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

antarctic lunar meteorites yamato 793169 asuka 881757 mil 05035 and met 01210 yamm launch pairing and possible cryptomare origin abstract the antarctic lunar meteorite meteorite hills met 01210 is a polymict regolith breccia dominantly composed of mare basalt components one relatively large 2 7 4 7 mm basalt clast in met 01210 met basalt shows remarkable mineralogical similarities to the lunar meteorite crystalline mare basalts yamato y 793169 asuka a 881757 and miller range mil 05035 all four basalts have similar rock texture mineral assemblage mineral composition pyroxene crystallization trend and pyroxene exsolution lamellae the estimated tio 2 contents 2 0 wt of the met basalt and mil 05035 are close to the bulk rock tio 2 contents of y 793169 and a 881757 these similarities suggest that y 793169 a 881757 mil 05035 and the met basalt came from the same basalt flow which we designate the yamm basalt the source basalt pairing of the yamm is also supported by their similar ree abundances crystallization ages approx 3 8 3 9 ga and isotopic compositions low u pb low rb sr and high sm nd the pyroxene exsolution lamellae which are unusually coarse up to a few microns by mare standards imply a relatively slow cooling in an unusually thick lava and or subsequent annealing within a cryptomare reported noble gas and cre data with close launch ages 1 ma and ejection depths deeper than several meters among the four meteorites further indicate their simultaneous ejection from the moon despite the marginally close terrestrial ages pairing in the conventional earth entry sense seems unlikely because of the remote recovery sites among the yamm meteorites the high abundance 68 of mare components in met 01210 estimated from a two component mixing model calculation could have resulted from either lateral mixing at a mare highland boundary or vertical mixing in a cryptomare the proportion of mare materials in met 01210 is greater than in apollo core samples at the mare highland boundary the burial depth several meters deep inferred from the lack of surface irradiation of met 01210 exceeds the typical mare regolith thickness a few meters thus the source of the yamm meteorites is likely a terrain of locally high mare highland mixing within a cryptomare we searched for a possible source crater of the yamm meteorites within the well defined cryptomare based on the multiple constraints obtained from this study and published data an unnamed 1 4 km diameter crater 53 w 44 5 s on the floor of the schickard crater is the most suitable source for the yamm meteorites the 238 u 204 pb value of the yamm basalts is extremely low relative to those of the apollo mare basalts but comparable to those of the luna 24 very low ti basalts the low source indicates a derivation from a less differentiated mantle with a lack of kreep components although the chemical sources of materials and heat source of melting might be independent the heat source that generated the source magma of the yamm and luna 24 basalts may not be related to kreep unlike the case of the apollo basalts the distinct chemical and isotopic compositions of mantle sources between the apollo basalts and the yamm lunar 24 basalts imply differences in mantle composition and thermal evolution between the procellarum kreep terrane pkt and non pkt regions of the nearside

distinguishing between basalts produced by endogenic volcanism and impact processes a non destructive method using quantitative petrography of lunar basaltic samples abstract impact processes play an important role in shaping and reshaping the surfaces of airless planetary bodies such processes produce regoliths and generate melts that crystallize and record the homogenization of the geology at the impact site if the volume of melt is substantial the resultant crystallized product has an igneous texture and may be free of xenolithic clasts making it difficult to distinguish from melts produced by endogenic magmatic processes this has been clearly demonstrated during the return of the apollo samples from the moon where apollo 14 basalt 14310 was initially described as a mare basalt and was only subsequently reclassified as an impact melt following detailed and time consuming crystallization experiments another way of distinguishing lunar impact melts from endogenically derived mare basalts is through the quantification of the highly siderophile elements hse pd rh ru ir pt os which have relatively low abundances in pristine lunar samples but are high in meteorites and therefore may be enriched in impact melts however these analyses consume relatively large quantities of valuable sample and because of mass constraints cannot be performed on many lunar samples in this paper we present a quantitative petrographic method that has the potential to distinguish lunar impact melts from endogenically derived mare basalts using plagioclase and olivine crystal size distributions csds the slopes and intercepts of these csds are used to show that olivine from impact melts displays a steeper csd relative to olivine from mare basalts for plagioclase generally impacts melts display csds with shallower gradients than those from endogenous mare basalts and as for olivines plot in a distinct field on a csd slope vs csd intercept plot using just a thin section to distinguish impact melts from mare basalts enables the goals of future robotic sample return missions to determine the age of the south pole aitken basin in the moon because such missions will potentially only return small 2 4 mm rocklets for analysis obviating hse analyses for impact melt identification

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

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

understanding the lunar surface and space moon interactions the surface of the moon is a critical boundary that shapes our understanding of the moon as a whole all geologic mapping and remote sensing techniques utilize only the outermost portion of the moon before leaving the moon for study in our laboratories all lunar samples that have been studied existed at or very near the surface with the exception of the deeply probing geophysical techniques our understanding of the interior of the moon is derived from surficial but not superficial information coupled with boundary of the lunar crust it is the lower boundary layer of the tenuous lunar atmosphere and constitutes both a source and a sink for atmospheric gases the surface is also where the moon interacts with the space environment causing changes in the physical nature of lunar materials and provides a laboratory for the study of processes that occur on all airless bodies the data obtained remotely by the galileo clementine and lunar prospector missions as well as data derived from lunar meteorites have resulted in major changes to our understanding of global distributions of chemistry and rocks this chapter summarizes the current understanding of this critical interface the surface of the moon in its role as the lower boundary of the lunar atmosphere the upper boundary of the crust and the window through which we view through remote sensing the composition of the crust and the history of the moon in this post lunar prospector time the view of the moon has changed lending new perspectives to lunar samples and lunar processes but the new view will likely remain in flux as we continue to digest the results from these recent space missions and move forward to a new era of lunar exploration despite the freshness of our perspective this is an important moment to capture

petrogenesis and chronology of lunar meteorite northwest africa 4472 a kreepy regolith breccia from the moon northwest africa nwa 4472 is a polymict lunar regolith meteorite the sample is kreep rich high concentrations of potassium rare earth elements and phosphorus and comprises a heterogeneous array of lithic and mineral fragments these clasts and mineral fragments were sourced from a range of lunar rock types including the lunar high magnesian suite the high alkali suite kreep basalts mare basalts and a variety of impact crater environments the kreep rich nature of nwa 4472 indicates that the sample was ejected from regolith on the nearside of the moon in the procellarum kreep terrane and we have used lunar prospector gamma ray remote sensing data to show that the meteorite is most similar to and most likely sourced from regoliths adjacent to the imbrium impact basin u pb and pb pb age dates of nwa 4472 phosphate phases reveal that the breccia has sampled pre nectarian 4 35 ga rocks related to early episodes of kreep driven magmatism some younger phosphate u pb and pb pb age dates are likely indicative of impact resetting events at 3 9 4 ga consistent with the suggested timing of basin formation on the moon our study also shows that nwa 4472 has sampled impact melts and glass with an alkali depleted incompatible trace element rich high sc low rb th ratios low k compositional signature not related to typical apollo high k kreep or that sampled by kreepy lunar meteorite sayh al uhaymir sau 169 this provides evidence that there are numerous sources of kreep rich protoliths on the moon

kreep cumulates in the western lunar highlands ion and electron microprobe study of alkali suite anorthosites and norites from apollo 12 and 14 alkali suite anorthosites and norites are the second most common plutonic rock association in the western lunar highlands after the magnesian suite but their origin poses an enigma for most petrologic models of lunar crustal evolution some models suggest that the alkali and magnesian suites formed from distinct unrelated parental magmas whereas other models propose that both suites formed from the same parental magma the contrast in major element chemistry of the cumulus phases in each suite is difficult to reconcile with their similar incompatible element chemistry we present herein a detailed ion microprobe sims and electron microprobe study of seven alkali suite rocks our data show that most alkali suite anorthosites preserve major and trace element characteristics acquired during their formation as igneous cumulate rocks and that these characteristics can be used to reconstruct the parental magma composition the data indicate that cumulates of the alkali suite crystallized from magmas with rare earth element ree contents approximately 0 6 2 0xhigh k kreep and small but consistently positive eu anomalies eu eu super approximately 2 relative to kreep snyder and others 1995a have proposed that the alkali suite parental magma is similar to apollo 15 pristine kreep basalt our model suggests that the major element composition of cumulus plagioclase in most alkali suite rocks is too sodic for the calculated crystal line of descent of pristine kreep basalt and that assimilation of pre existing calcic anorthosite is required this conclusion is supported by the ree patterns of the alkali suite parental magma determined here we propose that alkali suite anorthosites formed as flotation cumulates in kreepy plutons that may have formed norites as complementary bottom cumulates the alkali flotation cumulates reflect fractional crystallization of their parental pluton local equilibrium crystallization assimilation of plagioclase rich roof rock and episodic magma mixing during convective overturn of the crystallizing magma bodies texturally pristine alkali anorthosites exhibit petrographic characteristics that are consistent with their origin as cumulates in a kreepy pluton including abundant modal plagioclase post cumulus pyroxenes both augite and pigeonite that generally lack exsolution lamellae and that have equilibration temperatures of 950 1100 degrees c relict igneous textures and in some cases igneous lamination the lack of cumulus mafic phases in rocks that should be pyroxene saturated suggests separation of the plagioclase by flotation not sinking assimilation of plagioclase from older anorthositic highlands crust is indicated by the high eu contents of the cumulates and by the positive eu anomalies in their calculated parental melts relative to high k kreep mixing of the evolved alkali suite parental magma with primitive melt occurred episodically as shown by reverse zoning profiles in some cumulus plagioclase injection of this primitive hot magma into the crystallizing pluton may have induced convective overturn of the magma chamber

determination of planetary basalt parentage a simple technique using the electron microprobe many basaltic meteorites are being discovered in old and new meteorite suites including those from cold deserts e g antarctica and hot desert environments it is important to establish the specific planetary body source proven techniques for establishing planetary parentage include stable isotopic signatures especially oxygen certain elemental ratios in bulk samples and certain elemental ratios in specific minerals some of these techniques are expensive require considerable sample preparation and are adversely affected by weathering processes on the parent body or on earth we have been seeking key major and minor elemental ratios in pyroxene olivine and feldspar that can be measured by the electron microprobe on standard thin sections these ratios may be preserved in unweathered portions of mineral grains and thus see through weathering processes in addition if the sample is too small to provide a representative bulk composition it may still have key information recorded in individual minerals we have found that some of the most useful chemical parameters are fe mn atomic in olivine or pyroxene and the percent anorthite an in plagioclase solid solutions a plot of fe mn in pyroxene and or olivine verses an defines compositional fields that are significantly different for earth mars moon 4 vesta and the angrite parent body this method may be especially powerful when combined with oxygen isotope data

los angeles the most differentiated basaltic martian meteorite los angeles is a new martian meteorite that expands the compositional range of basaltic shergottites compared to shergotty zagami que94201 and eet79001 b los angeles is more differentiated with higher concentrations of incompatible elements e g la and a higher abundance of late stage phases such as phosphates and k rich feldspathic glass the pyroxene crystallization trend starts at compositions more ferroan than in other martian basalts trace elements indicate a greater similarity to shergotty and zagami than to que94201 or eet79001 b but the mg fe ratio is low even compared to postulated parent melts of shergotty and zagami pyroxene in los angeles has 0 7 4 m thick exsolution lamellae 10 times thicker than those in shergotty and zagami opaque oxide compositions suggest a low equilibration temperature at an oxygen fugacity near the fayalite magnetite quartz buffer los angeles cooled more slowly than shergotty and zagami slow cooling coupled with the ferroan bulk composition produced abundant fine grained intergrowths of fayalite hedenbergite and silica by the breakdown of pyroxferroite shock effects in los angeles include maskelynitized plagioclase pyroxene with mosaic extinction and rare fault zones one such fault ruptured a previously decomposed zone of pyroxferroite although highly differentiated the bulk composition of los angeles is not close to the low ca si composition of the globally wind stirred soil of mars

laboratory evaluation of smear zone and correlation between permeability and moisture content in this study the extent of the smear zone and the reduction of permeability and water content within the smear zone were investigated using a large scale consolidometer the installation of vertical drains by means of a mandrel causes significant disturbance of the subsoil surrounding the mandrel resulting in a smear zone the extent of the smear zone for moruya clay new south wales australia was estimated on the basis of normalized permeability and the reduction of water content by taking undisturbed samples horizontally and vertically at different locations this study reveals that a significant reduction in water content and horizontal permeability takes place towards the drain whereas the variation in the vertical permeability is negligible the smear zone for moruya clay was found to be 2 5 times the equivalent radius of the mandrel with the horizontal permeability varying from 1 09 to 1 64 an average of 1 34 times smaller than that of the undisturbed zone finally a correlation between the permeability decrease and water content reduction within smear zone is proposed

lateral response of piles in weak calcareous sandstone existing design methods for laterally loaded piles in soft rock have insufficient supporting case history data and consequently cannot be regarded as having a high level of reliability this paper addresses the shortage of experimental data by describing the results from four instrumented lateral load tests on drilled and grouted piles installed in weak calcareous sandstone the derived lateral load transfer p y curves are first compared with existing approaches for weak rock and cemented soils the paper then examines the potential of using cone penetration test cpt data directly for the design analysis of laterally loaded piles in weak rock it is shown that equivalent elastic moduli of the rock controlling values of qc at the test site are very similar to those controlling lateral pile response this finding is used to formulate a simple bilinear p y approximation of the lateral response that requires qc data and an estimate of the rock s effective stress strength parameters it is shown that such

petrology and geochemistry of alkali gabbronorites from lunar breccia 67975 clasts of an unusual type of lunar highlands igneous rock alkali gabbronorite have been found in apollo 16 breccia 67975 the alkali gabbronorites form two distinct subgroups magnesian and ferroan modes and bulk compositions are highly varied the magnesian alkali gabbronorites are composed of bytownitic plagioclase or2 5an82 89 hypersthene wo3 5en49 62 augite wo39 42en36 44 a silica mineral and trace ba rich k feldspar the ferroan alkali gabbronorites are composed of ternary plagioclase or11 22an65 74 pigeonite wo6 9en35 47 augite wo38 40en29 35 ba rich k feldspar and a silica mineral trace minerals in both subgroups are apatite ree rich whitlockite and zircon the magnesian and ferroan alkali gabbronorites appear to have formed by progressive differentiation of the same or closely related parent magmas the compositional data indicate that these magmas were ree rich the ternary plagioclase is probably a high temperature metastable phase formed during crystallization in composition and mineralogy the 67975 alkali gabbronorites show many similarities to apollo 12 and 14 alkali norites alkali gabbronorites and alkali anorthosites and all these rocks together constitute a distinctive alkali suite in addition the alkali gabbronorites show some similarities to kreep basalts mg norites and some felsites these data suggest genetic links between some or all of these types of pristine rocks two types of relationships are possible the first is that alkali suite rocks crystallized in plutons of kreep basalt magma and kreep basalts are their extrusive equivalents the second is that the alkali suite rocks and some felsites all crystallized in plutons of mg norite parent magmas and kreep basalt magmas formed by remelting of these plutons additional studies are needed to resolve which of these hypotheses is correct

los angeles a tale of two stones we compare and contrast the mineralogy and petrology of the 2 stones of the extremely ferroan and cr poor martian meteorite los angeles the 2 stones are similar in many characteristics strongly suggesting that they originated from a single flow or shallow intrusion however stone 2 is more ferroan and enriched in late stage materials than its larger and more widely studied sibling stone 2 has a far higher abundance 25 vol than stone 1 10 vol of combined opaques meaning not only conventional opaque minerals but also and more abundantly fine grained symplectitic intergrowths of fayalite ferroan augite silica interpreted as pyroxferroite breakdown material pbm the bulk composition of the pbm is close to that of stoichiometric pyroxferroite with roughly 45 wt feo extensive zonation within the pyroxenes of both stones is consistent with origin by closed system fractional crystallization of the parent basaltic melt s however the compositional and modal disparity between the two stones suggests that they formed in an environment where at least mild multi cm scale differentiation occurred probably in both stones crystallization began from similar melts with mg 27 28 mol but during crystallization significant migration of the melt component occurred perhaps by crystal settling and or filter pressing stone 2 acquired an enhanced proportion of residual melt and thus higher proportions of late stage materials such as pbm oxides and phosphates within the pbm clinopyroxene poikiloblastically encloses fayalite and silica at least some of the pbm had already formed by decomposition of pyroxferroite before the major shock that caused the very scarce brecciation within los angeles however the low abundance of fractures within pbm in comparison to pyroxene and some other minerals may be an indication that the textures of pbm regions typically did not assume their final detailed configuration until after the last major shock the steep slope of a pyroxene mg cr correlation suggests that igneous crystallization occurred at higher fo2 in los angeles than in otherwise similar shergottites such as que 94201 shergotty and zagami

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

cryptomare magmatism 4 35 gyr ago recorded in lunar meteorite kalahari 009 the origin and evolution of the moon remain controversial one notable point of controversy being the timing of the beginning and end of basaltic volcanism in the lunar mares or plains lunar research over the past three decades has suggested that mare volcanism occurred mainly after the late heavy bombardment that ended 3 9 billion years ago because most of known mare basalts lunar meteorites and returned apollo and luna samples and remote sensing data indicate crystallization ages younger than 3 9 billion years but a new u pb dating of minerals in the lunar meteorite kalahari 009 gives an age of roughly 4 35 billion years for a lunar basalt this suggests that the volcanism started as early as 4 35 billion years ago relatively soon after lunar formation and differentiation and that kalahari 009 is our first sample of a cryptomare from the moon the result of u pb dating of minerals in a lunar meteorite kalahari 009 is reported analyses of five grains associated with basaltic clasts give an age of 4 35 0 15 billion years these are thought to represent the crystallization ages of parental basalt magma making kalahari 009 one of the oldest known mare basalt this suggests that mare basalt volcanism on the moon started as early as 4 35 billion years ago the origin and evolution of the moon remain controversial1 2 with one of the most important questions for lunar evolution being the timing and duration of basaltic mare magmatism1 3 4 5 6 7 8 here we report the result of ion microprobe u pb dating of phosphates in a lunar meteorite kalahari 009 which is classified as a very low ti mare basalt breccia in situ analyses of five phosphate grains associated with basaltic clasts give an age of 4 35 0 15 billion years these ancient phosphate ages are thought to represent the crystallization ages of parental basalt magma making kalahari 009 one of the oldest known mare basalts we suggest that mare basalt volcanism on the moon started as early as 4 35 gyr ago relatively soon after its formation and differentiation and preceding the bulk of lunar volcanism which ensued after the late heavy bombardment around 3 8 3 9 gyr refs 7 and 8 considering the extremely low abundances of incompatible elements such as thorium and the rare earth elements in kalahari 009 ref 9 and recent remote sensing observations illustrating that the cryptomaria tend to be of very low ti basalt type10 11 12 we conclude that kalahari 009 is our first sample of a very low ti cryptomare from the moon

evolution of the lunar crust sims study of plagioclase from ferroan anorthosites abstract the lunar crust down to a depth of 65 km is composed of older 4 5 ga ferroan anorthosites and younger 4 43 4 17 ga mg suite lithologies which include dunites troctolites and norites the anorthosites are generally inferred to represent floating cumulates in a lunar magma ocean possible depth 800 km moon s radius 1 738 km the cumulates that are inferred to be located near the base of the magma ocean are dominantly olivine and pyroxene the last dregs of the magma ocean are enriched in incompatible elements and have been named kreep k rare earth elements p kreep formed in this manner is probably concentrated near the crust mantle boundary at 70 km depth we are attempting to characterize melts parental to ferroan anorthosites and mg suite norites by analyzing rees la ce nd sm eu dy er yb and ba sr and y in their cumulus plagioclase if the cumulus grains have not been compromised by postcrystallization effects and if we know the relevant mineral melt partition coefficients ds we can invert the trace element data for plagioclase to parental melt compositions melts parental to ferroan anorthosites are estimated to contain ree at concentrations ten to fifty times chondrites melts parental to the earlier crystallizing anorthosites lower ree have virtually no eu anomaly while melts parental to later crystallizing anorthosites higher ree have small negative eu anomalies this is qualitatively consistent with the fractionation of eu relative to other ree by crystallization of plagioclase with large positive eu anomalies melts parental to the mg suite have much higher total ree and very large negative eu anomalies the characteristics of mg suite norite parental magmas may have been derived by the assimilation of kreep near the crust mantle boundary by mg rich basaltic melts formed deeper in the cumulate pile or near the contact between the lower cumulate horizons of the magma ocean and primitive unprocessed lunar mantle 800 km

lunar meteorite queen alexandra range 94281 glass compositions and other evidence for launch pairing with yamato 793274 abstract lunar meteorite queen alexandra range 94281 is remarkably similar to yamato 793274 pairing in the conventional earth entry sense is difficult to reconcile with the 2500 km separation between the find locations for these two samples nonetheless both of these regolith breccias are dominated by very low ti vlt mare basalt the pyroxenes of which feature exsolution lamellae on a remarkably coarse scale typical lamella width 0 5 1 m by mare standards the pyroxenes also show similar compositional variations e g fe vs ti trends which confirm parentage from vlt mare basalt plots using al2o3 or feo as a tracer of the highland component indicate indistinguishable internal mare highland geochemical mixing trends the same two distinctive glass types dominate the mare glass populations of both breccias glass type yq1 features 0 37 0 63 wt tio2 10 17 wt mgo and 9 11 wt al2o3 glass type yq2 features higher tio2 0 99 1 22 wt which is inversely correlated with mgo 12 6 13 8 wt and nearly constant 8 8 wt al2o3 all of these similarities suggest that y 793274 and que 94281 are a launch pair which we designate yq most of these similarities also extend to another mare breccia meteorite elephant moraine 87521 however the eet 87521 mare basalt is unusually v poor 88 g g whereas the yq mare component contains 166 g g queen alexandra range 94281 features a variety of textural domains discrete patches of dark matrix material appear to represent clods of mature regolith that have been mixed with a coarser relatively immature material interior to a frothy fusion crust are areas of massive glass that probably formed as a splash coating on que 94281 when it was still on the moon the coarse yq and eet 87521 pyroxene exsolution features imply relatively slow cooling in either a very shallow sill or an unusually thick ponded lava and or later annealing within a cryptomare mare pyroclastic glasses including the two yq varieties are systematically mgo rich compared to crystalline mare basalts this disparity may be a consequence of limited survival of graphite the main fuel for explosive volcanism during formation of the mare source regions as magma ocean cumulates graphite 2 2 g cm3 survived preferentially in regions that avoided extensive early melting and thus remained mgo rich an apparent bimodality in the tio2 contents of mare volcanics especially the pyroclastic glasses also seems a plausible consequence of petrogenesis by remelting of magma ocean cumulates cumulates deposited after the magma ocean evolved to ilmenite saturation had vastly higher tio2 contents than cumulates deposited shortly before the yq regolith s subequal proportions of mare and highland matter are consistent with derivation from a terrain close to a mare highland boundary however a similar mixture might also develop through vertical mixing in a cryptomare or a region of thin mare coverage thus unfortunately the yq bulk composition is not a very useful clue to the identity of the source crater

four lunar mare meteorites crystallization trends of pyroxenes and spinels we studied crystallization trends of pyroxene and spinel in four antarctic meteorites known to be derived from mare regions of the moon y 793169 and a 881757 ya meteorites are unbrecciated igneous basalts eet 87521 is a fragmental breccia and y 793274 is a regolith breccia all have relatively low bulkrock tio2 content and the ya meteorites are uncommonly ancient our electron probe microanalysis epma data indicate that the ya meteorites and the dominant mare components of y 793274 and eet 87521 conform to a general trend for ti poor low ti and very low ti mare basalts their pyroxenes show a strong correlation between fe fe mg fe and ti ti cr ti both ratios typically increasing from core to rim these trends presumably reflect local crystallization differentiation of interstitial melt previous studies m j drake and coworkers have suggested that the detailed configurations of such fe vs ti trends may reflect the bulk tio2 contents of the parent magmas basalts as a more systematic approach to this problem we plot bulk rock tio2 as a function of the fe 0 50 intercept of each rock s pyroxene fe vs ti trend we call this intercept the fe normalized ti based on our data for eet 87521 the ya meteorites and apollo 12 basalts 12031 and 12064 plus literature data for several other ti poor mare basalts we find a strong correlation between fe normalized ti and the bulk tio2 content of the parent basalt this correlation confirms that fragmental breccia eet 87521 is nearly pure very low ti vlt basalt and that the ya meteorites for which bulk rock tio2 results scatter due to unusually coarse grain size a 881757 or scarcity of available sample y 793169 are pieces of an uncommonly ti poor but not quite vlt variety of low ti mare basalt extrapolating from this correlation the dominant mare component of regolith breccia y 793274 is probably of vlt affinity besides the normal mare pyroxene trend of strong correlation between fe and ti y 793274 includes two additional pyroxene compositional trends both showing a wide range of ti despite relatively constant and low by mare standards fe the most magnesian of these trends consists of a single clast with a mode of orthopyroxene mgo rich ilmenite these two trends are of uncertain origin possibly one or both represents the highland component of this regolith breccia although unlike most highland pyroxenes these appear relatively unaltered by impact brecciation and metamorphism compositions of spinels in the coarse grained a 881757 show an extraordinary distribution chromite and ulvospinel components vary among grains but are nearly constant within grains despite its old age and unusually coarse grain sizes mineralogical evidence i e heterogeneity within both pyroxene and spinel typical pyroxene exsolution scale very coarse by mare standards but exceeded by the pyroxenes of eet 87521 and y 793274 indicates that a 881757 was cooled only slightly more slowly than typical mare basalts and may have formed near the center of an uncommonly thick lava flow both of the vlt basaltic lunar meteorite breccias eet 87521 and y 793274 are composed dominantly of pyroxenes with exsolution coarser than normal for mare basalts possibly vlt basalt flows tend to be systematically thicker and thus more slowly cooled than more ti rich flows

lunar feldspathic meteorites constraints on the geology of the lunar highlands and the origin of the lunar crust abstract the composition of the lunar crust provides clues about the processes that formed it and hence contains information on the origin and evolution of the moon current understanding of lunar evolution is built on the lunar magma ocean hypothesis that early in its history the moon was wholly or mostly molten this hypothesis is based on analyses of apollo samples of ferroan anorthosites 90 plagioclase molar mg mg fe mg 75 and the assumption that they are globally distributed however new results from lunar meteorites which are random samples of the moon s surface and remote sensing data show that ferroan anorthosites are not globally distributed and that the apollo highland samples used as a basis for the model are influenced by ejecta from the imbrium basin in this study we evaluate anorthosites from all currently available adequately described lunar highland meteorites representing a more widespread sampling of the lunar highlands than apollo samples alone and find that 80 of them are significantly more magnesian than apollo ferroan anorthosites interestingly luna mission anorthosites collected outside the continuous imbrium ejecta are also highly magnesian if the lunar highland crust consists dominantly of magnesian anorthosites as suggested by their abundance in samples sourced outside imbrium ejecta a reevaluation of the lunar magma ocean model is a sensible step forward in the endeavor to understand lunar evolution our results demonstrate that lunar anorthosites are more similar in their chemical trends and mineral abundance to terrestrial massif anorthosites than to anorthosites predicted in a lunar magma ocean this analysis does not invalidate the idea of a lunar magma ocean which seems a necessity under the giant impact hypothesis for the origin of the moon however it does indicate that most rocks now seen at the moon s surface are not primary products of a magma ocean alone but are products of more complex crustal processes

ion microprobe investigation of plagioclase and orthopyroxene from lunar mg suite norites implications for calculating parental melt ree concentrations and for assessing postcrystallization ree redistribution the lunar mg suite which includes dunites troctolites and norites makes up to 20 30 of the moon s crust down to a depth of 60 km the remainder is largely anorthosite this report focuses on norites which consist mostly of orthopyroxene and plagioclase because we have found that both phases are effective recorders of their parental melt compositions in an earlier report we analyzed orthopyroxene from twelve samples three from apollo 14 two from a 15 and seven from a 17 by sims for eight ree la ce nd sm eu dy er yb inversion of these data to estimated melt compositions yielded extremely high ree concentrations similar to kreep in this study we report sims ree data for plagioclase from these same twelve samples the major objective of this study is to estimate parental ree concentrations from both orthopyroxene and plagioclase data to see if both data inversions produce concordant melt compositions and thus better constrain the composition of melts parental to mg suite norites the estimated ree concentrations from both phases show some evidence of slight postcrystallization ree redistribution comparison of the observed ratio of ree for pyroxene plagioclase to the ratio of the ds for pyroxene plagioclase is consistent with ree redistribution which involves lree diffusing from pyroxene into plagioclase and hree diffusing from plagioclase into pyroxene however apparently these postcrystallization exchanges have not seriously affected our ability to estimate melt ree concentrations the estimated melt ree concentrations using both plagioclase and orthopyroxene are similar to high k kreep especially for melts parental to a 15 norites this study provides support for mineral trace element inversion estimates for parental melts even though these lunar crustal lithologies experienced high temperature annealing apparently the cores of plagioclase and pyroxene continue to carry a record of their igneous crystallization history