the petrology geochemistry and age of lunar regolith breccias miller range 090036 and 090070 insights into the crustal history of the moon meteorites ejected from the surface of the moon as a result of impact events are an important source of lunar material in addition to apollo and luna samples here we report bulk element composition mineral chemistry age and petrography of miller range mil 090036 and 090070 lunar meteorites mil 090036 and 090070 are both anorthositic regolith breccias consisting of mineral fragments and lithic clasts in a glassy matrix they are not paired and represent sampling of two distinct regions of the lunar crust that have protoliths similar to ferroan anorthosites 40ar 39ar chronology performed on two subsplits of mil 090070 33 a pale clast impact melt and a dark glassy melt component shows that the sample underwent two main degassing events one at 3 88 ga and another at 3 65 ga the cosmic ray exposure data obtained from mil 090070 are consistent with a short 8 9 ma exposure close to the lunar surface bulk rock feo tio2 and th concentrations in both samples were compared with 2 degree lunar prospector gamma ray spectrometer lp grs data sets to determine areas of the lunar surface where the regolith matches the abundances observed on the sample we find that mil 090036 bulk rock is compositionally most similar to regolith surrounding the procellarum kreep terrane whereas mil 090070 best matches regolith in the feldspathic highlands terrane on the lunar farside our results suggest that some areas of the lunar farside crust are composed of ferroan anorthosite and that the samples shed light on the evolution and impact bombardment history of the ancient lunar highlands

heterogeneity in lunar anorthosite meteorites implications for the lunar magma ocean model the lunar magma ocean model is a well established theory of the early evolution of the moon by this model the moon was initially largely molten and the anorthositic crust that now covers much of the lunar surface directly crystallized from this enormous magma source we are undertaking a study of the geochemical characteristics of anorthosites from lunar meteorites to test this model rare earth and other element abundances have been measured in situ in relict anorthosite clasts from two feldspathic lunar meteorites dhofar 908 and dhofar 081 the rare earth elements were present in abundances of approximately 0 1 to approximately 10 chondritic ci abundance every plagioclase exhibited a positive eu anomaly with eu abundances of up to approximately 20 ci calculations of the melt in equilibrium with anorthite show that it apparently crystallized from a magma that was unfractionated with respect to rare earth elements and ranged in abundance from 8 to 80 ci comparisons of our data with other lunar meteorites and apollo samples suggest that there is notable heterogeneity in the trace element abundances of lunar anorthosites suggesting these samples did not all crystallize from a common magma source compositional and isotopic data from other authors also suggest that lunar anorthosites are chemically heterogeneous and have a wide range of ages these observations may support other models of crust formation on the moon or suggest that there are complexities in the lunar magma ocean scenario to allow for multiple generations of anorthosite formation

lunar meteorite queen alexandra range 93069 a lunar highland regolith breccia with very low abundances of mafic components lunar meteorite que 93069 found in antarctica is a mature anorthitic regolith breccia with highland affinities that was ejected from the moon 0 3 ma ago the frequency distribution of mineral and lithic clasts gives information about the nature of the regolith and subregolith basement near the ejection site as well as about the abundances of rock types shocked to different degrees prior to the breccia formation thin section que 93069 37 consists of 67 5 vol fine grained 130 m constituents and 32 5 vol mineral and lithic clasts and an impact melt vein the most abundant types of these clasts are intragranularly recrystallized anorthosites and plagioclases together 26 3 vol and feldspathic fine grained to microporphyritic crystalline melt breccias 21 9 vol mafic crystalline melt breccias are extremely rare 1 3 vol granulitic lithologies are 10 4 vol recrystallized feldspathic melt breccias are 15 0 vol and glasses are 3 5 vol the impact melt vein cutting across the entire thin section was probably formed subsequent to the lithification process of the bulk rock at pressures below 20 gpa because the bulk rock never experienced a higher peak shock pressure lunar meteorite que 93069 has a higher abundance of clear glass occurring within melt spherules glassy fragments and an impact melt vein than lunar meteorites alha81005 y 791197 y 82192 3 y 86032 or mac 88104 5 the high abundance of melt spherules indicates that this lunar meteorite contains the highest content of typical regolith components mafic crystalline melt breccias are much rarer in que 93069 than in all other lunar highland regolith breccias the extremely low abundance of mafic components may constrain possible areas of the moon from which the breccia was derived the source area of que 93069 must be a highland terrain lacking significant mafic impact melts or mare components

crystal bearing lunar spherules impact melting of the moon s crust and implications for the origin of meteoritic chondrules crystal bearing lunar spherules clss in lunar breccia 14313 14315 14318 soil 68001 24105 and impact melt rock 62295 samples can be classified into two types feldspathic and olivine rich feldspathic clss contain equant tabular or acicular plagioclase grains set in glass or a pyroxene olivine mesostasis the less common olivine rich clss contain euhedral or skeletal olivine set in glass or possess a barred olivine texture bulk chemical and mineral chemical data strongly suggest that feldspathic clss formed by impact melting of mixtures of ferroan anorthosite and mg suite rocks that compose the feldspathic crust of the moon it is probable that olivine rich clss also formed by impact melting but some appear to have been derived from distinctively magnesian lunar materials atypical of the moon s crust some clss contain reversely zoned relic plagioclase grains that were not entirely melted during cls formation thin 5 m thick rims of troilite or phosphate and chemical gradients in glassy mesostases attributed to metasomatism in a volatile rich na k p rich environment crystal bearing lunar spherules were rimmed and metasomatized prior to brecciation compound cls objects are also present these formed by low velocity collisions in an environment probably an ejecta plume that contained numerous melt droplets factors other than composition were responsible for producing the crystallinity of the clss we agree with previous workers that relatively slow cooling rates and long ballistic travel times were critical features that enabled these impact melt droplets to partially or completely crystallize in free flight moreover incomplete melting of precursor materials formed nucleation sites that aided subsequent crystallization clearly clss do not resemble meteoritic chondrules in all ways the two types of objects had different precursors and did not experience identical rimming processes and vapor fractionation appears to have played a less important role in establishing the compositions of clss than of chondrules however the many detailed similarities between clss and chondrules indicate that it is more difficult to rule out an origin for some chondrules by impact melting than some have previously argued differences between clss chondrules and their host rocks possibly can be reconciled with an impact melt origin for some chondrules when different precursors the higher gravity of the moon compared to chondrite parent bodies and the likely presence of nebular gas during chondrule formation are taken into account

the development of divergent margins insights from the north volcanic zone iceland abstract iceland is a natural laboratory where plate separation and mid ocean ridge formation can be studied directly in the field in this setting it is not fully understood how magma interacts with faulting and fissuring and how rift zones propagate in order to improve the understanding of how these processes operate we conducted a detailed field study about the kinematics and propagation of 33 holocene faults along the n s theistareykir rift north volcanic zone and mapped all tension fractures this rift hosts the holocene theistareykir central volcano for which ground deformation data insar and gps indicate an inflating shallow magma chamber throughout 2006 2008 analyses of the cumulative fault slip distribution at 696 sites show two opposite directions of fault rift propagation the first more developed is directed northwards and affects the area located north of theistareykir volcano whereas south of the volcano the rift propagates southwards tension fractures increase in frequency with respect to faults outwards from the volcano along a n s to nne ssw direction the presence of aligned vents dykes and topographic bulging along some of the n s structures and the active magma chamber below theistareykir volcano suggest that faults and tension fractures propagate following repeated dyke intrusions from the magma chamber outward along the plate margin the fact that the rift is more developed north of the volcano than south of it is interpreted as the effect of buttressing from another coterminous magma chamber sitting below a neighbouring central volcano other causes for the general observed pattern such as tectonic stresses mechanical interaction of faults and changes in the rheological characteristics of rocks are discussed as well

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

a study of the physics of telluric current flow at very low frequencies in the earth s crust summary interpretation of the effects of natural electromagnetic induction is often in terms of models in which changes in resistivity at great distances from the point of measurement are not taken into account in this paper we will try to show that this is not a valid approximation for very low frequency telluric currents flowing near the surface in the earth s crust when the material separating the crust from the mantle has a sufficiently high electrical resistance in this case the shape and dimensions of the circuit as well as the resistivity distribution along the whole length of the path followed by the currents play a part in determining the induced electromagnetic field a number of experimentally verifiable consequences follow from this

alha 81005 moon mars petrography and giordano bruno meteorite alha 81005 a glassy regolith breccia is beyond any reasonable doubt of lunar origin according to its petrographic chemical and isotopic characteristics the sample was shocked at most to 15 gpa during ejection and supports the possibility of some meteorites being of martian origin most lithic fragments are feldspathic granulitic impactites cataclastic anorthosites and impact melts all typical lunar lithologies mineral fragments are derived from plutonic troctolitic and noritic rocks varied mare basalt like extrusive rocks and the identified lithic fragment types neither petrographically nor chemically are there significant components in alha 81005 which were previously unknown a mare basalt component restricts the origin of the sample with remotely sensed data which eliminates most frontside as well as farside groundtrack regions it makes the probability of ejection from giordano bruno near the moon s ne limb far greater than from any other lunar crater

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

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

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

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

concentrations of radioactive elements in lunar materials as an aid to interpreting data obtained remotely on the distribution of radioactive elements on the lunar surface average concentrations of k u and th as well as al fe and ti in different types of lunar rocks and soils are tabulated the u th ratio in representative samples of lunar rocks and regolith is constant at 0 27 k th ratios are more variable because k and th are carried by different mineral phases in nonmare regoliths at the apollo sites the main carriers of radioactive elements are mafic i e 6 8 fe impact melt breccias created at the time of basin formation and products derived therefrom

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

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

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

mineralogy and geochemistry of lunar meteorite queen alexandra range 93069 queen alexandra range que 93069 is a glass rich regolith breccia derived from the lunar highlands the high abundance of glassy fragments the presence of agglutinates the small size of all mineral and glass fragments the presence of mostly melt rocks and the low abundance of pristine lunar crustal rocks all indicate that que 93069 is derived from a mature regolith this conclusion is also supported by its high siderophile element content the most common mafic mineral is pyroxene with compositions that indicate derivation from ferroan ant suite rocks rare gabbro differentiation products may be indicated by the presence of silica fayalitic olivine and one pyroxferroite grain lithic fragments are mostly meta melt rocks of ant composition the glass compositions are dominated by troctolitic anorthosite compositions followed by gabbroic anorthosite and noritic anorthosite most glasses are ol normative in composition some rare basic glasses of noritic composition were observed glass fragments and matrix glasses are alkali poor except for some rare alkali rich shards the bulk chemical composition of que 93069 as well as the rare earth element ree abundance pattern is very similar to that of other highlands meteorites such as mac 88105 and y 86032 and to average lunar highlands crust one small porous clast was found to be very rich in volatile elements as well as in most lithophile and siderophile elements as this sample also contains abundant sulfides the enrichments could be related to element mobilization and redistribution by volatile sulfur species

history of the paired lunar meteorites mac88104 and mac88105 derived from noble gas isotopes radionuclides and some chemical abundances abstract noble gas isotopes radionuclides and chemical abundances were studied in the lunar meteorites mac88104 and mac88105 collected in the macalpine hills area of antarctica the concentrations of the noble gas isotopes and the radionuclide activities in the two meteorites are essentially identical proving that the two meteorites are paired from 40k 40ar dating we obtain a gas retention age of 3550 400 ma typical for lunar surface material probably before breccia compaction the mac88104 5 material resided for 630 200 ma at an average shielding depth of 85 g cm 2 that is about 50 cm below the lunar surface in the lunar regolith as judged from the concentration of cosmic ray produced kr and xe isotopes although this duration of lunar regolith residence is relatively long mac88104 5 represent immature regolith material the concentration of solar wind implanted noble gases are two orders of magnitude lower than those in mature lunar soil the reason for that might be the relatively high average shielding the 40 ar 36ar ratio of the trapped component is 5 7 1 0 indicating an intermediate antiquity of the material we estimate that the solar wind and lunar atmospheric particles were implanted about 2000 ma ago the radionuclide activities allow us to derive the exposure history of the mac88104 5 material the duration of the moon earth transfer was 0 24 ma production of the radionuclides on the lunar surface immediately before ejection is possible but duration and shielding depth for such an exposure cannot be determined from our data we obtain a terrestrial age of 0 1 tterr 0 6 ma and an ejection time of mac88104 5 from the moon of 0 1 tejection 0 8 ma the exposure histories of the lunar meteorites discussed in this work indicate that at least two impact events are required for their ejection from the moon our first noble gas results for lunar meteorite yamato 793274 show that it represents mature lunar regolith material with relatively high concentrations of solar wind implanted noble gases and a duration of several hundred million years of exposure to cosmic rays

chemical information content of lunar thermal and epithermal neutrons simulations of equilibrium thermal and epithermal neutron flux spectra for the moon have been studied to determine their chemical information content most of this information resides in a single parameter the ratio of macroscopic absorption to energy loss cross sections although this parameter cannot specify the chemistry of lunar soils uniquely it provides an index that can be used to quantitatively separate anorthositic from mafic chemistries hydrogen abundances can best be derived from measurements of the epithermal neutron flux which is strongly related to its macroscopic energy loss cross section the ratio of thermal to epithermal neutron flux measured by lunar prospector is shown to agree quantitatively with simulations this agreement is used to show that the highlands terrane on the farside of the moon is anorthositic containing high percentages of plagioclase and possibly a range of mg suite minerals with a high mg mg fe atomic ratio our best estimate of the abundance of feo is 2 with an upper limit of 5

constraints on the thermal and mixing history of lunar surface materials and comparisons with basaltic meteorites we have measured the induced thermoluminescence tl properties of mare basalts highland rocks glasses regolith breccias soils and core samples we also performed a series of heating experiments and made cathodoluminescence cl observations of apollo 16 soils the data are readily interpreted in terms of feldspar being the dominant source of tl and cl the known luminescence properties of feldspar and history of the samples for example the tl sensitivity of the mare basalts is lower than that of the highland basalts by about an order of magnitude probably due to the differing feo content of their feldspars similarly the tl properties of regolith breccias can readily be explained in terms of thermal processes similar to those experienced by the soils and by mixing of highland and mare components our major new observations and interpretations include 1 that there are maturity dependent variations in the tl and cl properties of the core samples which reflect thermal annealing and melting during regolith working 2 that the most primitive material in lunar samples in terms of their thermal histories is located in the immature lunar soils and 3 that there is no tl evidence for widespread long term thermal metamorphism of lunar samples tl being particularly sensitive to low level metamorphism in extraterrestrial materials in this latter respect lunar samples differ from basaltic meteorites which otherwise have very similar properties and histories we argue that this reflects a greater tendency toward thick regoliths on asteroid sized bodies

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

terrestrial 81kr kr ages of antarctic meteorites the production rate of 38ar in meteorites p 38 has been determined as a function of the sample s chemical composition from 81kr kr exposure ages of four eucrite falls the cosmogenic 78kr 83kr ratio is used to estimate the shielding dependence of p 38 from the true 38ar exposure ages and the apparent 81kr kr exposure ages of nine antarctic eucrite finds terrestrial ages are calculated they range from about 3 105a pecora escarpment 82502 to very recent falls thiel mountains 82502 polymict eucrites from the allan hills a78132 a79017 and a81009 have within the limits of error the same exposure age 15 2 106a and the same terrestrial age 1 1 105a this is taken as strong evidence that these meteorites are fragments of the same fall a similar case are the elephant moraine polymict eucrites a79005 a79006 and 82600 with an exposure age of 26 106a and a terrestrial age of 1 8 105a eeta79004 may be different from this group because its exposure age and terrestrial age are 21 106a and 2 5 105a respectively the distribution of terrestrial ages of allan hills meteorites is discussed meteorites from this blue ice field have two sources directly deposited falls and meteorites transported to the allan hills inside the moving antarctic ice sheet during the surface residence time meteorites decompose due to weathering processes the weathering half life is about 1 6 105a from the different age distributions of allan hills and yamato meteorites it is concluded that meteorite concentrations of different antarctic ice fields need different explanations

constraints on the structure of the martian interior determined from the chemical and isotopic systematics of snc meteorites the crystallization ages of martian snc meteorites give evidence that martian volcanism has continued until recent times perhaps until the present these meteorites also indicate that the mantle source regions of this volcanism are modestly to extremely depleted by terrestrial standards these 2 observations produce a conundrum how is it that such depleted source regions have produced basaltic magma for such a long time this contribution attempts to quantify the radiogenic heat production in 2 distinct martian mantle source regions those of the shergottites and nakhlites compared to the depleted upper mantle of the earth morb the nakhlite source region is depleted by about a factor of 2 and the shergottite source region is depleted by a factor of 6 according to current geophysical models the nakhlite source contains the minimum amount of radioactive heat production to sustain whole mantle convection and basalt generation over geologic time a corollary of this conclusion is that the shergottite source contains much too little radioactivity to produce recent 200 ma basalts a model martian interior with a deep nakhlite mantle that is insulated by a shallow shergottite mantle may allow basalt production from both source regions if the divide between the nakhlite shergottite mantles acts as a thermal boundary layer similarities between lunar and martian isotopic reservoirs indicate that the moon and mars may have experienced similar styles of differentiation

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

petrography mineralogy and geochemistry of lunar meteorite sayh al uhaymir 300 we report here the petrography mineralogy and geochemistry of lunar meteorite sayh al uhaymir 300 sau 300 sau 300 is dominated by it fine grained crystalline matrix surrounding mineral fragments plagioclase pyroxene olivine and ilmenite and lithic clasts mainly feldspathic to noritic mare basalt and kreepy rocks are absent glass melt veins and impact melts are present indicating that the rock has been subjected to a second impact event feni metal and troilite grains were observed in the matrix major element concentrations of sau 300 al 2 o 3 21 6 wt and feo s 16 wt are very similar to those of two basalt bearing feldspathic rei regolith breccias calcalong creek and yamato y 983885 however the rare earth element ree abundances and pattern of sau 300 resemble the patterns of feldspathic highlands meteorites e g queen alexandra range que 93069 and dar al gani dag 400 and the average lunar highlands crust it has a relatively lree enriched 7 to 10 x ci pattern with a positive eu anomaly similar to 11 x ci values of fe mn ratios of olivine pyroxene and the bulk sample are essentially consistent with l lunar origin sau 300 also contains high siderophile abundances with a chondritic ni ir ratio sau 300 has experienced moderate terrestrial weathering as its bulk sr concentration is elevated compared to other lunar meteorites and apollo and luna samples mineral chemistry and trace clement abundances of sau 300 fall within the ranges of lunar feldspathic meteorites and fan rocks sau 300 is a feldspathic impact melt breccia predominantly composed of feldspathic highlands rocks with a small amount of mafic component with a bulk mg of 0 67 it is the most mafic of the feldspathic meteorites and represents a lunar surface composition distinct from any other known lunar meteorites oil the basis of its low th concentration 0 46 ppm and its lack of kreepy and mare basaltic components the source region of sau 300 could have been within a highland terrain a great distance from the imbrium impact basin probably on the far side of the moon

composition and evolution of the lunar crust in the descartes highlands apollo 16 samples from the north ray crater ejecta blanket apollo 16 were investigated by petrographic microscope electron microprobe instrumental neutron activation and xray fluorescence analyses and 40ar 39ar and rb sr dating techniques nine major groups of monomict and polymict breccias were defined on the basis of microscopic texture and these were further subdivided into chemical subgroups on the basis of characteristic elements such as al mg fe cr ree ni and co the polymict breccias fragmental breccias granulitic breccias and impact melt breccias are the result of multiple impact induced mechanical mixing and melting and of thermal and impact metamorphism of rock and mineral clasts derived from primordial igneous crustal rocks for calculations of mixing models it was found that end members consisting of the pristine igneous rock components present as discrete samples at the apollo 16 site and supplemented by kreep dunite and a meteoritic component yield the best fits for the composition of polymict breccias the end member rocks a re ferroan anorthosite various magnesian gabbronorites including sodic ferrogabbro and feldspathic lherzolite and spinei troctolite the following model is proposed for the composition and stratigraphy of the target for north ray crater the lower section of the stratigraphy is composed of a megabreccia with clasts of highly feldspathic polymict breccias kreep free old eastern highland rock suite interpreted as nectaris ejecta descartes formation the top section contains kreep bearing polymict breccias kreep bearing young western highland rock suite and appears to be similar to the lithologies found in the cayley plains this material interpreted as cayley formation may be a distant facies of imbrium basin ejecta deposits of the imbrium basin the petrographic differences between these two major selenographic units the descartes and the cayley formations in the apollo 16 area are more distinct than the chemical differences the petrographic and chemical composition of the primordial igneous upper crust in the regions of the nectaris and imbrium basins has been calculated by subtraction of the kreep and meteoritic components from the bulk composition of the descartes and cayley materials the nectaris crust which is better constrained consists of 86 87 a northosite 4 sodic ferrogabbro 0 5 1 3 feldspathic lherzolite 6 8 regular magnesian gabbronorite 1 8 2 8 dunite and 0 1 spinel troctolite a model for the evolution of the upper lunar crust in the descartes highlands is proposed on the basis of isotope ages and clast matrix relationships of polymict breccias essential features of this model in sequenial order are 1 development of multiple layers of kreep free early feldspathic fragmental megabreccias and impact melt sheets on the primordial crust in the time period from 4 4 aeons to the time of the nectaris impact which could have occurred as late as 3 85 aeons ago 2 excavation of these megabreccias by the nectaris event and deposition of a nectarian feldspathic fragmental megabreccia in the descartes area 3 introduction of kreep basaltic material into the upper crust mainly west and northwest of the descartes site and formation of kreepy impact melt sheets most probably from 4 05 to 3 80 aeons ago 4 imbrium impact at 3 8 aeons ago and deposition of kreep bearing imbrian feldspathic fragmental breccias at the descartes site which form the cayley formation and 5 redeposition mixing and melting of all preexisting breccias yielding kreep bearing and kreep poor post cayley fragmental breccias and melt ejecta glass bombs as the result of small impacts craters 1 5 km in diameter in the cayley plains and the descartes mountains respectively

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

constraining the source regions of lunar meteorites using orbital geochemical data lunar meteorites provide important new samples of the moon remote from regions visited by the apollo and luna sample return missions petrologic and geochemical analysis of these meteorites combined with orbital remote sensing measurements have enabled additional discoveries about the composition and age of the lunar surface on a global scale however the interpretation of these samples is limited by the fact that we do not know the source region of any individual lunar meteorite here we investigate the link between meteorite and source region on the moon using the lunar prospector gamma ray spectrometer remote sensing data set for the elements fe ti and th the approach has been validated using apollo and luna bulk regolith samples and we have applied it to 48 meteorites excluding paired stones our approach is able broadly to differentiate the best compositional matches as potential regions of origin for the various classes of lunar meteorites basaltic and intermediate fe regolith breccia meteorites are found to have the best constrained potential launch sites with some impact breccias and pristine mare basalts also having reasonably well defined potential source regions launch areas for highland feldspathic meteorites are much less well constrained and the addition of another element such as mg will probably be required to identify potential source regions for these

anorthosite formation by plagioclase flotation in ferrobasalt and implications for the lunar crust abstract the sept iles layered intrusion quebec canada is dominated by a basal layered series made up of troctolites and gabbros and by anorthosites occurring 1 at the roof of the magma chamber 100 500 m thick and 2 as cm to m size blocks in gabbros of the layered series anorthosite rocks are made up of plagioclase with minor clinopyroxene olivine and fe ti oxide minerals plagioclase displays a very restricted range of compositions for major elements an 68 an 60 trace elements sr 1023 1071 ppm ba 132 172 ppm and sr isotopic ratios 87 sr 86 sr i 0 70356 0 70379 this compositional range is identical to that observed in troctolites the most primitive cumulates of the layered series whereas plagioclase in layered gabbros is more evolved an 60 an 38 the origin of sept iles anorthosites has been investigated by calculating the density of plagioclase and that of the evolving melts the density of the feo rich tholeiitic basalt parent magma first increased from 2 70 to 2 75 g cm 3 during early fractionation of troctolites and then decreased continuously to 2 16 g cm 3 with fractionation of fe ti oxide bearing gabbros plagioclase an 69 an 60 was initially positively buoyant and partly accumulated at the top of the magma chamber to form the roof anorthosite with further differentiation plagioclase 60 became negatively buoyant and anorthosite stopped forming blocks of anorthosite autoliths even fell downward to the basal cumulate pile the presence of positively buoyant plagioclase in basal troctolites is explained by the low efficiency of plagioclase flotation due to crystallization at the floor and or minor plagioclase nucleation within the main magma body dense mafic minerals of the roof anorthosite are shown to have crystallized from the interstitial liquid the processes related to floating and sinking of plagioclase in a large and shallow layered intrusion serve as a proxy to refine the crystallization model of the lunar magma ocean and explain the vertically stratified structure of the lunar crust with gabbro noritic rocks at the base and anorthositic rocks at the top we propose that the lunar crust mainly crystallized bottom up this basal crystallization formed a mafic lower crust that might have a geochemical signature similar to the magnesian suite without kreep contamination while flotation of some plagioclase grains produced ferroan anorthosites in the upper crust

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

chemistry of the calcalong creek lunar meteorite and its relationship to lunar terranes the calcalong creek lunar meteorite is a polymict breccia that contains clasts of both highlands and mare affinity reported here is a compilation of major minor and trace element data for bulk clast and matrix samples determined by instrumental neutron activation analysis inaa petrographic information and results of electron microprobe analyses are included the relationship of calcalong creek to lunar terranes especially the procellarum kreep terrane and feldspathic highlands terrane is established by the abundance of thorium incompatible elements and their kreep like ci chondrite normalized pattern feo and tio2 the highlands component is associated with apollo 15 kreep basalt but represents a variant of the kreep derived material widely found on the moon sources of calcalong creek s mare basalt components may be related to low titanium lt and very low titanium vlt basalts seen in other lunar meteorites but do not sample the same source the content of some components of calcalong creek are found to display similarities to the composition of the south pole aitken terrane what appear to be vlt relationships could represent new high aluminum low titanium basalt types

early differentiation of the moon evidence from trace elements in plagioclase bulk samples and plagioclase mineral grains from lunar cataclastic ferroan anorthosites were analyzed for trace elements by instrumental neutron activation analysis some pure plagioclase crystals have lower concentrations of cr co sc and heavy rees than previous analyses indicated concentrations of sr eu na ga and the rees in plagioclases from different anorthosites vary in a systematic way and the trace element patterns of plagioclases from pristine norites and troctolites are very different from the plagioclase pattern of anorthosites the following model is suggested to account for these observations 1 melting of a large fraction of the moon formation of a magma ocean precipitation of olivine and later pyroxene followed by flotation of cumulus plagioclase 2 mixing of kreep with a mafic component enriched in mg cr and co 3 precipitation of noritic and troctolitic cumulates and metallic iron from this magma and 4 eruption of these kreep and mg rich lavas and or distribution of these materials over the front side of the moon by basin forming impacts 3 9 4 0 b y ago

exposure histories of lunar meteorites alha81005 mac88104 mac88105 and y791197 the cosmogenic radionuclides sup 41 ca sup 36 cl sup 26 al and sup 10 be in the allan hills 81005 macalpine hills 88104 macalpine hills 88105 and yamato 791197 meteorites were measured by accelerator mass spectrometry ams sup 53 mn in allan hills 81005 and yamato 791197 was measured by activation these four lunar meteorites experienced similar histories they were ejected from near the surface of the moon ranging in depth down to 400 g cm sup 2 and had very short transition times less than 0 1 ma from the moon to the earth a comparison of the cosmogenic nuclide concentrations in macalpine hills 88104 and macalpine hills 88105 clearly indicates that they are a pair from the same fall

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

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

lunar highland meteorite dhofar 026 and apollo sample 15418 two strongly shocked partially melted granulitic breccias studies of lunar meteorite dhofar 026 and comparison to apollo sample 15418 indicate that dhofar 026 is a strongly shocked granulitic breccia or a fragmental breccia consisting almost entirely of granulitic breccia clasts that experienced considerable post shock heating probably as a result of diffusion of heat into the rock from an external hotter source the shock converted plagioclase to maskelynite indicating that the shock pressure was between 30 and 45 gpa the post shock heating raised the rock s temperature to about 1200 c as a result the maskelynite devitrified and extensive partial melting took place the melting was concentrated in pyroxene rich areas all pyroxene melted as the rock cooled the partial melts crystallized with fine grained subophitic poikilitic textures sample 15418 is a strongly shocked granulitic breccia that had a similar history but evidence for this history is better preserved than in dhofar 026 the fact that dhofar 026 was previously interpreted as an impact melt breccia underscores the importance of detailed petrographic study in interpretation of lunar rocks that have complex textures the name impact melt has in past studies been applied only to rocks in which the melt fraction formed by shock induced total fusion recently however this name has also been applied to rocks containing melt formed by heating of the rocks by conductive heat transfer assuming that impact is the ultimate source of the heat we urge that the name impact melt be restricted to rocks in which the bulk of the melt formed by shock induced fusion to avoid confusion engendered by applying the same name to rocks melted by different processes

lunar meteorite dhofar 1428 feldspathic breccia containing kreep and meteoritic components we have studied the feldspathic lunar meteorite dhofar 1428 chemically and petrologically to better understand the evolution of the lunar surface dhofar 1428 is a feldspathic regolith breccia derived from the lunar highland bulk chemical and mineral compositions of dhofar 1428 are similar to those of other feldspathic lunar meteorites we found a few clasts of evolved lithologies such as k rich plagioclases and quartz monzogabbro dhofar 1428 contains approximately 1 wt of chondritic materials like cm chondrite on the basis of abundances of platinum group elements ru rh pd os ir and pt

the materials of the lunar procellarum kreep terrane a synthesis of data from geomorphological mapping remote sensing and sample analyses major features of the moon s procellarum kreep terrane include subdued relief and extensive resurfacing with mare basalt consistent with high concentrations of th and other heat producing elements at depth we relate the chemistry of sampled materials to the geomorphology th surface concentrations determined by the lunar prospector 2 pixels and feo and tio2 concentrations derived from clementine ultraviolet visible spectral data on the basis of geologic maps each pixel was classified as mare terra or mixed near the periphery of the terrane terra pixel compositions are relatively feldspathic in the interior they mainly represent imbrium basin rim or ejecta deposits and are mainly incompatible trace element rich norites and presumably represent materials from a thick section tens of kilometers of the pre imbrium crust of the terrane excavated by the imbrium event although imbrium ejecta are the principal source of surface terra materials the imbrium event did not create the th rich procellarum kreep terrane broad continuous expanses of mare pixels are observed with little interruption from protruding terra or terra penetrating craters the mare basalt dominated regoliths of these areas have a wide range of tio2 concentrations 18 leading to the conclusion that the high th concentrations are in the mare basalts and are not present in the regoliths as terra derived materials volcanic glasses and impact glasses of mare basalt composition collected from the procellarum kreep terrane support this conclusion

petrography mineralogy and trace element geochemistry of lunar meteorite dhofar 1180 here we report the petrography mineralogy and trace element geochemistry of the dhofar 1180 lunar meteorite dhofar 1180 is predominantly composed of fine grained matrix with abundant mineral fragments and a few lithic and glassy clasts lithic clasts show a variety of textures including cataclastic gabbroic granulitic ophitic subophitic and microporphyritic both feldspathic and mafic lithic clasts are present most feldspathic lithic clasts have a strong affinity to ferroan anorthositic suite rocks and one to magnesian suite rocks mafic lithic clasts are moderately to extremely fe rich the ti ti cr fe fe mg compositional trend of pyroxenes in mafic lithic clasts is consistent with that of low ti mare basalts glasses display a wide chemical variation from mafic to feldspathic some glasses are very similar to those from apollo 16 soils kreep components are essentially absent in dhofar 1180 one glassy clast is rich in k ree and p but its mg mg fe is very low 0 25 it is probably a last stage differentiation product of mare basalt molar fe mn ratios of both olivine and pyroxene are essentially consistent with a lunar origin

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

lunar meteorite regolith breccias an in situ study of impact melt composition using la icp ms with implications for the composition of the lunar crust dar al gani dag 400 meteorite hills met 01210 pecora escarpment pca 02007 and macalpine hills mac 88104 88105 are lunar regolith breccia meteorites that provide sampling of the lunar surface from regions of the moon that were not visited by the us apollo or soviet luna sample return missions they contain a heterogeneous clast population from a range of typical lunar lithologies dag 400 pca 02007 and mac 88104 88105 are primarily feldspathic in nature and met 01210 is composed of mare basalt material mixed with a lesser amount of feldspathic material here we present a compositional study of the impact melt and impact melt breccia clast population i e clasts that were generated in impact cratering melting processes within these meteorites using in situ electron microprobe and la icp ms techniques results show that all of the meteorites are dominated by impact lithologies that are relatively ferroan mg 10 and have low incompatible trace element ite concentrations i e typically 10 ppm sm high magnesium suite typically 70 mg or high alkali suite high ites sc sm ratios 2 target rocks instead the meteorite mafic melts are more ferroan kreep poor and sc rich and represent mixing between feldspathic lithologies and low ti or very low ti vlt basalts as pca 02007 and mac 88104 05 were likely sourced from the outer feldspathic highlands terrane our findings suggest that these predominantly feldspathic regions commonly contain a vlt to low ti basalt contribution

dhofar 081 a new lunar highland meteorite the lunar meteorite dhofar 081 found as a single fragment of 174 g in the dhofar region of oman is a shocked feldspathic fragmental highland breccia dominated by anorthosite rich lithic and mineral clasts embedded into a fine grained mostly shock melted clastic matrix major mineral phases in the bulk rock are ca rich plagioclase an96 5 99 5 pyroxene fs21 9 46 2wo3 0 41 4 and olivine fa29 3 47 8 accessory phases include fe ni metal ilmenite and ti cr rich spinel dhofar 081 contains subordinate crystalline fragments of large anorthosites intersertal impact melt rocks microporphyritic impact melt breccias dark fine grained impact melt breccias large cataclastic feldspars and irregularly shaped brown glass clasts mafic components are rare and no genuine regolith components were found in the sections studied minerals in dhofar 081 show homogeneously distributed shock features intergranular recrystallization strong fracturing and mosaicism in feldspar as well as a high density of mostly irregular fractures in pyroxene and olivine localized impact melting caused by one or several impacts led to a strong lithification based on these effects an equilibration shock pressure of about 15 20 gpa is estimated for the strongest shock event in dhofar 081 devitrification of the glassy material in the rock indicates thermal annealing after shock melting suggesting that the 15 20 gpa shock event predated the ejection event according to the concentrations of implanted solar noble gases dhofar 081 represents a polymict clastic breccia deposit with possibly a minor regolith component a similar noble gas record of dhofar 081 and macalpine hills 88104 05 suggests the possibility of a source crater pairing of both meteorites as indicated by noble gas measurements pairing of dhofar 081 with the other lunar meteorites found in oman dhofar 025 and dhofar 026 is unlikely

nb zr fractionation on the moon and the search for extinct 92nb a comprehensive zr isotopic study was conducted on eleven lunar basalts and highland rocks to search for evidence of the extinct nuclide 92nb which decays to 92zr with a half life of 36 ma internal isochrons were determined for two early highland rocks 77215 and 60025 no resolvable zr isotopic variations were detected in this wide range of lunar samples and thus there is no evidence for the former existence of live 92nb on the moon the nb zr ratios of lunar ilmenites and bulk rock samples vary by only a factor of two to three relative to the chondritic nb zr ratio no evidence for larger nb zr fractionation was found this limited fractionation and late isotopic closure of the source region prevents the formation of measurable 92zr anomalies in high ti mare basalts as a consequence it is not possible to draw conclusions from the 92nb 92zr chronometer about the timing of early lunar differentiation and to constrain the role of ilmenite in the source region of high ti mare basalts however the fractionation is still sufficient to deduce an upper limit for the initial 92nb 93nb ratio of the solar system of 5 10 4

a noble gas data collection of lunar meteorites we collected the published noble gas data of altogether 35 lunar meteorites this compilation includes the stable isotopes of he ne ar kr and xe we also give a summary of cosmogenic trapped and radiogenic noble gas components of lunar meteorites for which data are available in the literature

experimental investigation of the partitioning of phosphorus between metal and silicate phases implications for the earth moon and eucrite parent body abstract the solid metal silicate melt partition coefficient for p d p has been determined experimentally at 1190 c and 1300 c the dependence of the partition coefficient on oxygen fugacity has been investigated and is consistent with a valence state of 5 for p in the silicate melt the experimental partition coefficients are given by log d p 1 21 log o 2 15 95 at 1190 c log d p 1 53 log o 2 17 73 at 1300 c the experimentally determined partition coefficients may be used to interpret the low p la ratios of the earth moon and eucrites relative to c1 chondrites the low p la ratios in the eucrites may be explained by partitioning of p into 5 to 25 of a sulfur bearing metallic liquid assuming equilibration and separation of the liquid metal from the silicates at low degrees of partial melting of the silicates the low w la ratios in the eucrites compared to c1 chondrites require the separation of an additional 2 to 10 solid metal the lowering of both p la and w la ratios in the moon may be explained by partitioning of p and w into metal during formation of a small core by separation of liquid metal from silicate at low degrees of partial melting of the silicates the w la ratios in the earth and moon are virtually indistinguishable while p la ratios differ by a factor of two the concentrations of feo also appear to be different these observations are difficult to reconcile with the hypothesis of a terrestrial origin of the moon following formation of the earth s core but are consistent with independent formation of the earth and moon

petrology chemistry and isotopic compositions of the lunar highland regolith breccia dar al gani 262 lunar meteorite dar al gani 262 dg 262 found in the libyan part of the sahara is a mature anorthositic regolith breccia with highland affinities the origin from the moon is undoubtedly indicated by its bulk chemical composition radionuclide concentrations noble gas n and o isotopic compositions and petrographic features dar al gani 262 is a typical anorthositic highland breccia similar in mineralogy and chemical composition to queen alexandra range que 93069 about 52 vol of the studied thin sections of dar al gani 262 consist of fine grained 100 m constituents and 48 vol is mineral and lithic clasts and impact melt veins the most abundant clast types are feldspathic fine grained to microporphyritic crystalline melt breccias 50 2 vol includes recrystallized melt breccias whereas mafic crystalline melt breccias are extremely rare 1 4 vol granulitic lithologies are 12 8 vol intragranularly recrystallized anorthosites and cataclastic anorthosites are 8 8 and 8 2 vol respectively and devitrified glasses are 2 7 vol impact melt veins 5 5 vol of the whole thin sections cutting across the entire thin section were probably formed subsequent to the lithification process of the bulk rock at pressures below 20 gpa because the bulk rock never experienced a higher peak shock pressure mafic crystalline melt breccias are very rare in dar al gani 262 and are similar in abundance to those in que 93069 the extremely low abundance of mafic components and the bulk composition may constrain possible areas of the moon from which the breccia was derived the source area of dar al gani 262 must be a highland terrain lacking significant mafic impact melts or mare components on the basis of radionuclide activities an irradiation position of dg 262 on the moon at a depth of 55 85 g cm3and a maximum transit time to earth 0 15 ma is suggested dar al gani 262 contains high concentrations of solar wind implanted noble gases the isotopic abundance ratio 40ar 36ar 3 is characteristic of lunar soils the terrestrial weathering of dg 262 is reflected by the occurrence of fractures filled with calcite and by high concentrations of ca ba cs br and as there is also a large amount of terrestrial c and some n in the sample which was released at low temperatures during stepped heating high concentrations of ni co and ir indicate a significant meteoritic component in the lunar surface regolith from which dg 262 was derived

investigating the shock histories of lunar meteorites miller range 090034 090070 and 090075 using petrography geochemistry and micro ftir spectroscopy fourier transform infrared ftir spectroscopy and cathodoluminescence cl imaging techniques combined with electron microprobe analyses have been used to determine the physical state of feldspathic phases that have been subject to varying levels of shock in the grouped lunar meteorites miller range 090034 090070 and 090075 six feldspathic phases have been identified based on spectral textural and chemical properties a specific infrared wavelength band ratio 1064 932 cm 1 equivalent to 9 40 10 73 m chosen because it can distinguish between some of the feldspathic phases can be used to estimate the pressure regimes experienced by these phases in addition ftir spatial mapping capabilities allow for visual comparison of variably shocked phases within the samples by comparing spectral and compositional data the origin and shock history of this lunar meteorite group has been determined with each of the shocked feldspathic phases being related to events in its geological evolution as such we highlight that ftir spectroscopy can be easily employed to identify shocked feldspathic phases in lunar samples estimate peak shock pressures and when compared with chemical data can be used to investigate their shock histories

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

mineralogy geochemistry and 40ar 39ar geochronology of lunar granulitic breccia northwest africa 3163 and paired stones comparisons with apollo samples abstract the lunar meteorites northwest africa nwa 3163 4881 and 4483 are paired stones classified as granulitic breccias at 2 4 kg these three stones constitute one of the largest known lunar meteorite masses here we describe the petrography mineralogy and chemistry of nwa 3163 4881 and 4483 and present 40 ar 39 ar data for two of the meteorites two pyroxene thermometry indicates that the rocks equilibrated at 1050 50 c which represents the high temperature low pressure event that generated their characteristic recrystallization textures and reset their ar systematics stepped heating in situ infrared laser microprobe 40 ar 39 ar geochronology yields a mean age of 3327 29 ma for nwa 3163 and a more disturbed release spectrum for nwa 4881 nwa 4881 shows an upward trending pattern suggesting that it may have had a 40 ar 39 ar age of 3 0 ga but that it was partially reset at 2 6 ga nwa 3163 et al exhibit shock effects including maskelynitized plagioclase shock veins and melt pockets which are absent in the apollo granulitic breccias although the apollo and meteorite samples are texturally similar and have comparable bulk compositions and equilibration temperatures their trace and siderophile element contents point to distinct parental lithologies derived from different regions of the moon based on mineralogical and geochemical differences between the apollo and meteorite samples we conclude that the parent rock s of the paired nwa meteorites came from an area outside the imbrium region and that they underwent high temperature granulite event metamorphism long after the late heavy bombardment

antarctic meteorite alha 81005 a piece from the ancient lunar crust a 128 mg sample of the antarctic meteorite alha 81005 was analysed for major and trace elements by instrumental neutron activation techniques the meteorite or at least its major components may be older than 4 billion years and represent a piece of the ancient lunar crust before the formation of the large basins on the front side of the moon the evidence is derived from the low absolute content of incompatible elements and their slightly different fractionation pattern from kreep the dominant source for these elements on the front side the basically chondritic pattern of siderophile elements ni co ir au is clearly distinguished from younger basin related meteoritic components