the oxygen isotope composition petrology and geochemistry of mare basalts evidence for large scale compositional variation in the lunar mantle to investigate the formation and early evolution of the lunar mantle and crust we have analysed the oxygen isotopic composition titanium content and modal mineralogy of a suite of lunar basalts our sample set included eight low ti basalts from the apollo 12 and 15 collections and 12 high ti basalts from apollo 11 and 17 collections in addition we have determined the oxygen isotopic composition of an apollo 15 kreep k potassium ree rare earth element and p phosphorus basalt sample 15386 and an apollo 14 feldspathic mare basalt sample 14053 our data display a continuum in bulk rock delta o 18 values from relatively low values in the most ti rich samples to higher values in the ti poor samples with the apollo 11 sample suite partially bridging the gap calculation of bulk rock delta o 18 values using a combination of previously published oxygen isotope data on mineral separates from lunar basalts and modal mineralogy determined in this study match with the measured bulk rock delta o 18 values this demonstrates that differences in mineral modal assemblage produce differences in mare basalt delta o 18 bulk rock values differences between the low and high ti mare basalts appear to be largely a reflection of mantle source heterogeneities and in particular the highly variable distribution of ilmenite within the lunar mantle bulk delta o 18 variation in mare basalts is also controlled by fractional crystallisation of a few key mineral phases thus ilmenite fractionation is important in the case of high ti apollo 17 samples whereas olivine plays a more dominant role for the low ti apollo 12 samples consistent with the results of previous studies our data reveal no detectable difference between the delta o 17 of the earth and moon the fact that oxygen three isotope studies have been unable to detect a measurable difference at such high precisions reinforces doubts about the giant impact hypothesis as presently formulated

interior of the moon the presence of garnet in the primitive deep lunar mantle new trace element data have been generated by inductively coupled plasma mass spectrometry icp ms for 65 high and low ti mare basalts from the apollo 11 12 14 15 and 17 landing sites these data demonstrate that ratios of the high field strength elements and yttrium are generally chondritic in the mare source regions for the low ti basalts but nonchondritic in the high ti basalts and potassium rare earth elements and phosphorus kreep such differences can be explained by addition and subtraction respectively of ilmenite this interpretation is consistent with derivation of the basalts from lunar magma ocean lmo cumulates through which late stage ilmenite has sunk and mixed with earlier magma ocean products compositional differences between the mare basalts and volcanic glass beads suggest that at least some of the latter were derived from a garnet bearing source region siderophile and chalcophile element data suggest that the garnet bearing source escaped the lmo melting event and thus represents primitive moon material the remaining glasses are generally very low ti vlt and appear to have been derived from early lmo cumulates i e olivine and orthopyroxene similar to the vlt basalts the remaining glasses were derived from below the lmo cumulates and as the magmas rose they underwent sequential assimilation to varying degrees initially of an ilmenite rich cumulate followed by a kreep component this study presents geochemical evidence for the existence of garnet in a mare source and demonstrates the likelihood that the lmo was not whole moon thus preserving primitive lunar material which has acted as the source region for at least some of the volcanic glasses

the influence of ambient groundwater discharge on exchange zones induced by current bedform interactions summary we use numerical modeling to investigate the interactions between laminar flow in a water column current bedform induced flow in underlying permeable sediments and discharge of deep groundwater to the water column groundwater discharge reduces the spatial extent of current induced exchange zones within the sediments and may completely prevent the development of current bedform induced flow at high groundwater discharge although exchange zone size is reduced by groundwater discharge the reduction in exchange flux is not significant suggesting reduced residence times of materials cycled through these smaller zones fluid exchange zones tend to be centered around the reattachment points of eddies that also mark the location of flow divides within the sediments while deep groundwater is discharged preferentially along troughs exchange zone depth and the water column reynolds number are functionally related through a morgan mercer flodin model the relationship between the current induced flux through the sediments and the reynolds number is described by low order monotonic polynomial functions

meteomod a numerical model for the calculation of melting crystallization relationships in meteoritic igneous systems the meteomod model is a computer program designed to calculate melting crystallization relationships in igneous systems compositionally similar to ordinary chondrites and basaltic achondrites the core of meteomod is a set of empirically calibrated equations called geothermometers which describe equilibria between silicate melt and minerals such as olivine orthopyroxene pigeonite augite plagioclase and metallic fe in terms of pressure temperature and liquid compositions the silicate mineral geothermometers are calibrated from a database containing the compositions of melts and minerals produced in melting experiments on 113 meteoritic and 141 synthetic systems the metallic iron silicate melt geothermometer is calibrated from a database of 396 melting experiments the meteorite melting model or meteomod calculates crystallization temperatures and contents of major end members in mineral solid solutions with accuracies of 10 15 c and 1 2 mol respectively input parameters for the program are 1 increment in crystallization degree 2 one of 12fo2 buffers routinely used in petrology 3 shift from the buffer in log units if any 4 a choice of equilibrium or fractional crystallization trajectory 5 terminal crystallization degree 6 contents of ten major elements in wt 7 a set of minor and trace elements in parts per million 8 the number of initial compositions to be modeled in a single computation run the output consists of a series of tables that list equilibrium temperatures o fugacities and proportions of melt and minerals and their compositions as a function of the degree of crystallization the results of application of meteomod to modeling of melting crystallization of the st severin ll chondrite are compared with the experimental data of jurewicz et al 1995

hydraulic and thermal response of groundwater surface water exchange to flooding in an experimental aquifer summary the effects of flooding on interactions between streams and shallow aquifers are poorly studied due to the unpredictable nature of flooding events this study examines groundwater surface water interactions in a constructed experimental meander over several simulated flood events using hydrologic and thermal monitoring detailed steady state hydraulic head measurements were taken of the stream surface and in 59 piezometer nests during baseflow bankfull flow and overbank flooding conditions allowing for three dimensional hydrologic characterization additionally a lithium tracer test was conducted and pressure transducers and thermistors were deployed to capture transient behavior results demonstrate extensive coupling between the stream and adjacent alluvial aquifer under all discharge conditions water table elevation responds rapidly to changes in stream stage and re equilibrates to order of magnitude increases in discharge within about 1 h though flooding elevates the water table steady state hydraulic gradients within the meander are independent of stream stage this results from the flow boundary condition imposed by the stream which deepens in response to flooding but has a slope that is essentially independent of discharge in addition to the stream boundary flow within the meander is also controlled by loss of stream water to the subsurface which directs hydraulic gradients towards the base of the meander finally the temperature distribution within the meander during normal and bankfull flow mimics the water table distribution and results from advected warm stream water being progressively cooled by vertical conduction in the direction of groundwater flow these findings suggest that areas of high reaction rates within meanders hot spots will be sensitive to whether a stream reach is gaining or losing water to the subsurface further the location of these hot spots of is likely independent of stream stage though other controls on reaction rates may be affected

on the connection between mare basalts and picritic volcanic glasses the evolution of the major element compositions of mare basaltic liquids and coexisting crystals in low pressure fractionation processes has been modeled in order to examine the postulated link between picritic volcanic glasses and mare basalts existing models of equilibrium and fractional crystallization longhi 1977 1982 have been modified to include expressions for the cr spinel liquidus surface and the boundary between the armalcolite and ilmenite surfaces average molar partition coefficients for armalcolite liquid pairs are also included in the modifications results of the calculations show that most mare basalts are not derived by simple low pressure fractionation from parents with the compositions of picritic glasses as tabulated by delano 1986a also there is no indirect evidence as yet for posteruption fractionation of picritic magmas in the form of sufficiently magnesian mare type olivines at the apollo 12 and 15 landing sites however the calculations do suggest that luna 24 ferrobasalt and apollo 11 high k basalts could have been derived by simple near surface fractionation of known picritic compositions also xenocrystic olivines with mare like concentrations of tio2 and cao in high ti basalt 74275 provide evidence for the existence of a picritic magma at the apollo 17 site more importantly the calculations indicate that the picritic magmas would have fractionated to produce basalts with bulk and mineral compositions generally similar to those of mare basalts these latter results favor the hypothesis that mare basalts have fractionated nonprimary compositions and that the small number of observed linkages between basalts and picritic parents is a consequence of limited sampling

stream aquifer interactions and hyporheic exchange in gaining and losing sinuous streams 1 the irregular planform morphology of rivers leads to formation of hyporheic zones along its banks this study investigates how hyporheic exchange in stream banks whose planform is idealized as sinusoidal is affected by net gains from and net losses of water to the adjacent aquifer these effects are studied via numerical modeling of groundwater flow adjacent to sinuous channels across a broad range of sinuosity and gain loss magnitude hyporheic zone areas and fluxes both decrease exponentially with increasing magnitude of net gain or loss relative to the case where the stream has no net flux of water neutral residence time through the hyporheic zone also decreases with gain loss magnitude the hyporheic zones become constrained near the apex of bends indicating that these areas could be hot spots for mixing and biogeochemical processing hyporheic zones in channels with smaller sinuosity are more prone to hyporheic flux and area reduction while very sinuous channels are able to maintain a hyporheic zone even under largely losing or gaining conditions equations fitted to the suite of simulation results allow for prediction of hyporheic flux area and residence time on the basis of aquifer hydraulic conductivity channel sinuosity and the ratio of along valley and across valley mean head gradients

petrogenesis of primitive and evolved basalts in a cooling moon experimental constraints from the youngest known lunar magmas abstract we have conducted high temperature experiments over a range of pressures to constrain the petrogenesis of the youngest sampled lunar magmas which have contrasting primitive and evolved compositions our results indicate that at 3 ga melting still occurred within the same mantle depth range that produced crystalline mare basalts for the previous 1 ga although our data cannot support or confirm that the shallowest extents of melting moved deeper into the mantle by 3 ga as is predicted by most thermal evolution models furthermore melting still occurred in regions with low abundances of heat producing elements basaltic lunar meteorite nea 003a has some of the lowest abundances of incompatible trace elements among all mare basalts and no negative eu anomaly our experiments show that nea 003a is multiply saturated with olivine and low ca pyroxene on its liquidus at 1 1 gpa 215 km and 1330 c if the primitive nea 003a liquid composition is a minimally modified melt the relatively low mg of its source region 73 75 its lack of a eu anomaly and its chondritic initial nd isotopic composition indicate its source region likely escaped mixing during mantle overturn with later stage magma ocean cumulates that formed after plagioclase saturation this condition would require the sources of the ultramafic glasses to have experienced cumulate mixing or for assimilation of later stage magma ocean cumulates by the ultramafic glass parental magmas before eruption in order to account for their higher mg s and deeper negative eu anomalies alternatively nea 003a may have undergone some fractional crystallization in which case its more primitive source region would be deeper than 215 km and may approach the depth range of the ultramafic glass source regions iron and incompatible trace element rich basaltic lunar meteorites lap 02205 nwa 032 479 and nwa 4734 have nearly identical bulk compositions and have a multiple saturation point on their high pressure liquidus at

magmatic evolution of the moon although incomplete because of the imperfect and somewhat random sampling of rock types by the apollo and luna missions 1969 1976 the history of lunar magmatism has been reconstructed by numerous researchers over the past three decades these reconstructions have illustrated the continuous nature of lunar magmatism from 4 6 to approximately 2 0 ga and the large influence of early differentiation and catastrophic bombardment on lunar mantle dynamics magmatism and eruptive style in this review we group magmatism into multiple stages of activity based on sampled rock types and evaluate the models for each stage stage 1 is early lunar differentiation and associated magmatism partial melting of the moon soon after accretion was responsible for producing an anorthositic crust and a differentiated lunar interior the extent of lunar melting and mantle processing depends strongly on the mechanisms that induced melting estimates for the time over which melting and crystallization occurred range from tens to hundreds of millions of years stage 2 is the disruption of lunar magma ocean cumulates soon after the crystallization of most of the lunar magma ocean the cumulate pile experienced gravitational overturn this resulted in transport of late forming cumulates into the deep lunar mantle and mixing of magma ocean cumulates on a variety of scales stage 3 is the post magma ocean highland magmatism whereas the ferroan anorthositic crust was probably produced during the crystallization of a magma ocean the slightly younger mg suite and alkali suite plutonic rocks may have been generated by decompressional melting of early magma ocean cumulates during cumulate pile overturn a kreep and crustal signature was incorporated into these primitive basaltic magmas through assimilation near the base of the lunar crust or through melting of a hybridized mantle the alkali suite could represent either the differentiation products of mg suite parental magmas or a separate but contemporaneous episode of basaltic magmatism stage 4 is pre basin volcanism sample analysis and remote sensing data indicate that early lunar volcanism kreep basalts and high alumina basalts was contemporaneous with periods of highlands plutonism and catastrophic bombardment of the lunar surface the relationship between early stages of lunar volcanism and the contemporaneous plutonism is not clear the kreep basalts may be volcanic equivalents to both the mg suite and alkali suite stage 5 is the late remelting of magma ocean cumulates and eruption of mare basalts basin associated eruption of mare basalts occurred during and following the late stages of catastrophic bombardment this volcanic activity was possibly an extension of the thermal event that initiated pre basin volcanism mare basalts exhibit a wide range of composition resulting from near surface fractionation of chemically distinct primary basaltic magmas most likely mare basalts were produced by small to moderate degrees of partial melting of hybrid cumulate sources in the deep lunar mantle alternatively the mixed chemical signatures observed in many mare basalts may be interpreted as indicating assimilation of late stage evolved cumulates by melts produced deep in the cumulate pile the wide range of compositions exhibited by the mare basalts compared with earlier episodes of basaltic magmatism may reflect the thermal regime in the lunar mantle that limited the extent of partial melting and melt source homogenization

effect of experimental wood addition on hyporheic exchange and thermal dynamics in a losing meadow stream 1 stream restoration structures such as large wood can enhance shallow river groundwater exchange or hyporheic exchange and alter temperature dynamics in restored reaches we added and then removed channel spanning logs in a second order mountain meadow stream to test short term impacts on hyporheic exchange streambed temperatures and surface water temperatures based on vertical seepage measurements and numerical simulations of hyporheic fluid and heat flow large wood addition increased hyporheic exchange and altered streambed temperatures in this losing stream meter scale hyporheic exchange cells formed beneath large wood upwelling pore water downstream of logs stabilized diel temperature cycles across 8 of the streambed creating localized but potentially valuable thermal refuge exchange rates were 0 1 of channel discharge too small to impact the range of diel temperature signals in surface water however the lag between downstream and upstream diel temperature signals was slightly greater with large wood which may indicate that surface storage zones rather than hyporheic storage zones increased thermal retardation losing conditions limited the spatial extent and rates of hyporheic exchange near large wood impacts of large wood reintroduction on hyporheic exchange depend on ambient groundwater discharge or recharge streambed permeability channel froude number large wood blockage ratio and large wood spacing in many streams large wood reintroduction may increase hyporheic habitat volume and complexity but may not increase exchange rates enough to alter surface water temperature or chemistry surface storage zones such as eddies and pools can still influence heat and solute retention in the channel

a model for lateral hyporheic flow based on valley slope and channel sinuosity 1 the meandering of rivers results in head gradients across point bar deposits leading to hyporheic exchange the flow of groundwater from and back to the stream two models for predicting horizontal fluid flux through the hyporheic zone one based solely on valley slope and another that uses both valley slope and channel sinuosity are presented in this article both models require knowledge of aquifer hydraulic conductivity the models are developed via a suite of groundwater flow simulations with boundary conditions taking a variety of channel geometries idealized as sinusoidal and valley slopes that we assume are similar to that of the water table functional predictive models are developed by fitting a line or surface to discrete model output which covers the spectrum of most natural meandering rivers since the fitted models only require channel slope and or sinuosity plus hydraulic conductivity they are amenable for regional estimation of hyporheic flux using digital terrain data

lunar volcanic glasses and their constraints on mare petrogenesis abstract volcanic glasses from the apollo 11 14 15 and 16 landing sites have been analyzed for major elements and ni by electron microprobe the 19 varieties of volcanic glass define two distinct chemical arrays that provide new insights into a the petrogenesis of mare basalts and b the structure of the deep lunar interior a simple model is proposed whereby mare basaltic liquids may have been derived from two isolated cumulate systems occurring at depths of 300 km and 400 km each system was itself composed of two lithologic components low ti vs high ti that underwent hybridization assimilation or mixing to generate the large compositional range of magmas observed within each array while the distribution of the two components within each system was locally heterogeneous data indicate that the components themselves were chemically uniform on at least a regional scale the surface correlated volatiles associated with the lunar volcanic glasses seem to have come from some other reservoir within the moon the simplicity of the chemical relationships observed among the lunar volcanic glasses allow specific predictions to be made we believe that they should readily reveal any strengths or weaknesses of this new model

the effect of streambed topography on surface subsurface water exchange in mountain catchments a numerical hydrological simulation suggested that water exchange between stream channels and adjacent aquifers is enhanced by convexities and concavities in streambed topography at st kevin gulch an effluent stream in the rocky mountains of colorado subsurface hydraulic gradients and movement of ionic tracers indicated that stream water was locally recharged into well defined flow paths through the alluvium stream water filled flow paths in the alluvium referred to as substream flow paths returned to the stream a short distance downstream 1 to 10 m recharge to the substream flow paths occurred where stream water slope increased at the transition from pools 1 to steeper channel units 5 20 return of substream flow paths to the stream occurred where stream water slope decreased at the transition from steeper channel units to pools a net water flux calculation is typically used to characterize water and solute fluxes between surface and subsurface zones of catchments along our study reach at st kevin gulch the net inflow of water from subsurface to stream 1 6 ml s 1 m 1 underestimated the gross inflow 2 7 ml s 1 m 1 by 40 the influence of streambed topography is to enhance hydrological fluxes between stream water and subsurface zones and to prolong water sediment contact times these effects could have important consequences for solute transport retention and transformation in catchments

pristine lunar glasses criteria data and implications major element analyses of several thousand glasses from all of the apollo landing sites have resulted in the identification of 25 groups of pristine i e volcanic glass the nickel in these pristine glasses is shown to be indigenous not meteoritic contamination and to be correlated with mg the chemical data indicate that these glasses are consistently better candidates for primary magmas than the majority of crystalline mare basalts the pristine glasses support the view that assimilative processes ringwood and kesson 1976 involving two cumulate systems in the differentiated mantle operated during mare petrogenesis the reality of those assimilative interactions is evident by the occurrence of two linear arrays among the chemistries of the glasses data suggest that these cumulate components in the differentiated mantle persist for lateral distances of at least 1000 km and therefore appear to be products of a vast magma ocean that existed early in lunar history alternative hypotheses claiming that the highlands crust and mare source regions were produced by serial magmatism without a magma ocean have not yet considered all of the constraints derived from the pristine glasses

the effect of river bend morphology on flow and timescales of surface water groundwater exchange across pointbars summary head gradients along meandering rivers induce surface water groundwater exchange across pointbars we analyze this exchange process by finite element modeling of groundwater flow and transport through model generated river planforms taken from previous studies the river is considered as a constant head boundary that decreases linearly along the direction of the channel this leads to an irregular groundwater flowfield in the pointbar that is controlled by channel sinuosity simulations under homogeneous aquifer conditions shows that the variable flowpath lengths coupled with the heterogeneous flow velocities lead to non fickian transport characterized by power law residence time distributions this anomalous transport behavior is enhanced by increased aquifer dispersivity the broad transit time distribution implies that time dependent chemical transformation processes in near stream zones may be equally variable as the flowfield even in the absence of heterogeneity in aquifer hydraulic properties

assimilation by lunar mare basalts melting of crustal material and dissolution of anorthite we discuss techniques for calculating the amount of crustal assimilation possible in lunar magma chambers and dikes based on thermal energy balances kinetic rates and simple fluid mechanical constraints assuming parent magmas of picritic compositions we demonstrate the limits on the capacity of such magmas to melt and dissolve wall rock of anorthitic troctolitic noritic and kreep quartz monzodiorite compositions significant melting of the plagioclase rich crustal lithologies requires turbulent convection in the assimilating magma and an efficient method of mixing in the relatively buoyant and viscous new melt even when this occurs the major element chemistry of the picritic magmas will change by less than 1 2 wt diffusion coefficients measured for al2o3 from an iron free basalt and an orange glass composition are 10 12 m2 s 1 at 1340 c and 10 11 m2 s 1 at 1390 c these rates are too slow to allow dissolution of plagioclase to significantly affect magma compositions picritic magmas can melt significant quantities of kreep which suggests that their trace element chemistry may still be affected by assimilation processes however mixing viscous melts of kreep composition with the fluid picritic magmas could be prohibitively difficult we conclude that only a small part of the total major element chemical variation in the mare basalt and volcanic glass collection is due to assimilation fractional crystallization processes near the lunar surface instead most of the chemical variation in the lunar basalts and volcanic glasses must result from assimilation at deeper levels or from having distinct source regions in a heterogeneous lunar mantle

thermal regime of dune covered sediments under gaining and losing water bodies 1 we investigate the effects of current bed form induced flow and heat transport through permeable bottom sediments overlain by a marine or terrestrial water column that is gaining or losing deep groundwater heat transport is forced by the diel variation of temperature in the water column the investigation utilizes sequentially coupled simulations of turbulent flow in the water column and darcy flow and heat transport in the sediments the simulations address the question when where and by how much are diel water column temperature variations transmitted into sediments subjected to ambient groundwater discharge this is crucial information for detecting observing and predicting temperature sensitive biogeochemical and ecological processes in the bottom sediments when the groundwater gain or loss is small it has no appreciable effect on temperatures in the sediments which are controlled by heat conduction and current bed form induced heat advection as losing discharge increases the temperature signal from the water column penetrates deeper into the sediments with the largest temperature variations found under a downwelling zone along the stoss side of the bed form and damped temperature variations found near a narrow upwelling zone below the crest similar patterns are observed under gaining conditions but with temperature variations penetrating to shallower depths the interfacial exchange zone is diminished by upward movement of deep groundwater large gains or losses of deep groundwater prevent the formation of an interfacial exchange zone making heat transport almost vertically one dimensional the sensitivity of the sediment thermal regime to hydrodynamic conditions increases with increasing water column current reynolds number and with sediment permeability

are ureilites residues from partial melting of chondritic material the answer from magpox calculations performed using magpox show that no bulk compositions having chondritic ca al ratio and within the range of chondritic si mg ratios can produce the olivine pigeonite ureilites which constitute 65 of those for which modal abundances are known as residues of single stage equilibrium partial melting calcium aluminum ratios of 2 3 5 ci are required in addition all the ureilites could not have formed from a single composition at various degrees of reduction because they show no correlation between pigeonite olivine ratio and mg ratio materials with various al mg ratios ranging from subchondritic to superchondritic are required if these materials are primitive i e created by nebular processes rather than planetary igneous processes they are unknown in the meteorite record excess accretion relative to chondrites of 5 10 mol of a high temperature condensate component which was itself almost completely depleted in corundum due to early fractionation could create the necessary compositions the plausibility that such processes occurred on a parent body sized scale is difficult to assess in contrast lodranites can be produced as residues of 3 30 equilibrium partial melting of an average ordinary chondritic composition at the appropriate level of reduction although many features of ureilites suggest that they are relatively primitive residues produced by low degrees of melting of chondritic materials and thus resemble lodranites and other groups of primitive achondrites their predominantly pigeonite olivine mineralogy remains difficult to explain within this simple scenario

the origin and evolution of lunar high ti basalts periodic melting of a single source at mare tranquillitatis abstract five groups of basalts a b1 b2 b3 d with three principal ages exist at the apollo 11 site these range from the low k low rare earth element ree groups b1 b2 and b3 to the low k high ree group d basalts to the high k high ree group a basalts the group a basalts are the only high k 0 2 wt k2o basalts and youngest with an age of 3 59 02 ga groups b3 and b1 are 3 71 02 and 3 67 02 ga respectively group b2 basalts are the oldest at 3 85 02 ga group d basalts have not been dated fractionation modelling for major and trace elements indicates that the b1 basalts could have formed from a b3 like parent liquid the b2 and d basalts can also be related to liquids similar to the b3 b1 composition through the presence of varying amounts of modal whitlockite thus the entirety of low k high ti basalts at apollo 11 may have formed through melting of the same source region the group a basalt compositions are consistent with formation from a different parent liquid with the composition of apollo 11 orange glass modelling of major and trace elements in the apollo 11 orange glass indicate that the composition of the group a basalts is consistent with fractionation of this glass coupled with some assimilation 7 5 15 of an evolved kreep like material however this component is much younger than primitive kreep 4 4 ga this neukreep component similar to the composition of quartz monzodiorites described from the apollo 15 site probably represents evolved material formed during plutonism prior to the formation of the apollo 11 orange glass liquid

northwest africa 773 lunar mare breccia with a shallow formed olivine cumulate component inferred very low ti vlt heritage and a kreep connection abstract lunar meteorite northwest africa 773 herein referred to as nwa773 is a breccia composed predominantly of mafic volcanic components including a prominent igneous clast lithology the clast lithology is an olivine gabbro cumulate which on the basis of mineral and bulk compositions is a hypabyssal igneous rock related compositionally to volcanic components in the meteorite the olivine gabbro lithology exhibits cumulus textures and in our largest section of it includes some 48 olivine fo 64 to fo 70 average fo 67 27 pigeonite en 60 fs 24 wo 16 to en 67 fs 27 wo 6 11 augite en 50 fs 17 wo 33 to en 47 fs 13 wo 40 2 orthopyroxene en 70 fs 26 wo 4 11 plagioclase an 80 to an 94 and trace barian k feldspar ilmenite cr spinel re merrillite troilite and fe ni metal the mg fe ratios of the mafic silicates indicate equilibration of fe and mg however the silicates retain compositional variations in minor and trace elements that are consistent with intercumulus crystallization accessory mineralogy reflects crystallization of late stage residual melt both lithologies breccia and olivine cumulate of the meteorite have very low ti vlt major element compositions but with an unusual trace element signature compared to most lunar vlt volcanic compositions i e relative enrichment in light ree and large ion lithophile elements and greater depletion in eu than almost all other known lunar volcanic rocks the calculated composition of the melt that was in equilibrium with pyroxene and plagioclase of the cumulate lithology exhibits a kreep like ree pattern but at lower concentrations melt of a composition calculated to have been in equilibrium with the cumulate assemblage plus excess olivine yields a major element composition that is similar to known green volcanic glasses one volcanic glass type from apollo 14 in particular green glass b type 1 has a very low ti concentration and ree characteristics including extremely low eu concentration that make it a candidate parent melt for the olivine gabbro cumulate we infer an origin for the parent melt of nwa773 volcanic components by assimilation of a trace element rich partial or residual melt by a magnesian vlt magma deep in the lunar crust or in the mantle prior to transportation to the near surface accumulation of olivine and pyroxene in a shallow chamber eruption onto a volcanic surface and incorporation of components into local predominantly volcanic regolith prior to impact mixing of the volcanic terrain and related hypabyssal setting and ejection from the surface of the moon volcanic components such as these probably occur in the oceanus procellarum region near the site of origin of the green volcanic glasses found in the apollo 14 regolith

the systematics of light lithophile elements li be and b in lunar picritic glasses implications for basaltic magmatism on the moon and the origin of the moon lunar picrites represented by high mg volcanic glasses are thought to be products of either partial melting of the deep lunar mantle followed by rapid ascent or polybaric partial melting initiated in the deep lunar mantle the near primary compositions of these volcanic glasses provide us with a unique perspective for evaluating basaltic magmatism the characteristics and evolution of the lunar mantle and the origin of the moon the light lithophile elements lle li be b in planetary materials have been used to estimate planetary compositions and evaluate magmatic processes ion microprobe analyses of these glasses for lles were conducted using a cameca 4f ion microprobe this suite of glass beads ranged in tio2 from 0 3 to 17 wt seventy one individual glass beads were analyzed for the lles in addition core rim analyses of individual glass beads were made the lles show a wide range of variability with li ranging from 1 2 to 23 8 ppm be ranging from 0 06 to 3 09 ppm and b ranging from 0 11 to 3 87 ppm b be ranges from 0 40 to 4 6 li be ranges from 2 7 to 41 7 although 90 of the li be values range from 14 to 30 both b be and li be values for the picritic glasses are less than chondrite be nd for the glasses ranges from 04 to 06 and are similar to chondrite 058 traverses across individual beads indicate that they are generally homogeneous with regards to lles regardless of tio2 content the individual glass groups show limited variations in lle characteristics the exceptions to this observation are the a17 vlt and the a15 yellow glasses at individual apollo sampling sites the lle content is generally correlated to tio2 the high ti glasses are displaced toward higher li at similar b and be relative to the very low ti glasses lle concentrations also parallel the enrichments of other lithophile elements such as ba zr sr and rees as noted for other trace element characteristics glasses from each sampling site have similar lle signatures for example the apollo 14 glasses generally have higher lle concentrations relative to glasses of similar tio2 content from other sites the lle data support mantle inhomogeneity and lunar magma ocean lmo cumulate overturn models suggested by previous studies a kreep component had been incorporated into some of these picritic glasses this is consistent with other trace elements and probably reflects the recycling of kreep and or other late stage lmo cumulates into the deep lunar mantle the picritic glasses are compositionally distinct from the crystalline mare basalts in lles they are not related by either fractional crystallization or partial melting processes this suggests that they were derived from distinctively different mantle sources estimates of the bulk compositions of the earth and the moon have previously been made based on the assumption that the ratio of li to be is a direct measure of the ratio of the high temperature condensates htc refractory components to the mg silicates less refractory components in a planet we assert that if li be is to be used to estimate bulk moon composition the picritic glasses provide fewer pitfalls and a better estimate than the crystalline mare basalts differences in partition coefficients d for li and be indicate that fractional crystallization and partial melting will modify the libe ratio estimates based on the picritic glasses infer a higher li be for the bulk moon than estimated from the mare basalts this would indicate that the bulk moon is less refractory than previously calculated by li be and approaches the bulk composition of the earth

application of heat pulse injections for investigating shallow hyporheic flow in a lowland river 1 hyporheic zone processes can have significant impact on groundwater and surface water resources detailed knowledge of exchange flow patterns is crucial for understanding the ecohydrological and biogeochemical functioning of river corridors in particular small scale hyporheic exchange flow is still poorly understood partially because of the lack of adequate in situ monitoring technology this paper investigates the spatial heterogeneity of hyporheic exchange flow in a lowland river at multiple scales it demonstrates the conjunctive use of active heat pulse tracing at shallow depths 15 cm and vertical hydraulic gradients vhg at 120 150 cm streambed depth for improving the understanding of hyporheic exchange flow processes generally positive vhg indicated a regional dominance of groundwater up welling high and temporally variable vhg were used to identify confined conditions caused by low conductivity layers in the subsurface low connectivity while locations with lower and temporally less variable vhg indicated free groundwater up welling high connectivity in highly conductive sediments a heat pulse sensor hps was applied for identifying shallow hyporheic flow at three locations representative for high versus low streambed connectivity shallow hyporheic flow patterns were found to be spatially heterogeneous subsurface flow could only partially be explained by streambed topography surface water infiltration and horizontal flow coincided with inhibited groundwater up welling whereas locations with high streambed connectivity were characterized by increased up welling the combined information of spatiotemporal vhg variability and flow vector frequency distribution by hps has the potential to improve the understanding of impacts of streambed topography and subsurface stratification on hyporheic flow patterns

evolution of hydraulic conductivity in the floodplain of a meandering river due to hyporheic transport of fine materials 1 the hydraulic conductivity of riverbeds and shallow aquifers controls hyporheic flow and surface water groundwater exchange which is critical to aquatic systems we show that the hydraulic conductivity of shallow alluvial aquifers subject to sinuosity driven hyporheic flow is dynamic because of transport of fine materials we analyze changes in hydraulic conductivity over one year at a meander scale experimental river aquifer system using water table monitoring repeat in situ hydraulic tests grain size analysis and flow modeling with particle tracking areas with relatively high initial hydraulic conductivity became more permeable after one year while areas with lower initial hydraulic conductivity became less permeable particle tracking suggests fine materials were flushed from the more permeable portions of the aquifer and deposited in the less permeable areas down gradient since hydraulic conductivity evolution has feedback on flow static or synoptic hydraulic conductivity measurements in river hyporheic riparian systems may need to be revisited temporally changing hydraulic conductivity has the capacity to impact rates of ecological and biogeochemical processes

lunar regional dark mantle deposits geologic multispectral and modeling studies clementine five channel uv visible uvvis data have been used to study seven regional dark mantle deposits dmds on the moon the dmds were mapped in distribution to determine their extent and stratigraphic relationship to other geologic units based upon the spectral properties for each dmd the crystallization of the beads in each deposit was inferred and used to estimate cooling rates in the volcanic plumes that emplaced the deposits deposits with a high concentration of glasses reflect volcanic plumes that had low optical densities and high cooling rates whereas deposits dominated by crystallized beads indicate plumes with slower cooling rates due to higher optical densities spectral data from each of the regional dmds show that their glass crystallized bead ratio can be estimated based upon their 415 750 and 750 950 nm values and comparison to laboratory spectra for the beads patches of young dark mantle in the sinus aestuum dmd represent one extreme with the bluest color highest 415 750 and weakest glass band absorption lowest 750 950 of all the dmds at the other extreme is the aristarchus plateau dmd with the reddest color and strongest glass band absorption the other nearside dmds including taurus littrow sulpicius gallus rima bode and mare vaporum lie between these two extremes due to intermediate mixtures of the crystallized beads and glasses with other local soils the orientale ring dmd on the western limb is dominated by volcanic glasses and is spectrally similar to the localized dmds found in alphonsus crater we have identified a central vent for the orientale ring dmd and model the eruption as degassing of a near surface dike to produce a 20 km high umbrella shaped plume with ejection velocities of 360 m s and deposition of the glasses at an average radius of 80 km from the vent although we cannot identify the exact sources for the other regional dmds probably because they are buried beneath younger mare the eruptions most likely resulted from dikes breaching the surface and producing a volcanic plume dominated by larger greater than submillimeter hot clasts that formed mare and sinuous rules the small percent of clasts that form the volcanic beads are carried by the expanding gas cloud to large distances in some cases 100 km to produce the observed continuous regional dmds the lack of basalt samples that can be petrologically related to the volcanic glasses may be a result of their spatial separation with the basalts flowing into the basins while the beads are deposited both into the basins and on the adjacent highlands

apollo 15 yellow brown volcanic glass chemistry and petrogenetic relations to green volcanic glass and olivine normative mare basalts abstract apollo 15 yellow brown glass is one of twenty five high mg primary magmas emplaced on the lunar surface in pyroclastic eruptions forty spherules of this glass were individually analyzed by electron microprobe and inaa for major and trace elements e g sc v cr co la ce nd sm eu ho tm yb lu hf ta and u the abundances demonstrate that this primary magma was produced by partial melting of differentiated cumulates in the lunar mantle models are developed to explain the possible source regions of several apollo 15 and apollo 12 low ti mare magmas as being products of hybridization involving three ancient differentiated components of a primordial lunar magma ocean a early olivine orthopyroxene cumulates b late stage clinopyroxene pigeonite ilmenite plagioclase cumulates and c late stage inter cumulus liquid isotopic constraints on sm nd fractionation and least squares tests of potential mixing models require models of apollo 15 yellow brown glass and apollo 12 and 15 olivine mare basalts involving low f 3 cumulate remelting of sources in which olivine and orthopyroxene are residual phases models of the apollo 15 green glass composition indicate higher 4 7 degrees of melting but with only a slight preference for orthopyroxene rich relative to orthopyroxene free sources the modeled dependence on residual orthopyroxene in mare source regions places source depths at 400 km or greater in order to maintain olivine and orthopyroxene on the liquidus hybridization at such depths would likely result from convective overturn of the primordial magma ocean and suggests that separate fractionating masses were positioned at various depths our models for developing hybridized source regions of primary low ti mare magmas do not require selective contamination of primary liquids the preferred model for apollo 15 yellow brown glass is presented as the commingling of 95 early cumulate olivine orthopyroxene 1 9 clinopyroxene 0 27 pigeonite 1 7 plagioclase 0 02 ilmenite and 0 56 trapped liquid respective proportions for the apollo 15 olivine mare basalt source model are 98 5 0 37 0 0 79 0 16 and 0 13 and the proportions used for the preferred apollo 12 olivine mare basalt model are 97 6 0 73 0 24 0 77 0 42 and 0 21 our preferred model for the green glass source composition f 0 07 requires the commingling of 97 4 early olivine orthopyroxene 0 18 clinopyroxene 1 32 pigeonite 0 85 plagioclase and 0 28 trapped liquid

the impact of climate change human interference scale and modeling uncertainties on the estimation of aquifer properties and river flow components summary within the period 1978 2006 climate change and human interferences produced noticeable impacts on the hydrology of a small watershed known as the beca river basin climate change was characterized by a persistent raise in temperature 0 78 c decade 1 and a drop in the annual rainfall 300 mm decade 1 human interferences included the construction of a dam for electric power generation in 1998 and since then the transference of beca river flows from the dam lake to the adjacent t mega river the impacts on catchment hydrology comprised a decline of aquifer hydraulic conductivity and effective porosity by approximately one order of magnitude related to a water table lowering of about 17 m within the bedrock aquifer composed of weathered and fractured hercynian granites and paleozoic metassediments and of saprolite layers derived therefrom aquifer property estimates were compared across spatial scales namely the beca river and the nested sub basins scale sub basin aquifers are more porous and permeable than the basin aquifer because corresponding hydraulic circuits are shallower comparisons were also made between aquifer properties derived from measured and simulated stream flows which revealed effects of modeling uncertainties on the results river flows also suffered a substantial decrease in the course of climate change and human interference especially the overland flows 4 5 decrease and the base flows 2 3 decrease the inter flows were less affected 1 3 decrease because they were partly fed with water from the aquifer storage which in turn underwent depletion the hydrologic changes in the beca river basin anticipate important impacts on the local use of natural water in this context the aforementioned water table lowering may have caused limited access to shallow groundwater for activities such as crop irrigation from dug wells whereas the severe decline in overland flows and base flows had certainly reduced the availability of surface water for the refilling of dam lakes and of groundwater for the supply of public and private boreholes

transfer of nonsorbing solutes to a streambed with bed forms theory a theoretical analysis of the exchange of nonsorbing solutes between a permeable streambed and the overlying water of a stream or river is presented in this paper in a companion paper elliott and brooks this issue the results of experimental studies of such exchange are presented the analysis focuses on water movements into within and out of the bed which result from the presence of bed forms ripples and dunes and highlights the mechanisms of pumping and turnover pumping is the movement of fluid through the bed induced by steady dynamic pressure variations over bed forms turnover occurs as moving bed forms trap and release interstitial fluid the detailed analysis was used to generate the distribution of the residence time of solute within the bed which can be used to calculate the net mass exchange due to pumping and turnover

oxidation states and ascent history of the apollo 17 volcanic beads as inferred from metal glass equilibria abstract the composition mode of occurrence and relationships of metal blebs in the apollo 17 74001 2 core have been examined to provide insight into variations in oxidation states during ascent and eruption of the lunar volcanic glasses the 74001 2 core is composed of 99 orange volcanic glasses and their crystallized equivalents black beads with olivine phenocrysts metal blebs and in the upper 8 cm of the core lithic fragments composing the remaining 1 in an analysis of this core twenty nine metal blebs larger than 4 m in size were discovered in thin sections taken along the length of the 68 cm deep core these blebs are classified into three types on the basis of their shape composition and distribution fourteen of the metal blebs were found trapped inside or between olivine phenocrysts type i blebs microprobe analyses showed that these spherical blebs have a homogeneous composition of 85 fe 14 ni and 1 1 co from core to rim six type ii rounded blebs were discovered trapped inside volcanic beads their core compositions are similar to the type i but near the rim these blebs have a sharp decrease in fe and increase in ni content in the lower half of the 74001 2 core where the beads are predominantly black many contain 5 m amoeba shaped type iii metal blebs type iii blebs are composed of fe with trace amounts of ni two angular metal fragments could not be classified into any of the three types we propose that the type i blebs formed initially at 4 0 km depth and 1 3 log units below iw at a pressure of 200 bars and a temperature of 1320 c by the formation of c o gas during graphite oxidation once trapped by olivine phenocrysts the blebs were buffered from further reactions with the melt the type ii blebs remained in contact with the melt during ascent and experienced loss of fe to the surrounding melt phase by oxidation reactions which range from 1 3 to 0 9 log below iw finally type iii blebs formed either by exsolution of fe during crystallization in the fire fountain or by loss of volatiles originally coordinated with fe to the volcanic gas phase under the reduced conditions in the fountain

exploring the lunar mantle with secondary ion mass spectrometry a comparison of lunar picritic glass beads from the apollo 14 and apollo 17 sites abstract the major element characteristics of lunar picritic beads indicate that their composition approaches that of primary basaltic liquids and therefore may be our best geochemical mineralogical probes of the lunar interior the picritic magmas appear to represent partial melting of a variety of mantle mineral assemblages secondary ion mass spectrometry sims analysis of individual glass beads collected from the apollo 14 a 14 and apollo 17 a 17 landing sites shows that although there is substantial major minor tio 2 al 2 o 3 and trace element variation at each site the glasses from each site have distinguishable trace element signatures ba sr lree hree the incompatible element characteristics of glasses of nearly identical major element chemistry are strikingly different between sites the contrast between the a 14 and a 17 glasses appears to be the result of a higher kreep component in all the a 14 glasses the incorporation of evolved kreep component into high mg magmas is not a result of either assimilation or magma mixing but incorporation during the partial melting episode that produced the picritic magmas this is a more thermally efficient mechanism for incorporation of the kreep component into a picritic magma calculated mantle chemistries based upon glass compositions low degrees of partial melting and mineralogical components used in previous models suggest that the difference between a 14 and a 17 mantle sources is a 0 1 1 4 kreep intercumulate melt this difference will increase with an increase in the degree of partial melting in the model calculations this intercumulate melt may interstitially reside in an evolved high ti cumulate component the juxtaposition of evolved high ti cumulates kreep and primitive low ti cumulates mantle components has been attributed to original mantle inhomogeneities density contrasts during magma ocean crystallization and sinking of high density evolved cumulates into less dense primitive cumulates within the context of either magma ocean or serial magmatism type models regardless of the model the trace element signatures of glasses and the basalts indicate that the character of the a 14 mantle source is intrinsically different from that of the a 17 mantle source this indicates large scale lateral and vertical inhomogeneities in the lunar mantle

anatexis of lunar cumulate mantle in time and space clues from trace element strontium and neodymium isotopic chemistry of parental apollo 12 basalts abstract in an effort to elucidate the processes of lunar mantle melting and the magma evolution of mare basalts within oceanus procellarum on the western lunar near side we have analyzed seven fine grained to vitrophyric apollo 12 basalts for trace elements five of these also have been analyzed for nd and sr isotopic compositions these samples represent all three main groups identified among the apollo 12 mare basalts and have been proposed as parental melts to their respective groups i e olivine pigeonite and ilmenite basalts the sources for these low ti mare basalts are postulated to have formed from crystallization of a global magma ocean li be systematics combined with ree data indicate that the specific sources for the apollo 12 low ti mare basalts were generated after 82 94 crystallization of this lunar magma ocean in fact it seems that all mare basalts analyzed from the apollo collections were generated from cumulates precipitated in the last 20 of the magma ocean chemical compositions of fine grained pigeonite and olivine basalts are consistent with 7 9 nonmodal in proportions not defined by experimental petrology and phase equilibria melting of a source consisting of 48 olivine 30 calcic clinopyroxene and 22 pigeonite as per neal et al 1994b sm nd and rb sr abundance data also suggest that the pigeonite and olivine basalt source contained from 0 3 to 0 5 trapped residual liquid from the magma ocean the compositions of the two fine grained ilmenite basalts are consistent with 5 7 partial melting of a source with subequal proportions of olivine 45 5 and pigeonite 42 5 and lesser amounts of clinopyroxene 11 5 and entrained plagioclase 0 5 furthermore the ilmenite source was nearly devoid of trapped liquid isotopic systematics of the apollo 12 fine grained parental basalts are consistent with their derivation from two distinct mantle source regions both of these sources were lree depleted for extended periods of time up to 600 million years for the ilmenite basalt source and up to 900 million years for the pigeonite and olivine basalt source due in part to the relatively small proportion of low sm nd trapped residual magma ocean liquid in the source by integrating this information on parental low ti apollo 12 basalts with mare basalt and picritic glass data from other landing sites as well as telescopic and remote sensing data we propose a model for melting of the lunar interior the upper 400 500 km of the lunar mantle is a consequence of incipient melting of the moon and formation of a global magma ocean this magma ocean became progressively enriched in incompatible elements as it precipitated the cumulate upper mantle this incompatible earliest extensive mare magmas high ti mare basalts were generated at shallow depths in the mantle from cumulate source regions that had trapped relatively large proportions of this incompatible element enriched residual magma ocean liquid these source regions also contained the late crystallizing phase ilmenite and thus generated high ti magmas the trapped liquid component contained elevated abundances of heat producing elements k u and th increasing the fertility of associated source regions with time melting moved progressively deeper in the mantle to source regions with less of the residual heat producing magma ocean liquid due to density contrasts the ilmenite bearing upper portions of the lunar mantle sank into the cumulate pile possibly carrying more fertile material with it and allowing melting of more mg enriched source regions to form the high ti picritic glass beads thus the major controlling factors in the melting of the lunar interior could be the proportion of trapped magma ocean liquid in the cumulate source and the sinking of more fertile ilmenite bearing material into the lower mantle

seasonal variation in surface subsurface water exchange and lateral hyporheic area of two stream aquifer systems abstract we used two dimensional unconfined transient groundwater flow models to investigate the interface between stream and groundwater flow systems or hyporheic zone of two first order streams that drain catchments with distinctly different alluvial sediments and bedrock lithology particle tracking showed that lateral hyporheic area planimetric area of flow paths lateral to the stream that are recharged by and return to the stream with travel times of 10 days or less differed between the two study streams and varied with discharge within each system at the rio calaveras welded tuff lateral hyporheic area ranged from 1 7 to 4 m 2 over the annual cycle in the aspen creek system sandstone lateral hyporheic area 1 1 5 m 2 was restricted to roughly half of that observed at rio calaveras the size of the hyporheic zone lateral to the streams at both sites decreased by approximately 50 during high flows sensitivity analyses indicated that changes in the hydraulic conductivity of alluvial and streambed sediments and variation in recharge rates have greatest impact on the magnitude direction and spatial distribution of stream groundwater exchange

lunar magma transport phenomena abstract an understanding of the most significant events during the first ga or so of lunar history global differentiation associated with a lunar magma ocean lmo and the later generation of about 107 km3 of mare basalts depends profoundly on magma transport dynamics lmo evolution is dominated by the characteristics of hard turbulent convection of a fluid undergoing phase change quench protocrust formed at the ocean surface in early times is repeatedly disrupted by bolide impact ocean body tides and associated crustal foundering during this epoch the ocean temperature is set by the balance between convective heat brought to the surface and brown body radiation from the surface at later times the convective flow is organized into a number of regimes from top to bottom these include conductive crustal lid a viscous sublayer an inertial core a lower viscous sublayer and a mushy cumulate region crystal settling and flotation is restricted to the viscous sublayer regions dilatancy pumping may prevent the efficient expulsion of intercumulus melt during cumulate formation typical velocities within the inertial region are of order 10 m s because late stage ti rich cumulates are dense relative to the earlier mg rich cumulates hyper to sub solidus convection tends to mix lmo crystallization products numerical simulations that account simultaneously for compositional and thermal buoyancy effects indicate a characteristic mixing time 200 ma statistical measures of mixing variance and spatial correlation length quantify the details of mixing the darcy percolative and vein drain models of melt extraction are briefly discussed because compaction lengths are small 102 m the rate of melt extraction is governed by the balance between melt buoyancy and darcy friction differential melt matrix velocities are of order 10 km ma for nominal values appropriate for mare basalt melt extraction from a heterogeneous mixed lmo source transport of magma through the lunar lithosphere via a connected crack network seems highly probable for the range of inferred discharge rates applicable for lunar mare volcanism lmv 103 to 107 m3 s typical fracture widths and ascent speeds are 10 1 to 50 m and 10 1 to 10 m s respectively a simple model is proposed to evaluate the extent of fractionation as magma traverses cold lunar lithosphere if apollo green glasses are primitive and have not undergone significant fractionation en route to the surface then mean ascent rates of 10 m s and cracks of widths 40 m are indicated lunar tephra and vesiculated basalts suggest that a volatile component plays a role in eruption dynamics the predominant vapor species appear to be co co2 and cos near the lunar surface the vapor fraction expands enormously and vapor internal energy is converted to mixture kinetic energy with the concomitant high speed ejection of vapor and pyroclasts to form lunar fire fountain deposits such as the apollo 17 orange and black glasses and apollo 15 green glass

petrology and provenance of a very low titanium picrite clast in lunar highland regolith breccia 15295 clast 100 in regolith breccia 15295 could be a key to resolving the relationship s between mare basalts and lunar picritic glasses the clast is basaltic with texture mineralogy mineral compositions and calculated bulk composition suggesting that it crystallized in a thick lava flow or shallow intrusive body from a very low titanium vlt basaltic magma the estimated bulk composition of clast 15295 100 is primitive i e magnesian compared to those of known vlt basalts and is very close to those of vlt picritic green glasses especially the apollo 14 a green glass from these similarities we infer that clast 15295 100 is a crystalline product of a picritic magma similar to the apollo 14 a glass clementine and m3 remotely sensed data of the lunar surface were used to find areas that have chemical compositions consistent with those of clast 15295 100 not only near the apollo 15 site but in a broad region surrounding the site two regions are consistent with clast s 15295 100 compositional data the larger region is in southern mare imbrium and a smaller region is in the eastern half of sinus aestuum these locations should be considered as candidates for future missions focusing on sample science

a magma ocean on vesta core formation and petrogenesis of eucrites and diogenites abstract available evidence strongly suggests that the hed howardite eucrite diogenite meteorites are samples of asteroid 4 vesta abundances of the moderately siderophile elements ni co mo w and p in the hed mantle indicate that the parent body may have been completely molten during its early history during cooling of a chondritic composition magma ocean equilibrium crystallization is fostered by the suspension of crystals in a convecting magma ocean until the crystal fraction reaches a critical value near 0 80 when the convective system freezes and melts segregate from crystals by gravitational forces the extruded liquids are similar in composition to main group and stannern trend eucrites and the last pyroxenes to precipitate out of this ocean before convective lockup span the compositional range of the diogenites subsequent fractional crystallization of a main group eucrite liquid which has been isolated as a body of magma produces the nuevo laredo trend and the cumulate eucrites the predicted cumulate mineral compositions are in close agreement with phase compositions analyzed in the cumulate eucrites thus eucrites and diogenites are shown to have formed as part of a simple and continuous crystallization sequence starting with a magma ocean environment on an asteroidal size parent body that is consistent with vesta

ion microprobe studies of trace elements in apollo 14 volcanic glass beads comparisons to apollo 14 mare basalts and petrogenesis of picritic magmas abstract the major element geochemistry of picritic lunar glass beads indicates that they represent primary basaltic liquid compositions and as such provide unique information concerning the origin of mare basalts and characteristics of the lunar interior this study used ion microprobe techniques for trace element analysis of individual glass beads representing seven compositionally distinct types of picritic glass beads from the apollo 14 site high ti glasses 17 11 tio2 red black orange intermediate ti glasses 5 4 tio2 yellow low ti glasses 2 8 tio2 lap low alkali picritic papike et al 1989 very low ti glasses ba sr 1 of these glasses are different from low ti mare basalts at other sites but are similar to crystalline basalts at the apollo 14 site the intermediate to high ti picritic glasses exhibit a flat to slightly positive lree slope and a negative hree slope the orange glass has a higher total ree abundance and a slightly larger negative eu anomaly than the red black and yellow glasses relative to the apollo 17 high ti glasses apollo 14 high ti glasses are enriched in ree lree hree y v zr sr ba and ba sr and are similar in alkali elements li rb co and sc trace element modeling within the context of liquid lines of descent and major element characteristics indicates that the picritic glass beads at the a 14 site are not related by low pressure fractional crystallization to each other or to crystalline basalts at the apollo 14 or other landing sites a possible exception is the relationship between lap and basalts of the high al basalt suite the wide range of primary magma compositions and the lack of petrogenetic linkage via crystal fractionation to crystalline basalts indicates that either a wide compositional range of evolved mare basalts has not yet been sampled or a unique mechanism is selectively tapping these picritic magmas directly from their mantle source region the wide range of major and trace element characteristics of the volcanic glass beads is consistent with derivation from mineralogically distinct sources which consist of varying proportions of olivine orthopyroxene clinopyroxene ilmenite plagioclase kreep component the evolved kreep component may have been incorporated into these primary picritic magmas by either assimilation fractional crystallization type processes afc or by hybridization of the mantle source the former appears less likely due to the general systematic increase in incompatible elements relative to ti concentration and the apparent lack of crystallization that is required in afc type models the hybridization processes may be the result of sinker mechanisms as proposed by ringwood and kesson 1976 a manifestation of original mantle inhomogeneities or a magma ocean stirred by large impacts

petrogenesis of mare basalts a record of lunar volcanism returned rock and soil samples from our nearest planetary neighbor have provided the basis for much of our understanding of the origin and evolution of the moon of particular importance are the mare basalts which have revealed considerable information about lunar volcanism and the nature of the mantle as well as post magma generation processes this paper is a critical review of the petrogenetic models for the generation of mare basalts formulated over the last twenty years we have used all available mare basalt analyses to define a six fold classification scheme using tio2 contents as the primary division i e 1 wt very low ti or vlt 1 6 wt low ti 6 wt high ti a secondary division is made using al2o3 contents i e 11 wt low al 11 wt high al and a tertiary division is defined using k contents i e 2000 ppm low k 2000 ppm high k such divisions and subdivisions yield a classification containing twelve categories of which six are accounted for by the existing apollo and luna collections therefore we present our discussions in the form of six mare basalt rock types 1 1 high ti low al low k referred to as high ti low k 2 2 high ti low al high k referred to as high ti high k 3 3 low ti low al low k referred to as low ti 4 4 low ti high al low k referred to as high alumina 5 5 low ti high al high k referred to as vhk 6 6 vlt low al low k basalts referred to as vlt a variety of post magma generation processes have been invoked such as fractional crystallization either alone or combined with wallrock assimilation to explain the compositional ranges of the various mare basalt suites in order to evaluate these proposed petrogenetic processes this review is by rock type and is non site specific but for each rock type reference to particular lunar sample return missions is brought forth this permits a comparison of similarities and differences of broadly similar rock types correlated with geography on the moon which in turn allows a more thorough petrogenetic evaluation high ti mare basalts i e high ti low al low k are found at apollo 11 and apollo 17 sites however the a 11 basalts contain lower tio2 abundances a considerably larger range in trace element contents and the only occurrence of high ti high k mare basalts fractional crystallization and source heterogeneity within each site are the keys to understanding the petrogenesis of the high ti basalts low ti basalts including both low al k and high al k varieties are found at apollo 12 14 and 15 and luna 16 sites the low ti basalts exhibit a wide range of major and trace element compositions and require source heterogeneity fractional crystallization and some assimilation the high alumina mare basalts i e low ti high al low k are found at apollo 14 and luna 16 sites and exhibit a wide range of major and trace element compositions however in these examples source heterogeneity is not a major factor indeed fractional crystallization coupled with kreep assimilation particularly for the apollo 14 variants can explain the compositional ranges of these high alumina basalts the vhk mare basalts i e low ti high al high k have been sampled only at the apollo 14 locale and are products of a parental highalumina magma assimilating lunar granite very low ti vlt mare basalts i e vlt low al low k are found at apollo 17 and luna 24 sites fractional crystallization has had a major influence upon the range in vlt compositions but luna 24 vlt basalts have been derived from a source slightly different in composition from that for apollo 17 vlt varieties for example the luna 24 vlt basalts generally exhibit positive eu anomalies a unique property for mare basalts which almost always have negative eu anomalies the concept of a lunar magma ocean lmo is generally accepted and source modelling of all basalts invokes a mafic lmo cumulate source this is the only unifying model for mare basalt petrogenesis but the semantics and logistics of it are and will be debated for many years for example major convective overturn of the lmo appears plausible but whether this occurred on a local or planet wide scale to produce source heterogeneity remains to be determined

a three component model for the bulk composition of the moon abstract using detailed analyses of lunar pristine glasses as a basis delano 1986 we present a suite of models of lunar bulk composition which are based on the following assumptions i that the early moon differentiated into two primary reservoirs 1 an feo rich magma ocean and 2 an olivine rich residuum of fo90 and ii that this magma ocean then differentiated into an olivine dominated cumulate fo80 and a primitive liquid composition ppg thus in these models the bulk composition of the moon is given by a mixture of three components an early olivine residuum a later olivine orthopyroxene cumulate and ppg liquid with the constraint that the moon possess a ci chondritic mg al ratio our model lunar compositions are grossly similar to the lunar composition of ringwood et al 1987 and when projected from feo they appear very similar to the composition of the earth s upper mantle again when projected from feo our model magma ocean compositions are very similar to the bulk lunar composition derived by taylor 1982 remelting of cumulates from the magma ocean can produce the mare basalts and the pristine glasses remelting of the early residuum may be the source of the highly magnesian olivines found in the lunar highlands our ability to relate such diverse chemistries as the earth s mantle and taylor s moon is relatively model independent the model compositions discussed above are generated by assuming that the cumulate formed by equilibrium crystallization to better determine if there is a significant difference between the feo contents of the earth and the moon we have also calculated bulk lunar compositions whose cumulate component is formed by fractional crystallization a more realistic approximation we find that if the mg si ratios of the earth and moon are similar and if the early residue is dominated by olivine then the bulk silicate moon is 25 to 50 enriched in feo over the earth s upper mantle 10 to 13 wt feo for the moon as compared to 8 wt for the earth again the ultimate basis for this estimate of lunar feo is the set of lunar pristine glasses a characteristic of all our models is that refractory lithophile elements such as ca and al are calculated to be 2 to 3 times ci in the bulk silicate moon these abundances are largely determined by our requirement that the moon possess a chondritic mg al ratio to emphasize this point we discuss the implications of the choices of various mg al and mg si ratios in the calculation of bulk planetary compositions

basaltic magmatism on the moon a perspective from volcanic picritic glass beads abstract it is widely accepted that basaltic magmas are products of partial fusion of periodotite within planetary mantles as such they provide valuable insights into the composition structure and processes of planetary interiors those compositions which approach primary melt compositions provide the most direct information about planetary interiors and serve as a starting point to understand basaltic evolution within the collection of lunar samples returned by the apollo and luna missions are homogeneous picritic glass beads of volcanic origin these picritic glasses are our closest approximations to primary magmas as such these glass beads provide a unique perspective concerning the origin of mare basalts the characteristics of the lunar interior and processes in the early differentiation of the moon we have obtained trace element data for these picritic glasses using sims techniques these data and literature isotopic and experimental data on the picritic glasses are placed within the framework of mare basaltic magmatism the volcanic glasses are very diverse in their trace element characteristics for example they have a wide range of ree pattern shapes and concentrations like the crystalline mare basalts all picritic glasses have a negative eu anomaly unlike the crystalline mare basalts there is little correlation between the size of the eu anomaly and overall ree concentrations trace element differences among the various glasses suggests that a kreep component was incorporated into their mantle source this implies large scale mixing of the lunar magma ocean derived cumulate pile subtle differences among glasses suggest that local mixing of sources may also have been an important process preservation of subtle chemical differences in the picritic glasses and crystalline basalts may be interpreted as indicating that they were produced by small to moderate degrees of partial melting and that the lunar mantle did not experience extensive melting during episodes of mare volcanism several lines of evidence are consistent with the view that the picritic glasses were derived from mantle sources that were compositionally distinct from the sources for crystalline mare basalts these are parallel but no common liquid lines of descent chemical differences between picritic glasses and the more primitive crystalline mare basalts experimental studies indicating that the picritic glasses are multiply saturated at depths greater than that of the mare basalts differences in lead isotopic data and the mode of eruption i e fire fountaining for glass beads these data also provide circumstantial evidence that suggests that the picritic glasses were derived from a source somewhat more volatile rich than that of the mare basalts several petrogenetic models are suggested by the trace element characteristics of the picritic glasses 1 1 partial melting of heterogeneous lunar mantle at depths greater than 300 km to produce the parental magmas picritic for both the mare basalts and picritic glasses picritic magmas represented by glass beads were erupted to the surface with small degrees of fractional crystallization while mare basalts were produced by larger degrees of fractional crystallization 15 30 of similar but not identical picritic magmas 2 2 picritic magmas represented by the glass beads were generated at depths greater than 400 km in a volatile enriched relative to the mare basalt source heterogeneous mantle while mare basalts are fractional crystallization products of picritic magmas generated at depths of less than 400 km 3 3 the picritic magmas represented by the glass beads represent polybaric melting that initiated at depths of at least 1000 km a primitive mantle component or less processed cumulate mantle components may have been involved in the generation of the picritic glasses in any of these models

tidally driven multiscale pore water flow in a creek marsh system intertidal wetlands are complex hydrological systems characterized by strong dynamic interactions between coastal surface water and groundwater driven particularly by tides we simulated such interactions with a focus on three dimensional variably saturated pore water flow in a creek marsh system that bordered a tidally dominated main channel simulated intra tidal groundwater dynamics exhibited significant flow asymmetry with non zero mean flow velocities over the tidal period the tidally averaged flow led to pore water circulation with three dimensionality linked strongly to the marsh topography over a range of spatial scales near the creek bank around the creek meander and over long marsh sections inclined towards the main channel particle tracking revealed that time scales associated with these circulations differed by orders of magnitude under the simulated conditions the creek served as the main outlet of the pore water circulation paths especially those linked with infiltration into the upper marsh surface areas away from the main channel local net efflux influenced by the creek channel curvature varied along the creek but produced a total discharge largely proportional to the creek length water infiltrating the soil in the lower marsh surface areas away from the creek tended to discharge directly to the main channel however the total discharge to the main channel was much less than that into the creek this study highlights the hydrological complexity of intertidal marshes and the need for further research on interactions among marsh morphology hydrology and ecology which underpin the functionalities of these wetland systems

thermal and magmatic evolution of the moon as with all science our continually developing concepts of lunar evolution are firmly tied to both new types of observations and the integration of these observations to the known pool of data this process invigorates the intellectual foundation on which old models are tested and new concepts are built just as the application of new observational tools to lunar science in 1610 galileo s telescope and 1840 photography yielded breakthroughs concerning the true nature of the lunar surface the computational and technological advances highlighted by the apollo and post apollo missions and associated scientific investigations provided a new view of the thermal and magmatic evolution of the moon 1 1 pre apollo view of the thermal and magmatic evolution of the moon many of the early views of the moon manifested in mythology and art throughout the world were primarily tied to lunar and terrestrial cycles and the relationships between the sun and the moon prophetically myths involving the lunar deities mwuetsi from zimbabwe and coyolxauhqui from mexico told of rather violent or catastrophic events in which the moon was expunged from the earth numerous ancient scientific observations were made about the nature of the moon ranging from those uncovered in early neolithic sites that correctly identified mare crisium and mare humorum to the insights made by greek philosophers such as anaxagoras ca 500 428 b c and democritus ca 460 370 b c who attached terrestrial analogues to its character stone mountains with the advent of the telescope 1610 and photography 1840 as scientific tools for lunar exploration semiquantitative data could be collected that would provide an intellectual foundation for scientific interpretation initially modern terrestrial geological analogs were extended to the moon lunar highlands volcanic craters seas combined with the rigors of computational modeling these observational data were extended to predict the original thermal state of the moon and its thermal and magmatic history its proximity to the earth

a hydrogeomorphic river network model predicts where and why hyporheic exchange is important in large basins hyporheic exchange has been hypothesized to have basin scale consequences however predictions throughout river networks are limited by available geomorphic and hydrogeologic data and by models that can analyze and aggregate hyporheic exchange flows across large spatial scales we developed a parsimonious but physically based model of hyporheic flow for application in large river basins networks with exchange and subsurface storage nexss we applied nexss across a broad range of geomorphic diversity in river reaches and synthetic river networks nexss demonstrates that vertical exchange beneath submerged bed forms rather than lateral exchange through meanders dominates hyporheic fluxes and turnover rates along river corridors per kilometer low order streams have a biogeochemical potential at least 2 orders of magnitude larger than higher order streams however when biogeochemical potential is examined per average length of each stream order low and high order streams were often found to be comparable as a result the hyporheic zone s intrinsic potential for biogeochemical transformations is comparable across different stream orders but the greater river miles and larger total streambed area of lower order streams result in the highest cumulative impact from low order streams lateral exchange through meander banks may be important in some cases but generally only in large rivers

hyporheic zone hydrologic science a historical account of its emergence and a prospectus the hyporheic zone defined by shallow subsurface pathways through river beds and banks beginning and ending at the river is an integral and unique component of fluvial systems it hosts myriad hydrologically controlled processes that are potentially coupled in complex ways understanding these processes and the connections between them is critical since these processes are not only important locally but integrate to impact increasingly larger scale biogeochemical functioning of the river corridor up to the river network scale thus the hyporheic zone continues to be a growing research focus for many hydrologists for more than half the history of water resources research this manuscript partly summarizes the historical development of hyporheic zone hydrologic science as gleaned from papers published in water resources research from the birth of the concept of the hyporheic zone as a hydrologic black box sometimes referred to as transient storage zone to its adolescent years of being torn between occasionally competing research perspectives of interrogating the hyporheic zone from a surface or subsurface view to its mature emergence as an interdisciplinary research field that employs the wide array of state of the art tools available to the modern hydrologist the field is vibrant and moving in the right direction of addressing critical fundamental and applied questions with no clear end in sight in its growth there are exciting opportunities for scientists that are able to tightly link the allied fields of geology geomorphology hydrology geochemistry and ecology to tackle the many open problems in hyporheic zone science

a multiscale model for integrating hyporheic exchange from ripples to meanders 1 it is necessary to improve our understanding of the exchange of dissolved constituents between surface and subsurface waters in river systems in order to better evaluate the fate of water borne contaminants and nutrients and their effects on water quality and aquatic ecosystems here we present a model that can predict hyporheic exchange at the bed form to reach scale using readily measurable system characteristics the objective of this effort was to compare subsurface flow induced at scales ranging from very small scale bed forms up to much larger planform geomorphic features such as meanders in order to compare exchange consistently over this range of scales we employed a spectral scaling approach as the basis for a generalized analysis of topography induced stream subsurface exchange the spectral model involves a first order approximation for local flow boundary interactions but is fully three dimensional and includes the lateral hyporheic zone in addition to the flow directly beneath the streambed the primary model input parameters are stream velocity and slope sediment permeability and porosity and detailed measurements of the stream channel topography the primary outputs are the distribution of water flux across the stream channel boundary the resulting pore water flow paths and the subsurface residence time distribution we tested the bed form exchange component of the model using a highly detailed two dimensional data set for exchange with ripples and dunes and then applied the model to a three dimensional meandering stream in a laboratory flume having spatially explicit information allowed us to evaluate the contributions of both gravitational and current driven hyporheic flow through various classes of stream channel features including ripples dunes bars and meanders the model simulations indicate that all scales of topography between ripples and meanders have a significant effect on pore water flow fields and residence time distributions furthermore complex interactions across the spectrum of topographic features play an important role in controlling the net interfacial flux and spatial distribution of hyporheic exchange for example shallow exchange induced by current driven interactions with small bed forms dominates the interfacial flux but local pore water flows are modified significantly by larger scale surface groundwater interactions as a result simplified representations of the stream topography do not adequately characterize patterns and rates of hyporheic exchange

variability in the vertical hyporheic water exchange affected by hydraulic conductivity and river morphology at a natural confluent meander bend river confluences and their associated tributaries are key morphodynamic nodes that play important roles in controlling hydraulic geometry and hyporheic water exchange in fluvial networks however the existing knowledge regarding hyporheic water exchange associated with river confluence morphology is relatively scarce on the 14th and 15th of january 2016 the general hydraulic and morphological characteristics of the confluent meander bend cmb between the juehe river and the haohe river in the southern region of xi an city shaanxi province china were investigated the patterns and magnitudes of vertical hyporheic water exchange vhwe were estimated based on a one dimension heat steady state model while the sediment vertical hydraulic conductivity kv was calculated via in situ permeameter tests the results demonstrated that six hydrodynamic zones and their extensions were observed at the cmb during the test period these zones were likely controlled by the obtuse junction angle and low momentum flux ratio influencing the sediment grain size distribution of the cmb the vhwe patterns at the test site during the test period mostly showed upwelling flow dominated by regional groundwater discharging into the river the occurrence of longitudinal downwelling and upwelling patterns along the meander bend at the cmb was likely subjected to the comprehensive influences of the local sinuosity of the meander bend and regional groundwater discharge and finally formed regional and local flow paths additionally in dominated upwelling areas the change in vhwe magnitudes was nearly consistent with that in kv values and higher values of both variables generally occurred in erosional zones near the thalweg paths of the cmb which were mostly made up of sand and gravel this was potentially caused by the erosional and depositional processes subjected to confluence morphology furthermore lower kv values observed in downwelling areas at the cmb were attributed to sediment clogging caused by local downwelling flow the confluence morphology and sediment kv are thus likely the driving factors which cause local variations in the vhwe of fluvial systems

deciphering basaltic magmatism on the moon from the compositional variations in the apollo 15 very low ti picritic magmas picritic glass beads of volcanic origin have been interpreted as representing extremely primitive lunar magmas that approach primary magma compositions based on this they have been used for developing models for lunar magmatism estimating the mineralogical and chemical characteristics of their mantle sources constraining the dynamics and structure of the lunar mantle developing models for lunar core formation reconstructing the bulk composition of the moon and evaluating the genetic relationships between the earth and the moon yet we still do not truly understand many aspects of the compositional diversity among individual glass types or even within a single glass type using high precision ion microprobe techniques we have analyzed a total of forty very low ti glass beads from the apollo 15 a15 site and twenty additional picritic glass beads from other sampling sites for a suite of highly compatible ni co weakly compatible to weakly incompatible mn cr v and highly incompatible ce ti zr nb elements within the a15 very low ti glass population ni and co concentrations are positively correlated exhibit limited fractionation of ni co and are distinctive for individual glass groups as defined by major elements manganese is also colinear with both ni and co the highly incompatible elements also appear to be generally colinear with ni co and mn although there are distinguishable compositional offsets in the glass populations the ni co ratio does not differ dramatically among the very low ti glasses from other sampling sites although incompatible element concentrations may differ significantly these trace element data eliminate fractional crystallization and partial melting of a homogeneous source under extremely low fostaggered2 conditions as possible models for the origin of the compositional variations observed in the a15 very low ti glass population these data are consistent with the generation of these magmas through partial melting of a spatially restricted heterogeneous lunar magma ocean lmo cumulate sequence the compositional variation in these magmas can be produced by at least two different melting processes 1 partial melting of a cumulate sequence consisting of relatively early cumulates with a higher proportion of an intercumulus melt component green glass a d e and later cumulates with lower proportions of an intercumulus melt component green glass c 2 different degrees of partial melting of a cumulate sequence small degrees of partial melting less than 5 of a more primitive cumulate mantle source will generate one group of magmas green a d e whereas a group of other picritic magmas green c were produced by larger degrees of partial melting 10 to 20 of a mineralogically similar but a more evolved cumulate mantle source in both models the green b glass group is formed by either cumulate commingling or magma mixing processes these magmas cannot be rapidly transported from the source region to the lunar surface in a single eruptive event without extensive fractional crystallization yet the colinear relationship among ni co and mn is not compatible with extensive and variable fractional crystallization therefore a polybaric melting model as suggested by longhi 1992b appears to be the only alternative to producing relatively unfractionated apollo 15 very low ti picritic magmas with high pressure signatures the trace element data provides additional constrains for this type of model

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

petrogenesis of the apollo 14 high alumina basalts implications from ion microprobe analyses abstract in this study ion microprobe analyses of individual minerals are used to investigate the petrogenesis of the apollo 14 high al basalts we use trace element concentrations from individual minerals in the apollo 14 high al basalts to evaluate both endogenic and exogenic models the data show that if the apollo 14 high al basalts were produced by melting within the lunar mantle these basalts cannot be related to one another by closed system fractional crystallization of a single basaltic melt rather the trace element data show that variable amounts of a kreep component were added to the basalts by either assimilation mixing into mantle sources or impact melting single stage assimilation fractional crystallization models can only explain the data from this study if an excessively large mass of urkreep is assimilated into the parent magma before olivine crystallization alternatively the trace element data can be explained if the apollo 14 high al basalts were produced by melting multiple al rich mantle sources that contain different amounts of urkreep finally for impact melting to be a relevant process the data require that multiple large impact melts be formed from mixed kreep rich target lithologies the resulting impact melts must then crystallize to produce basalts with igneous textures high al2o3 concentrations uniform major element compositions and a wide range of incompatible trace element concentrations

pseudobrookite group oxide solutions and basaltic melts abstract orthorhombic bbmm r2 1 x 3 rx2 ti1 xo5 r3 r2 ti m1 ti r2 r3 2m2o5 solid solutions were first recognized in lunar rocks and then identified as such on earth even though they are less common than ilmenite and magnetite s l there is strong field experimental and theoretical evidence that they are not geological oddities besides pseudobrookite oxide solutions may have had a critical role in the petrogenesis of the mare basalts and lunar picritic glasses as a source of tio2 and may be present in other planetary bodies as well as materials they are of particular theoretical and practical interest because of the cation order disordering phenomena that affect their physical and mechanical properties and participation in the tio2 slag smelting process x ray crystallography and spectroscopy studies have shown that all the cations are in octahedral coordination occupying two nonequivalent sites with a 1 2 ratio evaluation of site fractions configurational entropy in r2 1 x 3 rx2 ti1 xo5 solutions and of the known properties of pseudobrookite group mgti2o5 suggests that r23 tio5 solutions may reach cation random distribution and thus entropy maxima at lower temperatures than r2 ti2o5 rich solid solutions as a result the entropy contribution to their thermodynamic stability may depend upon the r 2 r 3 ratio on the basis of computations experiments and chemography of mineral equilibria it is inferred that 1 assemblages of pseudobrookite group ti oxide ilmenite rutile olivine and pyroxene s should be expected under lower crust and upper mantle conditions in the earth and conceivably in other planetary bodies including the earth s moon 2 reactions between pseudobrookite group ti oxide and olivine orthopyroxene and pseudobrookite group ti oxide or ilmenite can produce ilmenite or olivine saturated ti enriched liquids 3 lack of either ilmenite or pseudobrookite group ti oxide saturation in melts which are in equilibrium with orthopyroxene and olivine enriches these melts in tio2 4 the assemblage olivine orthopyroxene rutile has a large stability field and is probably replaced by olivine orthopyroxene ilmenite with increasing pressure and temperature and olivine orthopyroxene pseudobrookite group ti oxide with decreasing pressure and increasing temperature 5 lunar source regions nominally saturated in olivine orthopyroxene and pseudobrookite group ti oxide or ilmenite may produce the range of tio2 content in the lunar pristine glasses which apparently cannot be derived by partial melting of model late stage lunar magma ocean oxide silicate assemblages or equivalent bulk compositions

presidential address presented 2000 august 28 chicago illinois usa the eucrite vesta story many lines of evidence indicate that meteorites are derived from the asteroid belt but in general identifying any meteorite class with a particular asteroid has been problematical one exception is asteroid 4 vesta where a strong case can be made that it is the ultimate source of the howardite eucrite diogenite hed family of basaltic achondrites visible and near infrared reflectance spectra first suggested a connection between vesta and the basaltic achondrites experimental petrology demonstrated that the eucrites the relatively unaltered and unmixed basaltic achondrites were the product of approximately a 10 melt studies of siderophile element partitioning suggested that this melt was the residue of an asteroidal scale magma ocean mass balance considerations point to a parent body that had its surface excavated but remains intact modern telescopic spectroscopy has identified kilometer scale vestoids between vesta and the 3 1 orbit orbit resonance with jupiter dynamical simulations of impact into vesta demonstrate the plausibility of ejecting relatively unshocked material at velocities consistent with these astronomical observations hubble space telescope images show a 460 km diameter impact basin at the south pole of vesta it seems that nature has provided multiple free sample return missions to a unique asteroid major challenges are to establish the geologic context of the hed meteorites on the surface of vesta and to connect the remaining meteorites to specific asteroids

exploring the moon s surface for remnants of the lunar mantle 1 dunite xenoliths in mare basalts a crustal or mantle origin remotely sensed observations from recent missions e g grail kaguya chandrayaan 1 have been interpreted as indicating that the deep crust and upper mantle are close to or at the lunar surface in many large impact basins e g crisium apollo moscoviense if this is correct the capability of either impact or volcanic processes to transport mantle lithologies to the lunar surface should be enhanced in these regions somewhat problematic to these observations and interpretations is that examples of mantle lithologies in the lunar sample collection apollo program luna program lunar meteorites are at best ambiguous dunite xenoliths in high ti mare basalt 74275 are one of these ambiguous examples in this high ti mare basalt olivine occurs in three generations olivine associated with dunite xenoliths olivine megacrysts and olivine microphenocrysts the dunite xenoliths are anhedral in shape and are generally greater than 800 m in diameter the interior of the xenoliths are fairly homogeneous with regard to many divalent cations for example the mg mg mg fe 100 ranges from 82 to 83 in their interiors and decreases from 82 to 68 over the 10 30 m wide outer rim titanium and phosphorus x ray maps of the xenolith illustrate that these slow diffusing elements preserve primary cumulate zoning textures these textures indicate that the xenoliths consist of many individual olivine grains approximately 150 200 m in diameter with low ti al and p cores these highly incompatible elements are enriched in the outer fe rich rims of the xenoliths and slightly enriched in the rims of the individual olivine grains highly compatible elements in olivine such as ni exhibit a decrease in the rim surrounding the xenolith an increase in the incompatible element depleted cores of the individual olivine grains and a slight decrease in the interior rims of the individual olivine grains inferred melt composition liquid lines of descent and zoning profiles enable the reconstruction of the petrogenesis of the dunite xenoliths preservation of primary magmatic zoning ti p al and lack of textures similar to high pressure mineral assemblages exhibited by the mg suite shearer et al 2015 indicate that these xenoliths do not represent deep crustal or shallow mantle lithologies further they are chemically and mineralogically distinct from mg suite dunites identified from the apollo 17 site more likely they represent olivine cumulates that crystallized from a low ti mare basalt at intermediate to shallow crustal levels the parent basalt to the dunite xenolith lithology was more primitive than low ti basalts thus far returned from the moon furthermore this parental magma and its more evolved daughter magmas are not represented in the basalt sample suite returned from the taurus littrow valley by the apollo 17 mission the dunite xenolith records several episodes of crystallization and re equilibration during the last episode of re equilibration the dunite cumulate was sampled by the 74275 high ti basalt and transported over a period of 30 70 days to the lunar surface