feldspathic clasts in yamato 86032 remnants of the lunar crust with implications for its formation and impact history abstract low concentrations of th and fe in the yamato y 86032 bulk meteorite support earlier suggestions that y 86032 comes from a region of the moon far distant from the procellarum kreep terrain pkt probably from the lunar farside 39 ar 40 ar rb sr sm nd and sm isotopic studies characterize the chronology of y 86032 and its precursors in the mega regolith one of the rock types present in a light gray breccia lithology is an anorthosite characterized by plagioclase with an 93 i e more sodic than lunar fans but with very low 87 rb 86 sr and 87 sr 86 sr similar to those of fans fan stands for ferroan anorthosite this an93 anorthosite has nd isotopic systematics similar to those of nearside norites a fan like an97 anorthosite is present in a second light colored feldspathic breccia clast and has a more negative e nd value consistent with residence in a lree enriched environment as would be provided by an early plagioclase flotation crust on the lunar magma ocean lmo this result contrasts with generally positive values of e nd for apollo 16 fans suggesting the possibility of assymetric development of the lmo other possible explanations for the dichotomy in e nd values are advanced in the text the y 86032 protolith formed at least 4 43 0 03 ga ago as determined from a sm nd isochron for mineral fragments from the breccia clast composed predominantly of an93 anorthosite and a second clast of more varied composition we interpret the mineral fragments as being predominatly from a cogenetic rock suite an 39 ar 40 ar age of 4 36 4 41 0 035 ga for a third clast composed predominantly of an97 anorthosite supports an old age for the protolith initial 143 nd 144 nd in that clast was 0 64 0 13 e units below 143 nd 144 nd in reservoirs having chondritic sm nd ratios consistent with prior fractionation of mafic cumulates from the lmo a maximum in the 39 ar 40 ar age spectrum of 4 23 0 03 ga for a second sample of the same feldspathic breccia clast probably reflects some diffusive 40 ar loss lack of solar wind and lunar atmosphere implanted ar in the light gray breccia clast allows determination of an 39 ar 40 ar age of 4 10 0 02 ga which is interpreted as the time of initial brecciation of this litholgy after correction for implanted lunar atmosphere 40 ar impact melt and dark regolith clasts give ar ages of 3 8 0 1 ga implying melt formation and final breccia assembly 3 8 ga ago some breccia lithologies were exposed to thermal neutron fluences of 2 10 15 n cm 2 only about 1 of the fluence experienced by some other lunar highlands meteorites other lithologies experienced neutron fluences of 1 10 15 n cm 2 thus y 86032 spent most of the time following final brecciation deeply buried in the megaregolith the neutron fluence data are consistent with cosmogenic 38 ar cos cosmic ray exposure ages of 10 ma variations among differing lithologies in the amount of several regolith exposure indicators including cosmogenic noble gas abundances neutron capture induced variations in sm isotopic abundances and ir contents are consistent with a period of early 3 8 ga ago lunar regolith exposure subsequent deep burial at 5 m depth and ejection from the moon 7 10 ma ago

morphology of transverse aeolian ridges tars on mars from a large sample further evidence of a megaripple origin abstract using hirise digital terrain models dtms we developed a large morphological dataset to examine the three dimensional shape size and scaling of martian transverse aeolian ridges tars considerable debate exists on the characteristic morphology of tars and the origins of these enigmatic bedforms some researchers suggest polygenesis or multiple classes of similar bedforms reliably characterizing the morphology of tars is an essential prerequisite to developing and evaluating process based models of tar genesis and unraveling aeolian processes on the surface of mars we present measurements of tar morphology from a large dtm derived dataset n 2295 we focused on tars with simple morphologies in order enable more defensible discretization histograms and cumulative log frequency plots of morphometric parameters length width height elongation ratio and wavelength indicate the sample represents a continuum of bedforms from a single population a typical tar from our dataset is 88 5 m long longest planview axis 17 3 m wide shortest planview axis 1 3 m tall and has a wavelength of 25 8 m combined with these data the bulk of evidence presented to date suggests that interpreting tars as megaripples is the most viable working hypothesis

a model for the thermal and chemical evolution of the moon s interior implications for the onset of mare volcanism crystallization of the lunar magma ocean creates a chemically stratified moon consisting of an anorthositic crust and magma ocean cumulates overlying the primitive lunar interior within the magma ocean cumulates the last liquids to crystallize form dense ilmenite rich cumulates that contain high concentrations of incompatible radioactive elements the underlying olivine orthopyroxene cumulates are also stratified with later crystallized denser more fe rich compositions at the top this paper explores the chemical and thermal consequences of an internal evolution model accounting for the possible role of these sources of chemical buoyancy rayleigh taylor instability causes the dense ilmenite rich cumulate layer and underlying fe rich cumulates to sink toward the center of the moon forming a dense lunar core after this overturn radioactive heating within the ilmenite rich cumulate core heats the overlying mantle causing it to melt in this model the source region for high tio2 mare basalts is a convectively mixed layer above the core mantle boundary which would contain small and variable amounts of admixed ilmenite and kreep this deep high pressure melting as required for the generation of mare basalts occurs after a reasonable time interval to explain the onset of mare basalt volcanism if the content of radioactive elements in the core and the chemical density gradients above the core are sufficiently high but within a range of values that might have been present in the moon regardless of details implied by particular model parameters gravitational overturn driven by the high density of magma ocean fe rich cumulates should concentrate high tio2 mare basalt sources and probably a significant fraction of radioactive heating toward the center of the moon this will have important implications for both the thermal evolution of the moon and for mare basalt genesis

first in situ analysis of dust devil tracks on earth and their comparison with tracks on mars in this study we report about the first in situ analysis of terrestrial dust devil tracks ddts observed in the turpan depression desert in northwestern china passages of active dust devils remove a thin layer of fine grained material 63 m cleaning the upper surface of coarse sands 0 5 1 mm this erosional process changes the photometric properties of the upper surface causing the albedo differences within the track to the surroundings measurements imply that a removal of an equivalent layer thickness of 2 m is sufficient to form the dark dust devil tracks our terrestrial results are in agreement with the mechanism proposed by greeley et al 2005 for the formation of ddts on mars

latitude dependent nature and physical characteristics of transverse aeolian ridges on mars 1 narrow angle images from the mars orbiter camera moc have revealed the common occurrence of small scale 100 m wavelength bright transverse aeolian ridges tars on the surface of mars moc images were used to assess the broad distribution of tars from 90 n to 90 s between 180 e and 240 e to investigate their relationship to latitude elevation thermal inertia geologic units local slopes and surface roughness out of 5112 examined images from the primary mission 520 10 contain evidence of tars 92 of the images with tars are located between 50 latitude and very few occur in the middle to upper latitudes or polar regions of either hemisphere tars are observed at elevations from 5 km to 3 km with the highest frequency 26 between 1 and 0 km there is no systematic relationship between the distribution of tars and global thermal inertia measurements most tars occur in geologic units associated with the channel system materials 39 and the olympus mons aureole 33 at a length scale of 1 85 km pixel the average local slopes for images with and without tars are 1 92 and 1 36 respectively of the parameters investigated the latitudinal trend of tars in both hemispheres appears to be predominantly related to surface roughness with a positive linear correlation between the surface roughness of geologic units and frequency of tars r2 0 87 factors affecting the semiglobal distribution of tars are likely related to the climate and wind regimes in which they formed but do not provide definitive evidence for either saltation or reptation formation mechanisms

the variety of lithologies in the yamato 86032 lunar meteorite implications for formation processes of the lunar crust abstract we performed a petrologic mineralogical geochemical and isotopic study of several lithologies in the y 86032 feldspathic breccia this study leads us to conclude that y 86032 likely originated on the lunar farside y 86032 is composed of several types of feldspathic clasts granulitic breccias and minor basaltic clasts set in a clastic matrix we identify an an97 anorthosite that has an contents similar to those of nearside fans mg molar mg mg fe 100 values vary significantly from 45 to 80 covering the ranges of both nearside fans and the mg gap between fans and the mg suite a light gray feldspathic lg breccia making up 20 of the investigated slab 5 2 3 6 cm2 mainly consists of fragments of anorthosites an93 anorthosite more sodic than nearside fans lg also contains an augite plagioclase clast which either could be genetically related to the an93 anorthosite or to slowly cooled basaltic magma intruded into the precursor rock the na rich nature of both an93 anorthosite and this clast indicates that the lg breccia was derived from a relatively na rich but incompatible element poor source the mg variation indicates that the an97 anorthosite is a genomict breccia of several types of primary anorthosites granulitic breccias in y 86032 have relatively high mg in mafic minerals the highest mg values in mafic minerals for the an97 anorthosite and granulitic breccias are similar to those of mg rich lithologies recently described in dhofar 489 basaltic clasts in the dark gray matrix are aluminous and the zoning trends of pyroxene are similar to those of vlt or lt basalts the crystallization of these basaltic clasts pre date the lithification age of the clastic matrix at 3 8 ga the low k contents of plagioclase in both the anorthositic and basaltic clasts and generally low incompatible element abundances in all the lithologies in y 86032 indicate that kreep was not involved during the formation of the precursor lithologies this observation further suggests that urkreep did not exist in the source regions of these igneous lithologies all these facts support the idea that y 86032 was derived from a region far distant from the pkt and that the lithic clasts and fragments are indigenous to that region an an97 anorthositic clast studied here has distinct sm nd isotopic systematics from those previously found for another an97 anorthositic clast and an93 anorthosite and suggests either that an97 anorthosites come from isotopically diverse sources or that the sm nd isotopic systematics of this clast were reset 4 3 ga ago these lines of geochemical isotopic and petrologic evidence suggest that the lunar crust is geochemically more heterogeneous than previously thought

lunar apatite with terrestrial volatile abundances the moon is thought to be depleted relative to the earth in volatile elements such as h cl and the alkalis nevertheless evidence for lunar explosive volcanism has been used to infer that some lunar magmas exsolved a co rich and co 2 rich vapour phase before or during eruption although there is also evidence for other volatile species on glass spherules until recently there had been no unambiguous reports of indigenous h in lunar rocks here we report quantitative ion microprobe measurements of late stage apatite from lunar basalt 14053 that document concentrations of h cl and s that are indistinguishable from apatites in common terrestrial igneous rocks these volatile contents could reflect post magmatic metamorphic volatile addition or growth from a late stage interstitial sulphide saturated melt that contained 1 600 parts per million h 2o and 3 500 parts per million cl both metamorphic and igneous models of apatite formation suggest a volatile inventory for at least some lunar materials that is similar to comparable terrestrial materials one possible implication is that portions of the lunar mantle or crust are more volatile rich than previously thought

transverse aeolian ridges tars on mars aeolian processes are probably the dominant ongoing surface modification process on mars as demonstrated by observations of dunes ripples yardangs ventifacts wind streaks dust devils and dust storms large dark dunes ldds are particularly common and were first recognized in the 1960 s from mariner data however another population of smaller often brighter ripple like aeolian bed forms that are morphologically distinct from ldds has been observed in recent higher resolution images calculations of saltation path length under martian conditions suggest these small bed forms could have formed as small barchanoid dunes or as mega ripples also known as granule ripples these features have therefore been called transverse aeolian ridges tars as this label has no genetic inference we have begun a study of tars that examines all high resolution mars orbiter camera data 1 5 to 8 m pixel resolution in a 45o longitude wide pole to pole swath we aim to determine the geographic distribution of tars assess whether they are active and to identify possible sediment sources we have already made some key observations first we present a new classification of tar deposits based on crest ridge morphology of individual forms and the size and degree of topographic control of the entire sediment mass second we present associations of tars with ldds slope streaks dust devils tracks and small impact craters that provide clues as to whether tars are currently active finally we present preliminary pole to pole survey results for the northern hemisphere that show clusters of tar deposits in the low latitudes suggesting possible unique sediment sources in these regions

discordant iron rich ultramafic pegmatites in the bushveld complex and their relationship to iron rich intercumulus and residual liquids the iron rich ultramafic pegmatites comprise a suite of coarse grained rocks that form discordant bodies within the layered sequence of the bushveld complex these pegmatites which are considerably more abundant than is generally realized provide evidence for the differentiation of iron rich residual melts the pegmatites are composed largely of iron rich olivine and clinopyroxene together with ti magnetite and ilmenite feldspar is characteristically absent but paradoxically the pegmatites preferentially replace anorthositic cumulates two subgroups are recognized olivine clinopyroxene pegmatite and fe ti oxide pegmatite with increased stratigraphic height the pegmatites become richer in fe ti oxides thus olivine clinopyroxene pegmatite is prevalent in the upper critical and lower main zones whereas fe ti oxide pegmatite is restricted to the upper main and upper zones zoned pegmatite with a core of fe ti oxide pegmatite is transitional between the two subgroups new whole rock and electron microprobe analyses of olivine clinopyroxene pegmatite from the upper critical and lower main zones provide convincing evidence that their composition is directly related to height cryptic compositional variations are analogous to those displayed by the layered cumulates but for a given height the pegmatites are always more evolved compositions of clinopyroxene in the pegmatites reflect a near linear relationship with height whereas cumulus pyroxenes display upward iron enrichment trends complicated by replenishment and reaction with trapped intercumulus liquid the olivine clinopyroxene pegmatite formed by magmatic replacement of earlier formed cumulates in response to infiltration of iron rich melts suitably differentiated melts comprised intercumulus and residual liquids derived from thick anorthosite layers the absence of feldspar although not fully understood is attributed to an immiscible relationship between dense iron rich melts and light silica alkali rich liquids the latter infiltrated upward to be reincorporated into the resident magma the iron rich melts however drained down into the crystallizing cumulate pile channelling along early formed fractures and joints was significant locally resulting in huge pipe like bodies of pegmatite the iron rich melts became increasingly differentiated with height partly in response to the fractional crystallization of more evolved cumulates the olivine clinopyroxene pegmatites are related to infiltration of fe ti oxide rich silicate melt whereas fe ti oxide pegmatite is ascribed to fe ti oxide liquid as originally argued by bateman 1951 the bushveld complex followed the fenner trend of almost uninterrupted iron enrichment evidence of pronounced iron enrichment is however manifested in the discordant iron rich ultramafic pegmatites several thousands of metres below the height at which iron rich cumulates are observed

transverse aeolian ridges tars on mars ii distributions orientations and ages transverse aeolian ridges tars 10 m scale ripple like aeolian bedforms with simple morphology are widespread on mars but it is unknown what role they play in mars wider sediment cycle we present the results of a survey of all mars global surveyor narrow angle images in a pole to pole study area 45 longitude wide following on from the classification scheme and preliminary surveys of balme et al balme m r berman d c bourke m c zimbelman j r 2008a geomorphology 101 703 720 and wilson and zimbelman wilson s a zimbelman j r 2004 j geophys res 109 e10 doi 10 1029 2004je002247 we searched more than 10 000 images and found that over 2000 reveal at least 5 areal cover by tars the mean tar areal cover in the study area is about 7 3 in the northern hemisphere and 11 in the southern hemisphere but tars are not homogenously distributed they are concentrated in the mid low latitudes and almost absent poleward of 35 n and 55 s we found no clear correlation between tar distribution and any of thermal inertia kilometer scale roughness or elevation we did find that tars are less common at extremes of elevation we found that tars are most common near the equator especially in the vicinity of meridiani planum in which area they have a distinctive barchan like morphology and in large southern hemisphere impact craters tars in the equatorial band are usually associated with outcrops of layered terrain or steep slopes hence their relative absence in the northern hemisphere tars in the southern hemisphere are most commonly associated with low albedo intercrater dune fields we speculate that the mid latitude mantling terrain e g mustard j f cooper c d rifkin m k 2001 nature 412 411 414 kreslavsky m a head j w 2002 j geophys res 29 15 doi 10 1029 2002gl015392 could also play a role in covering tars or inhibiting saltation we compared tar distribution with general circulation model gcm climate data for both surface wind shear stress and wind direction we performed gcm runs at various obliquity values to simulate the effects of changing obliquity on recent mars climate we found good general agreement between tar orientation and gcm wind directions from present day obliquity conditions in many cases but found no good correlation between wind shear stress and tar distribution we performed preliminary high resolution crater count studies of tars in both equatorial and southern intracrater dunefield settings and compared these to superposition relationships between tars and large dark dunes our results show that tars near dunefield appear to be younger than tars in the equatorial regions we infer that active saltation from the large dunes keeps tars active but that tars are not active under present day condition when distal to large dunes perhaps supporting the interpretation that tars are granule ripples we conclude that local geology rather than wind strength controls tar distribution but that their orientation matches present day regional wind patterns in most cases we suggest that tars are likely most perhaps only active today when they are proximal to large dark dune fields

application of self organizing map and srtm data to characterize yardangs in the lut desert iran abstract yardangs an exclusive landform due to intensive wind erosion cover a large area in the hyper arid lut desert of iran this paper presents a new approach using self organizing map som as unsupervised algorithm of artificial neural networks for analysis and characterization of yardangs nowadays the shuttle radar topography mission srtm with 3 arc sec data approximately 90 m resolution and nearly world wide coverage provides uniform good quality data the srtm 3 arc sec data were re projected to a 90 m utm grid bivariate quadratic surfaces with moving window size of 5 5 were fitted to this dem the first derivative slope steepness and the second derivatives minimum maximum curvature and cross sectional curvatures were calculated as geomorphometric parameters used as input to the soms 42 soms with different learning parameter settings e g initial and final radius number of iterations and the effect of random initial weights on average quantization error were investigated a som with a low average quantization error 0 1040 was used for further analysis feature space analysis morphometric signatures three dimensional inspection auxiliary data like landsat etm and high resolution satellite imagery from quickbird facilitated the assignment of semantic meaning to the output classes in terms of geomorphometric features results are provided in a geographic information system as thematic maps of landform entities based on form and slope e g yardangs ridge corridors valley or planar areas the results showed that all yardangs and corridors were clearly recognized and classified by this method when their width was larger than the dem resolution but became unrecognizable if their width is much smaller than the grid resolution the identified yardangs and corridors are aligned nnw sse parallel to the prevailing direction of the strong local 120 days wind and cover about 31 and 42 of the study area respectively the results demonstrate that som is a very efficient tool for analyzing aeolian landforms in hyper arid environments that provides very useful information for terrain feature analysis in remote regions

a progression of induration in medusae fossae formation transverse aeolian ridges evidence for ancient aeolian bedforms and extensive reworking a progression of induration erosion and redeposition of transverse and networked transverse aeolian ridges tars has been documented in the medusae fossae formation mff mars cratered and eroded aeolian bedforms are rarely observed on mars indicating that those found in the mff have been inactive for much longer than those found elsewhere indurated tars are observed to grade into faceted mff terrain indicating a genetic relationship between the two we propose that tar deposition induration and erosion have played a larger role in the surface morphology and evolution of the mff than previously recognized the deposition induration and erosion of tars indicate that the mff has undergone multiple cycles of reworking and that much of its current surface morphology does not reflect the circumstances of its primary emplacement copyright 2011 john wiley sons ltd

the transition between sand ripples and megaripples on mars abstract hirise images of small sand dunes and megaripples in gamboa and matara craters on mars raise intriguing questions regarding the relationship between sand ripples and megaripples the observations suggest that there might be a progressive transition from sand ripples to megaripples something worthy of consideration by the community as analysis of hirise images continues

subsurface structure of the petit spot volcanoes on the northwestern pacific plate 1 a seismic reflection survey was conducted in the northwestern pacific to investigate subsurface structure of small volcanoes considered to be formed by the newly discovered petit spot intra plate volcanism in contrast with an acoustically transparent sedimentary layer in the ambient northwestern pacific sedimentary layers are acoustically opaque with interbedded strong reflections beneath the volcanoes these reflections are possibly caused by inhomogeneous structure due to intrusion of central vent subhorizontal strong reflections at base of the sedimentary layer identified in the vicinity of volcanoes are probably reflections from sills of dense lavas flowing out within the sedimentary layer these volcanoes could be monogenetic volcanoes produced by small amount of magma intrusion 1 km3 in volume although such small volcanoes have never been discovered unless through a high resolution bathymetric mapping the invisible intra plate volcanism affects successive evolution modification of the crustal architecture of old age oceanic plates

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

chronological evidence that the moon is either young or did not have a global magma ocean a new age determination for a moon rock collected close to the site of the apollo 16 lander has yielded a surprisingly young age of around 4 360 million years this age would require either that the moon solidified some 200 million years after the formation of the solar system significantly later than is assumed by most lunar formation models or that the long held theory that the moon once had a primordial global magma ocean is flawed in the latter case much of the lunar crust could have been produced by non magma ocean processes such as serial magmatism chemical evolution of planetary bodies ranging from asteroids to the large rocky planets is thought to begin with differentiation through solidification of magma oceans many hundreds of kilometres in depth1 2 3 the earth s moon is the archetypical example of this type of differentiation evidence for a lunar magma ocean is derived largely from the widespread distribution compositional and mineralogical characteristics and ancient ages inferred for the ferroan anorthosite fan suite of lunar crustal rocks the fans are considered to be primary lunar flotation cumulate crust that crystallized in the latter stages of magma ocean solidification according to this theory fans represent the oldest lunar crustal rock type2 3 4 attempts to date this rock suite have yielded ambiguous results however because individual isochron measurements are typically incompatible with the geochemical make up of the samples and have not been confirmed by additional isotopic systems5 6 7 8 9 by making improvements to the standard isotopic techniques we report here the age of crystallization of fan 60025 using the 207pb 206pb 147sm 143nd and 146sm 142nd isotopic systems to be 4 360 3 million years this extraordinarily young age requires that either the moon solidified significantly later than most previous estimates or the long held assumption that fans are flotation cumulates of a primordial magma ocean is incorrect if the latter is correct then much of the lunar crust may have been produced by non magma ocean processes such as serial magmatism10

a new type of intra plate volcanism young alkali basalts discovered from the subducting pacific plate northern japan trench alkali pillow basalts were collected from the toe of the oceanward slope of the northern japan trench these alkali basalts formed as a result of a low degree of partial melting of pacific ocean mantle and rapid rise of the magma no fractionation in shallow magma chambers reconstructing pacific plate motion based on 40ar 39ar age dates of 5 95 0 31 ma for these basalts indicates that they erupted outboard of outer swell or forebulge of the japan trench in the nw pacific we suggest that these alkali basalts represent a new form of intra plate volcanism whereby magmatic activity occurs off the forebulge of the downgoing pacific slab perhaps using conduits related to fracturing of the slab during bending prior to subduction

subdivision of the mg suite noritic rocks into mg gabbronorites and mg norites mg suite noritic rocks can be divided into two groups the mg gabbronorites and the mg norites the rocks of these groups differ in ratios of high ca pyroxene to total pyroxene compositions of pyroxene and plagioclase assemblages of ti nb and zr bearing minerals compositions of chrome spinel bulk rock ti sm and sc sm and measured ages the two groups probably crystallized from different types of parent magmas two hypotheses are offered for the differences in composition of the parent magmas one hypothesis ascribes the differences to compositional heterogeneity of the mantle source areas the other hypothesis ascribes the differences to variations in extent of partial melting of the mantle source regions and variations in extent of assimilation of the anorthosite and the highly differentiated residual liquid that were produced during the primordial lunar differentiation

high resolution investigations of transverse aeolian ridges on mars abstract transverse aeolian ridges tars are the most pervasive aeolian feature on mars their small size requires high resolution data for thorough analyses we have utilized mars reconnaissance orbiter mro context camera ctx and high resolution image stereo experiment hirise images along with mro compact reconnaissance imaging spectrometer for mars crism spectroscopic data to study tars in detail tar deposits along with related dark dune material and layered terrains have been mapped in six study areas in order to identify sediment pathways and determine whether tars are sourced locally or from global wind borne materials tar morphology and orientation were mapped in grids within each study area the results show that tars are probably locally sourced we constructed four hirise digital terrain models dtms to measure tar heights widths spacing areas symmetry and to calculate sediment volumes results show that tars have average heights of 1 5 m are very symmetrical and are similar in form to terrestrial megaripples orthorectified hirise images taken 3 years apart were analyzed for tar movement and none was found superposed craters on equatorial tars give ages of 2 ma suggesting that these are relatively ancient and generally inactive aeolian deposits crism data were analyzed over tar deposits dark dune material and light toned terrains although the surfaces were somewhat obscured by dust cover the results did not show any remarkable difference between tars and other deposits we conclude that tars may be sourced from local materials and form in a similar way to terrestrial megaripples

semi automatic mapping of linear trending bedforms using self organizing maps algorithm abstract increased application of high resolution spatial data such as high resolution satellite or unmanned aerial vehicle uav images from earth as well as high resolution imaging science experiment hirise images from mars makes it necessary to increase automation techniques capable of extracting detailed geomorphologic elements from such large data sets model validation by repeated images in environmental management studies such as climate related changes as well as increasing access to high resolution satellite images underline the demand for detailed automatic image processing techniques in remote sensing this study presents a methodology based on an unsupervised artificial neural network ann algorithm known as self organizing maps som to achieve the semi automatic extraction of linear features with small footprints on satellite images som is based on competitive learning and is efficient for handling huge data sets we applied the som algorithm to high resolution satellite images of earth and mars quickbird worldview and hirise in order to facilitate and speed up image analysis along with the improvement of the accuracy of results about 98 overall accuracy and 0 001 quantization error in the recognition of small linear trending bedforms demonstrate a promising framework

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

extremely high temperatures and paleoclimate trends recorded in permian ephemeral lake halite although the late paleozoic deglaciation is arguably one of the best deep time analogs for current and predicted climate change quantitative paleotemperature data from this interval are generally lacking we reconstruct extreme paleoweather conditions and paleoclimate changes from permian nippewalla group probably uppermost leonardian kungurian north america ephemeral lake halite by using fluid inclusion homogenization temperatures to directly measure the water temperature when the halite precipitated in these depositional settings this is an excellent air temperature proxy extremely high temperatures to 73 c and large diurnal temperature ranges are evidenced in the lower nippewalla group suggesting conditions more extreme than anywhere on earth today in contrast the upper nippewalla group was cooler maximum temperature was 43 c and diurnal temperature ranges were smaller though even these conditions are similar to modern extremely hot environments comparison to prior studies suggests that these results may be indicative of regional patterns this study represents the first pre quaternary high resolution quantitative data set of extreme paleoweather and possible paleoclimate trends from fluid inclusions in halite and provides new insight into climate change during the late paleozoic deglaciation

cross sectional profiles of sand ripples megaripples and dunes a method for discriminating between formational mechanisms cross sectional profiles of sand ripples megaripples and sand dunes provide a useful tool for discriminating between formation by ripple and dune processes feature width defined as the basal break in slope along the profile to either side of the crest represents a good standard for comparison of profile attributes across more than three orders of magnitude aspect ratio height width as a function of log width separates measurements into clusters representing differing mechanisms of formation scaling both height and distance for individual profiles by feature width facilitates comparison of profile shapes across three orders of magnitude in width the data presented here should prove useful for evaluating possible mechanisms of origin for aeolian features observed remotely including on planetary bodies copyright 2012 john wiley sons ltd

alkali gabbronorite ultra kreepy melt rock and the diverse suite of clasts in north ray crater feldspathic fragmental breccia 67975 lunar breccia 67975 is a feldspathic fragmental breccia from north ray crater apollo 16 it contains clasts of alkali gabbronorite and ultra kreepy mafic fragment laden melt breccias which are unique among apollo 16 samples both are alkali and iron rich rocks with moderate to high ree concentrations they more strongly resemble apollo 14 gabbronorites and alkali anorthosites and kreep rich rocks than they do other apollo 16 samples the other clasts in 67975 are the ferroan anorthosites feldspathic melt rocks and magnesian granulites which are typical of other feldspathic fragmental breccias examination of bulk and mineral compositions of other breccias and melt rocks suggests that alkali gabbronorite may be a minor component in other north ray crater breccias and feldspathic melt rocks this implies that alkali gabbronorite was a fairly early 4 0 b y crustal component in the north ray crater region

earth aeolian wind streaks comparison to wind data from model and stations wind streak is a collective term for a variety of aeolian features that display distinctive albedo surface patterns wind streaks have been used to map near surface winds and to estimate atmospheric circulation patterns on mars and venus however because wind streaks have been studied mostly on mars and venus much of the knowledge regarding the mechanism and time frame of their formation and their relationship to the atmospheric circulation cannot be verified this study aims to validate previous studies results by a comparison of real and modeled wind data with wind streak orientations as measured from remote sensing images orientations of earth wind streaks were statistically correlated to resultant drift direction rdd values calculated from reanalysis and wind data from 621 weather stations the results showed good agreement between wind streak orientations and reanalysis rdd r 0 78 a moderate correlation was found between the wind streak orientations and the weather station data r 0 47 a similar trend was revealed on a regional scale when the analysis was performed by continent with r ranging from 0 641 in north america to 0 922 in antarctica at sites where wind streak orientations did not correspond to the rdds i e a difference of 45 seasonal and diurnal variations in the wind flow were found to be responsible for deviation from the global pattern the study thus confirms that earth wind streaks were formed by the present wind regime and they are indeed indicative of the long term prevailing wind direction on global and regional scales

megaripples at wau an namus libya a new analog for similar features on mars abstract transverse aeolian ridges tars are curious aeolian megaripples on mars but there are few sites identified thus far to study as terrestrial analogs a new terrestrial analog site for tars has been found in and around an isolated volcano caldera in the sahara desert of libya the wau an namus volcano is potentially active and recognizable from space because of its strong albedo contrast wau an namus has large dark aeolian megaripple bedforms with the same horizontal length scales and overall planform patterns as observed for tars on mars some new patterns for these tar like features also have been found at wau an namus such as stripe like and clustered patterns which may shed new light on the formation of these features on both planets other aeolian features such as sand dunes and dust devil tracks are also evident in this region this is the first terrestrial analog site with dark megaripple features similar to some tars on mars the dark halo around wau an namus visible from space represents a unique site to study the formation and evolution of these mysterious features and thereby further our understanding of the probable recent history of the wind regime on mars

low pressure crystallization of a volatile rich lunar basalt a means for producing local anorthosites the presence of anorthosite in the lunar highlands containing plagioclase that is compositionally less calcic than plagioclase in the ferroan anorthosites cannot be readily explained by the current lunar paradigm in which lunar anorthosite was produced as a floatation cumulate in the lunar magma ocean phase equilibrium experiments were conducted to investigate whether such anorthosite could arise locally from crystallization of aluminous magma at shallow levels within the lunar crust the experiments were conducted on a synthetic analog of cl f and s bearing aluminous highland basalt 14053 at pressures of approximately 1 bar and f o 2 at qif pyroxene and plagioclase an 93 89 saturation occurs early and with continued crystallization the residual liquid evolves to a silica poor halogen fe and ti rich melt with a computed density of 3 1 g ml this liquid remains higher in density than the plagioclase over the crystallization interval providing the possibility of plagioclase melt separation by liquid draining a model is proposed in which alkali anorthosite consisting of sodic anorthite or bytownite coupled with underlying pyroxenite or harzburgite is produced locally during crystallization of plagioclase from al rich magmas at or within roughly a kilometer of the lunar surface in this model segregation of plagioclase would be attained by settling of ferromagnesian minerals to the bottom of a shallow magma chamber and draining of low viscosity low silica fe ti k ree p enriched residual basaltic melt to deeper regions of the crust or into topographic lows such residual melt may be represented by magma compositions similar to some of the intermediate to high ti mare basalts this model would provide a mechanism that can account for the more alkali anorthosite identified in widespread isolated locales on the moon and allow for variable ages for such anorthosite that may extend to ages of the mare basalts

investigation into the petrogenesis of apollo 14 high al basaltic melts through crystal stratigraphy of plagioclase abstract the petrogenesis of apollo 14 high al basaltic melts was studied using crystal stratigraphy which involves textural crystal size distributions csds and chemical analyses electron microprobe and laser ablation inductively coupled plasma mass spectrometry the samples studied here include pristine basalt 14072 and basaltic clasts from breccia 14321 and impact generated crystalline samples 14073 14276 and 14310 plagioclase was the focus of this study because of its relatively high modal abundances and because it was on the liquidus for much of the melt cooling histories plagioclase crystals were analyzed core to rim compositions where possible to test and refine petrogenetic models based upon whole rock compositions groups a b and c designations and to investigate basalt 14072 and impact melt crystallization textural studies have shown that each basalt group has distinctive plagioclase csds which are in turn distinctive from those of the impact melts evolution of the individual basaltic melts was studied by comparing the equilibrium melt compositions calculated from plagioclase compositions using relevant partition coefficients to fractional crystallization fc and assimilation and fractional crystallization afc models petrogenetic modeling of trace elements in group a basalts revealed that petrogenesis continued beyond 40 total crystallization required to model whole rock compositions and that there were open system processes that affected the magma during plagioclase crystallization petrogenetic modeling of pristine high al basalts 14072 and groups a b and c using trace elements shows that the equilibrium melt compositions do not fall on a single afc or fc trajectory this is consistent with fluctuating degrees of assimilation i e variable r values and or variable assimilant compositions during petrogenesis petrogenetic modeling reveals that the impact melts experienced only closed system fractional crystallization this work demonstrates the importance of crystal stratigraphy in revealing the intricacies of lunar basalt petrogenesis

a terrestrial analog for transverse aeolian ridges tars environment morphometry and recent dynamics abstract transverse aeolian ridges tars are a distinct aeolian bedform found on mars the formative processes evolution and geological significance of tars is poorly understood fundamentally it is unknown whether tars are dunes mega ripples or another bedform type we examined aeolian bedforms in the lut desert of iran as a terrestrial analog for martian tars from an objective sampling strategy with high resolution satellite imagery we developed a large morphometric dataset for comparison with existing martian tars we also examined the dynamics of the lut bedforms between 2004 and 2012 to determine if they were static or migrating results indicate that the range in the dimensions length width height and wavelength of the lut bedforms and martian tars overlap suggesting lut bedforms are a viable terrestrial tar analog our sample yielded median values of 55 18 m 9 80 1 02 m and 20 m for length longest planview axis width shortest planview axis height and wavelength respectively cumulative log frequency plots of morphometric parameters suggest the sample is from a single population and process mechanism although the vast majority of lut bedforms examined were static between 2004 and 2012 some migrated up to 0 09 myr 1 on average this is much slower than nearby dunes 4 12 myr 1 but is explained by the existence of a surface lag of coarse particles on the tar like bedforms the combination of morphometry surface sedimentology and slow migration rate indicate the lut bedforms are mega ripples which provides evidence supporting interpretation of martian tars as mega ripples testing the mega ripple hypothesis for martian tars requires measurements of their sedimentology which may be possible with the mars science laboratory rover curiosity as well as expanded measurements of tar morphometry to constrain their size shape and scaling

early crustal building processes on the moon models for the petrogenesis of the magnesian suite abstract the plutonic rocks of the magnesian suite mg suite represent the period of lunar basaltic magmatism and crustal growth 4 46 to 4 1 ga that immediately followed the initial differentiation of the moon by magma ocean lmo formation and crystallization the volume and distribution of the mg suite and its petrogenetic relationship to latter stages of lunar magmatism mare basalts remains obscure these plutonic rocks exhibit a range of compositions and include ultramafics troctolites spinel troctolites norites and gabbronorites a distinguishing characteristic of this suite is that they contain some of the most magnesium rich phases fo95 90 that had crystallized from lunar magmas yet they also are significantly enriched in an incompatible element component referred to as kreep a late stage product of lmo crystallization containing abundant potassium k rare earth elements ree phosphorous p uranium and thorium ion microprobe analyses of individual mineral phases olivine pyroxene and plagioclase from the mg suite have shown some very unexpected characteristics that have profound implications on the origin of these basaltic magmas although the mg suite lithologies are typified by silicates with relatively high mg early liquidus phases such as olivine are fairly low in ni co and cr relative to more iron rich olivines in the younger mare basalts the high y and ti y in early phases such as olivine and orthopyroxene indicate that the parental basaltic melts were high in incompatible elements and contained an ilmenite fractionation signature however the y in olivine from many of the troctolites and ultramafic lithologies are only slightly greater than that of the olivine in the mare basalts whereas olivine in the norites gabbronorites and apollo 14 troctolites are exceedingly high the kreep component may have been added to the mg suite parent magmas by assimilation or mixing into the mantle source the volume of kreep required to be added to the parental magmas of the mg suite tends to favor the latter mechanism for kreep incorporation the extremely high abundances of kreep in the norites and gabbronorites are a product of substantial crystallization 40 to 70 of kreep enriched mg suite parental magmas basaltic magmatism associated with kreep extended for over 1 5 billion years and appears to have changed over time the early stages of this style of lunar magmatism mg suite appear to represent melting of early lmo cumulates with low abundances of ni co cr and v later stages of kreep rich basaltic magmatism seemed to clearly involve melting of a variety of lmo cumulate assemblages with higher incompatible element enrichment it appears that the heat derived from the kreep component was instrumental in at least initiating melting of the lunar mantle over this period of time

mega ripples in iran a new analog for transverse aeolian ridges on mars abstract a new terrestrial analog site for transverse aeolian ridges tars is described in this study the lut desert of iran hosts large ripple like aeolian bedforms with the same horizontal length scales and patterns of tars on mars different classes of tars and different types of other aeolian features such as sand dunes zibars dust devil tracks and yardangs can be found in this area which signify an active aeolian region this area represents a unique site to study the formation and evolution of these enigmatic features with potential relevance toward a better understanding of tars on mars

precision topography of a reversing sand dune at bruneau dunes idaho as an analog for transverse aeolian ridges on mars abstract ten high precision topographic profiles across a reversing dune were created from a differential global position system dgps the shapes of the profiles reveal a progression from immature to transitional to mature characteristics moving up the dune when scaled by the basal width along each profile shape characteristics can be compared for profiles whose horizontal scales differ by orders of magnitude the comparison of width scaled bruneau dunes profiles to similarly scaled profiles of transverse aeolian ridges tars on mars indicates that many tars are likely similar to transitional or mature reversing sand dunes

gravel mantled megaripples of the argentinean puna a model for their origin and growth with implications for mars gravel megaripples in the puna of argentina are the most extreme aeolian megaripples on earth and are useful analogs for aeolian processes on mars field observations supplemented by experimental and numerical constraints on wind characteristics and aeolian transport reveal their conditions of formation and growth to be an aeolian geomorphology perfect storm the bedforms are formed on a substrate of weakly indurated ignimbrite aeolian deflation of which yields a bimodal lag of lithics and pumice clasts onto an undulating surface under normal wind conditions in this region the lithics are organized into bedforms on local upslopes and highs through creep induced by the impact of saltating sand and pumice the gravel bedforms grow through shadowing and trap sand and silt that is gradually kinetically sieved down to lift the gravel mantle upwards to form the megaripples these observations connote that the largest features are not ripples in the sense of migrating bedforms but rather nucleation sites of wind transported sediment strong control by bedrock topography means that the largest bedform wavelengths are not a result of particle trajectories and this complicates their comparison with other ripples and may require a new classification of relevance to mars the puna megaripples are morphologically and contextually similar to small ripple like transverse aeolian ridges tars moreover the puna gravels have similar equivalent weight mg to those composing granule ripples at meridiani planum and their local origin may have implications for the origin of sediment in martian aeolian bedforms finally the stable yet dynamic character of the puna megaripples could help reconcile current models of tars with periodic bedrock ridges that may be produced by aeolian erosion

the birth and death of transverse aeolian ridges on mars transverse aeolian ridges tars are small bright windblown deposits found throughout the martian tropics that stand a few meters tall and are spaced a few tens of meters apart the origin of these features remains mysterious more than 20 years after their discovery on mars this paper presents a new hypothesis that some of the tars could be indurated dust deposits emplaced millions of years ago during periods of higher axial obliquity it suggests that these tars are primary depositional bed forms that accumulated in place from dust carried by the winds in suspension perhaps in a manner comparable to antidunes on earth and were subsequently indurated and eroded to their current states by eons of sandblasting it points out examples of modern dust drifts and dune like features that appear to have been recently formed by dust accumulating directly onto the surface from atmospheric suspension it shows how these pristine dust deposits could evolve to explain the range of morphologies of the tars finally it explains how the known properties of many tars are consistent with this hypothesis including their composition thermal behavior and distribution

global silicate mineralogy of the moon from the diviner lunar radiometer we obtained direct global measurements of the lunar surface using multispectral thermal emission mapping with the lunar reconnaissance orbiter diviner lunar radiometer experiment most lunar terrains have spectral signatures that are consistent with known lunar anorthosite and basalt compositions however the data have also revealed the presence of highly evolved silica rich lunar soils in kilometer scale and larger exposures expanded the compositional range of the anorthosites that dominate the lunar crust and shown that pristine lunar mantle is not exposed at the lunar surface at the kilometer scale together these observations provide compelling evidence that the moon is a complex body that has experienced a diverse set of igneous processes

late cenozoic reorganization of the arabia eurasia collision and the comparison of short term and long term deformation rates the arabia eurasia collision deforms an area of 3 000 000 km2 of continental crust making it one of the largest regions of convergent deformation on earth there are now estimates for the active slip rates total convergence and timing of collision related deformation of regions from western turkey to eastern iran this paper shows that extrapolating the present day slip rates of many active fault systems for 3 7 million years accounts for their total displacement this result means that the present kinematics of the arabia eurasia collision are unlikely be the same as at its start which was probably in the early miocene 16 23 ma or earlier in some but not all active fault systems short term 10 year and long term 5 million year average deformation rates are consistent there is little active thickening across the turkish iranian plateau and possibly the interior of the greater caucasus these are two areas where present shortening rates would need more than 7 million years to account for the total crustal thickening and where there are structural and or stratigraphic data for pre late miocene deformation we suggest that once thick crust up to 60 km built up in the turkish iranian plateau and the greater caucasus convergence took place more easily by crustal shortening in less elevated regions such as the zagros simple folded zone the south caspian region and foothills of the greater caucasus or in other ways such as westward transport of turkey between the north and east anatolian faults the time and duration of this changeover are not known for certain and are likely be diachronous although deformation started or intensified in many of the currently active fault systems at 5 2 ma

the lunar magma ocean reconciling the solidification process with lunar petrology and geochronology abstract the moon is thought to have originated with a magma ocean that produced a plagioclase flotation crust as solidification proceeded ages of anorthositic crust range over at least 200 million years the model for solidification presented here integrates chemical and physical constraints of lunar magma ocean solidification to determine 1 the final thickness of flotation crust generated by a fractionally solidifying magma ocean 2 the timescale of crystallization before plagioclase is a stable phase 3 the timescale of solidification after the formation of the plagioclase flotation crust and 4 the post overturn lunar mantle composition and structure we find that magma oceans of as much as 1000 km depth are consistent with creating an anorthositic crust 40 to 50 km in thickness solidification of the magma ocean prior to formation of the flotation crust may occur on the order of 1000 years and complete solidification would require additional ten to tens of millions of years reconciling these short model timescales with radiometric dates of crustal samples requires either a very late forming moon combined with finding older crustal ages to be incorrect or calling on tidal heating of the crust by the early earth to prolong solidification gravitationally driven overturn of cumulates during tidal heating provides a mechanism for creating the compositions and ages of the lunar mg suite of crustal rocks further we find that upon crystallization the moon likely began with an azimuthally heterogeneous gravitationally stable mantle after magma ocean cumulate overturn this result may help explain the experimentally determined origin of picritic glasses at similar depths but from different source materials

the origin of the transverse instability of aeolian megaripples abstract flat sand beds subjected to wind stress are unstable and the wind action results in two types of aeolian sand ripples normal ripples and megaripples the distinction between the two types is based on two characteristics i the normal ripple pattern usually has a wavelength of up to 30 cm while the megaripple wavelength is on the order of meters and ii unimodal distributions of sand grain size lead to normal ripples while bimodal distributions result in megaripples on mars the distinction between the two types is more difficult to ascertain because the length scales of normal ripples and megaripples can overlap and often there is no detailed information regarding their grain size distribution unlike normal ripples megaripples show transverse instability whose mechanism remains elusive resulting in a much larger sinuosity of the crestline than normal ripples in this study we investigate the megaripples transverse instability by using field measurements wind tunnel experiments and numerical simulations of a three dimensional ripple model we show that a coarse grains accumulate at megaripple crests with a corresponding reduction of the lateral sand transport along the crest and b the transverse instability of megaripples is generated by a positive feedback between the height of the crest and the accumulation of coarse grains with more grains accumulating on the higher portions of the crest the outcomes of this positive feedback are that the thickness of the coarse grain armoring layer along the crest is not uniform and that it correlates with the crest height in turn these height differences drive the transverse instability such that higher portions of the ripple migrate more slowly than the lower sections creating a wavy crestline an analysis of martian ripple images shows variations in the sinuosity index suggesting that this characteristic can be useful in distinguishing between normal ripples and megaripples on mars

transverse aeolian ridges on mars first results from hirise images abstract three images obtained by the high resolution imaging science experiment hirise were analyzed for the information they could provide regarding transverse aeolian ridges tars on mars tars from five locations in a hirise image of the floor of ius chasma show remarkably symmetric cross sectional profiles with average slopes for the entire feature of 15 these results apply to tars that span an order of magnitude in wavelength and a factor of 6 in height a hirise image of gamboa impact crater in the northern lowlands shows low albedo sand patches

isotopic studies of ferroan anorthosite 62236 a young lunar crustal rock from a light rare earth element depleted source isotopic analyses of mineral fractions and whole rocks from the ferroan anorthosite 62236 yield a sm nd isochron with an age of 4 29 0 06 ga and an initial end143 value of 3 1 0 9 we have also measured end142 anomalies of 0 25 on two fractions of 62236 these values are higher than the value of 0 1 predicted if 62236 was derived from a chondritic source at 4 29 ga but are consistent with the positive initial end143 value the sm nd isotopic composition of 62236 has been modified by the capture of thermal neutrons such that the 147sm 144nd 143nd 144nd and 142nd 144nd ratios measured on the mineral fractions and whole rocks must be corrected the corrections do not significantly alter the sm nd isotopic results determined on 62236 despite the fact that the ar ar and rb sr isotopic systematics of 62236 have been reset by impact metamorphism at 3 93 0 04 ga the sm nd systematics appear to have been unaffected the sm nd isotopic systematics of 62236 provide several constrains on models of lunar crustal differentiation provided they have not been reset since crystallization first the relatively young age of 62236 as well as the old ages determined on several crustal plutonic rocks of the mg suite require multiple sources of magmas on the moon very early in its history second positive end143 values determined on all analyzed ferroan anorthosites suggest that they were derived from sources depleted in light rare earth elements and third models based on initial end143 and present day end142 values suggest that the source of 62236 was depleted in light rare earth elements at 4 46 ga in order to reconcile these observations with the lunar magma ocean model 1 the magma ocean must have existed for a very short period of time and may have had a sub chondritic nd sm ratio and 2 the youngest ferroan anorthosites such as 62236 cannot be cumulates from the magma ocean but must form by other processes