geochemical diversity of shergottite basalts mixing and fractionation and their relation to mars surface basalts the chemical compositions of shergottite meteorites basaltic rocks from mars provide a broad view of the origins and differentiation of these martian magmas the shergottite basalts are subdivided based on their al contents high al basalts al 5 wt are distinct from low al basalts and olivine phyric basalts both with al 4 5 wt abundance ratios of highly incompatible elements e g th la are comparable in all the shergottites abundances of less incompatible elements e g ti lu hf in olivine phyric and low al basalts correlate well with each other but the element abundance ratios are not constant this suggests mixing between components both depleted and enriched high al shergottites deviate from these trends consistent with silicate mineral fractionation the depleted component is similar to the yamato 980459 magma approximately 67 crystal fractionation of this magma would yield a melt with trace element abundances like que 94201 the enriched component is like the parent magma for nwa 1068 approximately 30 crystal fractionation from it would yield a melt with trace element abundances like the los angeles shergottite this component mixing is consistent with radiogenic isotope and oxygen fugacity data these mixing relations are consistent with the compositions of many of the gusev crater basalts analyzed on mars by the spirit rover although with only a few elements to compare other mars basalts fall off the mixing relations e g wishstone at gusev gale crater rocks their compositions imply that basalt source areas in mars include significant complexities that are not present in the source areas for the shergottite basalts

events of sediment deformation and mass failure in upper cretaceous estuarine deposits cameta basin northern brazil as evidence for seismic activity abstract event beds recording late cretaceous synsedimentary seismicity occur in the cameta subbasin northern brazil the deposits consist of nearly 40 m of kaolinized fluvio estuarine deposits the lower fluvial tidal influenced complex which carries a high quality commercial kaolin includes genetically related channel fill floodplain crevasse splay and mud plug deposits the upper estuarine deposits contain trace fossils indicating marine influenced settings thalassinoides ophiomorpha teichichnus diplocraterion skolithos cylindrichnus rhizocorallium and planolites and include heterolithic sandy and bioturbated units interpreted as tidal flat storm overwash and low energy estuarine bay deposits respectively in the upper portion of the estuarine lithosomes four successive events events 1 4 of synsedimentary brittle and ductile deformation and large scale sediment failure anomalous in estuarine settings were recognized and attributed to earthquakes event 1 is recorded by heterolithic and bioturbated deposits with vertical to subvertical fractures that disappear into underlying undeformed deposits event 2 is recorded by thin sharply bounded sections composed of heterolithic mudstone and very fine grained sandstone that shows convolute folds and pillow like structures event 3 is documented by intraformational conglomerate and breccia and minor mudstones and sandstones with abundant trace fossils skolithos and thalassinoides event 4 is characterized by vertical to subvertical fractures and faults with homogenized sandstone intrusions along their planes mostly developed in the upper parts of the deposits corresponding to event 3 a detailed analysis of facies relationships combined with consistent orientations of brittle deformation structures and the regional tectonics of the cameta subbasin suggests earthquakes as the triggering mechanism for sediment deformation and large scale mass failure

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

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 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

the meteoritical bulletin no 85 2001 september meteoritical bulletin no 85 lists information for 1376 newly classified meteorites comprising 658 from antarctica 409 from africa 265 from asia 262 of which are from oman 31 from north america 7 from south america 3 from australia and 3 from europe information is provided for 11 falls dergaon dunbogan gujba independence itqiy moravka oued el hadjar sayama sologne valera and worden noteworthy non antarctic specimens include 5 martian meteorites dar al gani 876 northwest africa 480 and 817 and sayh al uhaymir 051 and 094 6 lunar meteorites dhofar 081 280 and 287 and northwest africa 479 482 and 773 an ungrouped enstatite rich meteorite itqiy a bencubbin like meteorite gujba 9 iron meteorites and a wide variety of other interesting stony meteorites including ch ck cm co cr cv r enstatite and unequilibrated ordinary chondrites primitive achondrites hed achondrites and ureilites

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

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

weathering of meteorites from oman correlation of chemical and mineralogical weathering proxies with 14c terrestrial ages and the influence of soil chemistry fifty four fragments of ordinary chondrites from 50 finds representing all searched areas in central oman and all weathering stages were selected to compare the physical chemical and mineralogical effect of terrestrial weathering with 14c terrestrial ages 14c ages range from 2 0 to 49 kyr with a median value of 17 9 kyr the peak of the age range which is between 10 20 kyr falls in an arid climate period a comparison of the chemical composition of omani chondrites with literature data for unweathered h and l chondrites demonstrates a strong enrichment in sr and ba and depletion in s during weathering water contents in h chondrites increase with terrestrial age whereas l chondrites show a rapid initial increase followed by nearly constant water content correlating sr ba and h2o with age indicates two absorption trends i an initial alteration within the first 20 kyr dominated by h2o uptake mainly reflecting fe ni metal alteration and ii a second baand sr dominated stage correlated with slower and less systematic weathering of troilite that starts after h2o reaches 2 wt sulfur released from troilite partly combines with ba and sr to form sulfate minerals other parameters correlated with 14c age are degree of weathering color of powdered meteorites and the ni fe ratio chemical analyses of 145 soils show a high degree of homogeneity over the entire interior oman desert indicating large scale mixing by wind soil samples collected from beneath meteorite finds typically are enriched in ni and co confirming mobilization from the meteorites high cr and ni concentrations in reference soil samples which decrease from ne to sw are due to detrital material from ultramafic rocks of the oman mountains

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

the meteoritical bulletin no 95 the meteoritical bulletin no 95 reports 1093 282 non antarctic and 801 antarctic newly approved meteorite names and their recovery histories macroscopic descriptions petrography mineral compositions and geochemistry meteorites reported include lunar meteorites eucrites mesosiderites angrites ureilites an acapulcoite and h l ll r co cm ck and cv chondrites three new falls the bunburra rockhole australia eucrite and the recent nov 2008 buzzard coulee canada h4 chondrite and tamdakht morocco h5 chondrite are reported

comparative geochemistry of apollo 16 surface soils and samples from cores 64002 and 60002 through 60007 new data are presented for the concentrations of 23 to 27 elements in nine apollo 16 surface soil samples two subsplits each of 12 splits of core 60002 7 and one subsplit each of 10 splits of drive tube 64002 the surface soils are generally similar to other surface soils collected at their respective stations all ten 64002 samples are similar to each other and to the station 4 surface soils and distinctly different from soils at other stations high iron concentrations previously reported for these same subsplits of 60002 7 result primarily from meteoritic metal one sample from each core is contaminated by stainless steel the recently proposed ferroan anorthositic norites are required to explain the soil compositions a yet uncharacterized component with high concentrations of na sr and eu is also needed

impact melting of lunar meteorite dhofar 458 evidence from polycrystalline texture and decomposition of zircon abstract dhofar 458 is a lunar meteorite consisting mainly of olivine plagioclase intergrowths pyroxene plagioclase intergrowths and plagioclase fragments pyroxene plagioclase globules are also common in this study we report the discovery of a polycrystalline zircon in this lunar meteorite the polycrystalline zircon contains small vesicles and rounded baddeleyite grains at its margin the polycrystalline and porous texture of the zircon indicates high pressure shock induced melting and degassing baddeleyite grains are derived from decomposition of zircon under high postshock temperature the shock features in zircon indicates that the shock pressure in dhofar 458 was greater than approximately 60 gpa and the postshock temperature greater than approximately 1700 c the polycrystalline and degassing texture and decomposition zircon also strongly indicates that dhofar 458 is a clast rich impact melt rock during this shock event most components were melted and grains of mafic minerals are interstitial to lath like plagioclase grains large fragments of olivine and chromite also formed polycrystalline texture at margins and chemically reequilibrated with surrounding melts we suggest that pyroxene plagioclase globules could be remains of melted target clasts whereas vesicles may form during shock induced degassing of the rock the u pb isotopic data plot on a well defined discordant line yielding the age of the zircon of 3434 15 ma 2 this age is interpreted as the time of the impact event that melted dhofar 458 and caused decomposition and recrystallization of this zircon in dhofar 458 which reset this zircon s u pb age

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

analysing the origin of the upper cretaceous lower tertiary rio capim semi flint para state brazil under a sedimentologic perspective abstract the rio capim kaolin one of the largest kaolin reserves in the world currently under exploration is typified by a lower and an upper unit represented of a soft well structured kaolin and a semi flint kaolin respectively the latter term been applied here for a flint like fire clay consisting of indurated kaolinite which develops no plasticity when ground up the latter is characterized by its elevated hardness and massive nature which has been preliminarily attributed to stronger weathering relative to the underlying soft kaolin despite the overall massive aspect a detailed sedimentologic investigation of freshly exposed sections along open mines revealed a variety of structures in the semi flint kaolin that are attributed to primary sedimentary features the features include channel like forms having distinct lags of quartz sandstones at their bottoms these deposits intergrade with strata displaying a series of inclined lines defining lobed bodies that are locally highlighted by distinctively soft massive mud layers the lobes are internally truncated by undulating surfaces attributed to wave erosion the features described in this work are related to deposition of the semi flint kaolin unit in either distributary channels and mouth bar or tidal inlet and tidal delta areas associated with deltaic or wave dominated estuarine settings respectively the recognition of these deposits in the semi flint unit has large implications to analyze its composition which must have primarily included sand grain sizes at least in the case of the lobed strata the apparent muddy nature of the semi flint kaolin might be due at least in part to post depositional modification of a sandy unit composed most likely by grains of previously formed kaolinite derived from reworking of the underlying soft kaolin unit

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

cosmic ray exposure histories of the lunar meteorites aau 012 and shisr 166 we measured the concentrations and isotopic compositions of the stable isotopes of he ne ar kr and xe in the two lunar impact melt breccias abar al uj aau 012 and shisr 166 to obtain information on their cosmic ray exposure histories and possible launch pairing the latter was suggested because of their similar chemical composition aau 012 has higher gas concentrations than shisr 166 and clearly contains implanted solar wind gases indicating a shallow to moderate shielding for this meteorite in the lunar regolith the maximum shielding depth of aau 012 was most likely 310 g cm 2 and its lunar regolith residence time was 420 70 ma our results indicate that in shisr 166 the trapped component is a mixture of air and solar wind the low concentration of cosmogenic and solar wind gases indicate substantial diffusive gas loss and a shielding depth of 700 g cm 2 on the moon for shisr 166 all differences seen in the concentrations and isotopic compositions of the noble gases suggest that aau 012 and shisr 166 are most likely not launch pairs although a different exposure history on the moon does not exclude the possibility that the two meteorites were ejected by a single large impact event

some things we can infer about the moon from the composition of the apollo 16 regolith randy l korotev department of earth and planetary sciences and mcdonnell center for the space sciences washington university st louis missouri 63130 usa author s e mail address rlk levee wustl edu received 1996 september 16 accepted in revised form 1997 may 12 abstract characteristics of the regolith of cayley plains as sampled at the apollo 16 lunar landing site arereviewed and new compositional data are presented for samples of 1 mm fines soils and 1 2 mm rego lith particles as a means of determining which of the many primary igneous and secondary crystalline brec cias lithoiogic components that have been identified in the soil are volumetrically important and providing anestimate of their relative abundances more than 3 x 106 combinations of components representing nearly everylithology that has been observed in the apollo 16 regolith were systematically tested to determine which com binations best account for the composition of the soils conclusions drawn from the modeling include the fol lowing at the site mature soil from the cayley plains consists of 64 5 2 7 components representing prebasin materials anorthosites feldspathic breccias and a small amount 2 6 1 5 of total soil ofnonmare mafic plutonic rocks mostly gabbronorites on average these components are highly feldspathic with average concentrations of 31 32 a1203 and 2 3 feo and a molar mg mg fe ratio of 0 68 theremaining 36 of the regolith is syn and postbasin material 28 8 2 4 mafic impact melt breccias mimbs i e lkfm and vha basalts created at the time of basin formation 6 0 1 4 mare derived material impact and volcanic glass crystalline basalt with an average tio2 concentration of 2 4 and 1 postbasin meteoritic material the mimbs are the principal 80 90 carrier of incompatible traceelements rare earths th etc and the carrier of about one half of the siderophile elements and elementsassociated with mafic mineral phases fe mg mn cr sc most 71 of the fe in the present regolithderives from syn and postbasin sources mimbs mare derived material and meteorites thus althoughthe bulk composition of the apollo 16 regolith is nominally that of noritic anorthosite the noritic part themimbs and the anorthositic part the prebasin components are largely unrelated there is compositionalevidence that 3 4 of the soil is th rich material such as that occurring at the apollo 14 site and one frag ment of this type was found among the small regolith particles studied here if regolith such as that repre sented by the apollo 16 ancient regolith breccias was a protolith of the present regolith such regolith cannotexceed 71 of the present regolith the rest must be material added or redistributed since closure of theancient regolith breccias the postclosure material includes the mare derived material and the apollo 14 like component compositions of all mature surface soils from apollo 16 even those collected 4 km apart on the cayleyplains are very similar which is in stark contrast to the wide compositional range of the lithologies of whichthe soil is composed this uniformity indicates that the ratio of mimbs to feldspathic prebasin componentsis not highly variable in the megaregolith over distances of a few kilometers that there are no large sub surface concentrations of pure mafic impact melt breccia and that the intimate mixing is inherent to thecayley plains at a gross scale thus the mixing ofmafic impact melt breccias and feldspathic prebasin com ponents must have occurred during formation and deposition of the cayley plains such uniformity could nothave been achieved by small postdeposition impacts into a stratified megaregolith using this conclusion asone constraint and the known distribution of th on the lunar surface as another and the assumption that the im brium impact is primarily responsible for formation of the cayley plains arguments are presented that theapollo 16 mimbs derive from the imbrium region and consequently that one fourth of the apollo 16 regolithis primary imbrium ejecta in the form of mafic impact melt breccias

the iab iron meteorite complex a group five subgroups numerous grouplets closely related mainly formed by crystal segregation in rapidly cooling melts abstract we present new data for iron meteorites that are members of group iab or are closely related to this large group and we have also reevaluated some of our earlier data for these irons in the past it was not possible to distinguish iab and iiicd irons on the basis of their positions on element ni diagrams but we now show that plotting the new and revised data yields six sets of compact fields on element au diagrams each set corresponding to a compositional group the largest set includes the majority 70 of irons previously designated ia we christened this set the iab main group the remaining five sets we designate subgroups within the iab complex three of these subgroups have au contents similar to the main group and form parallel trends on most element ni diagrams the groups originally designated iiic and iiid are two of these subgroups they are now well resolved from each other and from the main group the other low au subgroup has ni contents just above the main group two other iab subgroups have appreciably higher au contents than the main group and show weaker compositional links to it we have named these five subgroups on the basis of their au and ni contents the three subgroups having au contents similar to the main group are the low au l subgroups the two others the high au h subgroups the ni contents are designated high h medium m or low l thus the old group iiid is now the slh subgroup the old group iiic is the slm subgroup in addition eight irons assigned to two grouplets plot between sll and slm on most element au diagrams a large number 27 of related irons plot outside these compact fields but nonetheless appear to be sufficiently related to also be included in the iab complex many of these irons contain coarse silicates having similar properties most are roughly chondritic in composition the mafic silicates show evidence of reduction during metamorphism in each case the silicate o isotopic composition is within the carbonaceous chondrite range 17o 0 3 in all but four cases these are within the so called iab range 0 30 17o 0 68 fine silicates appear to be ubiquitous in the main group and low au subgroups this requires that viscosities in the parental melt reached high values before buoyancy could separate these the well defined main group trends on element au diagrams provide constraints for evaluating possible models we find the evidence to be most consistent with a crystal segregation model in which solid and melt are essentially at equilibrium the main arguments against the main group having formed by fractional crystallization are a the small range in ir and b the evidence for rapid crystallization and a high cooling rate through the iron stability field the evidence for the latter are the small sizes of the iron crystals parental to the widmanstatten pattern and the limited thermal effects recorded in the silicates including retention of albitic plagioclase and abundant primordial rare gases in contrast crystal segregation in a cooling metallic melt and related processes such as incomplete melting and melt migration can produce the observed trends in the main group we infer that this melt was formed by impact heating on a porous chondritic body and that the melt was initially hotter than the combined mix of silicates and metal in the local region the melt cooled rapidly by heat conduction into the cooler surroundings mainly silicates we suggest that the close compositional relationships between the main group and the low au subgroups are the result of similar processes instigated by independent impact events that occurred either at separate locations on the same asteroid or on separate but compositionally similar asteroids

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

the regolith portion of the lunar meteorite sayh al uhaymir 169 sayh al uhaymir sau 169 is a composite lunar meteorite from oman that consists of polymict regolith breccia 8 44 ppm th adhering to impact melt breccia imb 32 7 ppm th in this contribution we consider the regolith breccia portion of sau 169 and demonstrate that it is composed of two generations representing two formation stages labeled ii and iii the regolith breccia also contains the following clasts ti poor to ti rich basalts gabbros to granulites and incorporated regolith breccias the average sau 169 regolith breccia bulk composition lies within the range of apollo 12 and 14 soil and regolith breccias with the closest correspondence being with that of apollo 14 but sc contents indicate a higher portion of mare basalts this is supported by relations between sm al2o3 feo cr2o3 tio2 sm eu and th k2o the composition can best be modeled as a mixture of high k kreep mare basalt and norite troctolite consistent with the rareness of anorthositic rocks the largest kreep breccia clast in the regolith is identical in its chemical composition and total ree content to the incompatible trace element ite rich high k kreep rocks of the apollo 14 landing site pointing to a similar source in contrast to apollo 14 soil sau 169 imb and sau 169 kreep breccia clast the sau 169 regolith is not depleted in k th indicating a low contribution of high th imb such as the sau 169 main lithology in the regolith the data presented here indicate the sau 169 regolith breccia is from the lunar front side and has a strong procellarum kreep terrane signature

speleothem evidence from oman for continental pluvial events during interglacial periods growth periods and stable isotope analyses of speleothems from hoti cave in northern oman provide a record of continental pluvial periods extending back over the past four of earth s glacial interglacial cycles rapid speleothem growth occurred during the early to middle holocene 6 10 5 ka b p 78 82 ka b p 120 135 ka b p 180 200 ka b p and 300 325 ka b p the speleothem calcite deposited during each of these episodes is highly depleted in 18 o compared to modern speleothems the d 18 o values for calcite deposited within pluvial periods generally fall in the range of 24 to 28 relative to the vienna peedee belemnite standard whereas modern speleothems range from 21 to 23 the growth and isotopic records indicate that during peak interglacial periods the limit of the monsoon rainfall was shifted far north of its present location and each pluvial period was coincident with an interglacial stage of the marine oxygen isotope record the association of continental pluvial periods with peak interglacial conditions suggests that glacial boundary conditions and not changes in solar radiation are the primary control on continental wetness on glacial interglacial time scales

anatomy of collapsed and re established delta front in lower cretaceous of eastern spitsbergen gravitational sliding and sedimentation processes spectacular coastal cliff exposures in an early cretaceous deltaic succession near kvalvagen in eastern spitsbergen norwegian arctic show a variety of styles of gravity driven deformation and resedimentation associated with delta front progradation and instability the large scale collapse involved a distributary channel sand unit some 20 m thick and the underlying delta slope prodelta shaly heterolithics the deformation was essentially brittle whereby large blocks of the delta front succession slid and rotated its gross style involved two large cuspate tear away scars at least 1 1 5 km wide and 50 60 m deep separated by narrow remnant buttresses of in situ strata the basement in the region was tectonically active and the delta front failure was most likely sei mically triggered initial infill of the collapse scars involved slumps and debris flows derived from scar walls and locally from the sliding blocks themselves these deposits partly smoothed the local topography created by the slide blocks this early infill was followed by deposition of thin mainly muddy turbidites probably shed from the scar walls by small localized failure renewal of fluvial supply of sand led to the main infill of the scar depressions this stage involved effluent generated turbidites heterolithic and increasingly sandier turbidites and liquefied sandflows derived from unstable oversteepened distributary mouthbars the mouth bar systems eventually achieved stability and prograded across the infilled scars they were affected by periodic storm wave attack and sudden increa es of water depth the scar infill at that stage was subject to minor growth faulting possibly related to new seismic tremors

facies architecture and sequential evolution of an incised valley estuarine fill the cujupe formation upper cretaceous to lower tertiary sao luis basin northern brazil abstract the cujupe formation upper cretaceous lower tertiary represents the uppermost part of the itapecuru group in the eastern margin of the sao luis basin northern brazil this unit consists of deposits formed mainly by tidal processes and is attributed to tidal channel subtidal bay fill tidal shoal sand flat and tidal delta depositional settings five stratigraphic intervals us1 us5 defined by discontinuity surfaces l1 l5 capped by lags were recognized within this unit the cujupe formation represents the estuarine fill of an incised paleovalley the estuarine nature of these deposits is suggested by several indirect lines of evidence including 1 tidally influenced facies associations that change rapidly over short distances 2 dominance of tidal channel deposits and 3 an ichnological assemblage suggestive of highly stressed brackish water conditions the five units and the bounding surfaces of the cujupe formation indicate a complex estuarine setting analysis of facies architecture within the stratigraphic intervals points to deposition in an estuary that changed dramatically from a wave dominated us1 us2 to a tide dominated one us3 such a change in style records amplification of the tidal prism which caused flooding of the estuary as the paleocoast dynamics shifted from wave dominated to tide dominated conditions the flooding process is interpreted to reflect rise in relative sea level during the transgression of the paleovalley the subsequent units us4 and us5 formed in a tide dominated estuarine setting but with increased fluvial influence their origin is attributed to high frequency episodes of progradation that took place during the turnaround from the transgressive to the highstand stage of the estuary evolution

exploratory flow duct experiments on combined flow bed configurations and some implications for interpreting storm event stratification abstract experiments were conducted to define equilibrium combined flow bed configurations developed under a wide range of oscillatory uo and unidirectional uu velocity components with a constant oscillation period of 8 5 sec and median grain size of 0 09 mm in the range of flows studied uo 0 0 80 m sec uu 0 0 25 m sec the bed phases are no movement small 2d ripples small 3d ripples large 3d ripples and plane bed small 2d ripples are stable at low uo and uu by increasing either velocity component the plan view bed configuration becomes progressively less regular as small 3d ripples develop small 3d ripples are stable at low to moderate uo and a wide r nge of uu under purely oscillatory flow as uo increases beyond about 0 40 m sec large scale hummocky bed forms become stable when a unidirectional component is applied these bed forms quickly develop a downstream asymmetry and generally move in the direction of uu the dip angles of the lee flanks increase with increasing uu although they remain less than the angle of repose at high oscillatory velocities uo 0 70 0 80 m sec plane bed is the stable bed phase when uu 0 05 m sec much hummocky cross stratification shows a preferred dip direction of the coset laminae our experiments support the idea that such cross stratification is produced by combined flow the large 3d ripples produced at high oscillatory velocities and small to moderate unidirectional velocities would presumably generate what might be called anisotropic hummocky cross stratification if we had been able to aggrade the bed during the runs this would be the case even in dominantly oscillatory flow the experiments show that even a weak unidirectional current of several centimeters per second superimposed upon a strong oscillatory flow results in bed forms that move predominantly in a single direction and that leave sets of laminae that dip predominantly in that direction in runs at large uo the purely oscillatory large scale bed forms were quickly planed off as uu was increased from zero but a series of almost stationary gentle undulations on the bed surface persisted for indefinitely long times where the original topographic highs were situated even at the highest unidirectional flow investigated 0 25 m sec this suggests a possible origin for the gentle undulation observed in cretaceous parallel laminated shallow marine sandstones described by arnott 1987 1988 with spacings up to a few meters and heights not much more than a centimeter

paleosurfaces from northeastern amazonia as a key for reconstructing paleolandscapes and understanding weathering products the characterization and mapping of paleoweathering surfaces as well as their associated deposits throughout the northeastern amazonia can be a useful tool for inter basin stratigraphic correlations and for establishing the evolution of landscapes and climates through time this type of investigation has led to the recognition of five weathering surfaces developed from the upper cretaceous through the quaternary designated here as s1 to s5 surface s1 occurs at the top of late cretaceous deposits represented by the ipixuna cujupe succession as well as on older precambrian and paleozoic rocks surface s2 marks the top of an indurated massive semi flint1 unit for cases in which surfaces s1 and s2 are amalgamated a thick lateritic paleosol displaying hexagonal branched concretions is present surface s3 occurs at the top of the pirabas and lower portion of the barreiras formations of late oligocene early miocene age and it is also associated with paleosol but has no lateritization when surface s3 is amalgamated with surfaces s1 and s2 bauxite is present in association with the underlying laterites surface s4 bounds the top of the middle to upper barreiras formation of middle miocene age as well as correlatable deposits known as the belterra clay this surface is marked by a lateritic paleosol having columnar concretions surface s5 occurs between a lower unit consisting of massive light red sands of the plio pleistocene post barreiras 1 sediments and an upper unit of yellow eolian sands of the holocene post barreiras 2 sediments the paleoweathering surfaces present in the northeastern amazonia enable the reconstruction of several depositional episodes represented by thin only few meters thick sedimentary units from the late cretaceous to the quaternary the creation of new accommodation space on subsiding areas gave rise to sediment accumulation during transgressions intervening weathering surfaces formed during significant falls in relative sea level associated with tectonically stable episodes the overprinting of weathering surfaces formed during different times and thus under different climatic conditions seems to have been crucial for the development of the various weathering products observed throughout the region which include economically important laterites bauxites semi flint beds and kaolin deposits this paper shows that the genesis of these deposits was controlled by the complex interplay of tectonics climate sediment deposition and erosion resulting in a complex evolution of paleolandscapes

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

mineralogy geochemistry and genesis of kaolins from the amazon region the kaolin deposits of the amazon region of brazil are of lateritic origin modified by subsequent reduced lacustrine and or swamp environment they are contemporaneous with lateritic bauxites found in the same region all formed from aluminium silicate rocks these are principally sedimentary rocks from the cretaceous period itapecuru and alter do chao but also include metamorphic and felsic volcanic rocks after erosion of the upper part of these profiles they became locally a substratum for swampy and or lacustrine environments mostly developed over the clayey saprolitic horizon where kaolin occurs the saprolitic horizon is made up mainly of iron mottled kaolinite which has been subject to an intense deferrification which has increased the kaolin brightness and thickness the kaolins are basically made up of well crystallized kaolinite quartz sometimes illite muscovite anatase and hematite in certain locations crandallite goyazite is also present the deposits studied differ from each other in the mineral content levels concentration of principal elements and in trace element distribution the greatest quantity of quartz and consequently sio2 is intrinsically related to the type of parent rock small sedimentary deposits occur in alluvial flood plains located not very far from the lateritic source

lunar granulites and their precursor anorthositic norites of the early lunar crust lunar granulites are breccias with metamorphic textures they are not pristine having been contaminated with meteoritic siderophiles nonetheless they constitute an abundant class of highlands rocks that are important because they are ancient and kreep free they may represent our best samples of the early lunar crust the granulites can be divided into ferroan and magnesian groups and each group can be subdivided on the basis of mineral composition and ree concentrations textural and compositional data show that some of the granulites especially 67215 and 67415 may be derived from distinct anorthositic norite precursors while some other granulites 79215 78155 are clearly polymict even the polymict granulites probably had anorthositic norites as their dominant precursors and not anorthosites norites or troctolites the granulites have compositions similar to those of the two lunar meteorites one of which yamato 791197 is ferroan the other alha81005 magnesian these meteorites are soil breccias from an unknown location distant from the apollo landing sites and contain anorthositic norites as abundant clasts compositions of granulites and lunar meteorites more closely resemble the average composition of lunar highlands as determined by remote sensing than do those of any other returned lunar samples the predominance of plutonic anorthositic norite precursors in material having the composition typical of highlands suggests that plutonic anorthositic norites were more abundant in the early lunar crust than is implied by their scarcity among pristine rocks from apollo missions

magnesian anorthosites and a deep crustal rock from the farside crust of the moon abstract among over thirty lunar meteorites recovered from the hot deserts and antarctica dhofar 489 is the most depleted in thorium 0 05 ppm feo and rare earth elements ree dhofar 489 is a crystalline matrix anorthositic breccia and includes clasts of magnesian anorthosites and a spinel troctolite the mg mg fe mol mg numbers 75 85 of olivine and pyroxene grains in this meteorite are higher than those of the apollo ferroan anorthosites such materials were not recovered by the apollo and luna missions however remote sensing data suggest that the estimated concentrations of th and feo are consistent with the presence of such samples on the farside of the moon the differentiation trend deduced from the mineralogy of the anorthositic clasts define a magnesian extension of the ferroan anorthosite fan trend constructed from the apollo samples the presence of magnesian anorthositic clasts in dhofar 489 still offers a possibility that the farside trend with magnesian compositions is more primitive than the fan trend and may require a revision of this classical differentiation trend the ar ar age of dhofar 489 is 4 23 0 034 gyr which is older than most ar ages reported for highland rocks returned by apollo the old ar ar age of impact formation of this breccia and the presence of a fragment of spinel troctolite of deep crustal origin suggest that a basin forming event on the farside excavated the deep crust and magnesian anorthosites before formation of imbrium

composition and maturity of apollo 16 regolith core 60013 14 abstract samples from every half centimeter dissection interval of double drive tube 60013 14 sections 60013 and 60014 were analyzed by magnetic techniques for fe concentration and surface maturity parameter i s feo and by neutron activation for concentrations of 25 lithophile and siderophile elements core 60013 14 is one of three regolith cores taken in a triangular array 40 50 m apart on the cayley plains during apollo 16 mission to the moon the core can be divided into three zones based both on i s feo and composition unit a 0 44 cm depth is compositionally similar to other soils from the surface of the central region of the site and is mature throughout although maturity decreases with depth unit b 44 59 cm is submature and compositionally more feldspathic than unit a regions of lowest maturity in unit b are characterized by lower sm sc ratios than any soil obtained from the cayley plains as a result of some unidentified lithologic component with low surface maturity the component is probably some type of mafic anorthosite that does not occur in such high abundance in any of the other returned soils unit c 59 62 cm is more mature than unit b and compositionally equivalent to an 87 13 mixture of soil such as that from unit a and plagioclase such as found in ferroan anorthosite similar soils but containing greater abundances of anorthosite plagioclase are found at depth in the other two cores of the array these units of immature to submature soil enriched to varying degrees compared to the mature surface soil in ferroan anorthosite consisting of 99 plagioclase are the only compositionally distinct subsurface similarities among the three cores each of the cores contains other units that are compositionally dissimilar to any soil unit in the other two cores these compositionally distinct units probably derive from local subsurface blocks deposited by the event s that formed the cayley plains the ferroan anorthosite with 99 plagioclase however must represent some subsurface lithology that is significant on the scale of tens of meters the compositional uniformity of the surface soil 0 10 cm depth over distances of kilometers reflects the large scale uniformity of the plains deposits the fine structure reflects small scale nonuniformity and the inefficiency of the impact mixing process at depths as shallow as even one meter

rayleigh wave tomography of the northeastern margin of the tibetan plateau abstract the convergence between the indian continent and the southern margin of eurasia has eventually led to the growth of the tibetan plateau eastward various models have suggested that a large scale flow in the lower crust or and the asthenosphere is responsible for the uplift of eastern tibet it has also been suggested that the continental flow may move around the thick lithosphere of the ordos plateau and the sichuan basin in order to investigate the validity of the crust mantle flow and its possible path we have used rayleigh wave tomography with sensitivity kernels to estimate both the phase velocity structure 20 143 s and the shear wave velocity structure 0 200 km across the northeastern margin of the tibetan plateau from the surface to 100 km our shear wave velocity model shows a prominent low velocity anomaly beneath northeastern tibet suggestive of a warm lithosphere its boundary lies at 105 e longitude which borders the western ordos plateau and sichuan basin from 125 km to 200 km our shear wave velocity model shows a low velocity channel beneath the qilian qinling orogen that lies between the ordos and sichuan blocks this channel may represent the asthenosphere given the fact that the lithosphere is 120 150 km thick in northeastern tibet and the qinling orogen we also inverted for the anisotropy parameters in the study area simultaneously with the velocity parameters the dominant fast direction is nww see generally consistent with the sks splitting results the calculated shear strain from gps and the fault slip rate measurements furthermore the fast directions in our anisotropic model vary only slightly with periods and the anisotropy magnitudes at long periods 100 143 s are large and exceed those at short medium periods 20 80 s indicating potentially although not necessarily vertically coherent deformation from the crust to the asthenosphere and possibly large deformation in the asthenosphere the deformation seems to be linked to the southeastward extrusion tectonics caused by the collision boundary force

depositional model of a macrotidal estuary and floodplain south alligator river northern australia the south alligator river northern territory of australia has a macrotidal estuary tidal influence spring tidal range 5 6 m at the mouth extends 105 km up the channel it is dominated by freshwater in the wet season december april with a salt wedge near the mouth but is well mixed and becomes saline throughout the dry season the tidal channel can be divided into four different channel types an estuarine funnel a sinuous meandering segment a cuspate meandering segment in which the inside of bends are pointed and an upstream tidal channel the distribution of morphologically defined land classes and morphological units within each land class on the floodplain flanking the estuary differs from one channel type to another several stratigraphic and morphostratigraphic units have been recognized from drill holes on the coastal and deltaic estuarine plains and a model of development is proposed on the basis of extensive radiocarbon chronology and palynology the coastal plain has prograded with most rapid sedimentation between 5000 and 3000 yr bp a similar pattern of progradation is identified in the estuarine funnel in the sinuous segment of the estuary the channel has migrated laterally across the floodplain previous channel positions are indicated by palaeochannels and the meander tract is occupied by laminated channel sediments within the cuspate segment there are numerous sinuous palaeochannels on the plains in the upstream segment the channel and palaeochannels have long straight reaches with irregular bends and discontinuous levees and channel avulsion is indicated mangrove mud is a widespread stratigraphic unit throughout the plains the initial phase of development is a transgressive phase 8000 6800 yr bp when mangrove forests extended landwards into a pre existing valley as sea level rose as sea level stabilized the transgressive phase was followed by a widespread mangrove phase termed the big swamp 6800 5300 yr bp the mangrove forests disappeared from most of the plains as vertical accretion continued and were replaced by grass and sedge covered floodplains during the sinuous phase about 5300 2500 yr bp the channel migrated laterally and eroded the deltaicestuarine plain and deposited lateral accretion deposits laminated channel sediments part of the channel of the south alligator river has then progressed from sinuous to cuspate in form and erosion of river banks has occurred transgressive and big swamp phases occurred under rising and stabilizing sea level respectively later morphodynamic channel adjustments occurred under conditions of stable sea level the depositional model has direct application to other estuaries in northern australia and may be applied to other areas where sea level change has been similar

spinel assemblages in lunar meteorites graves nunataks 06157 and dhofar 1528 implications for impact melting and equilibration in the moon s upper mantle

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

petrography and geochemistry of the lapaz icefield basaltic lunar meteorite and source crater pairing with northwest africa 032 we report on the bulk composition and petrography of four new basaltic meteorites found in antarcticalap lapaz icefield 02205 lap 02224 lap 02226 and lap 02436 and compare the lap meteorites to other lunar mare basalts the lap meteorites are coarse grained up to 1 5 mm subophitic low ti basalts composed predominantly of pyroxene and plagioclase with minor amounts of olivine ilmenite and a groundmass dominated by fayalite and cristobalite all of our observations and results support the hypothesis that the lap stones are mutually paired with each other in detail the geochemistry of lap is unlike those of any previously studied lunar basalt except lunar meteorite nwa northwest africa 032 the similarities between lap and nwa 032 are so strong that the two meteorites are almost certainly source crater paired and could be two different samples of a single basalt flow petrogenetic modeling suggests that the parent melt of lap and nwa 032 is generally similar to apollo 15 low ti yellow picritic glass beads and that the source region for lap comes from a similar region of the lunar mantle as previously analyzed lunar basalts

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

pb pb ages and initial pb isotopic composition of lunar meteorites nwa 773 clan nwa 4734 and dhofar 287 4constraining the duration of magmatic activity on the moon is essential to understand how the lunar mantle evolved chemically through time determining age and initial isotopic compositions of mafic lunar meteorites is a critical step in defining the periods of magmatic activity that occurred during the history of the moon and to constrain the chemical characteristics of mantle components involved in the sources of the magmas we have used the in situ pb pb sims technique to investigate eight lunar gabbros and basalts including six meteorites from the northwest africa nwa 773 clan nwa 2727 nwa 2700 nwa 3333 nwa 2977 nwa 773 and nwa 3170 nwa 4734 and dhofar 287a these samples have been selected as there is no clear agreement on their age and they are all from the dominant low titanium chemical group we have obtained ages of 2981 12 ma for nwa 4734 and 3208 22 ma for dhofar 287 for the nwa 773 clan four samples the fine grained basalt nwa 2727 and the three gabbros nwa 773 nwa 2977 nwa 3170 out of six yielded isochron calculated ages that are identical within uncertainties and yielding an average age of 3086 5 ma the age obtained for the fine grained basalt nwa 2700 is not precise enough for comparison with the other samples the gabbroic sample nwa 3333 yielded an age of 3038 20 ma suggesting that two distinct magmatic events may be recorded in the meteorites of the nwa 773 clan the present study aims to identify and assess all potential issues that are associated with different ways to date lunar rocks using u pb based methods to achieve this we have compared the new ages with the previously published data set the entire age data set from lunar mafic meteorites was also screened to identify data showing analytical issues and evidence of resetting and terrestrial contamination the data set combining the ages of mafic lunar meteorites and apollo rocks suggests pulses of magmatic activity with two distinct phases between 3950 and 3575 ma and between 3375 and 3075 ma with the two phases separated by a gap of approximately 200 ma the evolution of the pb initial ratios of the low ti mare basalts between approximately 3400 and 3100 ma suggests that these rocks were progressively contaminated by a kreep like component

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

geochemistry petrology and ages of the lunar meteorites kalahari 008 and 009 new constraints on early lunar evolution abstract kalahari 008 and 009 are two lunar meteorites that were found close to each other in botswana kalahari 008 is a typical lunar anorthositic breccia kalahari 009 a monomict breccia with basaltic composition and mineralogy based on minor and trace elements kalahari 009 is classified as vlt very low ti mare basalt with extremely low contents of incompatible elements including the ree the lu hf data define an age of 4286 95 ma indicating that kalahari 009 is one of the oldest known basalt samples from the moon it provides evidence for lunar basalt volcanism prior to 4 1 ga pre nectarian and may represent the first sample from a cryptomare the very radiogenic initial 176hf 177hf ehf 12 9 4 6 the low ree th and ti concentrations indicate that kalahari 009 formed from re melting of mantle material that had undergone strong incompatible trace element depletion early in lunar history this unusually depleted composition points toward a hitherto unsampled basalt source region for the lunar interior that may represent a new depleted endmember source for low ti mare basalt volcanism apparently the moon became chemically very heterogeneous at an early stage in its history and different cumulate sources are responsible for the diverse mare basalt types evidence that kalahari 008 and 009 may be paired includes the similar fayalite content of their olivine the identical initial hf isotope composition the exceptionally low exposure ages of both rocks and the fact that they were found close to each other since cryptomaria are covered by highland ejecta it is possible that these rocks are from the boundary area where basalt deposits are covered by highland ejecta the concentrations of cosmogenic radionuclides and trapped noble gases are unusually low in both rocks although kalahari 008 contains slightly higher concentrations a likely reason for this difference is that kalahari 008 is a polymict breccia containing a briefly exposed regolith while kalahari 009 is a monomict brecciated rock that may never have been at the surface of the moon altogether the compositions of kalahari 008 and 009 permit new insight into early lunar evolution as both meteorites sample lunar reservoirs hitherto unsampled by spacecraft missions the very low th and ree content of kalahari 009 as well as the depletion in sm and the lack of a kreep like signature in kalahari 008 point to a possible source far from the influence of the procellarum kreep terrane possibly the lunar farside

pb pb geochronology petrography and chemistry of zr rich accessory minerals zirconolite tranquillityite and baddeleyite in mare basalt 10047 abstract in situ u pb isotopic measurements were carried out by ion microprobe on the zr rich accessory minerals zirconolite cazrti2o7 tranquillityite fe82 zry 2ti3si3o24 and baddeleyite zro2 in low k high ti mare basalt 10047 collected during the apollo 11 mission the analysed minerals are concentrated in pockets of late stage mesostasis that comprises an intergrowth of silica barian k feldspar and si al k glass from a phaneritic subophitic basalt comprising mainly pyroxene plagioclase ilmenite cristobalite and troilite most zr rich minerals are unaltered however some tranquillityite is replaced by a complex intergrowth of zirconolite baddeleyite ilmenite and fayalite suggesting that the mineral became unstable during crystallization several baddeleyite crystals have also undergone alteration to secondary zircon zirconolite was analysed in thin section 10047 11 and tranquillityite and baddeleyite in 10047 227 using a 6 m primary ion beam both zirconolite and tranquillityite have significant u and low initial pb contents and are highly suitable for pb pb dating fifteen analyses of zirconolite give a 207pb 206pb age of 3708 7 ma 207pb 206pb 204pb 206pb isochron 95 confidence including renormalisation of ratios and twenty five analyses of tranquillityite give 3710 6 ma the 207pb 206pb dates are consistent with each other and refine results from an earlier study baddeleyite data were less precise mainly due to lower secondary ionisation efficiency our results show that zirconolite and tranquillityite can provide precise isotopic dates and given their presence in other samples they represent important u pb chronometers for refining lunar geology

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

kreepy lunar meteorite dhofar 287a a new lunar mare basalt dhofar 287 dho 287 is a new lunar meteorite found in oman on january 14 2001 the main portion of this meteorite dho 287a consists of a mare basalt while a smaller portion of breccia dho 287b is attached on the side dho 287a is only the fourth crystalline mare basalt meteorite found on earth to date and is the subject of the present study the basalt consists mainly of phenocrysts of olivine and pyroxene set in a finer grained matrix which is composed of elongated pyroxene and plagioclase crystals radiating from a common nucleii the majority of olivine and pyroxene grains are zoned from core to rim in terms of fe and mg accessory minerals include ilmenite chromite ulvaspinel troilite and feni metal chromite is invariably mantled by ulvaspinel this rock is unusually rich in late stage mesostasis composed largely of fayalite si k ba rich glass fluorapatite and whitlockite in texture and mineralogy dho 287a is a low ti mare basalt with similarities to apollo 12 a 12 and apollo 15 a 15 basalts however all plagioclase is now present as maskelynite and its composition is atypical for known low ti mare basalts the fe to mn ratios of olivine and pyroxene the presence of feni metal and the bulk rock oxygen isotopic ratios along with several other petrological features are evidence for the lunar origin for this meteorite whole rock composition further confirms the similarity of dho 287a with a 12 and a 15 sam ples but requires possible kreep assimilation to account for its rare earth element ree contents cooling rate estimates based on fo zonation in olivine yield values of 0 2 0 8 c hr for the lava typical for the center of a 10 20 m thick flow the recalculated major element concentrations after removing 10 15 modal olivine are comparable to typical a 15 mare basalts crystallization mod eling of the recalculated dho 287a bulk composition yields a reasonable fit between predicted and observed mineral abundances and compositions

pinpointing the source of a lunar meteorite implications for the evolution of the moon the lunar meteorite sayh al uhaymir 169 consists of an impact melt breccia extremely enriched with potassium rare earth elements and phosphorus thorium 32 7 parts per million ppm uranium 8 6 ppm potassium oxide 0 54 weight percent and adherent regolith the isotope systematics of the meteorite record four lunar impact events at 3909 13 million years ago ma 2800 ma 200 ma and 0 34 ma and collision with earth sometime after 9 7 1 3 thousand years ago with these data we can link the impact melt breccia to imbrium and pinpoint the source region of the meteorite to the lalande impact crater

compositional and lithological diversity among brecciated lunar meteorites of intermediate iron concentration we present new compositional data for 30 lunar stones representing about 19 meteorites most have iron concentrations intermediate to those of the numerous feldspathic lunar meteorites 3 7 feo and the basaltic lunar meteorites 17 23 feo all but one are polymict breccias some as implied by their intermediate composition are mainly mixtures of brecciated anorthosite and mare basalt with low concentrations of incompatible elements such as sm 1 3 g g these breccias likely originate from points on the moon where mare basalt has mixed with material of the fht feldspathic highlands terrane others however are not anorthosite basalt mixtures three 17 75 g g sm consist mainly of nonmare mafic material from the nearside pkt procellarum kreep terrane and a few are ternary mixtures of material from the fht pkt and maria some contain mafic nonmare lithologies like anorthositic norites norites gabbronorites and troctolite these breccias are largely unlike breccias of the apollo collection in that they are poor in sm as well as highly feldspathic anorthosite such as that common at the apollo 16 site several have high th sm compared to apollo breccias dhofar 961 which is olivine gabbronoritic and moderately rich in sm has lower eu sm than apollo samples of similar sm concentration this difference indicates that the carrier of rare earth elements is not kreep as known from the apollo missions on the basis of our present knowledge from remote sensing among lunar meteorites dhofar 961 is the one most likely to have originated from south pole aitken basin on the lunar far side

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

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

an analysis of apollo lunar soil samples 12070 889 12030 187 and 12070 891 basaltic diversity at the apollo 12 landing site and implications for classification of small sized lunar samples lunar mare basalts provide insights into the compositional diversity of the moon s interior basalt fragments from the lunar regolith can potentially sample lava flows from regions of the moon not previously visited thus increasing our understanding of lunar geological evolution as part of a study of basaltic diversity at the apollo 12 landing site detailed petrological and geochemical data are provided here for 13 basaltic chips in addition to bulk chemistry we have analyzed the major minor and trace element chemistry of mineral phases which highlight differences between basalt groups where samples contain olivine the equilibrium parent melt magnesium number mg atomic mg mg fe can be calculated to estimate parent melt composition ilmenite and plagioclase chemistry can also determine differences between basalt groups we conclude that samples of approximately 1 2 mm in size can be categorized provided that appropriate mineral phases olivine plagioclase and ilmenite are present where samples are fine grained grain size 0 3 mm a paired samples t test can provide a statistical comparison between a particular sample and known lunar basalts of the fragments analyzed here three are found to belong to each of the previously identified olivine and ilmenite basalt suites four to the pigeonite basalt suite one is an olivine cumulate and two could not be categorized because of their coarse grain sizes and lack of appropriate mineral phases our approach introduces methods that can be used to investigate small sample sizes i e fines from future sample return missions to investigate lava flow diversity and petrological significance

comparative zircon u pb geochronology of impact melt breccias from apollo 12 and lunar meteorite sau 169 and implications for the age of the imbrium impact abstract the ages of zircons from high th impact melt breccias imbs from meteorite sayh al uhaymir sau 169 and from rock fragments in soil samples from apollo 12 have been determined using the shrimp ii ion microprobe the imbs are very similar to each other in chemistry mineralogy and texture and the zircons from the kreep rich high th crystalline impact melt have similar u and th contents and identical ages within uncertainties of 3920 13 2 ma sau 169 and 3914 7 2 ma apollo 12 the age results support the idea that the high th imbs apollo 12 and sau 169 formed in the same impact event the similarity of composition and age suggest that sau 169 and the high th imb fragments of apollo 12 originated from the same area of the procellarum kreep terrane we interpret the age of zircon grains in the apollo 12 high th imb as a precise and direct determination of the age of the imbrium impact this age is significantly older than the commonly cited age of 3 85 ga but is similar to recent determinations from sims u pb dating of apollo 14 apatite grains and with anticipated revision of ages by 40 ar 39 ar and 87 rb 86 sr the present zircon 207 pb 206 pb age is the first direct zircon age determination of the imbrium impact event from an apollo sample previous measurements of zircon ages of apollo imbs have recorded events pre dating the imbrium basin forming event

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

western oceanus procellarum as seen by c1xs on chandrayaan 1 we present the analysis of an x ray fluorescence xrf observation of the western part of oceanus procellarum on the moon s nearside made by the chandrayaan 1 x ray spectrometer on 10th february 2009 through forward modelling of the x ray spectra we provide estimates of the mgo sio2 and al2o3 sio2 ratios for seven regions along the flare s ground track these results are combined with feo and tio2 contents derived from clementine multispectral reflectance data in order to investigate the compositional diversity of this region of the moon the ground track observed consists mainly of low ti basaltic units and the xrf data are largely consistent with this expectation however we obtain higher al2o3 sio2 ratios for these units than for most basalts in the apollo sample collection the widest compositional variation between the different lava flows is in wt feo content a footprint that occurs in a predominantly highland region immediately to the north of oceanus procellarum has a composition that is consistent with mixing between low ti mare basaltic and more feldspathic regoliths in contrast to some previous studies we find no evidence for systematic differences in surface composition as determined through x ray and gamma ray spectroscopy techniques

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

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

lunar regolith breccia dhofar 287b a record of lunar volcanism dhofar 287 dho 287 a recently found lunar meteorite consists in large part 95 of low ti mare basalt dho 287a and a minor attached portion 5 of regolith breccia dho 287b the present study is directed mainly at the breccia portion of this meteorite this breccia consists of a variety of lithic clasts and mineral fragments set in a fine grained matrix and minor impact melt the majority of clasts and minerals appear to have been mainly derived from the low ti basalt suite similar to that of dho 287a very low ti vlt basalts are a minor lithology of the breccia these are significantly lower in mg and slightly higher in ti compared to luna 24 and apollo 17 vlt basalts picritic glasses constitute another minor component of the breccia and are compositionally similar to apollo 15 green glasses dho 287b also contains abundant fragments of mg rich pyroxene and anorthite rich plagioclase grains that are absent in the lithic clasts such fragments appear to have been derived from a coarse grained mg rich na poor lithology a kreep component is apparent in chemistry but no highlands lithologies were identified the dho 287 basaltic lithologies cannot be explained by near surface fractionation of a single parental magma instead magma compositions are represented by a picritic glass a low ti na poor glass and a low ti na enriched source similar to the dho 287a parental melt compositional differences among parent melts could reflect inhomogeneity of the lunar mantle alternatively the low ti na poor and dho 287a parent melts could be of hybrid compositions resulting from assimilation of kreep by picritic magma thus the dho 287b breccia contains lithologies from multiple magmatic eruptions which differed in composition formational conditions and cooling histories based on this study the dho 287 is inferred to have been ejected from a region located distal to highlands terrains possibly from the western limb of the lunar nearside dominated by mare basalts and kreep rich lithologies

the meteoritical bulletin no 84 2000 august meteoritical bulletin no 84 lists information for 1341 newly classified meteorites comprising 842 from antarctica 341 from africa 66 from australia 48 from asia including 42 from the arabian peninsula 38 from north america 4 from europe and 2 from south america information is provided for 11 recent falls bilanga devri khera djoumine guangmingshan kitchener kobe leighlinbridge sabrum songyuan tagish lake and vissannapeta 4 martian meteorites dar al gani 670 735 dhofar 019 los angeles and sayh al uhaymir 005 008 3 lunar meteorites northwest africa 032 dhofar 025 and 026 an ungrouped enstatite rich meteorite zaklodzie 11 iron meteorites and a wide variety of other interesting stony meteorites including ck cm co cr cv r enstatite and unequilibrated ordinary chondrites primitive achondrites hed achondrites ureilites and aubrites

update 2012 2017 on lunar meteorites from oman this report presents bulk composition data for 10 lunar meteorite stones from oman for which the names have been approved since june 2012 on the basis of composition and reported find location four new meteorites are represented among this group of stones data from neutron activation analysis of 371 subsamples of all lunar meteorites from oman and saudi arabia analyzed in this laboratory are presented

uranium lead systematics of low ti basaltic meteorite dhofar 287a affinity to apollo 15 green glasses article i nfo dhofar 287 is a lunar meteorite found in oman in 2001 which consists of a major portion 95 of low ti mare basalt dho 287a and a minor attached part 5 of regolith breccia dho 287b here we report the u pb systematics of dho 287a using data collected with a sensitive high resolution ion microprobe shrimp in situ analyses of five merrillite and three apatite grains which are resistant to secondary petrologic events resulted in a total pb u isochron age of 3 34 0 20 ga in 238 u 206 pb 207 pb 206 pb 204 pb 206 pb 3 d space 95 confidence level the observed pb pb isochron of these eight phosphates coupled with four plagioclase grains alsoyieldeda 207 pb 206 pbageof3 35 0 13ga thisformationage whenconsideredasthecrystallizationageof

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

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

petrology geochemistry and age of low ti mare basalt meteorite northeast africa 003 a a possible member of the apollo 15 mare basaltic suite abstract northeast africa 003 nea 003 is a lunar meteorite found as a two paired stones 6 and 118 g in libya 2000 and 2001 the main portion 75 vol of the 118 g meteorite used for this study nea 003 a consists of mare basalt and a smaller adjacent portion 25 vol is a basaltic breccia nea 003 b nea 003 a has a coarse grained magmatic texture consisting mainly of olivine pyroxene and plagioclase the late stage mineral association is composed mainly of elongated plagioclase ilmenite troilite fayalite si k rich glass apatite and a rare sio2 phase other accessory minerals include ulvospinel chromite and trace fe ni metal olivine and pyroxene contain shock induced fractures and plagioclase is completely converted into maskelynite the fe mn values of the whole rock olivines and pyroxenes and the bulk rock oxygen isotopic composition provide evidence for the lunar origin of nea 003 a meteorite this is further supported by the presence of fe ni metal and the anhydrous mineral association nea 003 a is geochemically and petrographically distinct from previously described mare basalt meteorites and is not paired with any of them the petrography and major element composition of nea 003 a is similar to the composition of low ti olivine mare basalts from apollo 12 and olivine normative basalts from apollo 15 the nea 003 a meteorite shows obvious geochemical similarities in trace elements contents with apollo 15 olivine normative basalts and could represent a yet unknown geochemically primitive member of the olivine normative basalt series the meteorite is depleted in rare earth elements ree and incompatible trace elements indicating a primitive character of the parental magma the bulk rock chemical composition demonstrates that the parent melt of nea 003 a was not contaminated with kreep components as a result of magma mixing or assimilation processes results of crystallization modelling and low minimum cooling rate estimates 0 07 c h suggest that the parent melt of nea 003 a crystallized in the lower part of a lava flow containing cumulate olivine 10 and was probably derived from more primitive picritic magma by fractional crystallization processes sm nd dating yields an age of 3 09 0 06 ga which corresponds to the period of lower eratosthenian lunar volcanic activity and the near chondritic end value of 0 4 0 3 indicates that the meteorite could be derived from a slightly enriched mantle source similar to the apollo 15 green glasses ar ar step release results are inconsistent with sm nd ages suggesting that nea 003 a was exposed to one or more impact events the most extensive event took place at 1 8 ga and the shock intensity was likely between 28 and 45 gpa the absence of solar ar suggests that nea 003 a has not been directly exposed at the lunar surface but the cosmic ray exposure age of 209 6 ma suggests that nea 003 a resided in the upper regolith for part of its history

dynamic changes and processes in the mississippi river delta research in the modern delta of the mississippi river has revealed short term changes and processes that are of significant magnitude deltaic lobes each lobe covering an area of 30 000 sq km and having an average thickness of 35 km switch sites of deposition on an average of every 1 500 yr through short periods of geologic time this process results in a relatively thick accumulation of stacked deltaic cycles covering extremely large areas within a single delta lobe and operating on an even higher frequency are bay fills and overbank splays bay fills having areas of 250 sq km and thickness of 15 m require only 150 yr to accumulate four major events have taken place in the modern balize delta since 1838 overbank splays are much smaller covering areas of less than 2 sq km and having thicknesses of 3 m but are associated with high floods on the river at the river mouth continued progradation of the distributary channel can form distributary mouth sand bodies that have dimensions of 17 km long 8 km wide and a thickness of 80 m in a period of only 200 yr differential sedimentary loading at the river mouth results in formation of diapirs that display vertical movements in excess of 100 m in a period of 20 yr on the subaqueous delta platform sediment instabilities operate nearly continuously mass moving large quantities of shallow water deposits to deeper water environments via arcuate rotational slides and mudflow gullies and depositional lobes all of these changes and processes operate at differing spatial and temporal scales but all result in deposition of large volumes of sediment over extremely short periods of time

composition and origin of the clay cover on north brazilian laterites the belterra clay in northern brazil is a uniform yellowish unstratified kaolinitic clay with variable contents of gibbsite it is generally 5 10 m thick and covers a lateritic weathering crust on remnants of a dissected table land complete profiles with belterra clay the underlying bauxite laterite and saprolite bed rock were sampled in three areas of the amazon region the chemical and mineralogical data show a distinct affinity between the belterra clay and the underlying layers above all with the saprolite variations in the composition of the underlaying layers are reflected by the belterra clay among the structural and textural features important for the discussion of the origin of the belterra clay are the sharp contact between the clay cover and the underlying laterite as well as conglomeritic brecciate textures and occasional bedding structure in the upper part of the lateritic crust

microlites and nanolites in rhyolitic glass microstructural and chemical characterization we used transmission electron microscopy tem and scanning electron microscopy sem to study magmatic crystals in the ben lomond rhyolite lava dome taupo volcanic center new zealand using tem and sem to investigate the size distributions of these crystals we identified three size populations microphenocrysts 1 2 m wide microlites 0 6 m wide and smaller crystals 0 6 m wide which we term nanolites the predominant mineral phases of the microlites and nanolites are augites pigeonites and hypersthenes the compositions and microstructures within these pyroxenes indicate disequilibrium crystallization at approximately 850 900 c and undercoolings as high as 300 c from equilibrium crystallization temperatures complex microstructures resulting from subsolidus reactions in augite and pigeonite are consistent with moderate cooling rates within the upper obsidian layer of the ben lomond rhyolite dome this study demonstrates the existence of sub micron magmatic crystals in a rhyolite and illustrates the potential of tem to provide unique information about the crystallization and cooling histories of glassy volcanic rocks

the meteoritical bulletin no 86 2002 july abstract meteoritical bulletin no 86 lists information for 1154 newly classified meteorites comprising 661 from antarctica 218 from africa 207 from asia 203 of which are from oman 62 from north america 3 from south america and 3 from europe information is provided for 5 falls el idrissia undulung dashoguz el tigre and yafa noteworthy specimens include 7 martian meteorites dhofar 378 grove mountains 99027 northwest africa 856 1068 and 1110 and sayh al uhaymir 060 and 090 4 lunar meteorites dhofar 301 302 303 and 489 9 new iron meteorites a mesosiderite northwest africa 1242 an ungrouped stony iron meteorite dar al gani 962 and a wide variety of other interesting stony meteorites including ch ck cm cr cv r enstatite unequilibrated ordinary and ungrouped chondrites primitive achondrites howardite eucrite diogenite hed achondrites and ureilites

the petrogenesis of impact basin melt rocks in lunar meteorite shisr 161 this study explores the petrogenesis of shisr 161 an immature lunar regolith breccia meteorite with low abundances of incompatible elements a feldspathic affinity and a significant magnesian component our approach was to identify all clasts 0 5 mm in size in a thin section characterize their mineral and melt components and reconstruct their bulk major and minor element compositions trace element concentrations in representative clasts of different textural and compositional types indicate that the clast inventory of shisr 161 is dominated by impact melts that include slowly cooled cumulate melt rocks with mafic magnesian mineral assemblages minor exotic components are incompatible element rich melt spherules and glass fragments and a gas associated spheroidal precipitate our hypothesis for the petrologic setting of shisr 161 is that the crystallized melt clasts originate from the upper 1 km of the melt sheet of a 300 to 500 km diameter lunar impact basin in the moon s feldspathic highlands this hypothesis is based on size requirements for cumulate impact melts and the incorporation of magnesian components that we interpret to be mantle derived the glassy melts likely formed during the excavation of the melt sheet assemblage by an impact that produced a 15 km diameter crater the assembly of shisr 161 occurred in a proximal ejecta deposit of this excavation event a later impact into this ejecta deposit then launched shisr 161 from the moon our geochemical modeling of remote sensing data combined with the petrographic and chemical characterization of shisr 161 reveals a preferred provenance on the moon s surface that is close to pre nectarian riemann fabry basin

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

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

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

very high k kreep rich clasts in the impact melt breccia of the lunar meteorite sau 169 new constraints on the last residue of the lunar magma ocean abstract in the impact melt breccia imb of sayh al uhaymir sau 169 the most kreep rich lunar meteorite to date gnos et al 2004 clasts of a new type of lithologies were discovered consisting of ca poor and ca rich pyroxenes 60 8 vol ba rich k feldspar 27 9 vol phosphates 5 6 vol nb rich ilmenite 4 0 vol zircon 1 2 vol and minor sulfide 0 6 vol these mafic lithic clasts are more enriched in kreep component 1500 ci than the host meteorite and are highly enriched in potassium they are referred to as very high k vhk kreep lithology and probably most close to the last residual liquid of the lunar magma ocean without significant dilution by other mg rich magmas the fine grained matrix of the sau 169 imb has very similar mineral chemistry to the vhk kreep lithology but contains abundant plagioclase with trace k feldspar the matrix shows decoupling of k from the reep like component however it cannot be simply interpreted by mixing the vhk kreep lithology with anorthosites which should have diluted the reep like component with the same proportion sims pb pb dating was conducted on zircons in various petrographic settings and with different crystal habits all analyses show a main age peak at 3921 3 ma and a smaller one at 4016 6 ma the main age peak is identical to the previous pb pb age by gnos et al 2006 and u pb age by liu et al 2009 dating the catastrophic shock event contributed to the formation of sau 169 imb the older ages are consistent with the previous report of an older bulk u pb age by kramers et al 2007 suggestive of presence of relict crystals in a few large zircon grains the vhk kreep clasts predated the fine grained matrix but have the same zircon pb pb ages as the latter within the analytical uncertainties plagioclase was converted to maskelynite whereas zircon was shocked to diaplectic glass probably by a second event at 2 8 ga however the identical zircon pb pb ages of the amorphous parts and the remained crystalline areas indicate no resetting of pb pb isotopes by the later shock metamorphism or there was another severe impact event postdated solidification of the fine grained matrix within a few million years