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

a sims study of lunar komatiitic glasses trace element characteristics and possible origin abstract in apollo 16 regolith breccias wentworth and mckay 1988 identified a suite of minute sio 2 37 5 52 al 2 o 3 12 5 32 tio 2 0 1 1 6 and ultra mg character atomic mg mg fe 0 90 of the glasses suggest a variety of possible origins from complex impact processes to complex volcanic processes involving rather unusual and primitive magmatism trace element data derived from in situ secondary ion mass spectrometric sims analysis of individual glass beads show a wide range of concentrations la n 25 290 yb n 16 120 ba 80 1000 ppm zr 182 800 ppm sr 70 230 ppm with distinguishable trace element characteristics ba sr 1 la yb n 1 5 2 5 eu sm n 0 1 0 3 low siderophile element concentrations incompatible element concentrations are highly correlated to each other and to fe the extent of trace element depletion or enrichment in these glasses appears to be correlated to the siderophile character of the element ionization potential or experimentally determined silicate melt fe metal partition coefficients k d 1 for co fe k d k d 1 for ba ree zr the ultra mg glasses are depleted in co relative to a bulk moon mg co exhibited by many lunar samples volcanic glasses basalts regolith breccia estimated upper mantle the low co and high incompatible element concentrations diminish the possibility that these glasses are a product of lunar komatiitic volcanism or impact excavation and melting of a very high mg plutonic unit the low siderophile fe and co concentrations suggest a complex impact melt process which involved impact into compositionally variable targets reduction of feo to fe metal partitioning of siderophile elements into the metal phase and efficient separation of that phase from the impact droplets

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

rb sr and sm nd isotopic and ree studies of igneous components in the bulk matrix domain of martian breccia northwest africa 7034 the bulk matrix domain of the martian breccia nwa 7034 was examined petrographically and isotopically to better understand the provenance and age of the source material that make up the breccia both 147sm 143nd and 146sm 142nd age results for mineral separates from the bulk matrix portion of breccia nwa 7034 suggest that various lithological components in the breccia probably formed contemporaneously 4 44 ga ago this old age is in excellent agreement with the upper intersection ages 4 35 4 45 ga for u pb discordia and also concordia defined by zircon and baddeleyite grains in matrix and igneous textured clasts consequently we confirm an ancient age for the igneous components that make up the nwa 7034 breccia substantial disturbance in the rb sr system was detected and no age significance could be gleaned from our rb sr data the disturbance to the rb sr system may be due to a thermal event recorded by bulk rock k ar ages of 1 56 ga and u pb ages of phosphates at about 1 35 1 5 ga which suggest partial resetting from an unknown thermal event s possibly accompanying breccia formation the nwa 7034 bulk rock is lree enriched and similar to kreep rich lunar rocks which indicates that the earliest martian crust was geochemically enriched this enrichment supports the idea that the crust is one of the enriched geochemical reservoirs on mars that have been detected in studies of other martian meteorites

apollo 14 mare basalts petrology and geochemistry of clasts from consortium breccia 14321 eleven mare basalt clasts have been extracted from polymict lunar breccia 14321 for a combined petrologic and geochemical study by our consortium ten of these clasts are high al low ti mare basalts similar to those discovered previously at apollo 14 the other is a highly evolved tridymite ferrobasalt with low al and intermediate ti contents a high al ilmenite ferrobasalt from lunar breccia 14305 is the most evolved high al basalt described from the apollo 14 site the major and trace element characteristics of the basalts studied here allow them to be grouped into five compositional types that range from lree depleted to lree enriched some of these types may be related by varying percents of partial melting of the same source but at least two separate sources that differ by a factor of two in incompatible trace element concentrations are required the 14321 type basalts and vitrophyres have steep chondritenormalized hree slopes and may have formed by assimilation of intermediate k fra mauro kreep which is presumed to represent a partial melt of the lower crust the age of these basalts 3 9 aeons suggests that mare volcanism played an important role in the evolution of the early lunar crust

metasomatic products of the lunar magma ocean the role of kreep dissemination the origin of the incompatible element rich lunar component kreep is in the lunar magma ocean lmo the fractionated residual melt after crystallization of the lmo represents urkreep after warren and wasson 1979 the percentage of this residual melt is low enough to be within the realm of silicate liquid immiscibility sli this process has the ability to split the kreep signature into k and reep fractions which are manifest as lunar granite k and phosphate phases present in highland lithologies or as quartz ferrotroctolite in lunar soils reep we envisage this as a localized but significant process since only a small portion of urkreep undergoes sli norms of experimental and apollo 15 basaltic immiscible glasses suggest that thevreep fraction found in the lunar highlands has undergone post sli fractionation of at least fayalite this significantly reduces the density of the reep fraction and coupled with its low viscosity 10 15 poise it can percolate upward metasomatizing the lunar crust the higher viscosity of the granitic melt 30000 poise inhibits its mobility and it forms pods in the lower rust as required for vhk basalt petrogenesis with the identification of kreepy components the composition of urkreep can be calculated using experimental evidence the kreep components may be recombined to give the pre sli composition or liquid liquid kd s can be used to calculate a pre sli composition from lunar granite both calculated urkreep compositions are lower in mgo and al2o3 and higher in feo and p2o5 than reported low and high k kreep compositions the calculated ree abundances are higher and the ree profiles are slightly more lree enriched than the previously reported kreep compositions however the ree profile calculated using liquid liquid kd s is concave upwards compared to the lree enriched profile produced by recombining the kreep components pre sli whitlockite apatite fractionation occurred prior to immiscibility in order to generate the concave upwards profile the lree enriched profile represents the pre sli magma prior to phosphate fractionation the presence of superkreepy rock types can be accounted for by k and reep fraction assimilation and the compositions of olivine vitrophyres can now be modeled using analyzed lunar rock types without the inference of a mythical high mg component other more widespread kreepy rocks e g apollo 14 breccias apollo 15 kreep basalts lkfm basalts are produced by incorporation of the more widespread pre sli urkreep component the splitting of kreep into identifiable lithological components allows the petrogenesis and role of kreep in lunar evolution to be better understood

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 role of ilmenite in the source region for mare basalts evidence from niobium zirconium and cerium in picritic glasses abstract to investigate models for the generation of lunar high ti basalts we have analyzed lunar picritic glasses for zr nb ce and ti at high precision using ion microprobe techniques the picritic magmas represented by these glasses have experienced minor crystallization which has allowed us to partially eliminate the effects of post melting processes commonly experienced by crystalline high ti mare basalts the nb zr for these glasses ranges from 05 11 the high ti glasses generally tend to have higher values of nb zr 072 109 than the very low ti glasses 048 085 the crystalline mare basalts tend to have slightly higher nb zr than glasses with similar ti from the same site for example the apollo 17 a17 high ti basalts have nb zr of approximately 09 whereas the a17 high ti glasses have nb zr of 07 kreep has nb zr of approximately 06 thus zr is fractionated from nb to different degrees in the various picritic magmas the concentrations of zr nb and ce increase from the very low ti glasses to the high ti glasses and along the trajectory the nb ce and zr ce increase nb ce 25 1 6 and zr ce 4 15 for the picritic glasses overlap with kreep nb ce 36 and zr ce 5 zr ti and nb ti show a wide range of variation in these glasses both zr ti and nb ti in the glasses range from approximately 0014 to slightly less than 0003 the zr ti and nb ti for these glasses overlap with that of the crystalline mare basalts generally with increasing ti nb and zr zr ti and nb ti decrease the exceptions to this are the apollo 14 a14 glasses that exhibit an increase in nb ti and zr ti based on these data for the picritic glasses and experimentally determined partition coefficients for nb zr and ce the mantle sources for these picritic magmas are slightly to moderately fractionated from c1 chondrite and previous estimates of the bulk silicate moon our best fit model for our data and this observation is that both the very low ti and high ti picritic magmas were derived through small to moderate degrees of nonmodal melting of lunar mantle sources consisting of a mixture of late stage lmo cumulates derived after 95 crystallization of the lmo and early to intermediate lmo cumulates derived prior to 80 crystallization of the lmo the early lmo cumulates had nb zr zr ce and nb ce ratios near c1 chondrite whereas these ratios were fractionated in the late stage lmo cumulates this hybridization of mantle sources occurred during large scale overturning of the lmo cumulate pile the source for the low ti picritic magmas had very minor amounts of ilmenite whereas the source for the high ti picritic magmas probably contained less than 6 ilmenite for all the picritic magmas ilmenite was exhausted from the residua during melting models suggesting that the high ti magmas are derived through the assimilation of an ilmenite bearing cumulate layer or preferential assimilation of ilmenite by low ti primary magmas are not consistent with the nb zr ce and ti data magmas hubbard and minear 1975 wagner and grove 1993 1995 in particular the preferential assimilation by very low ti picritic magmas of ilmenite with expected nb ce 20 000 22 000 and nb zr 55 signatures would displace the resulting high ti magma too far from our observed data large scale overturning of the lmo cumulate pile also accounts for the trace element signatures found in the a14 picritic glasses the evolved signature found in these primitive very low ti picritic glasses is most likely a product of kreep incorporation into the lmo cumulate source rather than either contamination by evolved ilmenite bearing cumulates or incorporation of higher proportions of locally derived intercumulus melt

the constitution and structure of the lunar interior the current state of understanding of the lunar interior is the sum of nearly four decades of work and a range of exploration programs spanning that same time period missions of the 1960s including the rangers surveyors and lunar orbiters as well as earth based telescopic studies laid the groundwork for the apollo program and provided a basic understanding of the surface its stratigraphy and chronology through a combination of remote sensing surface exploration and sample return the apollo missions provided a general picture of the lunar interior and spawned the concept of the lunar magma ocean in particular the discovery of anorthite clasts in the returned samples led to the view that a large portion of the moon was initially molten and that crystallization of this magma ocean gave rise to mafic cumulates that make up the mantle and plagioclase flotation cumulates that make up the crust smith et al 1970 wood et al 1970 this model is now generally accepted and is the framework that unifies our knowledge of the structure and composition of the moon the intention of this chapter is to review the major advances that have been made over the past decade regarding the constitution of the moon s interior much of this new knowledge is a direct result of data acquired from the successful clementine and lunar prospector missions as well as the analysis of new lunar meteorites as will be seen results from these studies have led to many fundamental amendments to the magma ocean model much of what we know from sample analyses has been previously summarized elsewhere and only their most important aspects will be discussed in this chapter the reader is referred to the relevant chapters in the books basaltic volcanism on the terrestrial planets basaltic volcanism study project 1981 the

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

origin of the apollo 14 15 and 17 yellow ultramafic glasses by mixing of deep cumulate remelts abstract we examine the fo2 dependent melting conditions of the apollo 14 yellow intermediate ti ultramafic glasses and the melting processes that formed the full suite of lunar yellow ultramafic glasses multiple saturation experiments indicate that the apollo 14 yellow glass would have been in equilibrium with residual olivine and low ca pyroxene near 1530 c and 2 4 gpa at iw 2 at iw 2 the multiple saturation point moves to greater depth and higher temperature to 1580 c and 3 0 gpa combining the results of this study with that of krawczynski and grove 2012 on more ti rich apollo orange and red glass indicates that the fo2 induced change in multiple saturation pressure correlates with the fe ti molar feo tio2 mgo feo tio2 where tio2 all ti calculated as ti4 of the liquid further a decrease in the olivine fe mg exchange coefficient at lower fo2 suggests that fe2 is complexing more efficiently with ti3 at the expense of mg in the melt than it did with ti4 at higher fo2 processes involving assimilation and or fractionation and or melt wall rock reaction all fail to produce the within suite compositional variability observed in the apollo 14 15 and 17 yellow glasses mixing of remelted source cumulates combined with small amounts of olivine fractionation are the only mechanisms that can reproduce all three trends we present a quantitative model of the mixing process with simultaneous olivine fractionation remarkably the trends can be explained by mixing melts of an ultramafic source olivine pigeonite or orthopyroxene a clinopyroxene ilmenite bearing cumulate and kreep lunar mantle overturn is the most likely process that can reconcile the observed major and trace element compositional characteristics and the experimental results these two constraints are consistent with different models of lunar magma ocean crystallization snyder et al 1992 eklins tanton et al 2011 a complex hot thermal history is necessary to generate the magmas that mixed to form the yellow ultramafic glasses

ion and electron microprobe study of troctolites norite and anorthosites from apollo 14 evidence for urkreep assimilation during petrogenesis of apollo 14 mg suite rocks abstract most of the moon s highland crust formed during the period 4 65 4 45 ga ago from a vast magma ocean up to 800 km deep hess and parmentier 1995 this early lunar crust comprises fe rich anorthosites with calcic plagioclase compositions subsequent evolution of the highland crust was dominated by troctolites anorthosites and norites of the mg suite this plutonic series is characterized by calcic plagioclase and mafic minerals with high mg 100 mg mg fe these rocks evidently formed by partial melting of ultramafic rocks of the lunar mantle but their bulk rock incompatible element characteristics are too enriched to represent such a primitive source previous studies have suggested that this enrichment in incompatible trace elements is the result of metasomatism of the crust by fluids rich in ree and p the products of this suggested metasomatic event are ree rich phosphates typically whitlockite deposited interstitially alternatively the incompatible element rich nature of these plutonic rocks may represent a characteristic of their parent magma acquired prior to crystallization of the plutons in an effort to distinguish the origin of this important lunar rock series we have analyzed the ree content of primary cumulus phases in ten mg suite cumulates using sims along with their major and minor element compositions by electron microprobe analysis nine of these samples have high mg s consistent with their formation from the most primitive parent melts of the mg suite the data presented here show that mg suite troctolites and anorthosites preserve major and trace element characteristics acquired during their formation as igneous cumulate rocks and that these characteristics can be used to reconstruct related aspects of the parent magma composition our data show that primitive cumulates of the mg suite crystallized from magmas with ree contents similar to high k kreep in both concentration and relative abundance the highly enriched nature of this parent magma contrasts with its primitive major element characteristics as pointed out by previous workers this enigma is best explained by the mixing of residual magma ocean urkreep melts with ultramagnesian komatiitic partial melts from the deep lunar interior the data do not support earlier models that invoke crustal metasomatism to enrich the mg suite cumulates after formation or models which call for a superkreep parent for the troctolites and anorthosites

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 mare basalt magma source region and mare basalt magma genesis given the available data we find that the wide range of mare basaltic material characteristics can be explained by a model in which 1 the mare basalt magma source region lies between the crustmantle boundary and a maximum depth of 200 km and consists of a relatively uniform peridotite containing 73 80 olivine 11 14 pyroxene 4 8 plagioclase 0 2 9 ilmenite and 1 1 5 chromite 2 the source region consists of two or more density graded rhythmic bands whose compositions grade from that of the very low tio2 magma source regions 0 2 ilmenite to that of the very high tio2 magma source regions 9 ilmenite these density graded bands are proposed to have formed as co crystallizing olivine pyroxene plagioclase ilmenite and chromite settled out of a convecting magma which was also parental to the crust in which these crystals were suspended since the settling rates of the different minerals were governed by stoke s law the heavier minerals settled out more rapidly and therefore earlier than the lighter minerals thus the crystal assemblages deposited nearest the descending side of each convection cell were enriched in heavy ilmenite and chromite with respect to lighter olivine and pyroxene and very much lighter plagioclase the reverse being the case for those units deposited near the ascending sides of the convection cells simultaneously with this density controlled settling of the crystals the heating of the magma at the bottom of the convection cells resulted in the partial remelting of significant amounts of suspended but settling plagioclase ilmenite and pyroxene this partial remelting process was also partially responsible for the decrease in the ilmenite content from 9 to 0 2 between the very high tio2 and the very low tio2 source regions and caused the plagioclases and pyroxenes in the former source regions to be more sodic and clinopyroxene richer respectively than in the latter 3 during the mare basalt epoch radiogenic induced remelting of various parts of the density graded bands led to the formation of the initial mare basalt magmas the viscosity of melting systems which decreases rapidly at about 30 5 partial melting appears to have limited the degree of partial melting of the source region to about 30 2 4 these 30 partial melts rose to the crust mantle boundary where they pooled in magma storage chambers the magmas remained in these chambers for different lengths of time cooled to different degrees and lost 0 to 30 olivine or 30 olivine plus 0 to 20 pyroxene by fractional crystallization those magmas which remained in the chambers for very short times and lost no or essentially no olivine before eruption were the parental magmas of the pyroclastic glass units those magmas which lost increasing amounts of olivine pyroxene were the parental magmas of the apollo 12 and 15 magmas the apollo 11 and 17 magmas and the luna 16 and 24 magmas respectively this fractional crystallization phase in the genesis of the magmas explains both the pattern of the mare basalt magmas in the pseudo quaternary phase diagrams and the decrease in the siderophile contents of the magmas as a function of their degree of fractionation 5 the magma storage chambers being located at the crust mantle boundary were located in the zone where urkreep formed during the initial differentiation of the moon due to the low melting point of kreep compared with the initially high temperatures of the magmas residuals of the urkreep layer were assimilated by the cooling magmas since the urkreep materials underwent varying degrees of fractional melting early in lunar history these urkreep residuals had varying degrees of light ree depletion thus the assimilation of up to a few percent of these residuals caused the magmas to have differing eu and light ree depletion patterns as well as a wide range in their ree abundances 6 the fractional crystallization and urkreep residual assimilation phase of mare basalt magma genesis ended with the eruption of the magmas onto the lunar surface

mare glasses from apollo 17 constraints on the moon s bulk composition two previously unreported varieties of mare volcanic glass have been discovered in apollo 17 samples twenty three chemical types of volcanic glass have now been analyzed from the six apollo landing sites these volcanic glasses which may be samples of primary magmas derived from the differentiated lunar mantle define two linear arrays that seem to reflect regional if not global regularities among the source regions of these melts additional systematics among these glasses have been used to estimate the bulk composition of the moon the results suggest that the refractory lithophile elements e g ca al ti ree u are present at abundances of 1 7 chondrites the silicate portion of the moon appears to have a major element composition similar to a volatile si na k depleted earth s upper mantle the theory involving an earth fission origin of the moon can be tested further through trace element analyses e g ni on the volcanic glasses and through determination of the n 36ar ratio and noble gas isotopes from primordial lunar gas trapped within vesicles associated with mare volcanic glass

diagenesis and reservoir quality of bhuban sandstones neogene titas gas field bengal basin bangladesh abstract this study deals with the diagenesis and reservoir quality of sandstones of the bhuban formation located at the titas gas field of bengal basin petrographic study including xrd cl sem and bse image analysis and quantitative determination of reservoir properties were carried out for this study the sandstones are fine to medium grained moderately well to well sorted subfeldspathic arenites with subordinate feldspathic and lithic arenites the diagenetic processes include clay infiltration compaction and cementation quartz overgrowth chlorite kaolinite calcite and minor amount of pyrite dolomite and k feldspar overgrowth quartz is the dominant pore occluding cement and generally occurred as small euhedral crystals locally as large pyramidal crystals in the primary pores pressure solution derived from grain contact is the main contributor of quartz overgrowths chlorite occurs as pore lining and pore filling cement in some cases chlorite helps to retain porosity by preventing quartz overgrowth in some restricted depth interval pore occlusion by calcite cement is very much intense kaolinite locally developed as vermiform and accelerated the minor porosity loss due to pore occlusion kaolinite chlorite enhances ineffective microporosity kaolinite is a by product of feldspar leaching in the presence of acidic fluid produced during the maturation of organic matter in the adjacent miocene or deeper oligocene source rocks the relation between diagenesis and reservoir quality is as follows the initial porosity was decreased by compaction and cementation and then increased by leaching of the metastable grains and dissolution of cement good quality reservoir rocks were deposited in fluvial environment and hence quality of reservoir rocks is also environment selective porosity and permeability data exhibit good inverse correlation with cement however some data points indicate multiple controls on permeability reservoir quality is thus controlled by pore occluding cement textural parameters grain size pore size and sorting and depositional environment the reservoir finally resumed partly its pre cementation quality after development of secondary porosity

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

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

reading the moon s volcanic record by ion microprobe analysis of apollo 14 glass beads the application of secondary ion mass spectrometry to lunar volcanic problems is demonstrated by individually analyzing representative glass from the seven apollo 14 pyroclastic glass bead groups black orange yellow lap green a vlt and green b for selected trace elements e g rare earth elements ree ba sr zr v and co the trace element characteristics of glass beads are useful for differentiating impact from volcanic glass beads and identifying other volcanic glass types e g lap trace element modeling indicates that the bead groups are unrelated by low pressure fractional crystallization to each other to apollo 14 crystalline basalts or to basalts from other landing sites a possible exception is the relation between lap and apollo 14 aluminous basalts the absence of evolved basalts derived from primary magmas with volcanic glass compositions suggests either that these evolved basalts have not been sampled or that fire fountaining tapped mantle sources subtly different from crystalline mare basalt source regions hybridization of mantle source regions is preferred to assimilation fractional crystallization processes to explain the incorporation of the evolved potassium ree phosphorus kreep component identified in these primitive magmas apollo 14 volcanic glass and mare basalt trace element signatures indicate that the character of the apollo 14 mantle source region is intrinsically different from that of other sites which suggests that large scale mantle heterogeneities exist

apollo 14 very low titanium glasses melting experiments in iron platinum alloy capsules this paper describes two techniques that have been developed to produce fe pt alloy capsules for high pressure experiments and reports liquidus phase relations of the apollo 14 very low titanium glasses determined using fe rich capsules afe 0 6 the liquid is multiply saturated with olivine and clinopyroxene at 22 kbar the multiple saturation is at least 3 kbar higher than that determined using pure fe capsules and corresponds to a source region at least 60 km deeper if olivine and clinopyroxene were the residual phases however we still need independent data on iron activity or oxygen fugacity of the glasses in order to choose a container of optimum composition preliminary experiments in fe poor alloy capsules suggest that the valence state of iron and the crystallization sequence in the melt have changed possibly as a result of oxidizing materials entrapped during the iron plating processes the feo content of the charge decreases linearly with increasing run duration in experiments using pure fe capsules the observation that iron rich globules grow with time suggests that the equilibrium fe bleb fe2o3 liq 3 feo liq might be established in the liquid at high pressure if this explanation is correct an appreciable amount of feo in the liquid could actually be fe2o3 and some natural lunar volcanic glasses may contain ferric iron as well

apollo 14 aluminous mare basalts and their possible relationship to kreep thirty six aluminous mare basalt fragments from breccia 14321 and other apollo 14 basalts are statistically divided into two broad groups comprising five subgroups using la sm and yb data major element compositions petrographic characteristics and mineral compositions are similar for the five groups however there is an eight fold increase in ree abundances from group 5 to group 1 with group 1 having a ree pattern similar to kreep groups 1 to 3 may be related by partial melting of a source similar to that proposed by unruh et al 1984 for feldspathic basalt 12038 however groups 4 and 5 cannot be as closely matched by larger degrees of partial melting of this source groups 1 to 4 could also be produced by assimilation of a kreep component by a magma similar in composition to group 5 such a magma can be produced by partial melting of an olivine orthopyroxene source that crystallized from a magma with chondritic relative ree abundances

volatile and siderophile element geochemistry of the moon a reappraisal abstract lunar volcanic glasses lvg contain high abundances of many volatile elements as compared to mare basalts whereas the latter were derived from devolatilized source regions in the outer few hundred kilometers of the moon lvg are believed to come from a globally extensive source region at greater depths which is relatively rich in volatile components abundances of volatile elements in lvg and their source regions are reviewed and in many cases found to resemble those in the earth s mantle likewise siderophile element abundances including the highly siderophile elements ir os au and re are similar in the earth s mantle and in the source regions of lvg the close geochemical similarity between the lvg source region i e the lunar lower mantle and the terrestrial mantle constitutes strong evidence that protolunar material was derived primarily from the earth s mantle since highly siderophile elements are believed to have been added to the earth as an oxidised veneer at the end of its accretion and then convectively mixed into the mantle the removal of protolunar material from the earth must have occurred after this late addition which may represent carbonaceous chondritic or cometary material from the outer solar system it is widely believed that the moon was formed by the impact of a giant planetesimal on the protoearth the planetesimal is presumed to have formed in the inner solar system and to have differentiated internally into a mantle and core numerical modelling of the giant impact shows that most of the material now in the moon would have been derived from the mantle of the impactor however this is contradicted by the geochemical evidence provided by lvg which implies that the moon is composed mainly of material derived from the terrestrial mantle a possible answer to this dilemma is provided by the observation that the lvg source region reflects the geochemistry of the late oxidised veneer which accreted on the earth this suggests that protolunar material may have been removed from the earth s mantle by impacts from one or more high velocity 30 km s planetesimals composed mainly of ices and derived from the outer solar system the volatiles from the impacting planetesimals were lost after these collisions the impacts probably ejected material from the earth s mantle as jets of molten matter which was rapidly quenched thereby retaining a large proportion of its terrestrial volatile inventory

petrogenesis of the northwest africa 4898 high al mare basalt northwest africa nwa 4898 is the only low ti high al basaltic lunar meteorite yet recognized it predominantly consists of pyroxene 53 8 vol and plagioclase 38 6 vol pyroxene has a wide range of compositions en 12 62 fs 25 62 wo 11 36 which display a continuous trend from mg rich cores toward ca rich mantles and then to fe rich rims plagioclase has relatively restricted compositions an 87 96 or 0 1 ab 4 13 and was transformed to maskelynite the ree zoning of all silicate minerals was not significantly modified by shock metamorphism and weathering relatively large up to 1 mm olivine phenocrysts have homogenous inner parts with fo 74 and sharply decrease to 64 within the thin out rims 30 m in width four types of inclusions with a variety of textures and modal mineralogy were identified in olivine phenocrysts the contrasting morphologies of these inclusions and the chemical zoning of olivine phenocrysts suggest nwa 4898 underwent at least two stages of crystallization the aluminous chromite in nwa 4898 reveals that its high alumina character was inherited from the parental magma rather than by fractional crystallization the mineral chemistry and major element compositions of nwa 4898 are different from those of 12038 and luna 16 basalts but resemble those of apollo 14 high al basalts however the trace element compositions demonstrate that nwa 4898 and apollo 14 high al basalts could not have been derived from the same mantle source ree compositions of its parental magma indicate that nwa 4898 probably originated from a unique depleted mantle source that has not been sampled yet unlike apollo 14 high al basalts which assimilated kreepy materials during their formation nwa 4898 could have formed by closed system fractional crystallization

magnetic properties of east china sea shelf sediments off the yangtze estuary influence of provenance and particle size abstract the east china sea continental shelf offshore from the yangtze river estuary is a sedimentary system characterized by complicated hydrodynamic conditions and large variability in sediment texture granulometric geochemical and environmental magnetic analyses were carried out on surface sediments from this area to investigate the spatial variations of sediment composition and their underlying mechanisms magnetic properties of three particle size fractions 63 m were further analyzed to assist data interpretation our results reveal four distinct units subaqueous yangtze delta and inner shelf mud deposits unit a relict sands on the middle shelf unit b the transitional environment between unit a and b unit c and the area northern to unit a unit d the distributions of organic carbon iron manganese and their ratios mn fe suggest minor effects of reductive diagenesis on the surface sediment magnetic properties because of differences in sediment source and hydrodynamic conditions sediments in unit a have the highest ferrimagnetic and antiferromagnetic mineral concentrations as well as the finest ferrimagnetic grain size the significant variations of magnetic properties within unit a indicate the effect of particle size sorting during sediment transportation and deposition sediments in unit b have the coarsest ferrimagnetic grain size and the highest proportion of ferrimagnetic versus antiferromagentic minerals unit c which has a bimodal size distribution can be subdivided into a southern and northern part magnetically reflecting the influence of provenance and particle size the distinct magnetic characteristics of unit d are probably due to the strong influence of materials from the yellow river our results provide a new method for characterizing east china sea shelf sediments offshore of the yangtze river mouth against which the extent of the influence of the yangtze river on the east china sea can be examined furthermore it may provide a baseline for future long term monitoring in this sensitive continental margin environment that is influenced by the yangtze river