off velocity of saltating particles on a bed surface is a normal function and that of vertical lift off velocity is an exponential function the probability distribution of resultant lift off velocity of saltating grains can be expressed as a log normal function and that of lift off angle complies with an exponential function a numerical model for the vertical distribution of aeolian mass flux based on the probability distribution of lift off velocity is established the simulation gives a sand mass flux distribution which is consistent with the field data of namikas namikas s l 2003 field measurement and numerical modelling of acolian mass flux distributions on a sandy beach sedimentology 50 303 326 therefore these findings are helpful to further understand the probability characteristics of lift off grains in aeolian sand transport c 2007 elsevier b v all rights reserved

lunar highland meteorites and the composition of the lunar crust abstract major minor and trace element data obtained by neutron activation techniques and by spark source mass spectrometry ssms on two lunar meteorites mac88104 and mac88105 are reported both mac samples were also analysed for their contents and isotopic compositions of rare gases additional ssms data were obtained on four lunar highland meteorites previously found in antarctica alha81005 y791197 y82192 and y86032 mac88104 and mac88105 are very similar in chemistry suggesting that they are pieces of a single fall event the bulk chemical composition of mac88104 5 is not very different from the other lunar highland meteorites highly aluminous with relatively low contents of ree and siderophile element concentrations slightly above 1 of a ci chondritic level however mafic element concentrations mg cr mn etc are slightly lower in mac88104 5 than in the other lunar highland meteorites the contents of solar rare gases in the two mac samples are low indicating only a small regolith contribution in agreement with rare petrographically identifiable regolith components the mac samples and also y82192 and y86032 are classified as fragmental breccias with negligible regolith components in contrast to alha81005 and y791197 which are regolith breccias with high solar wind derived rare gas contents there is no correlation among lunar meteorites between peak shock pressures and solar gas contents indicating that peak shock pressures of up to 25 gpa do not lead to gas loss a low 26al activity vogt et al 1990 and high contents of cosmogenic rare gases in mac88104 5 suggest a long exposure 400 000 years in the lunar sub surface k ar ages are in excess of 3 9 by lunar highland meteorites and compositionally similar granulitic rocks from the apollo 16 and 17 landing sites contain about 1 of a ci chondritic component according to siderophile and volatile element contents but independent of the amount of regolith components apparently the major fraction of meteoritic elements in these rocks was not provided by micrometeorites impacting the regolith the abundances of siderophile e g ir and volatile elements may therefore reflect the last spike of accretion of the moon after the formation of the anorthositic crust lunar meteorites of highland origin are chemically different from the bulk of the apollo 16 highland samples in having higher fe mg ratios and lower contents and less fractionated patterns of incompatible and siderophile elements since lunar highland meteorites are associated with at least three but probably four different fall events and since they are not derived from chemically exotic front side terranes they may represent a better sampling of the average chemical composition of the lunar crust than previous estimates based on returned lunar samples and remote sensing data a comparison between an average highland composition derived by taylor 1982 and an estimate based on lunar highland meteorites shows that the taylor composition contains higher concentrations and more fractionated incompatible elements mainly because of a substantial amount of kreep a trace element rich highly fractionated component from the front side of the moon not present at the sites from which the lunar meteorites come

statistical analysis of sand grain bed collision process recorded by high speed digital camera a high speed digital camera was employed to record the sand grain bed collision process with image processing and a statistical method a series of parameters of the collision process were obtained the results show that the collision process of a grain with rebounding can be represented by two parameters the kinetic energy restitution coefficient and the collision angle both parameters satisfy a normal distribution and they are dependent on one another with an increase of the collision angle the distribution of the kinetic energy restitution gradually reduces from a broad to a narrow range with low values the percentage of vertical velocity restitution coefficients greater than 1 can reach 70 or more which ensures that the settling time of the sand grains in the air increases and that they receive more energy from the air to progress the saltation movement

petrography relationships and petrogenesis of the gabbroic lithologies in northwest africa 773 clan members northwest africa 773 2727 3160 3170 7007 and 10656

regolith breccia allan hills a81005 evidence of lunar origin and petrography of pristine and nonpristine clasts mno feo ratios in pyroxene texture abundant brown swirly glass in general typical of lunar regolith breccias and overall composition 75 plagioclase all indicate that allan hills a81005 is of lunar origin it is presumably from a heretofore unsampled region of the moon it differs in detail from other regolith samples e g it has exceptionally low contents of na and kreep a pristine clast contains exceptionally coarse augite compared to similar apollo samples alha81005 is not perceptibly more shocked than typical apollo regolith breccias therefore its discovery on earth lends further credence to suggestions that snc achondrites were derived by impact ejection from mars

tracking of saltating sand trajectories over a flat surface embedded in an atmospheric boundary layer abstract saltation is a major mechanism for the transport of soil particles in the present study we carried out wind tunnel tests to examine the saltating trajectories of two types of natural sand collected from a beach diameter d 300 500 m and 200 300 m respectively as well as sand from the taklimakan desert d 100 125 m in an atmospheric boundary layer consecutive images of saltating particles were recorded using a high speed digital camera at a rate of 2000 fps with a spatial resolution of 1024 1024 pixels the high temporal resolution of the acquired images enabled us to study the particle motion very close to the surface the saltating particle trajectories were reconstructed from consecutive images and the physical quantities characterizing the initial and final stages of the particle flight in the windward direction at friction velocities of about 10 25 above the threshold friction velocity u u t 1 11 1 26 were analyzed statistically in addition the transverse deviation of the saltating particles from the main streamwise direction was evaluated the results shed new light on the complicated motions involved in sand saltation and should prove useful in the evaluation and formulation of theoretical models

analysis of velocity profile measurements from wind tunnel experiments with saltation abstract investigations of wind field modification due to the presence of saltating sediments have relied heavily on wind tunnels which are known to impose geometric constraints on full boundary layer development there remains great uncertainty as to which portion of the vertical wind speed profile to analyze when deriving estimates of shear velocity or surface roughness length because the lower sections are modified to varying degree by saltation whereas the upper segments may be altered by artificially induced wake like effects thus it is not obvious which of several alternative velocity profile parameterizations e g law of the wall velocity defect law wake law should be employed under such circumstances a series of experimental wind tunnel runs was conducted across a range of wind speed using fine and coarse grained sand to collect high quality fine resolution data within and above the saltation layer using thermal anemometry and ruggedized probes after each run the rippled bottom was fixed with fine mist and the experiment repeated without saltation the measured wind speed profiles were analyzed using six different approaches to derive estimates of shear velocity and roughness length the results were compared to parameter estimates derived directly from sediment transport rate measurements and on this basis it is suggested that one of the six approaches is more robust than the others specifically the best estimate of shear velocity during saltation is provided by the logarithmic law applied to the profile data within about 0 05 m of the bottom despite the fact that this near surface region is where profile modification by saltating sediments is most pronounced uncertainty remains as to whether this conclusion can be generalized to field situations because progressive downwind adjustments in the interrelationship between the saltation layer and the wind field are anticipated in wind tunnels thereby confounding most analyses based on equilibrium assumptions

a ferroan region of the lunar highlands as recorded in meteorites mac88104 and mac88105 macalpine hills 88104 and 88105 mac88104 5 are paired meteorites of noritic anorthosite composition from the lunar highlands mac88105 is a breccia composed mainly of melt breccia clasts in a fine grained fragmental and partly glassy matrix the most abundant melt lithologies are feldspathic and are similar in composition to the bulk meteorite other melt lithologies include feldspathic melt rocks mafic melt breccias and a rare melt breccia relatively enriched in incompatible trace elements subordinate lithic clasts are granulitic breccias and ferroan relatively low mg mg fe igneous lithologies including troctolitic anorthosite anorthositic norite gabbronorite and anorthosite igneous clasts having mafic mineral compositions more magnesian than fo55 and en60 were not observed rare fragments of glass spheres and shards as well as glass clasts indicate that the meteorite was derived from an immature regolith the bulk composition of mac88105 is characterized by a molar mg mg fe ratio of 0 62 at the extreme low end of the range for meteorites from the lunar highlands its low concentrations of incompatible trace elements and feldspathic bulk composition 29 al2o3 suggest that it like the other lunar meteorites formed at a site far removed from the areas sampled by the apollo missions similarities in mineral compositions among the different lithologies of the breccia melt breccia clasts granulitic breccias igneous fragments and the distribution of mineral fragments suggest that most components of the meteorite were derived from a crustal section dominated by material with a noritic anorthosite composition and an affinity to the ferroan suite of plutonic rocks the mafic melt breccias have roughly peritectic melt compositions similar to many low k fra mauro melt breccias in the apollo collection but much more ferroan and represent a source material distinct from the noritic anorthosite moderate ce anomalies both positive and negative occur in some separated clasts and to a lesser extent in some small chips dominated by matrix but not in powder prepared from 20 g of bulk meteorite these anomalies are almost certainly terrestrial weathering effects one granulitic breccia clast is rich in siderophile elements as a result of a large amount of fe ni metal the auir ratio of the clast 0 64 ci normalized is distinctly different from that of metal rich impact melts from apollo 16 3 ci normalized the compositional range observed among the nonmare lunar meteorites alha81005 y791197 y82192 3 y86032 and mac88104 5 is equivalent to that observed among representative samples of 1 mm fines from apollo 16 thus compositional data provide little constraint on the number of impacts required to eject these meteorites from the moon

petrology and geochemistry of feldspathic impact melt breccia abar al uj 012 the first lunar meteorite from saudi arabia abar al uj aau 012 is a clast rich vesicular impact melt im breccia composed of lithic and mineral clasts set in a very fine grained and well crystallized matrix it is a typical feldspathic lunar meteorite most likely originating from the lunar farside bulk composition 31 0 wt al2o3 3 85wt feo is close to the mean of feldspathic lunar meteorites and apollo fan suite rocks the low concentration of incompatible trace elements 0 39ppmth 0 13ppm u reflects the absence of a significant kreep component plagioclase is highly anorthitic with a mean of an 96 9 ab 3 0 or 0 1 bulk rock mg is 63 and molar feo mno is 76 the terrestrial age of the meteorite is 33 4 5 2kyr aau 012 contains a similar to 1 4x1 5mm 2 exotic clast different from the lithic clast population which is dominated by clasts of anorthosite breccias bulk composition and presence of relatively large vesicles indicate that the clast was most probably formed by an impact into a precursor having nonmare igneous origin most likely related to the rare alkali suite rocks the im clast is mainly composed of clinopyroxenes contains a significant amount of cristobalite 9 0 vol and has a microcrystalline mesostasis although the clast shows similarities in texture and modal mineral abundances with some apollo pigeonite basalts it has lower feo and higher sio2 than any mare basalt it also has higher feo and lower al2o3 than rocks from the fan or mg suite its lower mg 59 compared to mg suite rocks also excludes a relationship with these types of lunar material

the impact process in aeolian saltation two dimensional simulations a critical event in the trajectory of a sand grain saltating in air is its interaction with the surface we examine the phenomenon of grain bed impacts in two dimensions using a combination of dynamical computer simulations analytical models and physical reasoning the results indicate that the grain bed collisions can be treated as two body collisions with the bed particle assuming an effective mass greater than its true mass also the presence of geometrical surface irregularities has a strong bearing on the interaction between saltating and surface grain populations as well as on the formation of small scale bedforms

impact glasses from the apollo 14 landing site and implications for regional geology 1 lunar impact glasses possess the unmodified refractory element ratios of the original fused target materials at the sites of impacts these target materials are regolith developed on different terrains and local rock types almost 800 glasses from the apollo 14 landing site have been analyzed by electron microprobe in this study these glasses show significant variation and hint at the existence of multiple terrains of differing compositions near the landing site to test this idea we have used clementine color image data to construct iron and titanium maps from which a petrologic map in an elemental system analogous to the sample database was made this map shows the regional provenance of apollo 14 samples and suggests that the highlands in the fra mauro region of the moon consist of a potassium rare earth element and phosphorus kreep rich basaltic debris layer that overlies a more feldspathic terrain in some areas this mapping effort demonstrates the efficacy of using clementine image data to place lunar sample information into a regional and ultimately global context lunar impact glasses and orbital data can provide geochemical constraints on the local and regional geology of the moon

feldspathic lunar meteorites pecora escarpment 02007 and dhofar 489 contamination of the surface of the lunar highlands by post basin impacts abstract pca pecora escarpment 02007 and dhofar 489 are both meteorites from the feldspathic highlands of the moon pca 02007 is a feldspathic breccia consisting of lithified regolith from the lunar surface it has concentrations of both incompatible and siderophile elements that are at the high end of the ranges for feldspathic lunar meteorites dhofar 489 is a feldspathic breccia composed mainly of impact melted material from an unknown depth beneath the regolith concentrations of incompatible and siderophile elements are the lowest among brecciated lunar meteorites among 19 known feldspathic lunar meteorites all of which presumably originate from random locations in the highlands concentrations of incompatible elements like sm and th tend to increase with those of siderophile elements like ir feldspathic meteorites with high concentrations of both suites of elements are usually regolith breccias iridium derives mainly from micrometeorites that accumulate in the regolith with duration of surface exposure micrometeorites have low concentrations of incompatible elements however so the correlation must reflect a three component system we postulate that the correlation between sm and ir occurs because the surface of the feldspathic highlands terrane has become increasingly contaminated with time in sm rich material from the procellarum kreep terrane that has been redistributed across the lunar surface by impacts of moderate sized post basin impacts the most sm rich regolith breccias among feldspathic lunar meteorites are about 3 enriched compared to the most sm poor breccias but this level of enrichment requires only a few percent sm rich material typical of the procellarum kreep terrane the meteorite data suggest that nowhere in the feldspathic highlands are the concentrations of k rare earths and th measured by the lunar prospector mission at the surface representative of the underlying bedrock all surfaces covered by old regolith as opposed to fresh ejecta are at least slightly contaminated dhofar 489 is one of 15 paired lunar meteorite stones from oman total mass of meteorite 1037 g on the basis of its unusually high mg fe ratio the meteorite is likely to have originated from northern feldspathic highlands

elephant moraine 87521 the first lunar meteorite composed of predominantly mare material abstract the trace element chemistry and detailed petrography of brecciated antarctic meteorite eet87521 reveal that it is not as originally classified a eucrite its fe mn ratio and bulk co content are far higher than expected for a eucrite an affiliation with the snc meteorites appears almost equally improbable on the basis of far lower ga al and na ca ratios in eet87521 only one known type of extraterrestrial material resembles eet87521 in all important respects for which constraints exist very low ti vlt lunar mare basalts even compared to vlt basalts eet87521 is enriched in ree however other varieties of high alumina low ti mare basalt are known that contain ree at even higher concentrations than eet87521 several clasts in eet87521 preserve clear vestiges of coarse grained igneous possibly orthocumulate textures mineralogically these coarse grained clasts are diverse e g olivine ranges from fo15 in one to fo67in another one clast with an anomalously fine grained texture is anor thositic and contains exceptionally mg rich pyroxene and na poor plagioclase along with the only feni metal in the thin section this clast is probably an impact melt breccia from the lunar highlands its feni metals have compositions typical of metals incorporated into lunar soils and polymict breccias as debris from metal rich meteorites however the low ni and ir contents of our bulk rock analysis imply that the proportion of impact projectile matter in our chip sample is probably small the moderate degree of lithologic diversity among the lithic clasts and the bulk composition in general indicate that eet87521 is dominated by a single rock type vlt mare basalt the fundamental distinction between mare and nonmare lunar materials has traditionally been based primarily on ti content and secondarily on such characteristics as ca al ratio and ree pattern however eet87521 recent studies of apollo 12 and apollo 14 rocks and the many apparent vlt basalts reported earlier as clasts in lunar highlands meteorites all tend to indicate that the dichotomy of lunar magmatism into distinct nonmare and mare styles may have been less abrupt than commonly envisaged

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

sixth foray for pristine nonmare rocks and an assessment of the diversity of lunar anorthosites eleven nonmare samples are characterized generally both compositionally and petrographically five are almost certainly pristine ferroan anorthosite 10056c alkali anorthosite 14047c ferroan anorthosite 14312c anorthositic troctolite 14321c3 and granite 14321c4 and four are probably pristine norite 14318c noritic anorthosite 67215 quasi pristine ferroan anorthosite 73217c and norite 78527 five are unique anorthosites extending the diversity of lunar anorthosites considerably alkali anorthosites particularly 14047c are extremely rich in incompatible elements the first anorthosite from apollo 11 with manifestations of pristinity 10056c appears to be a normal member of the ferroan group however the first pristine ferroan anorthosites from apollo 14 and 17 to be studied in detail 14312c and 73217c both have unusually sodic plagioclase by ferroan standards with only 75 plagioclase 67215 is the first large 273 g probably pristine ferroan sample with less than 83 plagioclase the nature of the correlations between longitude and such parameters as eu and sm concentrations and sc sm ti sm and ca na ratios among pristine ant samples has been elucidated because five of the new pristine samples are from a western site apollo 14 interestingly ferroan anorthosite 14312c has ca na sc sm and ti sm ratios close to the normal ferroan values but significantly displaced in the direction of the nonferroan western pristine rocks this suggests that the composition longitude relationships are as old as the late stages of the crystallization of the putative magma ocean

an unusual clast in lunar meteorite macalpine hills 88105 a unique lunar sample or projectile debris lunar meteorite macalpine hills mac 88105 is a well studied feldspathic regolith breccia dominated by rock and mineral fragments from the lunar highlands thin section mac 88105 159 contains a small rock fragment 400 350 m in size which is compositionally anomalous compared with other mac 88105 lithic components the clast is composed of olivine and plagioclase with minor pyroxene and interstitial devitrified glass component it is magnesian akin to samples in the lunar high mg suite and also alkali rich akin to samples in the lunar high alkali suite it could represent a small fragment of late stage interstitial melt from an mg suite parent lithology however olivine and pyroxene in the clast have fe mn ratios and minor element concentrations that are different from known types of lunar lithologies as fe mn ratios are notably indicative of planetary origin the clast could either 1 have a unique lunar magmatic source or 2 have a nonlunar origin i e consist of achondritic meteorite debris that survived delivery to the lunar surface both hypotheses are considered and discussed the meteoritical society 2014

geochemistry and petrography of the macalpine hills lunar meteorites abstract macalpine hills 88104 and 88105 are anorthositic lunar meteorites recovered from the same area in antarctica which are demonstrated to be paired samples of the same fall petrographic studies of matrix and clasts show that mac88104 5 is a polymict breccia dominated by impact melt clasts it contains a small amount of highland impact glass and very few regolith glass spherules it is better classified as a fragmental breccia than a regolith breccia the bulk composition is ferroan mg 63 and highly aluminous al 2 o 3 28 ree and other incompatible element concentrations are very low compositions of anorthositic granulitic and impact melt breccia clasts are very similar to but distinct from matrix composition mac88104 5 is very similar in composition to the other anorthositic lunar meteorites but each of the meteorites is distinct the anorthositic lunar meteorites especially mac88104 5 and y82192 3 86032 are very similar to north ray crater feldspathic fragmental breccias in compositon and petrography these fragmental lunar meteorites may have been ancient deeply buried breccias from the megaregolith comparisons of chemical petrographic features and exposure histories suggest that the twelve lunar meteorites were derived from two to nine but probably four to seven impacts onto the lunar surface discrepancies between the proportions of lunar meteorites and results of apollo missions may be due to unrepresentative sampling lunar meteorites provide valuable new information on the nature of the lunar crust

northwest africa 482 a crystalline impact melt breccia from the lunar highlands northwest africa 482 nwa 482 is a crystalline impact melt breccia from the moon with highlands affinities the recrystallized matrix and the clast population are both highly anorthositic clasts are all related to the ferroan anorthosite suite and include isolated plagioclase crystals and lithic anorthosites troctolites and spinel troctolites potassium rare earth element and phosphorus bearing kreep and mare lithologies are both absent constraining the source area ofthis meteorite to a highland terrain with little to no kreep component most likely on the far side of the moon glass is present in shock veins cutting through the sample and in several large melt pockets indicating a second impact event there are two separate events recorded in the 40ar 39ar system one at 3750 ma which completely reset the k ar system and one at 2400 ma which caused onlypartial degassing these events could represent respectively crystallization ofthe impact melt breccia and later formation of the glass or the formation of the glass and a later thermal event the terrestrial age of the meteorite is 8 6 1 3 ka this age corresponds well with the modest amount ofweathering in the rock in the form ofsecondaryphyllosilicates and carbonates based on terrestrial age and location lithology and chemistry nwa 482 is unique among known lunar meteorites

an experimental study of multiple grain size ejecta produced by collisions of saltating grains with a flat bed collision data are presented from coloured high speed films of three size fractions of sand grains saltating over a bed of the total grain population each fraction was colour tagged and the proportion of each size ejected by grains colliding with the surface was recorded on a number of films taken as the bed was progressively eroded the results confirm earlier findings that v3 v1 0 5 0 6 vn v1 08 and the rebound angle increases with decreasing grain size ejected grains are examined in relation to their size the impactor size ejection speed and angle and the number of ejecta per collision in addition changes in grain parameters are observed with time for fine impactors ejection speeds generally increase with a decrease in ejecta size but the fine fraction does not follow this trend for the coarse and medium impactors ejection angles are typically between 40 and 60 with coarse grains having shallower mean angles than fine ejecta the number of ejections per collision increases with a decrease in particle size for each impactor size the general tendency for coarse particles to be ejected at lower speeds and shallower angles than fine particles will lead to sorting of the grain sizes there is poor correlation between the forward momentum loss of the saltating grams at collision and both the forward momentum of the ejected grains and the number of ejected grains much of the forward momentum of the saltating grains is transfered to creeping grains the composition and geometry of the bed are considered to be important factors in the evolution of the saltation cloud

support for the lunar cataclysm hypothesis from lunar meteorite impact melt ages lunar meteorites represent a more random sampling of lunar material than the apollo or luna collections and as such lunar meteorite impact melt ages are the most important data in nearly 30 years with which to reexamine the lunar cataclysm hypothesis within the lunar meteorite breccias mac 88105 que 93069 dag 262 and dag 400 seven to nine different impact events are represented with 40ar 39ar ages between 2 76 and 3 92 billion years ago ga the lack of impact melt older than 3 92 ga supports the concept of a short intense period of bombardment in the earth moon system at approximately 3 9 ga this was an anomalous spike of impact activity on the otherwise declining impact frequency curve

lunar meteorites siderophile element contents and implications for the composition and origin of the moon abstract six lunar meteorites have thus far been discovered in antarctica although these meteorites are of undocumented lunar geographic provenance all other available lunar samples obtained from the apollo and luna programs came from a relatively minuscule region of the central nearside around which a polygon could be drawn covering just 4 7 of the lunar surface the five lunar meteorites that are now well studied represent at least two but probably three separate lunar source craters alha81005 and y791197 are probably from separate craters and compound meteorite y82192 6032 is certainly from a crater of its own at least alha81005 and y791197 and probably also at least in a loose sense y82192 6032 are highlands regolith breccias thus their compositions may be appropriately compared with compositions of apollo and luna highlands regolith samples compared with average highlands regolith samples from the central nearside apollo sites lunar meteorites have lower concentrations of siderophile elements in general and especially au ge and ni among anorthositic apollo samples i e mainly those from apollo 16 au ir and to a lesser extent ge ir ratios tend to be hyperchondritic most previous models for lunar regolith siderophile geochemistry assumed that the apollo 16 samples are representative of the overall lunar highlands such models tended to conclude that the hyperchondritic au ir and ge ir ratios were consequences of variations in the compositions of moon striking projectiles as a function of time it was even speculated that these temporal variations were consequences of the heterogeneous accretion of a moon with a general enrichment in refractory elements the lunar meteorites suggest that hyperchondritic au ir and ge ir are not general features of the highlands but peculiarities of the apollo 16 region or more generally the central nearside the high ni contents of the apollo 16 megaregolith substantially in excess of the ni implied by a model in which all meteoritic debris has an h chondritic ni ir ratio have been interpreted to imply that the mg rich fraction of the lunar crust is extremely ni rich and thus similar in siderophile geochemistry to terrestrial komatiites this coincidence has been interpreted as confirmation that the moon formed by modified fission from the earth s mantle after core formation plus late accretion effects had established the final siderophile pattern of the earth s mantle however the lunar meteorites and a survey of data for the luna 20 highlands regolith sample suggest that the high ni content of the apollo 16 regolith is strictly a peculiarity of the apollo 16 region and not a general feature of the moon s crust the anomalous siderophile composition of the central nearside regolith probably stems from a combination of regional heterogeneity in cratering projectile compositions plus regional enrichments in relatively labile siderophile elements most notably au ge and perhaps to a certain extent ni which might be loosely correlated with the anomalously high concentration of kreep over the central nearside

evidence of chemical heterogeneity within lunar anorthosite parental magmas abstract lunar anorthosites are known for displaying a limited range of plagioclase an content an 94 to 98 here we demonstrate that plagioclase trace element variations from apollo ferroan anorthosites fan samples collected by the apollo 15 and 16 missions display more significant chemical heterogeneity e g chondrite normalized la sm 0 33 5 42 than previously reported we report mineral plagioclase pyroxene and olivine major and trace element abundances for a suite of apollo fan samples in addition to anorthositic clasts within apollo 16 regolith breccias this suite of data extends the compositional range currently reported for apollo anorthosites and for anorthositic clasts previously found within lunar meteorites petrological classifications of the regolith breccia clasts e g anorthosite versus noritic anorthosites cannot always be accurately assessed due to the limited size

the magma ocean as an impediment to lunar plate tectonics potential for plate tectonics on a planet is determined by several factors besides the obvious one of temperature one of the most important of these is the ratio zc zl where zc and zl are the thicknesses of the crust and tectonic lithosphere respectively a high zc zl ratio imparts a low bulk density and thus a high buoyancy to the lithosphere cooling of the lithosphere can offset a limited degree of compositional buoyancy but for realistic assumptions regarding crustal and mantle densities lithosphere geotherms and the spatial variability of the zc zl ratio systematic lithosphere subduction i e plate tectonics is unlikely on any planet with average zc zl ratio greater than about 0 25 during a magma ocean phase zc zl must be 1 so systematic lithosphere subduction is impossible in general zl is closely linked to the average planet temperature whereas zc is only weakly related to t but is sensitive to the planet s pressure depth gradient dp dz i e its size which governs the fate of al during deep melting crystallization processes the moon has probably always had zc zl too high or in later times lithosphere thickness too high to sustain plate tectonics conceivably plate tectonics operated over the first few million years of lunar evolution particularly if the early interior was cooler than generally assumed and a true magma ocean never developed or only developed after gradual warming of the deep interior however weighing against this scenario in addition to the wide array of evidence in favor of the magma ocean hypothesis are the consistently moderate to young by lunar standards ages of geochemically evolved lunar rocks

the thermal and radiation exposure history of lunar meteorites we have measured the natural and induced thermoluminescence tl of seven lunar meteorites in order to examine their crystallization irradiation and recent thermal histories lunar meteorites have induced tl properties similar to apollo samples of the same provenance highland or mare indicating similar crystallization and metamorphic histories macalplne hills 88104 5 has experienced the greatest degree of impact regolith processing among the highland dominated meteorites the basaltic breccia que 94281 is dominated by mare component but may also contain a significant highland component for the mare dominated meteorites eet 87521 may have a significant highland impact melt component while asuka 881757 and y 793169 have been heavily shocked the thermal history of y 793169 included slow cooling either during impact processing or during its initial crystallization our natural tl data indicate that most lunar meteorites have apparently been irradiated in space a few thousand years with most less than 15 000 a elephant moraine 87521 has the lowest irradiation exposure time being less than 1 000 a either the natural tl of alha81005 asuka 881757 and y 82192 was only partially reset by lunar ejection or these meteorites were in small perihelia orbits less than or equal to 0 7 au

the isotopic record of lunar volcanism abstract the timing and extent of lunar volcanism was determined primarily by the internal thermal evolution of the moon a late heavy bombardment produced most of the observable lunar basins easily recognized stratigraphic markers and also may have influenced lunar volcanism most of the nearside basins seem to have been produced 3 8 4 0 ga ago during a period often referred to as the lunar cataclysm the pre cataclysm period was characterized by formation of the lunar crust plutonic rocks within the crust and pre mare volcanism isotopic analysis of breccia clasts pre dating the cataclysm has yielded an outline of this period the isotopic record of post cataclysm mare volcanism is clear but incomplete because samples from the youngest mare areas are lacking specifically the isotopic data show that some lunar anorthosites formed 4 45 ga ago consistent with early formation of an anorthositic lunar crust some mg suite norites troctolites and dunites also formed approximately contemporaneously with the oldest anorthosites but others are up to 200 300 ma younger more evolved rocks granites and quartz monzodiorites also formed between 4 4 and 4 0 ga ago the earliest known pre mare volcanism at 4 25 ga ago included aluminous mare like basalts and an olivine gabbronorite similar to apollo 12 basalts kreep basalt volcanism began at least 4 1 ga ago approximately contemporaneously with that of the ancient mare like basalts and continued during the cataclysm recorded instances of high ti mare basalt volcanism began during or immediately after the cataclysm low ti mare basalt volcanism is the most recent for which samples are available the isotopic data record an early primary lunar differentiation during which mare basalt sources formed probably by crystallization of cumulus minerals from a lunar magma ocean the isotopic record of post cataclysm basalts indicates a heterogeneous lunar mantle and can be explained by partial melting of cumulate sources but more complex petrogenesis also has been suggested more complex petrogenetic processes including assimilation and assimilation fractional crystallization afc seem to be required for pre mare volcanics the isotopic data contain a hint that petrogenesis of the oldest pre mare volcanics may be linked to formation of the so called procellarum basin possibly the oldest and largest lunar basin such a basin would provide a geologic context for the pre mare volcanics and its formation may have been a defining moment in lunar history

geochemistry and 40ar 39ar geochronology of impact melt clasts in feldspathic lunar meteorites implications for lunar bombardment history we studied 42 impact melt clasts from lunar feldspathic regolith breccias macalpine hills mac 88105 queen alexandra range que 93069 dar al gani dag 262 and dag 400 for texture chemical composition and or chronology although the textures are similar to the impactmelt clasts identified in mafic apollo and luna samples the meteorite clasts are chemically distinct from them having lower fe ti k and p thus representing previously unsampled impacts the 40ar 39ar ages on 31 of the impact melts the first ages on impact melt samples from outside the region of the apollo and luna sampling sites range from 4 to 2 5 ga we interpret these samples to have been created in at least six and possibly nine or more different impact events one inferred impact event may be consistent with the apollo impact melt rock age cluster at 3 9 ga but the meteorite impact melt clasts with this age are different in chemistry from the apollo samples suggesting that the mechanism responsible for the 3 9 ga peak in lunar impact melt clast ages is a lunar wide phenomenon no meteorite impact melts have ages more than 1 older than 4 0 ga this observation is consistent with but does not require a lunar cataclysm

new lunar meteorites impact melt and regolith breccias and large scale heterogeneities of the upper lunar crust we have analyzed nine highland lunar meteorites lunaites using mainly inaa several of these rocks are difficult to classify dhofar 081 is basically a fragmental breccia but much of its groundmass features a glassy fluidized texture that is indicative of localized shock melting also much of the matrix glass is swirly brown suggesting a possible regolith derivation we interpret dar al gani dag 400 as an extremely immature regolith breccia consisting mainly of impact melt breccia clasts we interpret dhofar 026 as an unusually complex anorthositic impact melt breccia with scattered ovoid globules that formed as clasts of mafic subophitic impact melt the presence of mafic crystalline globules in a lunar material even one so clearly impact heated suggests that it may have originated as a regolith our new data and a synthesis of literature data suggest a contrast in al2o3 incompatible element systematics between impact melts from the central nearside highlands where apollo sampling occurred and those from the general highland surface of the moon impact melts from the general highland surface tend to have systematically lower incompatible element concentration at any given al2o3 concentration than those from apollo 16 in the case of dhofar 026 both the bulk rock and a comparatively al poor composition 14 wt al2o3 7 g g sm extrapolated for the globules manifest incompatible element contents well below the apollo 16 trend impact melts from luna 20 57e distribute more along the general highland trend than along the apollo 16 trend siderophile elements also show a distinctive composition for apollo 16 impact melts ni ir averaging 1 8x chondritic in contrast lunaite impact melt breccias have consistently chondritic ni ir impact melts from luna 20 and other apollo sites show average ni ir almost as high as those from apollo 16 the prevalence of this distinctive ni ir ratio at such widely separated nearside sites suggests that debris from one extraordinarily large impact may dominate the megaregolith siderophile component of a nearside region 2300 km or more across highland polymict breccia lunaites and other kreep poor highland regolith samples manifest a strong anticorrelation between al2o3 and mg the magnesian component probably represents the chemical signature of the mg suite of pristine nonmare rocks in its most pure form unaltered by the major kreep assimilation that is so common among apollo mg suite samples the average composition of the ferroan anorthositic component is now well constrained at al2o3 29 30 wt implying about 17 19 wt modal mafic silicates in good agreement with the composition predicted for flotation crust over a ferroan magma ocean warren 1990

trapped noble gases indicate lunar origin for antarctic meteorite the isotopic abundances of the noble gases he ne ar kr xe are reported for antarctic meteorite alha81005 it contains solar wind implanted gases whose absolute and relative concentrations are quite similar to lunar regolith samples but not to other meteorites alha81005 also contains a large excess 40ar component which is identical to the component in lunar fines implanted from the lunar atmosphere large concentrations of cosmogenic 21ne 82kr and 126xe in alha81005 indicate a total cosmic ray exposure age of 2 108 years the noble gas data alone are strong evidence for a lunar origin of this meteorite

cogenetic rock fragments from a lunar soil evidence of a ferroan noritic anorthosite pluton on the moon abstract the impact that produced north ray crater apollo 16 landing site exhumed rocks that include relatively mafic members of the lunar ferroan anorthositic suite bulk and mineral compositions indicate that a majority of 2 4 mm lithic fragments from sample 67513 including impact breccias and monomict igneous rocks are related to a common noritic anorthosite precursor compositions and geochemical trends of these lithic fragments and of related samples collected along the rim of north ray crater suggest that these rocks derived from a single igneous body this body developed as an orthocumulate from a mixture of cumulus plagioclase and mafic intercumulus melt after the plagioclase had separated from any cogenetic mafic minerals and had become concentrated into a crystal mush 70 wt plagioclase 30 wt intercumulus melt we present a model for the crystallization of the igneous system wherein system is defined as cumulus plagioclase and intercumulus melt the initial accumulation of plagioclase is analogous to the formation of thick anorthosites of the terrestrial stillwater complex however a second stage of formation is indicated involving migration of the cumulus plagioclase intercumulus melt system to a higher crustal level analogous to the emplacement of terrestrial massif anorthosites compositional variations of the lithic fragments from sample 67513 are consistent with dominantly equilibrium crystallization of intercumulus melt the highly calcic nature of orthocumulus pyroxene and plagioclase suggests some reaction between the intercumulus melt and cumulus plagioclase perhaps facilitated by some recrystallization of cumulus plagioclase bulk compositions and mineral assemblages of individual rock fragments also require that most of the mafic minerals formed in close contact with cumulus plagioclase not as separate layers the distribution of compositions and by inference modes has a narrow peak at anorthosite and a broader larger peak at noritic anorthosite characteristics of the samples and their geochemical trends imply an origin in a system that was large relative to the unknown size of the impact that produced the brecccas of ferroan noritic anorthosite composition that were excavated later by the formation of north ray crater and they appear to be consistent with an origin of the suite within a perched plagioclase cumulate if the moon s crust formed by accumulation of plagioclase in a magma ocean ferroan noritic anorthosite formed as an orthocumulate is an alternative to extensive adcumulus formation of ferroan anorthosite 90 vol plagioclase this provides a relatively mafic ferroan anorthositic component 15 vol mafics which is required by mass balance models of compositions of polymict lunar crustal materials the inferred bulk composition of the system of cumulus plagioclase and intercumulus melt is similar to that of ferroan regolith breccia macalpine hills 88104 5 a lunar highland meteorite and may represent a common and widespread component of the moon s early highland crust

the ferroan anorthositic suite the extent of primordial lunar melting and the bulk composition of the moon the geochemical bimodality among compositionally pristine lunar rocks is strong evidence that a major component of the moon s crust is fundamentally unrelated to the plagioclase flotation crust that accumulated over the primordial magma ocean the ferroan anorthositic suite fas has all the characteristics expected for a series of magma ocean plagioclase flotation cumulates but we estimate based on mass balance for al2o3 that 30 wt of the crust and 20 wt of the crust s total al2o3 or roughly 15 of the bulk moon al2o3 content assumed to be 3 4 wt was emplaced by postmagma ocean mg suite serial magmatism remelting of plagioclase bearing magma ocean cumulates cannot plausibly account for the late emplacement of al2o3 because the only plagioclase rich cumulates produced by a deep ultramafic magma ocean would have mg ratios too low to engender the mg suite conceivably remelting of garnet rich magma ocean cumulates supplied the late al2o3 but only if the bulk moon al2o3 content is substantially higher than generally assumed high pressures in the magma ocean acted to enhance the py pyroxene pyroxene olivine ratio of the mo cumulates and the al2o3 content of whatever pyroxene formed remelting of pyroxene rich mo cumulates could conceivably have supplied the late mg suite al2o3 to the crust the source region would have to encompass roughly 40 wt of the mantle another possible source for late al2o3 addition is a large portion of the deepest mantle that avoided more than a slight degree of partial melting and thus remained al rich during formation of the magma ocean the source region would have to encompass 20 30 wt of the mantle ascent of diapiric masses from the lowermost mantle would likely coincide with trigger or be triggered by a large scale overturn of the gravitationally unstable mo cumulate pile with concomitant pressure release melting in which case the mg suite parental melts would be derived from a mix of deepest mo cumulates and the even deeper primitive mantle the popular giant impact hypothesis of lunar origin implies an extremely hot beginning for the moon suggesting that the deep interior was either molten or depleted in al2o3 by differentiation in hot protomoons as it formed origin of 30 wt of the moon s crust by postmagma ocean serial magmatism is more consistent with coaccretion models that form the moon without a giant hot impact in any scenario with a large fraction of the crust originating by partial remelting of deep magma ocean cumulates mass balance for al2o3 implies that the bulk moon normative py ratio must be greater than roughly 0 5 i e significantly higher than generally estimated in this respect the moon appears more compositionally similar to chondritic silicates than to the earth s upper mantle

macalpine hills 88104 and 88105 lunar highland meteorites general description and consortium overview abstract macalpine hills 88104 and 88105 are new lunar meteorites returned from antarctica by the 1988 1989 us meteorite collection team the two specimens were found in nearby locations and based on field and laboratory evidence are thought to be pieces of the same meteorite mac88105 is the largest lunar meteorite yet found 662g mac88104 5 is an anorthositic breccia consisting of numerous small clasts in a glassy matrix an origin on the moon is supported by the mineral bulk and oxygen isotope compositions a consortium of twenty research groups has studied these meteorites samples were prepared at the nasa johnson space center meteorite processing laboratory details of consortium plans and allocations are documented herein a summary list of lunar meteorites and an overview of consortium research is presented discussions in this and the following consortium papers involve the issue of paired meteorites and paired ejecta and what new information about the nature and evolution of the lunar crust is provided by the lunar meteorites

saltating particles over flat beds measurements of ejection and impact velocities trajectory lengths and maximum rise heights of sand grains median diameters 118 and 188 m in saltation over a flat sand bed in a wind tunnel have been obtained from the digitization of multiple image photo graphs the mean angle of ejection is found to be about 30 o from the horizontal rather than 90 o with mean vertical ejection velocity of about 2u where u is the friction velocity trajectories of saltating grains have been computed using the measurements of the initial ejection velocities and the mean velocity profile of the air flow

a comprehensive numerical model of steady state saltation comsalt 1 the blowing of sand by wind known as saltation ejects dust aerosols into the atmosphere creates sand dunes and erodes geological features we present a comprehensive numerical model of steady state saltation comsalt that in contrast to most previous studies can reproduce a wide range of measurements and can simulate saltation over mixed soils comsalt calculates the motion of saltating particles due to gravity fluid drag particle spin fluid shear and turbulence and explicitly accounts for the retardation of the wind due to drag from saltating particles furthermore we included a novel physically based parameterization of the ejection of surface particles by impacting saltating particles which matches experimental results comsalt is the first numerical saltation model to reproduce measurements of the wind shear velocity at the impact threshold i e the lowest shear velocity for which saltation is possible and of the aerodynamic roughness length in saltation it also reproduces a range of other saltation processes including profiles of the wind speed and particle mass flux and the size distribution of saltating particles as such comsalt is the first physically based numerical model to reproduce such a wide range of experimental data since we use a minimum of empirical relations comsalt can be easily adapted to study saltation under a variety of physical conditions such as saltation on other planets saltation under water and saltating snow

the role of meteoritics in spaceflight missions and vice versa research on extraterrestrial materials plays a critical role in formulating the science rationale and design for spacecraft missions and conversely spaceflight holds great promise for solving perplexing problems in meteoritics the connections between meteoritics and sample return missions are obvious meteorite research can define sampling strategies the capabilities of sampling devices acceptable levels of chemical contamination and physical alteration of samples and the conditions under which samples are stored prior to and during recovery for their part sample return missions can provide geologic context for meteorites increased sampling diversity including materials not sampled as meteorites such as unconsolidated regolith ices and atmosphere calibration for crater counting chronology and ground truth for remote sensing measurements of meteorite parent bodies meteoritics also relates to spacecraft flyby rendezvous and lander missions that do not necessarily return samples specific illustrations of this mutual relationship based on a selection of recent or planned spacecraft missions include identifying source asteroid classes for ordinary and carbonaceous chondrites and reconstructing their thermal and collisional histories galileo near clementine ii and muses c determining the extent to which cometary dust and interstellar grains are found as interplanetary dust particles and assessing volatile abundances isotopic compositions and molecular species in cometary nuclei stardust and rosetta understanding the compositions of ancient martian crust and the mantle sources for snc meteorites as well as inventorying the planet s volatile reservoirs and interactions mars pathfinder mars global surveyor and mars volatiles and climate surveyor assessing whether lunar meteorites provide a more representative chemical sampling of the highlands crust and of mare volcanism than do apollo samples galileo clementine and lunar prospector spaceflight is the first priority of the space agencies that fund most research on extraterrestrial materials and the continued level of support for such research may be linked in part to its use in exploration by spacecraft

examining the compositions of impactors striking the moon using apollo impact melt coats and anorthositic regolith breccia meteorites abstract impactors striking the moon since the formation of its crust have left an indelible imprint on the lunar surface in the guise of craters and associated impact rocks the lunar crust has low intrinsic abundances of the highly siderophile elements hse re os ir ru pt rh pd au at greater than 3000 times lower than in chondrite meteorites consequently during impact bolides with chondritic or differentiated iron rich compositions should impart elevated hse signatures to the lunar crust here we examine glassy lunar impact melt coats imc from the outside rims of apollo 16 cataclastic anorthosites 60015 65325 and breccias 65035 as well as both fragments and powders of antarctic anorthositic regolith breccia arb meteorites miller range 090034 36 70 75 and macalpine hills 88105 for their petrography mineral chemistry and bulk rock compositions the hse concentrations for imc range from 0 001 to 0 1 ci chondrite with measured 187os 188os between 0 1189 and 0 1366 anorthositic regolith breccia meteorites which have components with 2 6 4 1 ga ages have similar hse concentrations to imc but typically have lower 187os 188os 0 1164 0 1284 these latter os ratios are generally less radiogenic than those measured in 3 8 3 9 ga apollo impact melt breccias the apollo 16 imc are not well dated but their kreepy trace element signatures and associated ages of 3 7 to 3 8 ga for apollo 16 glasses might imply at least in part an origin from the imbrium or serenitatis basin forming impacts within the imc metal schreibersite troilite assemblages record significant inter element hse fractionation which is also reflected in bulk hse patterns for both imc and arb meteorites variations in relative and absolute hse compositions directly reflect the control of metal and sulfide segregation within and between impact melt and breccia lithologies collectively imc and arb meteorites exhibit approximately 50 of the variation in ru ir and 187os 188os observed in lunar impact melt breccias these results imply that significant variations in inter element compositions can occur during impact brecciation and melting and so some impact melt rock hse compositions may not record the compositions of impactors that struck the moon with fidelity nonetheless the generally low 187re 188os of lunar impact melt rocks means that osmium isotope ratios provide evidence for impact composition and a change from ordinary to carbonaceous like impactors either with time or location striking the moon

anorthosite assimilation and the origin of the mg fe related bimodality of pristine moon rocks support for the magmasphere hypothesis the lunar magma ocean or magmasphere hypothesis always controversial has required considerable revision in recent years the geochemical bimodality of pristine rocks epitomized by a diagram of na na ca versus mg ratio has led to proposals that a major fraction of the crust the mg rich suite formed as cumulates in numerous intrusions slightly younger than the magmasphere the precise origin of the bimodality has been elusive however one previous suggestion was that na was lost as a volatile before the ferroan anorthosites crystallized from the magmasphere whereas the mg rich intrusives retained all of their original na however this model cannot fully explain the bimodality because the same bimodal pattern is manifested by plotting eu al a ratio of involatile elements versus mg ratio assimilation probably helped to engender the bimodal patterns mass energy balance calculations indicate that large proportions of plagioclase were probably assimilated from the older magmasphere generated ferroan anorthosite crust by most of the mg rich intrusive melts the magmasphere in the absence of assimilation probably did not yield appreciable plagioclase the ferroan anorthosite crust until fractional crystallization of mafic silicates had diminished the melt mg ratio to about 0 42 however assuming identical initial melt composition an mg rich intrusion assimilating ferroan anorthosite and perhaps also a small proportion of urkreep would have reached plagioclase saturation at much higher mg about 0 66 the current version of the magmasphere hypothesis ferroan anorthosites magmasphere flotation cumulates mg rich rocks products of slightly younger localized intrusions appears to be the only plausible mechanism for engendering the mg fe related bimodality

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

evolved mare basalt magmatism high mg fe feldspathic crust chondritic impactors and the petrogenesis of antarctic lunar breccia meteorites meteorite hills 01210 and pecora escarpment 02007 antarctic lunar meteorites meteorite hills 01210 and pecora escarpment 02007 are breccias that come from different regolith lithologies on the moon met 01210 is composed predominantly of fractionated low ti basaltic material and is classified as an immature predominantly basaltic glassy matrix regolith breccia pca 02007 is a predominantly feldspathic regolith breccia consisting of metamorphosed feldspathic noritic troctolitic and noritic anorthosite clasts agglutinate and impact glasses as well as a number of basaltic clasts with mare and possible non mare affinities the basalt clasts in met 01210 have undergone fenner trend enrichments in iron and may also have witnessed late stage crystallization of zircon or a zirconium rich mineral some of the features of met 01210 are similar to other basaltic lunar breccia meteorites e g northwest africa 773 elephant moraine 87521 96008 yamato 793274 981031 but it is not paired with them the presence of metamorphic anorthositic clasts as well as agglutinates indicates a small regolith component similarities with previously discovered evolved e g lapaz icefield 02205 northwest africa 032 and ferroan e g asuka 881757 yamato 793169 basaltic lunar meteorites suggest a similar mare source region for met 01210 despite lack of evidence for pairing pca 02007 shares many features with other feldspathic regolith breccias e g yamato 791197 queen alexandra range 94281 including a high mg fe whole rock composition glass spherules agglutinate fragments and a diverse clast inventory spanning the range of ferroan anorthosite and high magnesium suite rocks some of the basalt fragments in this sample are fractionated and have an igneous origin however the majority of the basalt fragments are impact melt clasts pca 02007 supports previous studies of feldspathic lunar meteorites that have suggested an aluminous crust for the moon with compositions more similar to magnesium granulite breccias than ferroan anorthosites a chondrule like fragment found in pca 02007 and unlike any previously described lunar material is described and tentatively identified as the remnants of a chondritic lunar impactor this clast is porphyritic with equant olivines that have forsterite rich cores fo 98 extreme normal zonation to more fayalitic rims fo 44 and a mineral assemblage with rare earth element abundances distinct from described lunar material and more similar to chondrules found in ordinary or carbonaceous chondrites its discovery and description is significant for understanding the composition of lunar impactors previously the main evidence for chondritic lunar impactors was from chondritic relative abundances and near chondritic ratios of highly siderophile elements in lunar impact melt breccias however the presence of this clast along with two other chondritic clasts from apollo soils 12037 and 15602 provides clues to the identity of ancient meteorite impactors on the moon

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

feldspathic lunar meteorites and their implications for compositional remote sensing of the lunar surface and the composition of the lunar crust we present new compositional data for six feldspathic lunar meteorites two from cold deserts yamato 791197 and 82192 and four from hot deserts dhofar 025 northwest africa 482 and dar al gani 262 and 400 the concentrations of feo or al2o3 and th or any other incompatible element together provide first order compositional information about lunar polymict samples breccias and regoliths and regions of the lunar surface observed from orbit concentrations of both elements on the lunar surface have been determined from data acquired by orbiting spacecraft although the derived concentrations have large uncertainties and some systematic errors compared to sample data within the uncertainties and errors in the concentrations derived from orbital data the distribution of feo and th concentrations among lunar meteorites which represent 18 source regions on the lunar surface is consistent with that of 18 random samples from the surface approximately 11 of the lunar meteorites are low feo and low th breccias consistent with large regions of the lunar surface particularly the northern farside highlands almost all regoliths from apollo sites on the other hand have larger concentrations of both elements because they contain fe rich volcanic lithologies from the nearside maria and th rich lithologies from the high th anomaly in the northwestern nearside the feldspathic lunar meteorites thus offer our best estimate of the composition of the surface of the feldspathic highlands and we provide such an estimate based on the eight most well characterized feldspathic lunar meteorites the variable but high on average mg fe ratio of the feldspathic lunar meteorites compared to ferroan anorthosites confirms a hypothesis that much of the plagioclase at the surface of the feldspathic highlands is associated with high mg fe feldspathic rocks such as magnesian granulitic breccia not ferroan anorthosite geochemically the high mg fe breccias appear to be unrelated to the mafic magnesian suite rocks of the apollo collection models for the formation of the upper lunar crust as a simple flotation cumulate composed mainly of ferroan anorthosite do not account for the complexity of the crust as inferred from the feldspathic lunar meteorites

effect of the thermal gradient variation through geological time on basin modeling a case study the paris basin many studies investigated the thermal modeling of the paris basin for petroleum interests during the 1970s most of the softwares developed by oil companies or research centers were based on the assumption of a constant thermal gradient in order to take into consideration the variation of the thermal gradient during basin evolution we developed the thermo s visual basic 1d program we applied our model to twenty boreholes located along a cross section roughly running ew over 150 km in the center of the paris basin the numerical results were calibrated with organic matter maturity data thermo s simulates the amount of heat provided to the sedimentary organic matter the heat parameter simulated shows lateral variation along the cross section it decreases from rambouillet to trou aux loups boreholes 87 66 mw m2 at about 100 km more to the east whereas the heat flux value simulated is 73 mw m2 in st loup borehole the mean thermal gradient calculated for liassic horizons at 87 my for the rambouillet well is 50 4 c km this value is similar to previously published results by integrating the calculation of the thermal gradients and conductivities related to the burial of each stratigraphic sequence our approach points out variations in the thermal regimes the sedimentary organic matter som has been subjected to through geological time

simulation on sand grain bed collision mechanism cascade collision and ejection 1 abstract ejection of sand grains from a sand surface is assumed to result from cascade collision caused by the impact of a saltating particle allowing for only two body cascade collision and introducing new quantities such as the cross section for sand grain grain collisions and sand surface binding energy the theoretical model for the cascade collision of ion particles is applied to simulate sand grain bed collision processes the results of simulations indicate that the collision cascade events caused by impacting particles can eventually lead to the ejection of grains taking place from the sand surface the number of ejected grains at any surface point is found to be proportional to the fractional energy deposited at that point and inversely proportional to the sand surface binding energy this cascade collision model also confirms that the peak in the spatial distribution of ejected grains does not appear at the impact point but is located downwind and that the speed distribution of ejected grains at a fixed angle exhibits a peak having a value directly related to the ratio of surface binding energy to the mass of the ejected grain the angular distribution at a certain ejection speed also exhibits a maximum at an ejection angle near 90 the model also offers a new interpretation for the observed variability in the number of ejected grains under constant impact velocity this variability is directly related to the wide distribution of the energy deposition in the surface layer of the sand bed

characterization of multiple lithologies within the lunar feldspathic regolith breccia meteorite northeast africa 001 lunar meteorite northeast africa nea 001 is a feldspathic regolith breccia this study presents the results of electron microprobe and la icp ms analyses of a section of nea 001 we identify a range of lunar lithologies including feldspathic impact melt ferroan noritic anorthosite and magnesian feldspathic clasts and several very low titanium vlt basalt clasts the largest of these basalt clasts has a rare earth element ree pattern with light ree lree depletion and a positive euanomaly this clast also exhibits low incompatible trace element ite concentrations e g 0 1 ppm th 0 5 ppm sm indicating that it has originated from a parent melt that did not assimilate kreep material positive eu anomalies and such low ite concentrations are uncharacteristic of most basalts returned by the apollo and luna missions and basaltic lunar meteorite samples we suggest that these features are consistent with the vlt clasts crystallizing from a parent melt which was derived from early mantle cumulates that formed prior to the separation of plagioclase in the lunar magma ocean as has previously been proposed for some other lunar vlt basalts feldspathic impact melts within the sample are found to be more mafic than estimations for the composition of the upper feldspathic lunar crust suggesting that they may have melted and incorporated material from the lower lunar crust possibly in large basin forming events the generally feldspathic nature of the impact melt clasts lack of a kreep component and the compositions of the basaltic clasts leads us to suggest that the meteorite has been sourced from the outer feldspathic highlands terrane fht o probably on the lunar farside and within about 1000 km of sources of both low ti and vlt basalts the latter possibly existing as cryptomaria deposits

geochemical comparison of impact glasses from lunar meteorites alha81005 and mac88105 and apollo 16 regolith 64001 abstract most glasses that occur in lunar highland regolith are quenched droplets of impact melt the chemical compositions of these glasses are equivalent in the absence of volatile losses to the original target materials the compositional range of impact glasses in a regolith reflects the chemical diversity that existed throughout the region up to the time of system closure e g breccia formation since these glasses are a product of widespread and random sampling both in terms of space and time they can be used for geochemical exploration of the moon the major element compositions of impact glasses occurring in three samples of lunar feldspathic regolith alha81005 mac88105 apollo 16 64001 have been determined by electron microprobe the glass populations among these three unrelated samples are compositionally distinct while most of the impact glasses within each of these three samples are compositionally similar to the regolith in which they are found up to 40 of the impact glasses are different some of the compositionally exotic glasses were ballistically transported from other areas of the moon and thereby provide information about the compositional range of regoliths that exist elsewhere since the geological setting of the apollo 16 region is well known compared to the source areas of the lunar meteorites the apollo 16 glasses provide a ground truth for interpretations the thirty four impact glasses in meteorite alha81005 overlap the compositional range of feldspathic regoliths represented by all of the lunar highland meteorites i e y86031 y82192 y791197 mac88105 alha81005 and are compositionally distinct from highland regoliths sampled by apollo 14 apollo 16 apollo 17 and luna 20 a small proportion of alha81005 glasses contain a mare component no kreep glasses were observed due to their scarcity only ten impact glasses in lunar meteorite mac88105 were analyzed the spherules occur in two broadly defined compositional groups one group of glasses is similar to the bulk composition of mac88105 whereas the other group is more mafic all of these glasses are distinct from highland regoliths sampled by apollo 14 apollo 16 and apollo 17 and luna 20 a low ti mare glass was also analyzed in mac88105 no kreep glasses were observed the two hundred and fifty three aluminous impact glasses analyzed in apollo 16 regolith 64001 display a prominent grouping of compositions equivalent to the local regolith in addition about 10 of the glasses in 64001 are distinct from the local regolith and chemically resemble the lunar highland meteorites alha81005 mac88105 these glasses may record the chemical composition of an ancient regolith that occurred in the apollo 16 region prior to the arrival of kreep and mare components twentythree percent of the glasses in 64001 have high ti mare affinities these mare glasses are clearly exotic to the apollo 16 site and have been transported from distances of at least 300 km

northwest africa 032 product of lunar volcanism mineralogy major element compositions of minerals and elemental and oxygen isotopic compositions of the whole rock attest to a lunar origin of the meteorite northwest africa 032 nwa 032 an unbrecciated basalt found in october 1999 the rock consists predominantly of olivine pyroxene and chromite phenocrysts set in a crystalline groundmass of feldspar pyroxene ilmenite troilite and trace metal whole rock shock veins comprise a minor but ubiquitous portion of the rock undulatory to mosaic extinction in olivine and pyroxene phenocrysts and micro faults in groundmass and phenocrysts also are attributed to shock several geochemical signatures taken together indicate unambiguously that nwa 032 originated from the moon the most diagnostic criteria include whole rock oxygen isotopic composition and ratios of fe mn in the whole rock olivine and pyroxene a lunar origin is documented further by the presence of fe metal troilite and ilmenite zoning to extremely fe rich compositions in pyroxene the ferrous oxidation state of all fe in pyroxene and the rare earth element pattern with a well defined negative europium anomaly this rock is similar in major element chemistry to basalts from apollo 12 and 15 but is enriched in light rare earth elements and has an unusually high th sm ratio some apollo 14 basalts yield a closer match to nwa 032 in rare earth element patterns but have higher concentrations of al2o3 ar ar step release results are complex but yield a whole rock age of ca 2 8 ga suggesting that nwa 032 was extruded at 2 8 ga or earlier this rock may be the youngest sample of mare basalt collected to date noble gas concentrations combined with previously collected radionuclide data indicate that the meteorite exposure history is distinct from currently recognized lunar meteorites in short the geochemical and petrographic features of nwa 032 are not matched by apollo or luna samples nor by previously identified lunar meteorites indicating that it originates from a previously unsampled mare deposit detailed assessment of petrographic features olivine zoning and thermodynamic modelling indicate a relatively simple cooling and crystallization history for nwa 032 chromite spinel olivine and pyroxene crystallized as phenocrysts while the magma cooled no faster than 2 c hr based on the polyhedral morphology of olivine comparison of olivine size with crystal growth rates and preserved fe mg diffusion profiles in olivine phenocrysts suggest that olivine was immersed in the melt for no more than 40 days plumose textures in groundmass pyroxene feldspar and ilmenite and fe rich rims on the phenocrysts formed during rapid crystallization cooling rates 20 to 60 c hr after eruption

in quest of lunar regolith breccias of exotic provenance a uniquely anorthositic sample from the fra mauro apollo 14 highlands polymict samples can be used to establish mass balance constraints regarding the bulk composition of the lunar crust and to gauge the degree of regional heterogeneity in the composition of the lunar crust the most ideally polymict type of sample is finely mixed regolith lunar soil or its lithified equivalent regolith breccia fortunately lunar regolith breccias can occasionally be found at great distances from their points of origin most of the known lunar meteorites are regolith breccias we are searching for examples of exotic regolith samples among the apollo regolith breccia collection most of the 21 apollo regolith breccias analyzed for this study strongly resemble the local soils over which they were collected nine regolith breccias from apollo 16 are surprisingly mature compared to previously analyzed apollo 16 regolith breccias and six of the seven from apollo 16 station 5 have lower more local soil like mg ratios than previously analyzed regolith breccias from this station several of the apollo 14 regolith breccias investigated show significantly highermg and lower al than the local soils the most interesting sample we have investigated is 14076 1 from a lithology that constitutes roughly half of a 2 0 g pebble the presence of spherules indicates a regolith derivation for 14076 1 yet its highly aluminous 30 wt al2o3 composition is clearly exotic to the 1 6 km traverse surface over which the apollo 14 samples were collected this sample resembles soils from the descartes apollo 16 highlands far more than it does any other polymict sample from the fra mauro apollo 14 region the i sfeo maturity index is extremely low but this may be a result of thermal annealing a variety of siderophile elements occur in 14076 1 at typical regolith concentrations the chemistry of the second most aluminous regolith sample from apollo 14 14315 can only be roughly approximated as a mixture of local regolith and 14076 1 like material however the low a priori statistical probability for long distance horizontal transport by impact cratering along with the relatively high contents of incompatible elements in 14076 1 despite its high al content suggest that this regolith breccia probably originated within a few hundred kilometers of the appollo 14 site if so its compositional resemblance to ferroan anorthosite tends to suggest that the regional crust is or originally was far richer in ferroan anorthosite than implied by the meager statistics for pristine rocks from this site thus 14076 1 tends to strengthen the hypothesis that ferroan anorthosite originated as the flotation crust of a global magmasphere

the flux profile of a blowing sand cloud a wind tunnel investigation abstract the flux profile of a blowing sand cloud or the variation of blown sand flux with height is the reflection of blown sand particles that move in different trajectories and also the basis for checking drifting sand here we report the wind tunnel results of systematic tests of the flux profiles of different sized sands at different free stream wind velocities the results reveal that within the 60 cm near surface layer the decay of blown sand flux with height can be expressed by an exponential function q h a exp h b where q h is the blown sand transport rate at height h a and b are parameters that vary with wind velocity and sand size the significance of coefficient a and b in the function is defined a represents the transport rate in true creep and b implies the relative decay rate with height of the blown sand transport rate the true creep fraction the ratio of the sand transported on the surface h 0 to the total transport varies widely decreasing with both sand size and wind speed the flux profiles are converted to straight lines by plotting sand transport rate q h on a log scale the slope of the straight lines that represents the relative decay rate with height of sand transport rate decreases with an increase in free stream wind velocity and sand grain size implying that relatively more of the blown sand is transported to greater heights as grain size and wind speed increase the average saltating height represented by the height where 50 of the cumulative flux percentage occurs increases with both wind speed and grain size implying that saltation becomes more intense as grain size and or wind velocity increase

mineralogy petrology and shock history of lunar meteorite sayh al uhaymir 300 a crystalline impact melt breccia sayh al uhaymir sau 300 comprises a microcrystalline igneous matrix grain size s4 the association of maskelynite with melt pockets and shock veins indicates a subsequent local 28 45 gpa shock stage s2 s3 excursion which was probably responsible for lofting the sample from the lunar surface subsequent fracturing is attributed to atmospheric entry and probable breakup of the parent meteor

on wind velocity profile measurements taken in wind tunnels with saltating grains this paper reviews some aspects of wind tunnel experiments on sand transporting winds it follows previous papers that have discussed the influence of the outer region of the boundary layer on wind velocity measurements this influence was quantified with the use coles wake function in this paper this correction is applied to six previously described wind velocity profiles an attempt is made to calculate the profile parameter ii from these measurements the values found were not consistent with the expected ii which was determined by coles for clean air flow this value ii 0 55 was assumed to be valid in previous analyses for sand transporting winds evidence for a mutual dependency of friction velocity and profile parameter is presented and the difficulty in determining u is pointed out it is suggested that the constant stress region of the boundary layer should be kept large enough for measurements when coles wake function is not to be used in the data analysis

petrogenesis of lunar highlands meteorites dhofar 025 dhofar 081 dar al gani 262 and dar al gani 400 the petrogenesis of four lunar highlands meteorites dhofar 025 dho 025 dhofar 081 dho 081 dar al gani 262 dag 262 and dar al gani 400 dag 400 were studied for dho 025 measured oxygen isotopic values and fe mn ratios for mafic minerals provide corroboratory evidence that it originated on the moon similarly fe mn ratios in the mafic minerals of dho 081 indicate lunar origin lithologies in dho 025 and dho 081 include lithic clasts granulites and mineral fragments a large number of lithic clasts have plagioclase an and coexisting mafic mineral mg that plot within the gap separating ferroan anorthosite suite fan and high magnesium suite hms rocks this is consistent with whole rock ti sm ratios for dho 025 dho 081 and dag 262 which are also intermediate compared to fan and hms lithologies although ion microprobe analyses performed on dho 025 dho 081 dag 262 and dag 400 clasts and minerals show far stronger fan affinities than whole rock data suggest most clasts indicate admixture of 12 hms component based on geochemical modeling in addition coexisting plagioclase pyroxene ree concentration ratios in several clasts were compared to experimentally determined plagioclase pyroxene ree distribution coefficient ratios two dho 025 clasts have concordant plagioclase pyroxene profiles indicating that equilibrium between these minerals has been sustained despite shock metamorphism one clast has an intermediate fan hms composition these lunar meteorites appear to represent a type of highland terrain that differs substantially from the kreep signatured impact breccias that dominate the lunar database from remote sensing data it is inferred that the lunar far side appears to have appropriate geochemical signatures and lithologies to be the source regions for these rocks although the near side cannot be completely excluded as a possibility if these rocks are indeed from the far side their geochemical characteristics may have far reaching implications for our current scientific understanding of the moon

porosities of lunar meteorites strength porosity and petrologic screening during the meteorite delivery process porosity has been directly measured for eight lunar meteorite breccias and calculated for two more on the basis of literature density measurements lunar meteorite regolith breccias display systematically low porosity in comparison to otherwise analogous apollo regolith breccias among seven meteoritic regolith breccias porosity ranges from 1 to 11 and averages 7 5 1 3 2 whereas for 44 analogous apollo samples porosities mostly calculated from literature density data the average is 25 1 7 the origin of this disparity is enigmatic but the trend probably reflects mainly a bias in favor of strong compact breccias among fragments that manage to survive the violent process of launch to lunar escape velocity 2 38 km s in addition compaction during launch may play an important role the population of lunar meteorites is clearly not a random unmodified sample of lithic materials near the surface of the parent body

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

giant saltation on mars saltation the motion of sand grains in a sequence of ballistic trajectories close to the ground is a major factor for surface erosion dune formation and triggering of dust storms on mars although this mode of sand transport has been matter of research for decades through both simulations and wind tunnel experiments under earth and mars conditions it has not been possible to provide accurate measurements of particle trajectories in fully developed turbulent flow here we calculate the motion of saltating grains by directly solving the turbulent wind field and its interaction with the particles our calculations show that the minimal wind velocity required to sustain saltation on mars may be surprisingly lower than the aerodynamic minimal threshold measurable in wind tunnels indeed mars grains saltate in 100 times higher and longer trajectories and reach 5 10 times higher velocities than earth grains do on the basis of our results we arrive at general expressions that can be applied to calculate the length and height of saltation trajectories and the flux of grains in saltation under various physical conditions when the wind velocity is close to the minimal threshold for saltation

field measurement and numerical modelling of aeolian mass flux distributions on a sandy beach the vertical and horizontal distributions of aeolian mass flux were measured at oceano dunes california and these data were used to evaluate a numerical model of saltation grain size analyses showed that the distributions of the modal sediment size class corresponded closely to those of the total sediment population and modelling thus focused on replicating the distributions of the mean grain size although much previous work has assumed that the mean launch speed of saltating particles varies in proportion to shear velocity simulations using a constant mean launch speed were found to yield the closest approximations to the mass flux distributions observed in the field both exponential and gamma distributions of launch velocity produced realistic simulations although the latter approach required the inclusion of an additional reptation component to achieve good results a range of mean launch angles and an equivalent sphere correction were also found to generate comparable results providing the other input parameters could be varied freely all the modelling approaches overestimated the proportion of mass flux occurring at the bottom of the vertical distributions and underestimated the proportion occurring at the upwind end of the horizontal distributions no theoretical shortcoming that would account for these small but systematic discrepancies could be identified and experimental error thus represents a more plausible explanation the conclusion that mean grain launch speeds are essentially constant and independent of shear velocity suggests that the additional kinetic energy extracted by grains under more energetic wind conditions is largely transferred to the bed and that increases in the transport rate are therefore driven primarily by the ejection of additional grains it is suggested that the kinetic energy of rebounding grains is constrained by the ability of the bed to resist deformation equivalent to a plastic limit hence grains of larger mass diameter rebound from the bed at lower speeds and follow shorter lower trajectories as has been widely observed previously

cobalt and nickel concentrations in the komatiite component of apollo 16 polymict samples reply to r l korotev abstract we agree with korotev that the abundances of siderophiles in apollo 16 breccias are anomalously large but do not accept his hypothesis that they were supplied by the impact of a hitherto unknown type of meteorite possessing a grossly non chondritic composition co ni and other siderophiles in apollo 16 breccias display systematic relationships which imply that a substantial proportion of these siderophiles were present as oxidised species in the lunar crust prior to the impacts of chondritic type meteorites with the lunar surface these pre existing indigenous lunar siderophiles were reduced to the metallic state to varying degrees during impact bombardment and became alloyed with chondritic meteoritic metal in this manner the metallic particles of complex and unusual compositions now present at the a16 site were formed the indigenous siderophiles present in the a16 crust prior to meteoritic bombardment may themselves have been derived from two distinct sources one endogenous and the other exogenous the first corresponds to basic and ultrabasic magmas formed by partial melting of the moon s deep interior which were erupted and then and intimately mixed into the lunar crust the latter represents basic and ultrabasic material ejected from the earth s primitive crust by early meteorite bombardment which then fell upon the lunar surface the siderophiles present in each of these components display terrestrial like abundance patterns because they are both ultimately of terrestrial origin the anomalously high abundances of siderophiles at the a16 site may reflect an important contribution from ejected terrestrial material overall the siderophile abundance patterns present in lunar highland breccias represent mixtures of terrestrial and chondritic components

a komatiite component in apollo 16 highland breccias implications for the nickel cobalt systematics and bulk composition of the moon the lunar crust at the apollo 16 landing site contains substantial amounts of a primitive component in which the ferromagnesian group of elements is concentrated the composition of this component can be retrieved via an analysis of mixing relationships displayed by lunar breccias it is found to be a komatiite which is compositionally similar to terrestrial komatiites both in major and minor elements the komatiite component of the lunar crust is believed to have formed by extensive degrees of melting of the lunar interior at depths greater than were involved in the formation of the lunar magma ocean which was parental to the crust after formation of the anorthositic crust it was invaded by extensive flows and intrusions of komatiite magma from these deeper source regions the komatiites became intimately mixed with the anorthosite by intensive meteoroid impacts about 4 5 b y ago thereby accounting for the observed mixing relationships displayed by the crust the compositional similarity between lunar and terrestrial komatiites strongly implies a corresponding similarity between the compositions of their source regions in the lunar interior and the earth s upper mantle the composition of the lunar interior can be modelled more specifically by combining the komatiite composition with its liquidus olivine composition as determined experimentally in proportions chosen so as to produce a cosmochemically acceptable range of mg si ratios for the bulk moon except for higher feo and lower na2o the range of compositions thereby obtained for the bulk moon is very similar to the composition of the earth s upper mantle the effects of meteoritic contamination on the abundances of cobalt and nickel in lunar highland breccias were subtracted on the assumption that the contaminating projectiles were chondritic the cobalt and nickel residuals thereby obtained were found to correlate strongly with the mg fe content of the breccias demonstrating that the co and ni are associated with the ferromagnesian component of the breccias and are genuinely indigenous to the moon the lunar highland co and ni residuals also display striking ni co versus ni correlations which follow a similar trend to those displayed by terrestrial basalts picrites and komatiites the lunar trends provide further decisive evidence of the indigenous nature of the co and ni residuals and suggest the operation of extensive fractionation controlled by olivine liquid equilibria in producing the primitive component of the lunar breccias indigenous nickel abundances at the apollo 14 15 and 17 sites are much lower than at the apollo 16 site although rocks from all sites follow the same ni co versus ni trends it is suggested that the primitive component at the apollo 14 15 and 17 sites was generally of basaltic composition in contrast to the komatiitic nature of the apollo 16 primitive component

mac88105 a regolith breccia from the lunar highlands mineralogical petrological and geochemical studies abstract the new large lunar meteorite mac88105 is a dense breccia with lithic and mineral clasts and fragments set into a welded matrix it is a regolith breccia which shows some recrystallization and evidence for a late shock event during which anorthositic glass veins were formed shock effects most probably due to the impact ejection from the moon are present throughout the sample and require a shock pressure of about 25 30 gpa in agreement with observations made on other lunar meteorites some components of mac88105 have been subjected to a shock pressure of about 40 45 gpa as evident from melt pockets in a clast the population of lithic clasts in mac88105 is similar to other lunar highland breccias vitric breccias are more abundant than granulitic breccias and plutonic rock fragments the presence of devitrified glass spheres and shards supports a regolith origin most common are metameltbreccias consisting of abundant anorthitic plagioclase clasts and a dense fine grained matrix some fine grained hornfelsic to granulitic metabreccias are also present lithic clast compositions are predominantly anorthositic noritic or noritic anorthositic and anorthositic troctolitic spinel bearing rocks are present but do not belong to the spinel troctolite group a spinel bearing clast in mac88105 consists of anorthite pigeonite spinel and indicates a different heritage possibly similar to spinel cataclasites described from apollo 17 the pyroxenes in mac88105 have somewhat unusual compositions orthopyroxenes and augites appear to be rare most lithologies breccias and igneous rocks contain solely pigeonite we have found one igneous mafic rock a gabbro which has a low mg number and is possibly of mare origin a metal grain of a composition similar to metal in h chondrites supports the interpretation of mac88105 as a regolith breccia the bulk composition of mac88105 is similar to the other lunar highland meteorites the ree contents are slightly higher than for the other anorthositic meteorites with a smaller positive eu anomaly this is in agreement with a possible kreep contribution possibly introduced from glasses macs 8105 is a mixture of rocks with a predominant contribution from the anorthosite suite and small admixtures from other rock types mare basalt mg suite which becomes obvious in plots of molar mg or sm content vs the ti sm ratio the siderophile element abundances in mac88105 are similar to other highland meteorites and show the characteristic co excess and a au ir ratio similar to the other anorthositic meteorites and lower than the hyperchondritic ratio in apollo 16 rocks thus support the notion that the lunar meteorites are a more representative sample of the lunar highlands than the apollo samples the chemistry and mineralogy of mac88105 is different from that of the other lunar meteorites and suggests a different source which is supported by cosmic ray and noble gas data at this time it seems likely that about four individual impact events have been responsible for delivering the seven highland meteorites mac88105 and other lunar meteorites are important as they are probably random samples from the lunar surface and may thus be more representative than the apollo and luna rocks which come from only a small area of the moon

two stage models for lunar and terrestrial anorthosites petrogenesis without a magma ocean two stage diapiric models for lunar ferroan anorthosites and terrestrial massif anorthosites are examined the lunar model is developed to explain early lunar differentiation in the absence of a magma ocean if correct the terrestrial model serves as an analog for the development of lunar anorthositic diapirs there is field and textural evidence of transport of mostly crystalline anorthositic material within the terrestrial complexes this evidence combined with the absence of anorthositic lavas and phase equilibrium constraints inhibiting the production of hyperaluminous magmas is consistent with the detachment of plagioclase rich crystalline mushes from large uppermost mantle plutons and multiple diapiric intrusion of these mushes into the upper sialic crust with attendant anatexis rudimentary dynamical calculations suggest that a simple single layer source for the diapirs is improbable either there were several parental magma chambers or there was a single large chamber that was repeatedly replenished the lunar model is a development of wetherill s 1975 suggestion that following accretion the outer portion of the moon consisted of a stack of overlapping layered intrusions and that reheating of these intrusions mobilized their anorthositic layers which intruded upwards to produce the anorthositic lunar crust dynamical calculations show that gravitational instabilities in anorthositic layers 1 km thick could develop into diapirs on a reasonable time scale 50 100 m y only if the outer portion of the moon was partially remelted we suggest that partial melting of the interior due to the decay of long lived radionuclides with the subsequent onset of global convection heated the stack of intrusions from below thus causing melting and allowing the anorthositic diapirs to grow and ascend fairly rapidly as the convecting zone thickened a mass expulsion of anorthositic material out of the lunar interior may have occurred

apollo 16 site geology and impact melts implications for the geologic history of the lunar highlands the geology of the apollo 16 site is reconsidered on the basis of data from photogeology geochemical remote sensing and lunar samples the site possesses an upper surface of anorthositic gabbro and related rocks mafic components were deposited as basin ejecta the events involved in its geological evolution were the nectaris impact and the imbrium impact the role of large local craters in the history of the region was to serve as topographic depressions to accumulate basin ejecta the most abundant melt composition at apollo 16 is an aluminous variety of lkfm basalt supplied by the nectaris impact as ejected basin impact melt the mafic lkfm melt may have been supplied by the imbrium impact more aluminous melt groups are probably derived from local small craters the remainder of the deposits in the region are composed of anorthositic clastic debris derived from the nectaris basin the local crustal substrate and imbrium and other basins

petrology and chemistry of hyperferroan anorthosites and other clasts from lunar meteorite alha81005 thirteen previously undescribed clasts from lunar meteorite allan hills a81005 include one that is a cataclastic hyperferroan noritic anorthosite mafic minerals in this clast low ca pyroxene with mg 52 and olivine with fo 41 have very low mg compared to most lunar anorthosites described before the discovery of 81005 siderophile element concentrations are low and indicate that the clast is compositionally pristine rare earth elements ree are 2 5 10 times more abundant and slightly more fractionated than in previously described ferroan anorthosites another probably pristine clast is a granulitic gabbroic norite that has low ca pyroxene with mg 53 hyperferroan anorthosites are a significant component of 81005 extreme iron enrichment and high ree abundances indicate that these rocks formed late in the evolution of the magma from which the ferroan anorthosite suite formed plagioclase was not enriched in na even at these late stages another clast is a cataclastic ferroan anorthosite fo 66 that might be pristine of the remaining 10 clasts nine are granular to cataclastic rocks primarily anorthositic troctolites or troctolitic anorthosites and two are impact melt breccias all of which probably represent mixtures of pristine rock types the former have ree that are essentially unfractionated relative to chondrites and range in abundance from 1 5 3 cl and the latter are similar to bulk 81005 ree 5 8 cl siderophile element abundances are high and indicate the presence of a significant meteoritic component our data indicate that 81005 has only a small kreep potassium rare earth elements phosphorus component this is consistent with previous results

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

megaregolith insulation and the duration of cooling to isotopic closure within differentiated asteroids and the moon ages determined for extraterrestrial samples by the sm nd and rb sr techniques are commonly assumed to record igneous crystallization events because in solid silicates nd and sr diffuse at exceedingly slow rates however we find that for coarse grained igneous cumulate rocks from the moon or from a large thoroughly brecciated asteroid this assumption may not be reliable the moon and at least one asteroid the parent body of the eucrite diogenite and howardite meteorites appear to have been largely molten at or about the time they formed we have modeled global cooling of the moon and large r 40 250 km asteroids starting at or near the solidus a crucial factor in determining the prevailing interval ic of cooling between igenous crystallization and isotopic closure for any given depth in the crust is the extent to which the body is insulated by a regolith megaregolith layer of porous fragmental impact debris given plausible assumptions regarding the thicknesses of such layers on the moon and the eucrite parent asteroid and regarding the radius of the eucrite asteroid our results indicate that deep crustal regions tend to remain above the nd and sr isotopic closure temperature for intervals that are long in comparison to the precision of modern nd and sr based age measurements and in comparison to suggested chronologic scenarios of global differentiation ic intervals of as long as 100 m y may be common among available samples of primordial deep crustal cumulates from both bodies chronologies for the gross solidification of the moon and the eucrite asteroid should allow for the possibility that any single age for a coarse grained plutonic or cumulate textured rock might be many tens of millions of years younger than the igneous crystallization age

remelting mechanisms for shallow source regions of mare basalts abstract two mechanisms are studied which could induce remelting at shallow depths within the moon a radioactive heating model in which remelting is the result of lateral variations of the heat source concentration emplaced by the end of the initial differentiation event and a thermal insulation model in which remelting is induced by lateral variations of near surface conductivity as a result of a high porosity ejecta blanket created by basin forming impacts the effects of these perturbations are studied by evaluating the thermal evolution of an otherwise radially symmetric lunar model the radioactive heating models predict extensive pre basin volcanism which would probably remove from the source region many of the heat producing elements potentially responsible for melting therefore localized high concentrations of heat producing elements emplaced early would most probably not be heat sources for the basin filling mare basalts however they are plausible heat sources for pre basin mare basalts the thermal insulation model predicts a delay of about 200 m y between impact and volcanism thermal insulation may also allow for the persistence of source regions for young basalts at shallow depths if greater basin ages are correct from 4 2 to 3 9 ga and most volcanism occurred between 3 8 and 3 6 ga then the thermal insulation model may explain the delay between impact and basin filling if the basins formed during a terminal cataclysmic event at about 3 9 ga then the earliest stages of basin filling at about 3 8 ga may have been a result of melting beneath the basin as a result of mantle uplift basin filling may have been characterized by a migration of the source region from beneath the basin to beneath the adjacent highlands cooling of the top 200 km beneath the basin after 200 m y because of its high surface conductivity is consistent with the mascon support requirement

estimation of some aeolian saltation transport parameters a re analysis of williams data a new method for analysing observed aeolian sand transport rate profiles of the kind obtained by williams is presented the method involves a mathematical model of aeolian saltation detailed information about the saltation process can be calculated from the transport rate profile by means of this model the method is used to perform a re analysis of williams trap data among the main findings of this analysis is that the grain borne shear stress appears to be a smaller fraction of the total shear stress than assumed by bagnold owen in their theories of aeolian saltation other findings are that the probability distribution of the jump height of the grains does not depend much on the wind speed once the saltation is established and that the vertical component of the mean launch velocity decreases with the grain size it is approximately inversely proportional to the grain diameter our estimates of the landing angles indicate that estimates of the impact angles obtained from photographically recorded trajectories are too small due to biased sampling the influence of grain shape on the transport characteristics is mainly due to changes in the grains ability to jump when hitting the bed it is found that angular grains have a lower mean jump height than spherical grains

aeolian particle flux profiles and transport unsteadiness vertical profiles of aeolian sediment flux are commonly modeled as an exponential decay of particle mass transport with height above the surface data from field and wind tunnel studies provide empirical support for this parameterization although a large degree of variation in the precise shape of the vertical flux profile has been reported this paper explores the potential influence of wind unsteadiness and time varying intensity of transport on the geometry slope curvature of aeolian particle flux profiles field evidence from a complex foredune environment demonstrates that i the time series of wind and sediment particle flux are often extremely variable with periods of intense transport referred to herein as sediment flurries separated by periods of weak or no transport ii sediment flurries contribute the majority of transport in a minority of the time iii the structure of a flurry includes a ramp up phase lasting a few seconds a core phase lasting a few seconds to many tens of seconds and a ramp down phase lasting a few seconds during which the system relaxes to a background low intensity transport state and iv conditional averaging of flux profiles for flurry and nonflurry periods reveals differences between the geometry of the mean profiles and hence the transport states that produce them these results caution against the indiscriminate reliance on regression statistics derived from time averaged sediment flux profiles especially those with significant flurry and nonflurry periods when calibrating or assessing the validity of steady state models of aeolian saltation

vertical profiles of aeolian sand mass flux abstract vertical profiles of the horizontal mass flux of blown sand are investigated experimentally using a passive vertical array in a wind tunnel considering lower sampling efficiency of the sand trap in the near bed region this investigation is complemented by the measurements of the longitudinal profiles of mass flux made using a horizontal sand trap the experiments were conducted with two test sands and five different stream velocities in the upper part of the vertical profile the measured data exhibit an exponential decay distribution with a positive deviation occurring in the near bed region the measured longitudinal profiles are similar to the measured vertical profiles linking both profiles and the modes of sand transport it is possible that saltating sand grains give rise to the well known exponential decay distribution of mass flux and that creeping and reptating grains force a deviation from it a simple equation applicable for both the vertical and the longitudinal sand mass flux variations is introduced and the parameters are estimated from experimental data

the macalpine hills lunar meteorite and implications of the lunar meteorites collectively for the composition and origin of the moon the mac88104 mac88105 meteorite is a lunar highlands regolith breccia even more anorthositic than previously available samples of highlands regolith clasts studied include two unusual pristine rocks one a 2 5 mm slightly granulitic clast rated as probably pristine contains extraordinarily fe rich fo40 olivine the other a 5 mm clast with clear vestiges of a poikilitic cumulate texture has silicate compositions that extend the range of the mg suite in the direction of the high mg end of the ferroan anorthositic suite the pyroxene of the latter clast is relatively ca rich and poorly equilibrated by lunar cumulate standards suggesting that it may have formed in an uncommonly shallow intrusion the four lunar highlands meteorites are all regolith breccias or in one case a marginal type between regolith breccia and ordinary polymict breccia and they probably represent three to four separate lunar source craters the proportion of regolith breccias is higher among lunar highlands meteorites than among rock samples from the classic highlands site apollo 16 9 regolith breccias for the majorelement composition of the crust the highlands meteorites confirm that the two low th central nearside sites luna 20 and especially apollo 16 are approximately representative the consistently high al2o3 composition indicated for the upper crust supports the magmasphere hypothesis for the trace element composition of the crust the highlands meteorites indicate that the central nearside apollo and luna sites are in several respects grossly unrepresentative concentrations of siderophile elements are far lower in highlands meteoritic regolith breccias than in their central nearside counterparts the high overall siderophile levels and hyperchondritic niir and auir ratios characteristic of highlands materials from apollo 16 and apollo 14 are evidently idiosyncracies of the central nearside concentrations of incompatible elements including k th and u are far lower in the highlands meteorites than in regolith samples from the central nearside this trend implies that certain lower limits on the bulk moon content of u and associated refractory lithophile elements should be relaxed models of lunar origin implying large enrichments of refractory lithophile elements are not favored by the new constraints from these meteorites

a potpourri of pristine moon rocks including a vhk mare basalt and a unique augite rich apollo 17 anorthosite analysis of previously unstudied apollo lithic fragments continues to yield surprising results among this year s samples is a small anorthosite fragment 76504 18 the first pristine anorthosit e found from apollo 17 this unique lithology strongly resembles the main type of apollo anorthosites ferroan anorthosites but 76504 18 has a far higher ratio about 9 of high ca pyroxene to low ca pyroxene higher na in its plagioclase higher contents of incompatible elements such as ree and a higher eu al ratio assuming that 76504 18 is a cumulate with less than 45 trapped liquid its parent melt probably had a negative eu anomaly in all these respects 76504 18 seems more likely than other ferroan anorthosites to be closely related to typical mare basalts apparently this anorthosite was among the latest to form by plagioclase flotation above a primordial magmasphere typical mare basalt source regions probably accumulated at about the same time or even earlier another previously unstudied fragment 14181c is a vhk very high potassium basalt that is similar in most respects to typical aluminous apollo 14 mare basalt but has a k la ratio of 1050 this lithology probably formed after a normal apollo 14 mare basaltic melt partially assimilated granite new data for siderophile elements in apollo 12 mare basalts indicate that only the lowest of earlier data are trustworthy as being free of laboratory contamination

a numerical study of particle motion and two phase interaction in aeolian sand transport using a coupled large eddy simulation discrete element method wind blown sand movement considered as a particle laden two phase flow was simulated by a new numerical code developed in the present study the discrete element method was employed to model the contact force between sand particles large eddy simulation was used to solve the turbulent atmospheric boundary layer motions of sand particles were traced in the lagrangian frame within the near surface region of the atmospheric boundary layer interparticle collisions will significantly alter the velocity of sand the sand phase is quite dense in this region and its feedback force on fluid motion cannot be ignored by considering the interparticle collision and two phase interaction four way coupling was achieved in the numerical code profiles of sand velocity from the simulations were in good agreement with experimental measurements the mass flux shows an exponential decay and is comparable to reported experimental and field measurements the turbulence intensities and shear stress of sand particles were estimated from particle root mean square velocities distributions of slip velocity and feedback force were analysed to reveal the interactions between sand particles and the continuous fluid phase

grain scale simulations of loose sedimentary beds the example of grain bed impacts in aeolian saltation sediment transport by wind is one of many processes of interest to the geomorphologist in which grain to grain contacts play an important role in order to illustrate the modelling of collections of frictional inelastic sedimentary grains with the particle dynamics method pdm we use the grain impact process in aeolian saltation as a specific example in pdm all the forces on each particle are evaluated at a sequence of small time steps and the newtonian equations of motion are integrated forward in time interparticle forces at grain contacts are treated as springs with prescribed stiffness normal force and by a coulomb friction law tangential force particle inelasticity is represented by spring damping the granular splash resulting from saltation impacts is assessed for sensitivity to the choice of grain properties and the integration time step we find that for the range of impact speeds and impactor masses relevant to aeolian settings grain splashes are relatively insensitive to grain stiffness grain inelasticity and grain friction and that the pattern of ejection from the bed is largely controlled by bed microtopography a large set of impact realizations involving a variety of impact points on a small set of target beds is used to collect the appropriate statistics for describing the stochastic splash process the splash function representing these statistics is then available for use in calculations over longer time scales such as the evolution of the saltation curtain the details given here will enable the interested reader to adapt pdm modelling to other types of clastic sedimentary systems

lunar and terrestrial crust formation planetary crusts may be accreted produced in primordial differentiation or built up piecemeal by serial magmatism the existence of old polygenetic laterally heterogeneous partial melt rocks in the lunar highlands suggests that the moon produced its early crust by serial magmatism this view can be reconciled with lunar eu anomalies previously thought to support the magma ocean model of crust formation if complications in the fractionation of mare basalts are recognized phase equilibrium and magmatic density information for mare basalts suggest a model in which plagioclase fractionation can occur even though plagioclase is not a near liquidus phase the cryptic fractionation of clinopyroxene in morb provides a precedent for this model the necessity for a lunar magma ocean is questioned but a role for a terrestrial magma ocean of sorts at depth is suggested

wind tunnel experimental investigation of sand velocity in aeolian sand transport sand velocity in aeolian sand transport was measured using the laser doppler technique of pdpa phase doppler particle analyzer in a wind tunnel the sand velocity profile probability distribution of particle velocity particle velocity fluctuation and particle turbulence were analyzed in detail the experimental results verified that the sand horizontal velocity profile can be expressed by a logarithmic function above 0 01 in while a deviation occurs below 0 01 m the mean vertical velocity of grains generally ranges from 0 2 m s to 0 2 m s and is downward at the lower height upward at the higher height the probability distributions of the horizontal velocity of ascending and descending particles have a typical peak and are right skewed at a height of 4 turn in the lower part of saltation layer the vertical profile of the horizontal rms velocity fluctuation of particles shows a single peak the horizontal rms velocity fluctuation of sand particles is generally larger than the vertical rms velocity fluctuation the rms velocity fluctuations of grains in both horizontal and vertical directions increase with wind velocity the particle turbulence intensity decreases with height the present investigation is helpful in understanding the sand movement mechanism in windblown sand transport and also provides a reference for the study of blowing sand velocity c 2007 elsevier b v all rights reserved