G. Ryder (1987) the Moon. Reviews of Geophysics 25(2)

Home , Graham Ryder, KREEP, Lunar meteorite, Ryder (crater)

REVIEWSOF GEOPHYSICS,VOL. 25, NO. 2, PAGES277-284, MARCH1987 U.S. NATIONAL REPORT TO INTERNATIONAL UNION OF GEODESY AND GEOPHYSICS 1983-1986

The Moon

GRAHAM RYDER

Lunar and Planetary Institute, Houston, Texas

INTRODUCTION on the origin of the Moon have been written [Wood, 1986; Boss, 1986a; Stevenson,1986]. S.R. Taylor [1982] wrote a book that summarizedthe Moon The collisional ejection hypothesisinvokes a catastrophic as we knew it at the start of the quadrennium.Since then lunar collison late in or after the formation of the Earth, ejection sciencehas continued (perhapsto the surpriseof many), and of material to produce a disk of material (not a fully-formed provided us with many new ideas and "facts" about the Moon Moon), and a coalescenceof this material to producethe Moon and its past and presentenvironment. Lunar scienceis not [e.g., Wood, 1986; Hartrnann, 1986]. There are severalvariants moribund. Some aspectshave receivedinsufficient attention of thisbasic model: for instance,the collisionneed not be singular despitethe potential for advances.For instance,there has been [e.g., Ringwood, 1986a,b]; and Boss[1986b] suggestedthat spin little experimentalphase petrology relevant to lunar rocks.Some up of the Earth by an oblique large-bodyimpact could cause fieldslack the possibilityof new data, e.g., geophysics(although massshedding of mantle material, contributingto the disk. The reinspectionof the data continues).But the lunar samplesprovide concept of collisional impact is not new, as it derives from a continuing resourcefrom which some of the Moon's secrets Hartmann and Davis [1975] and Cameron and Ward [1976]. can, with carefulwork, be revealed,and terrestrialspectroscopic What really happened was a conflation of developments:(1) observationsprovide new data. Most important,perhaps, is that a realizationthat the traditional hypothesesof capture,fission, the framework for interpreting data is continually being and coaccretioncould not explain the M oon'sfeatures or were improved, so that our level of sophisticationis continually in some way implausible;indeed, collisional ejection appears increased. Lessons from terrestrial and meteorite studies are used to be the only mechanismwhich is not ruled out by dynamical to elucidate our lunar data, and in return, the Moon remains constraints[Boss and Peale, 1986]; (2) developmentof a better a major proving ground for ideas about the evolved bodies understandingof the growth of planetsfrom planetesimalsand of the solar system.In this review, prominenceis given to two the dynamicsof the early solar system,which showsthat large major developments which have taken place in the last bodyimpacts would be both possible and expected [ Wetherill, quadrennium:interest in and a possibleconsensus on the origin 1986;Hartmann and Vail, 1986],rather than ad hoc aspreviously of the Moon; and the recognitionand study of meteoritesfrom supposed;(3) the stimulationof the conferencefocussed attention the Moon. Less spaceis devotedto more "traditional" topics, on the hypothesis[Hartmann et al., 1986]. While the hypothesis not becausethey are actually lessimportant to lunar science, is now popular, it has not been proven, and it is not clear but because the advances are less dramatic. that it satisfies,or can satisfy,all observationaldata. Important calculations,for instanceon emplacementof ejectainto Earth THE ORIGIN OF THE MOON orbit rather than its reaccretion or total loss, and on three- The Apollo mission samplesdemonstrated that the Moon dimensionalsimulations of impact, are in progress[review in is a differentiated,evolved body, and not the primitive, cold Stevenson,1986]. The improvementin computingfacilities over body whichUrey had supposed.No clearreading of lunar origin the last decade have been very important in making the came from early Apollo science,which did however provide calculationsnecessary to amplify and constrainthe hypothesis. clues and constraints by better characterizing the Moon, Wetherill [1986] followed the natural orbital and collisional including demonstratinga very hot early period, an age the evolution of 500 initial planetesimalsto planetary formation. same as the Earth, and oxygen isotopeslying on the Earth's Later accumulationin all simulationsis characterizedby giant massfractionation line but differingfrom mostmeteorites. There impacts (up to 3X Mars size) which are sufficientto explain followed a period during which little attentionwas paid to the the large angular momentum of the Earth-Moon system(which origin of the Moon. However, during the last quadrennium, is not explainedby coatcreation).Such impacts can alsoexplain the origin of the Moon became a very active field of study, the Earth's obliquity [Hartmann and Vail, 1986]. One problem and the hypothesisthat the Moon was producedfollowing the with the collisionalejection hypothesis is showinghow material impact of a large (Mars-sized?)body into the Earth emerged can be emplacedinto orbit (rather than reaccretedor lost). One as a front-runner. This interest stemsfrom work inspired by way might be for the material to be vapor, not solid [Cameron, the Conferenceon the Origin of the Moon held in Kona, Hawaii, 1985, 1986; Thompsonand Stevenson,1983; Stevenson,1986], in October, 1984, itself inspired by the Lunar and Planetary so that gas pressureeffects become important. Viscousstresses Sample Team, and cosponsoredby the Lunar and Planetary or gravitational torques can redistribute some angular Institute, NASA, and the Division of Planetary Sciencesof the momentum [Stevenson, 1986] to help achieve orbit. Such an American AstronomicalSociety. The conferenceproduced an expanding vapor model can place enough material into abstractvolume [Hartmann et al., 1984] and a book of pertinent geocentric orbit to make the Moon [Cameron, 1985, 1986; papers[Hartmann et al., 1986]. Three important review papers Stevenson,1986]. Thompsonand Stevenson[1983] arguedthat the disk would remain hot and largely vaporizedthrough most Copyright 1987 by the •merican Geophysœcal Union. of its existencebut nonethelessexpand outsidethe Roche limit and cool within 100 years, and coalesce.The short time-scale Paper number 7R0059. 8755-1209/87/007R-0059515. O0 of accretionand the relativelyhigh temperatureof the solids

277 RYDER:THE MOON would producea partly or wholly molten Moon. Boss[1986b] new information about the characterand evolutionof the Moon, found that although dynamic fission was unlikely, spin up and prove that rocks can be ejectedfrom planetarybodies up produced by tangential impact could have contributed to at least lunar size without melting or even appreciable substantialmatter to a prelunardisk. Durisenand Scott [ 1984] shocking.Much of the work on ALHA 81005 was reported had removedan objectionto fission,but Bossand Mizuni [ 1985] at the 14th Lunar and Planetary ScienceConference [Abstracts found that planetaryviscosities, even of molten bodies,are too for Special Sessionon Meteorites from Earth's Moon, Lunar high for natural fissionto occur. and PlanetaryScience XIV] and in a specialissue of Geophysical The postulatedimpact is beyondany human experience,and ResearchLetters [Vol. 10, 9, 1983]; much of the work on the attempts to "scale" known impacts are probably doomed other meteoriteswas presented in two SpecialSessions on Lunar [Stevenson,1986]. Numerical three-dimensional simulations are Meteorites at the Tenth and Eleventh Symposiaon Antarctic in their infancy [Cameron, 1985; Benz et al., 1986a,b; Kipp Meteoritesin Japan (Special Session:Lunar Meteorites, 1985, and Melosh, 1986],and it would be prematureto usethe results 1986). as firm constraints. ALHA 81005 was the last of 373 samplescollected in the The Moon's compositionis at least roughly similar to that 1981- 1982season, in January, 1982.It wasrecognized as unique of the Earth'smantle [review by Drake, 1986a]and this evidence by its collector,John Schutt[Marvin, 1983].Its unusualnature wasa powerfulmotivator of the fissionhypothesis. Some authors wasdescribed in initial processing[Score, 1982], and its similarity have suggestedthat the compositionsare very similar indeed, to somelunar rockswas observed in thin section[Mason, 1982]. e.g., Ringwood [1986a,b] believesthat the siderophilepatterns Y-791197 was collected in November, 1979, but was not in the Earth are controlled by complex processesrelated to recognizedas lunar until much later [ Yanaiand Kojima, 1984]. core formation and uniqueto the Earth; he alsofinds the lunar Y-82192 and Y-82193, collectedclose together, were recognized siderophile abundance patterns to be similar to the Earth's as probablelunar samplesduring their preliminaryexamination mantle. He thus postulatesa number of large impactsinto the and are probablyfragments of the samefall [ Yanaiet al., 1986]. Earth producinga ring of mantle-derivedplanetesimals. Wiinke The evidence that these meteorites are lunar is manifold. The and Dreibus [1986] find the chemical similarities to be samples are all anorthositic regolith breccias, with the compelling.Others stronglydisagree with supposedsimilarities petrographic and chemical characteristicsof lunar rocks, [e.g., Drake, 1983, 1986a,b; Taylor, 1986; Kreutzbergeret al., including Fe/Mn about 70, from the highlands[e.g., Warren 1986; and othersin Hartmann et al., 1986],finding differences et al., 1983c; Warrenand Kallemeyn, 1986; Ostertaget al., 1985; in siderophiles,refractory elements, and Mg/Fe, among others. Lindstrom et al., 1985]. Perhapsmost decisiveare the oxygen Warren [1986] however finds the Mg/Fe's to be similar, but isotopemeasurements on ALHA 81005 [Mayeda et al., 1983] becauseof fractional condensationof the ring, arguesagainst and Y-791197[Clayton et al., 1984]. Rare gas data for ALHA the collisionalejection model. Cameron[1985, 1986] finds that 81005 show relative and absolute abundances similar to lunar most of the disk from a large impact is produced from the regoliths,butunlike any known meteorites [Bogard and Johnson, projectile, not the Earth. If so, then severalchemical features 1983; Eugster et al., 1985]; similar resultswere obtained for becomefree parameters.Furthermore, both the Moon and the Y-791197[Takaoka, 1985] and Y-82192[Takaoka, 1986].Lunar Earth's mantle could havechanged by continuedcore formation anorthositicsamples have Pb isotopicsignatures that are unique and meteoritic infall since lunar origin [e.g., Newsom, 1984] amongall solarsystem materials: Their high 2ø7/2ø6pb and 206/ so that the identificationand significanceof chemicalsimilarities 2ø4pbresult from two stagesof U-Pb evolutionwith high U/ and differencesremains an opaqueyet potentiallyfruitful field. Pb from 4.5 to 3.9 Ga ago and a drastic decreasein this ratio Nonetheless,lunar geology, petrology, chemistry,and physics at 3.9. Ga ago. ALHA 81005 [Chen and Wasserburg,1985] must continue to work together toward as clear a picture as and Y-791197 [Nakamura et al., 1985] show these same Pb possibleof the initial natureof the Moon. characteristics,providing strong independentevidence for their The origin of the Moon appearsto requirea disk of volatile- lunarorigin. (Data for Y-82192plot insteadon the 2ø7/2ø4pb and iron-depletedmaterial in Earth orbit. The collisionalmodel versus2ø6/2ø4pb geochron, and thus are not similar to lunardata appearsto producethat, but other methodshave been invoked and the sample might be contaminated with meteoritic or too, such as using differentiatedbodies with separationof the terrestrialPb; [Nakamura et al., 1986]).Ar and Sr isotopicdata metal-rich parts [reviewedand referencedin Warren, 1986, and for the Yamato meteoritesalso give indications that much of others in Hartmann et al., 1986]. The origin of the Moon is the material has the typical 3.9 Ga age of lunar highlandsrocks under intense study, and the field is largely in the realm of [Kaneoka and Takaoka, 1985;Nakamura et al., 1985; Takaoka, physics.The impact hypothesisis attractivebecause at present 1985]. Nagata and Funaki [1985] found Y-791197 to have it has no stronglynegative attributes, but that may be because uniquely lunar magneticproperties, including the coexistence it is still in primitive form; greatereffort on the positiveattributes of pure metalliciron and kamacitewith 5-12% Ni. The absence is needed[Stevenson, 1986]. of nuclearparticle tracks in ALHA 81005 and Y-791197[Sutton and Crozaz, 1983; Crozaz, 1985] and somecosmogenic nuclide LUNAR METEORITES FROM ANTARCTICA data for all of them [Nishiizumi et al., 1986] demonstratea much shortertime in spacethan most meteorites.Thermolum- At the openingof the quadrennium,no lunar meteoriteshad inescencestudies [Sutton and Crozaz, 1983;Sutton, 1985]also been recognized. There are now four. Allan Hills 81005 was demonstratetransit times of less than 2500 years, if the loss thefirst meteoriteto be positivelyidentified with a specificparent of naturalthermoluminescence is a resultof shockheating during body [Bogard, 1983]. The other three are from the Japanese ejectionrather than solar heatingin near-sunorbit or heating Yamato collection:Y-791197, Y-82192, and Y-82193 [ Yanai et during atmosphericentry. al., 1984, 1986; Yanaiand Kojiima, 1984, 1985]. All four lunar All four meteoritesare regolith breccias,containing varied meteoritesare rather small: 31, 52, 37, and 27 g respectively. clasttypes including glass, and with glassymatrices. However, Their significancefar outweighstheir mass,for they provide exceptfor Y-82192 and Y-82193, they are not petrographically RYDER:THE MOON 279 or chemicallyidentical. The KREEP component(with high at lower temperatures[Kaneoka and Takaoka, 1985]. Bulk incompatibleelement abundances with a distinctpattern) which samples(= matrix+clasts)of Y-82192gave 4øAr-39Ar ages of characterizesmost of the brecciasand soils collectedby the 4.2 Ga for the high temperaturerelease (90% of radiogenicAr) Apollo and Luna missionsis lackingin all four meteorites[e.g., and a K-Ar age of 4.0+0.4 Ga [Kanaoka and Takaoka, 1986; Warren and Kallemeyn, 1986;Fukuoka et al., 1986] which have Takaoka, 1986]. Some of the lower temperaturefractions gave incompatibleelements less than 2% thosein KREEP. The lunar ages older than 4.5 Ga and probably indicate contamination meteoritesthus appearto have beenderived from a location(s) with terrestrialAr [ Takaoka, 1986]. Weberet at. [ 1986]reported distinctfrom the area sampledby spacecraft,and they are even an Ar age of 3.8.Ga. Takahashiet at. [1986] measuredRb and possiblyfrom the farside. Sr isotopicratios for materialsin Y-791197,finding "isochrons" The lunar meteorites have similar incompatible element correspondingwith 3.9 Ga ages,although the small spreadin patterns, but different abundances,with Y-791197 having the Rb/Sr giveslarge errors (0.3 Ga). The initial 87Sr/86Sr are very highest(about 7X chondrites)and Y-82192 and Y-82193 having low and confirm the low KREEP abundancesof the samples. the lowest (2-3X chondrites) abundances[e.g., Warren and The radiogenicisotope data are consistentwith that part of Kallemyn, 1986; Lindstrom et al., 1985; Ostertaget al., 1985; the Moon representedby the sampleshaving undergone an Bischoff and Palme, 1986; Fukuoka et al., 1986; Nakamura impact history similar to the Apollo and Luna sites. Clearly et al., 1986a,b]. The chondrite-normalizedREE patterns are the redistribution of KREEP at 3.9 Ga was not global, nor slightlyenriched in light rare earth elements,and have positive can the common 3.9 Ga agesbe ascribedto redistributionof Eu anomalies.The samplesalso differ in atomic Mg/(Mg+Fe): KREEP by a singleimpact suchas the Imbrium event. ALHA 81005--•72,Y-82192-62-65, and Y-791197-0.60 [e.g., The lunar meteoritesdid not spend much time in space, Warrenand Kattemeyn,1986; Nakamura et at., 1986a,b]. (Most accordingto track studies[Sutton and Crozaz, 1983; Crozaz, Apollo 16 regolith brecciasfall between these extremes.) Y- 1985], natural thermoluminescence[Sutton and Crozaz, 1983; 791197 appearsto be distinctlymore enrichedin volatiles such Sutton, 1985], and cosmogenicnuclide exposure studies [ Tuniz asZn and Ga [ Ostertaget at., 1985;Kaczarat et at., 1985;Bischoff et at., 1983; Nishiizumi et at., 1986]. The cosmogenicnuclide and Palme, 1986] and somesplits are among the most volatile- data are a function of exposureon the Moon and in space, enriched lunar materials known [Kaczaral et at., 1985]. The and residencetime on the Earth. They indicate that ALHA volatilesare probably of lunar, not terrestrial,origin. 81005 was probably transportedin lessthan 100,000years. The ALHA 81005 contains abundant magnesian granulitic cosmogenicnuclide data indicate terrestrial residenceages of brecciasand many hyperferroananorthosite clasts, in a matrix 170,000yr (+50,000 yr) for ALHA 81005 and lessthan 100,000 which includesswirly brown glass[e.g., Treirnanand Drake, years for Y-791197, Y-82192, and Y-82193 [Nishiizumi et at., 1983; Ryder and Ostertag,1983; Goodrichet at., 1984, 1985]. 1986]. The ALHA 81005 data agree with the terrestrial age It alsocontains glass spheres and varied feldspathic melt breccias. of morethan 90,000 yr derivedfrom 8•Krdata [Eugster et at., Treiman and Drake [1983] recognizeda mare basalt clast. Y- 1985]. 791197 contains much less glass and agglutinitic material That the four meteoriteswere ejected from the Moon by [Ostertaget at., 1985] and much lessmagnesian granulite [e.g., impact is not in doubt. This ejectionwas accompaniedby only Lindstrom et at., 1985]; mare basalt clasts have also been minor shocking,less than 25 GPa [Ryder and Ostertag, 1983; observedin Y-791197 [Lindstrom et al., 1985]. Y-82192 and Y- Ostertaget al., 1985].This itselfis significant,for it demonstrates 82193contain even less glass [Bischoffand Palme, 1986; Takeda that rocks can be ejectedfrom large planets without melting. et at., 1986], and mare componentsdo not seemto have been There had been dynamical objectionsto such removals, of recognizedin them. The marecomponent in the lunar meteorites particular significanceto the origin of Shergottitemeteorites is rare. Most of the clastsare of types generallyrecognized as Mars samples,but the lunar demonstrationhas spurredthe for Apollo and Luna highland samples,with the exceptionof productionof plausiblephysical models for suchejection [e.g., a very smallapatite-rich ferroan anorthositictroctolite fragment Melosh, 1985]. The question of whether the lunar meteorites [Goodrich et al., 1985] of complex igneous origin. The representone impact or more than one impact has not yet been proportionsare different in each [except the paired ones] and answered, and the lunar location(s) are not established.The the absence of KREEP clasts is distinctive. meteoritesare similar but not identical to each other, and are Solar-wind implanted gases in ALHA 81005 showed more dissimilarin major element abundancesthan are Apollo abundancesand patternssimilar to lunar regoliths,with exposure 16 regolithbreccias, which were collectedin an area specifically agesof more than 200 m.y. [Bogard and Johnson,1983; Eugster chosen to straddle two separate formations [Warren and et at., 1985]. Y-791197 contains similar solar-wind gases Kallemeyn, 1986]. Thus if all four were blasted off together, [Kaneoka and Takaoka, 1985; Takaoka, 1985]. Both samples evidentlythey were not closetogether before the impact, or were probably irradiated near the lunar surface for several the impact was in an exceptionallyheterogeneous area. The hundredmillion years.In contrast,the noblegas concentrations presenceof mare basaltsis one constrainton their origin. One in Y-82192are two ordersof magnitudelower [Takaoka, 1986; possibilityis Giordano Bruno, a very young crater according Weberet at., 1986].Radiogenic 4øAr was not lost recently, to its bright rays, which is 20 km in diameter (larger than the cosmic-rayirradiation agesare short in contrastwith ALHA Apollo 16 traversearea) and in a complex highlandsterrain 81005and Y-791197, and •3•Xe is not in excess,all indicating [seeRyder and Ostertag,1983]. heavyshielding by burial (500 g/cm 2 or more) rather than impact loss[Takaoka, 1986].There is really no indicationthat Y-82192 MARE BASALTS evercontained solar-wind gases; thus there are samplesof lunar regolithwhich have never been exposedto the solar wind for During the quadrennium,several advances were made in our any appreciabletime [Weber et at., 1986]. understandingof the ages and magmatic processesof mare 4øAr-39Arstudies on Y-791197showed a hightemperature volcanism on the Moon. Taylor et al. [1983] reported the ageof 3.9-4.1Ga for a clast,although half the 39Ar was released existenceof a marebasalt more than 4.2 Ga old (Rb-Sr isochron), i)80 RYDER:THE MOON the oldest mare fragment then identified. Petrographicallyit in its interior [Tatsumotoet aL, 1986]. Thesevolcanic glasses is similar to some Apollo 12 basalts,but was a clast in an are a potentially useful sourceof information, but the work Apollo 14 breccia.In a studyof more Apollo 14 mare basalts, requiredwill not be easyto do. Daschet al. (manuscriptin preparation)found a rangeof ages, includingone sample4.33 Ga old. At the other end of the age IGNEOUS ROCKS OF THE LUNAR HIGHLANDS CRUST spectrum,Schultz and Spudis[1983] reportedphotogeological evidencefor the youngestbasalt flows visible, perhaps only 1.0 The Moon has an igneously-differentiatedcrust 55-75 km Ga old. Apollo 14 samplesof mare basaltsproduced other new thick. Its composition and evolution are important in types.One set(5 groups)possibly formed by variedassimilation constrainingthe Moon's bulk compositionand origin. The of KREEP [Shervaiset aL, 1985a;Dickinson et aL, 1985]. Most diversityof the lunar highlands,both in the rocktypes it contains are about 4.1 Ga old (Dasch et aL, manuscriptin preparation). and its lateral variations, which has been known for some time Another, a very-high K basalt, accordingto petrochemical [Taylor, 1982], has been emphasizedin the last quadrennium. [Shervaiset aL, 1985b] and isotopicdata [Shih et aL, 1986] The report of a workshop on the igneousrocks of the lunar appearsto have selectivelyassimilated a graniticcomponent; highlandswas publishedin 1983 [Longhi and Ryder, 1983]. Rb-Sr, Ar-Ar, and Sm-Nd determinationsshow crystallization Sincethen, many new fragmentsof igneousrocks, small pieces 3.8 Ga ago. Lu-Hf isotopic determinationson mare basalts of soilsand breccias,have been found and their petrography [ Unruh et aL, 1984] with Sm-Nd data suggestthat mare basalts and chemistrystudied; there have been few isotopic studies. were derived by small (< 10%) degreesof partial melting of The rock types cover a wide range including granites(sensu cumulatesources. Lu/Hf ratios are consistentwith this scenario lato) and dunitc,as well as newlyrecognized types such as alkali [Fujimaki and Tatsumoto, 1984]. However,the Lu/Hf data gabbronorites and magnesian anorthosites[Warren et al., indicatethat assimilationcannot be acceptedas a major process 1983a,b, 1986a; Lindstrom, 1984; Lindstrom et al., 1984; in explainingthe generaldiversity of lunar mare basalts.The Goodrichet al., 1986; Warrenand Kallemeyn, 1984].The lunar prevalenceor otherwiseof contaminationof variouskinds in meteoritesalso produced an extremevariety of anorthositewhich the chemistryof mare basaltsis an activefield; the fluid, high- is hyperferroan[e.g., Goodrich et al., 1984]. The Apollo 17 temperaturelavas could erode surface materials during extrusive site remainsdevoid of ferroan anorthositeswith the possible flow. The possiblemultiple use of rilles (e.g., Hadley Rille at exception of one small fragment [Warren et al., 1986a]. An Apollo 15) could includesuch erosion, already postulated for Apollo 15 ferroan anorthosite fragment contains metal and terrestrial komatiites. higher siderophileelement abundancesthan is usual, and Volcanicglasses are seento be important cluesto the interior indicatesthe uncertaintyof any attemptto estimatethe overall of the Moon, becausethey are more primitivethan crystalline siderophileabundances of the igneouscrust [Warren et al., basalts,and someeven contain volatiles from primitivereservoirs 1986b]. [review by Delano, 1986]. Phase relationssuggest that these Jamesand Flohr [ 1983]proposed a geneticdistinction between magmas come from rather deep in the mantle (400 km), gabbronorites, which have important amounts of high-Ca particularlyif the assumptionof multiple saturationat melt pyroxene,and the majority of the Mg-suite rocks, which have removalis made. Binder[ 1985]has alternativelymodelled mare little or no high-Ca pyroxene.Alkali anorthosites[Warren et magma compositionsand isotopiccharacteristics with shallow al., 1983b; $hervais et al., 1983] may be related to Mg-suite melting(< 200 km) of largepercentages, leaving generally olivine rocks or KREEP. Very evolved rock types have been found in the source,subsequent olivine (+ pyroxene)fractionation in and analyzed:a granite clast from the Apollo 14 landing site shallowmagma chambers, and crustalassimilations. The model, studiedby $hih et al. [1985] formed about 4.1 Ga ago (Rb- which is complexand includestrapped melt in the sourcesand Sr, Sm-Nd) in the shallowcrust and was excavatedand heated remeltingin convectingmagma chambers,is claimedto account 3.9 Ga ago(39Ar-4øAr). Comœston et al. [1984]applied high for trace chemicaland radiogenicisotopic data for both mare resolutionion microprobetechniques to obtain older (> 4.3 basaltsand pyroclasticglasses. Ga) U-Pb agesfor zirconsin evolved"granitic" lithologies. A It is obviousthat the originsof lunar mare basalts,and what 1 g sampleof "felsite"has been discoveredamong Apollo 12 they tell us about the lunar interior is not a closedbook but samples[Warren et al., 1986b].4øAr-39Ar dating of an olivine- an area of diverseopinion. More detaileddata on mare magmas, rich ferroan anorthositefragment from breccia67915 showed particularlyvolcanic glasses, is necessary(and is partly being somememory of an agein excessof 4.1 Ga [Marti et al., 1983]. acquired)to allow better modellingto understandthe varied These newly-discoveredrock fragmentshave been used in processesat work. Unfortunately,many mare glasstypes occur improvingour understandingof the evolutionof the lunar crust only as dispersedpieces of glass,most too small for detailed and the rock types within it. Warren [1985] gave an excellent studies[Delano, 1986].Nonetheless, some detailed work is being reviewof lunar crustaligneous rocks and ideas about their origins done; $œangleret al. [1984] dated yellow volcanicglass from and relationships,including conceptsdeveloped over the last the Apollo 15 site as 3.62+0.07 Ga using a laser probe and few years.An importantone of thesewas the partialreplacement the4øAr-39Ar technique, and found two varieties of theApollo of the term "magma ocean" with the more general term 15 greenglasses to be the same(3.41+0.12, 3.35+0.18 Ga) and "magmasphere,"which hypothetically consistsof a partially in agreementwith previousanalyses. Isotopic analysesof the molten zone (magmifer; [Shirley, 1983]) and an overlying highly-volatile elementswithin rare vesiclesin glasseshave completelymolten zone. A givenmodel can haveany proportion recently begun [Barraclough and Marti, 1985], and INAA of the two. In Shirley's[1983] model the completelymolten analysesof individualgroups of glassesis in progress(R. Schmitt zone, which continuallycrystallized and was replenished,was group). The primitive componentsmay be from the interior never more than 7 km thick. Some form of a model with a of the Moon, but the storyis certainlycomplicated, for example, magmaspherewith a large-scalemolten zone to produce the by the observationthat the primitive Pb on the surfaceof the anorthositiccrust first and then to complexly intrude it with Apollo 15 greenvolcanic glass has a sourcedifferent from that mantle-derived but variously modified magrnas (Mg-suite, RYDER:THE MOON 28 '1

KREEP) appearsto fit the known rock characteristicsand other neither is derived solely from its underlying unit. Korotev et constraints [e.g., Warren, 1985, 1986; Palme et at., 1984]. at. [1984] also concludedthat the Station 4 core soils were a Nonethelessalternatives for the production of the ferroan complex mixture of Cayley, Descartes,and other materials, anorthositeshave been seriouslypresented, including Shirleyg including mare basalt. There is as yet no consensual [1983] replenishmentmodel, diapiric anorthosites[Longhi and understandingof the origins of and differencesbetween the Ashwat, 1985] and serialmagmatism [ Walker, 1983].There are Cayley Plains and the Descartes Mountains. Melt rocks are compellingreasons to believethat the early lunar differentiation an important constituentat the site, although Spudis [1984] affected deep parts of the Moon, as summarizedby Warren revisedprevious estimates down to 10%. There are three main [1985]:the absenceof maficcumulates complementary to ferroan chemicalgroups; the VHA (very high alumina) group, which anorthosites,the Eu anomalies inferred for mare basalt sources occursin dimict breccias,has been interpreted as the Nectaris (although these anomalies in the basalts themselves were melt [Spudis, 1984], but McKinley et at. [1984] suggesteda explained instead by shallow-levelcrystallization and replen- muchgreater uncertainty. An evenmore aluminousgroup which ishment by Walker [1983]), and the high abundance of is rather young (3.8 Ga, [e.g., Deutsch and St6ffier,, 1986] is plagioclasein the crust,which is about75% at the surface,among similar in compositionto the Apollo 16 fragmental breccias. others. Assimilation of both ferroan anorthosites and KREEP- The apparent lack of an appropriate young, large sourcecrater related materials may have modified the later productsof the lead Deutsch and St6ffier [1986] to propose the radical magmasphere[e.g., Warren, 1986]. It does not appear at all conclusionthat Imbrium, whoseejecta they suggestobliterated likely that the compositionaldiversity of the crustalrocks can the source crater, is lessthan 3.8 Ga old. The validity of this be explainedby differentiationduring one magmaticevent. The conclusion is far from established. continuedanalysis of new highlandrock typeswill improve our The geologyand petrologyof the Apollo 15 landing site was understandingof the lunar crustal evolution and how much, the focus of a review covering its highland aspectsfrom local and in what way, the mantle was a part of the process. petrologyto basinformation, but alsoincluding mare volcanism, Emphasizing the difficulty of understandinglunar crustal in a workshop in 1985 and related work [Spudis and Ryder, formation are on-goinganalog studiesof rocksfrom terrestrial 1985, 1986]. Work stimulatedby this workshopis in progress. intrusions.They suggestthat we do not really know enough Lateral variations(and inferred depth variations)have been aboutthe formationof rocksin terrestrialsystems either [Salpas studiedby reexaminingthe Apollo orbital data and interpreting et al., 1983;Ryder and Spettel, 1983]. it in the light of known petrology[e.g., Davis and Spudis, 1985]. New data from Earth-basedspectroscopic measurements is also POLYMICT ROCKS OF THE LUNAR HIGHLANDS CRUST increasingour comprehensionof lateral variations[e.g., Spudis et at., 1984; Lucey et at., 1986]. Pieters and Withetms[1985] Most highlands rocks are not igneous but are some form obtained such data which implied the dominance of olivine in of breccia. They range from friable fragmental brecciasto the central peak of Copernicus.Several studies have attempted coherentclast-free impact melts. They have beenstudied recently to improve our understanding of craters, particularly the even as small bits from mare sites[Simon et at., 1983, 1985a; generationof large ones, including basins[e.g., Croft, 1985; Laut, 1986, Laut et at., 1983]. Coarse fines from the Apollo Spudiset at., 1984]. 12 site confirmed the KREEPy, Apollo 14-like nature of the highlandscrust there, includingalkali anorthositesand norites; SEISMIC STRUCTURE AND THE LUNAR INTERIOR in contrast, ferroan anorthositesappear to be absent [Simon and Papike, 1985]. Conversely,at the Apollo 11 site, coarse There have been no new geophysicalobservations of the fines showedthe highlandsto be fairly simlar to the Apollo Moon, but Nakamura [1983] reported an improved analysis 16 highlands[Simon et at., 1983]. Brecciasfrom Apollo 14 and of the Apollo seismicdata. The model which is most likely 16 have been studied [e.g., $hervais et at., 1983; Heusseret to representreality is characterizedby a velocity increasein at., 1985; James et at., 1984; Lindstrom and Lindstrom, 1986] the middle mantle (depth 400 km) rather than a decreaseas in an attempt to decipherthe ancientcomponents of the crust. had beenestimated before. Geophysical constraints can and have Understanding the geology of the Apollo 16 landing site, beenused to placeconstraints on the chemistryand mineralogy particularlythe originand relationships of the photogeologically- of the interior; suchstudies are now being revisedon the basis definedunits, the Cayley and DescartesFormations, is the goal of the Nakamura [1983] seismicprofile [Hood and Jones,1986; of many petrochemicalstudies of both soils and breccias[e.g., Mueller and Phillips, 1986]. In general, models that assume Spudis, 1984; St6ffier et al., 1985; Basu and McKay, 1984a,b; only uppermantle differentiation, that are more aluminous,have Korotev et al., 1984; McKinley et al., 1984; ReimoM et al., thermal gradients which are strong in the upper mantle but 1985; See et at., 1986; Morris et at., 1986]. St6ffier et at. [1985] weak in the lower mantle, produce calculatedvelocity profiles studiedthe petrographyand chemistryof many samplesfrom more nearlymatching the Nakamura [ 1983]velocity model, but North Ray Crater, applyingtheir knowledgeof crater dynamics are not unique. A small metallic core (1-4% lunar mass) in to assessthe immediateprovenance of the samplesfrom within such models is needed to be consistent with the moment of the crater. Their interpretation is that a lower KREEP-poor inertia constraint. The inferred interior characteristics are sectionof the crater representsthe DescartesFormation, which important in establishinglunar evolutionand origin. is Nectaris ejecta; a top section of KREEP-bearing rocks is Cayley and may be a distal faciesof the Imbrium ejecta. They LUNAR REGOLITH suggestfrom the clastscontents of the brecciasthat evenNectaris could be as young as 3.85 Ga old. Basu and McKay [1984] For science,lunar regolith studiesare really lessconcerned comparedsoils from Station 4 (high up on the Mountain) and with the Moon than they are with exogenicprocesses, and so Station 11 (also generallyconsidered to be Descartes-derived) theywill be barelyconsidered here. The lunar regolithis produced and found them to be different, although mixing suggeststhat by continuousimpacting, and recentexperimental simulations RYDER:THE MOON have clarified the processesof regolith productionfrom rock. papers in Mendell [1986]. This volume coverstransportation, They haveconfirmed the role of preferentialfusing of the finest logistic, scientific,and exploitational aspectsof a lunar base. fractionin producingagglutinitic glass [H6rz et al., 1984;Simon Of more immediate concernis the possibilityof a lunar polar et al., 1985]. There have been several petrographic-chemical orbiter, which would be useful not only in planning a lunar studiesof soils and regolith breccias(which are lithified, fossil base, but in understandingthe Moon. Such a mission is soils) [e.g., Smith et al., 1985, Simon et al., 1984, 1985a, and prominent in NASA's plans, but like all planetary science McKay et al., 1986] as well as the characteristicsof agglutinates missions,is currently something of an unknown. The Lunar [Basu and McKay, 1985; McKay and Basu, 1983; Laul et al., GeoscienceObserver would carry a battery of instruments,with 1984]. The interaction of the soil componentswith the solar luck could fly in the early 90's, and would contribute greatly wind and cosmicrays continuesto be a productivefield, in to answering fundamental questions in lunar science[LGO part improvingour knowledgeof the productionrates themselves Science WorkshopMembers, 1986]. A review of lunar science [e.g., Nishiizumi et al., 1983, 1984a,b] for variousnuclides, and [Lunar GeosciencesWorking Group, 1986] acknowledgesthe in part providing cluesto past historiesof the solar wind [e.g., continuing fundamental importance of lunar science in a Fourcade and Clayton, 1984]. Eugster et al. [1985a, b] planetarycontext, recommending that missionsfor both science demonstratedthe complex,multistage exposure history of lunar and future manned lunar base support be given high priority regolith. by NASA. Lunar sciencewas, in the previousquadrennium, perhapsin an interregnum;it now seemsto bein an expansionary THE FUTURE phase,adding to its breadthwith studiesof lunar samplesaimed at their utility as well as their secretsabout the universe. One aspectthat interestslunar scientistsis new spacecraft missions to the Moon. A considerable amount of effort has been devoted to the emplacementof a manned base on the Acknowledgments. This review was written while the author was a staff scientistat the Lunar and PlanetaryInstitute, which is operated Moon, whichwould, of course,greatly increase knowledge about by the Universities Space Research Associationunder contract no. the Moon. This effort has included conferencesand scholarly NASW-4066 with the National Aeronauticsand SpaceAdministration. articles, and much of this is summarized in the collection of This paper is Lunar and PlanetaryInstitute contributionno. 612.

REFERENCES

Arndt, J., W. v. Engelhardt, I. Gonzalez-Cabeza,and B. Meier, Boss,A. P., Proto earth massshedding and the origin of the Moon, Delano, ' W., Pristine lunar glasses:criteria, data, and implications, Formationof Apollo 15 greenglass beads, Proc. Lunar Planet.Sct. Icarus,in press,1986b. Proc. Lunar Planet. Sct. Conf 16th, in J. Geophys.Res., 91, D201- Conf 15th, in J. Geophys.Res., 89, C225-C232, 1984. Boss,A. P., and H. Mlzum, Dynamic fissioninstability of dlsslpauve D213, 1986. Baldwin, R. B., Relative and absoluteages of in&mdual craters and proto planets,Icarus, 63, 134-152, 1985 Delano, J. W., and D. H. Lmdsley, Mare glassesfrom Apollo 17 the rate of tufaIlson the Moon m the post-lmbriumperiod, Icarus. Boss,A. P., and S. J. Peale, Dynamical constraintson the origin of Constraintson the Moon's bulk composition,Proc. Lunar Planet 61, 63-91, 1985. the Moon, in Ortgin of the Moon, edited by W. K. Hartmann, R Sci. Conf 14th, in J Geophys.Res., 88, B3-BI6, 1983 Barraclough,B. L. and K. MarU, In searchof the Moon's indigenous J. Phillips, and G. J Taylor, pp. 59-101, Lunar and Planetary Deutsch,A and D. StOffler, Rb-Sr analysison Apollo 16 melt rocks volatdes:noble gases and nitrogenin veslcularlunar glasses(abstract), Institute, Houston, 1986. and the ageof Imbnum, Geochtm.Cosmochtrn. Acta, in press,1986. in Lunar and PlanetaryScience X VI, pp. 31-32. Lunar and Planetary Bratt, S. R, S C. Solomon, J. W. Head, and C. H. Thurber, The Dickinson,T., G J. Taylor, K Ked, R. A. Schmitt,S S Hughes, Institute, Houston, 1985. deep structureof lunar basins:implications for basinformation and and M. R. Smith, Apollo 15alummous mare basaltsand their possible Barron, A.M., and P. N. Shlve, Effectsof thermal cyclingon magnetic modification,J. Geophys.Res., 90, 3049-3064, 1985. relationshipto KREEP, Proc. Lunar Planet.Sct. Conf 15th, in J. propertiesof lunaranalogs, J. Geophys.Res, 89, 11573-11579,1984. Buczynskl,D. G., and P Wade, The topographyof the Phocyhdes GeophysRes., 90, C365-C374, 1985 Basu, A., and D. S. McKay, Petrologlccomparisons of Cayley and and Nasmyth area of the Moon, Brtttsh Astron. Assoc J, 95, 106 Drag,T. P., H. G Thode,and C. E. Rees,Sulphur content and sulphur Descarteson the basisof Apollo 16 soilsfrom Stations4 and 11, 109, 1985. isotopecomposition of orangeand blackglasses in Apollo 17 drive Proc. Lunar Planet.Sct. Conf 14th, in J Geophys.Res.. 89, B535 Burns,R. G., and M D. Dyar, Spectralchemistry of greenglass-beanng tube 74002/1, Geochtm.Cosmochtrn Acta, 47, 491-496 B54 I, 1984a. 15426regolith, Proc. Lunar Planet. Sct. Conf 14th, in J Geophys. Drake, M. J., Geochemicalconstraints on the origin of the Moon, Basu, A., and D. McKay, Petrologlcprofile of Apollo 16 regohthat Res., 88, B221-B228, 1983 Geochtm. Cosmochtrn.Acta, 47, 1739-1767, 1983 Station 4, Proc. Lunar Planet. Sct. Conf 15th, in J Geophys.Res., Cameron, A. G. W., The impact theory for the ong•n of the Moon, Drake, M. J., Is lunar bulk materialsimilar to Earth'smantle?, in Ortgtn 89, C133-C142, 1984b. in Origtn of The Moon, edited by W. K. Hartmann, R. J. Phillips, of the Moon, edited by W K. Hartmann, R. J. Phillips,and G. Basu,A., and D. McKay, Chemicalvariability and originof agglutlmhc and G J. Taylor, pp. 609-616, Lunar and Planetary !nstitute, J. Taylor, pp. 105-124, Lunar and PlanetaryInstitute, Houston, glass,Proc Lunar Planet.Sct. Conf 16th, in J. Geophvs.Res., 90, Houston, 1986. 1986a. D87-D94, 1985. Cameron,A. G. W., Formationof the prelunaraccretion disk, Icarus, Drake, M. J., Siderophdeelements in planetarymantles and the origin Bell, J. F., and B. R. Hawke, Lunar dark-haloed impact craters. origin 62, 319-327, 1985. of the moon, Proc. Lunar Planet. Sct. Conf 17th, in J. Geophys. and implicationsfor early mare volcanism,J. Geophys.Res., 89, Cameron, A. G W, and W. R. Ward, The origin of the Moon (abstract), Res., 91, in press,1986b. 6899-6910, 1984. in Lunar SctenceVII, pp. 120-122, Lunar and Planetary!nstitute, Duke, M B., W. W. Mendell, and B. B. Roberts, Towards a lunar Benz, W., W. L. Slattery, and A. G. W. Cameron,The origin of the Houston, 1976. baseprogramme, Space Pohcy, February, 49-61, 1985. Moon andthe singleimpact hypothesis, ! Icarus,in press,1986a. Cashore, J., and A Woronow, A new Monte Carlo model of lunar Dunsen, R H., and E. H. Scott, Implications of recent numerical Benz, W., W. L. Slattery, and A G. W. Cameron,The origin of the megaregohthdevelopment, Proc. Lunar Planet. Sct. Conf 15th, in calculationsfor the fissiontheory of the origin of the Moon, Icarus, Moon: 3D numerical simulations of a giant impact (abstract), in J Geophys.Res., 90, C811-C815, 1985. 58, 153 158, 1984. Lunar and PlanetarySctence XVII, pp. 40-41, Lunar and Planetary Chen,J. H., and G. J. Wasserburg,U-Th-Pb isotopicstudies on meteorite Dyar, M.D., Experimentalmethods for quenchingstructures in lunar- Institute, Houston, 1986b. ALHA-81005 and Ibitlra (abstract),in Lunar PlanetarySctence XVI, analog silicate melts' vanauons as a function of quench media and Binder,A. B., Mare basaltgenesis: modelling trace elements and isotopic pp. 119-120, Lunar and PlanetaryInst•tute, Houston, 1985. composition,Proc. Lunar Planet. Sct. Conf 15th, in J Geophys. ratios, Proc. Lunar Planet. Sct. Conf 16th, in J. Geophys Res., Chen, H.-K., and D. H. Lindsley,Apollo 14 Very Low Titaniumglasses. Res, 89, C233-C239, 1984. 90, D19-D30, 1985. melting experimentsin iron-platinum alloy capsules,Proc. Lunar Eugster,O., Multistageexposure history of the 74261soil constituents, Binder,A. B., The depthsof the mare basaltsource region, Proc. Lunar Planet. Sct. Conf 14th, in J. Geophys Res.,88, B335-B342, 1983. Proc. Lunar Planet. Sct. Conf. 16th, in J. Geophys.Res., 90, D95- Planet Sct Conf 15th,in J. GeophysRes., 90, C396-C404,1984. Clayton, R. N., T. K. Mayeda, and K. Yanm, Oxygen isotopic DI02, 1985. Binder, A. B., and H.-C. Gunga, Young thrust-fault scarps in the compositionsof some Yamato meteorites,Mere. Nat. Inst. Polar Eugster,O., P. Eberhardt,J. Gelss,N. Groglet, M. Jungck, F Meier, highlands:Evidence for an initiallytotally molten Moon, Icarus,63, Res., Spec. IssueNo. 35, 267-271, 1984. M. Morgell, and F. Niederer,Cosmic ray exposureh•stones of Apollo 421 441, 1985. Collinson, D. W., On the existence of magnetic fields on the moon Binder,A. B., and J. Oberst,High stressshallow moonquakes Evidence between3.6 Ga ago and the present,Phys. Earth Planet. Inter., 32, 14, Apollo 15 and Apollo 16 rocks,Proc. Lunar Planet.Sct. Conf. 14th, in J. Geophys.Res., 89, B498-B512, 1984a. for an initially totally molten Moon, Earth Planet. Sct. Left., 74, 102-116, 1984. Eugster,O., P Eberhardt,J. Gelss,N. Groglet, and H. Schwaller,Cosmic 149-154, 1985. Collinson,D. W., Primaryand secondarymagnetizations in lunar rocks Birnie, D. P. l!I, and M.D. Dyar, Coolingrate calculationsfor sdlcate -- implicationsfor the ancientmagnehc field of the Moon, Earth, rayexposure histories and 235U-•36Xe dating of Apollo11, Apollo 12, and Apollo 17 mare basalts,Proc Lunar Planet.Sct. Conf 15th, glasses,Proc. Lunar Planet.Sct. Conf 16th, in J. Geophys.Res., Moon, and Planets,33, 31-58, 1985. in J. Geophys.Res., 89, C171-C181, 1984b. 91, D509-D513, 1986. Compston, W., I. S. Williams, and C. Meyer, U-Pb geochronology Bischoff, A., and H. Palme, Volatile-richclasts from lunar meteorite of zircons from lunar breccla 73217 using a sensitivehigh mass- Eugster,O., S. Niedermann,and U. Krahenbuhl,Cosmic ray exposure Yamato-791197(abstract), in Papers Presentedto the Eleventh resolutionion microprobe,Proc. Lunar Planet. ScœConf 14th, in ageand terrestrial age of the lunarmeteorite ALHA 81005(abstract), Symposturnon AntarcucMeteorites, pp. 28-30, National Institute J. Geophys.Res., 89, B525-B534, 1984. Meteontics, 20, 642-643, 1985. of Polar Research,Tokyo, 1986. Croft, S. K., The scalingof complex craters,Proc. Lunar Planet. Sct. Fourcade,S., and R. N. Clayton, Nitrogen isotopesin lunar highlands Blanford, G. E., Particle track measurementsin lunar regolith brecclas, Conf 15th, in J. Geophys.Res., 90, C828-C842, 1985. breccias,Earth Planet. Sct. Letters, 68, 7-18, 1984. Earth, Moon, and Planets, 31,221-227, 1984. Crozaz, G., A search for nuclear particle tracks in lunar meteorite Fujimakl, H., and M. Tatsumoto,Lu-Hf constraintson the evolution Bogard, D. (Ed.), A meteoritefrom the Moon, Geophys.Res. Left., Yamato-791197 (abstract), in Papers Presented to the Tenth of lunar basalts,Proc. Lunar Planet. Sct. Conf 14th, in J. Geophys 10, 773-837, 1983. Syrnposturnon Antarcttc Meteorties, p 110, National Institute of Res., 89, B445-B458, 1984. Bogard,D.D., and P. Johnson,Trapped noble gases indicate lunar origin Polar Research,Tokyo, 1985. Fukuoka, T., J. C. Laul, M. R. Smith, and R A. Schmitt, Chemistry for Antarctic meteorite,Geophys. Res. Left., 10, 801-803, 1983. Davies,G. F., Heat depositionand retentionin a solid planetgrowing of Yamato-82192and -82193Antarctic meteorites (abstract), in Papers Boslough,M. B., S. M. Rigden,and T. J. Ahrens,Hugoniot equation by impacts,Icarus, 63, 45-68, 1985. Presentedto the Eleventh Symposmrnon Antarcttc Meteorites, pp. of state of anorthositeglass and lunar anorthoslte,Geophys. J. R. Davis, P. A., and P. D. Spudis,Petrologic province maps of the lunar 40-42, National Institute of Polar Research,Tokyo, 1986. Astron. Soc., 84,455-473, 1986. highlandsderived from orbital geochemicaldata, Proc. Lunar Planet Glass, B. P., Lunar sample 14425, not a lunar tektae, Geochtm Boss,A. P., The origin of the moon, Sctence,231,341-345, 1986a. Sct. Conf 16th , in J. Geophys Res.,90, D61-D74, 1985 CosrnochtrnActa, 50, 111 113, 1986. RYDER:THE MOO• 2 • •

Glass,B. P., andJ. A. O'Keefe,Lunar sample 14425: Corrected analysis, Lunar meteoritesYamato-791197 and ALHA-81005: the same yet the filling-in of Fraunhofer lines in moonlight, Proc. Lunar Planet. Science,229, 1410, 1985. different (abstract),in PapersPresented to the Tenth Sumposium Sci. Conf 15th, in J. Geophys.Res., 89, C240-C244, 1984. Golombek, M.P., and G. E. McGill, Grabens, basin tectonics,and on Antarctic Meteorites,pp. 119-121, National Institute of Polar Pieters,C. M., The compositionof the lunar highlandcrust from near- the maximumtotal expansionof the moon, J. Geophys.Res., 88, Research,Tokyo, 1985. infraredspectroscopy, Rev. Geophys.,24, 557-578, 1986. 3563-3578, 1983. Longhi,J., and L. D. Ashwal,Two-stage models for lunar and terrestrial Pieters,C. M., and D. E. Wilhelms,Origin of olivine at Copernicus, Goodrich,C. A., G. J. Taylor, K. Keil, W. V. Boynton,and D. H. anorthosites:petrogenesis without a magma ocean, Proc. Lunar Proc. Lunar Planet. Sct. Conf 15th, in J. Geophys.Res., 90, C415- Hill, Petrologyand chemistryof hyperferroananorthosites and other Planet. Sci. Conf 15th, in J. Geophys.Res., 90, C571-C584, 1985. C420, 1985. clasts from lunar meteorite ALHA-81005, Proc. Lunar Planet. Sci. LonghiJ., and G. Ryder(Eds.), Workshop on PristineHighlands Rocks Pieters, C. M., J. B. Adams, P. Mouginis-Mark, S. H. Zisk, J. W. Conf 15th, in J. Geophys.Res., 89, C87-C94, 1984. and the Early History of the Moon, LPI Tech.Rpt. 83-02, 92 pp., Head, T. B. McCord, and M. Smith, The nature of crater rays: the Goodrich,C. A., G. J. Taylor, and K. Keil, An apatite-rich,ferroan, Lunar and Planetary Institute, Houston, 1983. Copernicusexample, J. Geophys.Res., 90, 12393-12413, 1985. mafic lithology from lunar meteorite ALHA-81005, Proc. Lunar Lunar GeosciencesWorking Group, Status and Future of Lunar Proceedingsof the Tenth Symposiumon Antarctic Meteorites, 1985, Planet. Sci. Conf 15th, in J. Geophys.Res., 90, C405-C414, 1985. Geoscience,NASA SP-484, 54 pp., 1986. Part A: Reportsof ConsortiumStudies on the Yamato-791197(Lunar Goodrich,C. A., G. J. Taylor, K. Keil, G. W. Kallemeyn,and P. H. Lucey, P. G., B. R. Hawke, C. M. Pieters,J. W. Head, and T. B. meteorite),Mem. Nat. Inst. Polar Res. Spec.Issue, 41, 3-164, Tokyo, Warren, Alkali norite, troctolites,and VHK mare basaltsfrom breccia McCord, A compositionalstudy of the Aristarchusregion of the 1985. 14304, Proc. Lunar Planet. Sci. Conf 16th, in J. Geophys.Res., Moon using near-infraredreflectance spectroscopy, Proc. Lunar Rmtala, J., 'Ierra scarpsindicating youngest terra taults on the Moon, 91, D305-D318, 1986. Planet. Sci. Conf 16th, in J. Geophys.Res., 91, D344-D354, 1986. Earth, Moon, and Planets,31, 63-71, 1984. Grimm, R. E., and S.C. Solomon,Tectonic tests of proposedpolar Lumme, K., H. Karttunen, and W. M. Irvine, Roughnessof the lunar Rasmussen,K. L., and P. H. Warren, Megaregoliththickness, heat wanderpaths for Mars and the Moon, Icarus,65, 110-121, 1986. soil, Earth, Moon, and Planets,33, 19-29, 1985. flow, and the bulk compositionof the moon,Nature, 313, 121-124, Hartmann,W. K., Moon origin:The impact-triggerhypothesis, In Ortgtn Marh, K., U. Aeschlimann,P. Eberhardt,J. Geiss,N. Grrgler, D. T. 1985. of the Moon, edited by W. K. Hartmann, R. J. Phillips, and G. Josk, J. C. Laul, M.-S. Ma, R. A. Schmitt, and G. J. Taylor, Pieces Reimold, W. U., and R. Borchardt,Subophitic lithologies in KREEP- J. Taylor, pp. 579-608, Lunar and PlanetaryInstitute, Houston, 1986. of the ancient lunar crust: Ages and compositionof clasts in rich poikilitic impact melt rocksfrom Cayley Plains, Apollo 16- Hartmann, W. K., R. J. Phillips, and G. J. Taylor (Eds.), Papers consortiumbreccia 67915, Proc. Lunar Planet. Sci. Conf 14th, in remnantsof a volcanichighland crust? Earth Planet. Sct. Lett., 67, Presentedto the Conferenceon the Origin of the Moon, 60 pp., J. Geophys.Res., 88, BI65-BI75, 1983. 9-18, 1984. Lunar and PlanetaryInstitute, Houston, 1984. Marvin, U. B., The discoveryand initial characterizationof Allan Hills Reimold, W. U., L. E. Nyquist, B. M. Bansal, J. L. Wooden, C.-Y. Hartmann, W. K. and D. R. Davis, Satellite-sizedplanetesimals and 81005: The first lunar meteorite, Geophys. Res. Lett., 10, 775-778, Shih, H. Weismann,and I. D. R. MacKinnon, Isotope analysisof lunar origin, Icarus,24, 504-515, 1975 1983. crystallineimpact melt rocks from Apollo 16 stations 11 and 13, Hartmann, W. K., and S. M. Vail, Giant impactors:plausible sizes Marvin, U. B., and D. Walker, A transientheating event in the history North Ray Crater, Proc. Lunar Planet. Sci. Conf 15th, in J. Geophys. and populations,in Origtnof the Moon, editedby W. K. Hartmann, of a highlandstroctolite from Apollo 12 soil 12033, Proc. Lunar Res., 90, C431-C448, 1985. R. J. Phillips, and G. J. Taylor, pp. 551-566, Lunar and Planetary Planet. Sci. Conf 15th, in J. Geophys.Res., 90, C421-C429, 1985. Ringwood, A. E., Terrestrialorigin of the Moon, Nature, 322, 323- Institute, Houston. 1986. Mason, B., in Antarctic Meteorite Newsletter,5, No. 4, 1982. 328. 1986a. Hartmann, W. K., R. J. Phillips, and G. J. Taylor (Eds.), Origin of Mayeda, T. K., R. N. Clayton, and C. A. Molini-Velsko, Oxygen and Ringwood, A. E., Compositionand origin of the Moon, in Origin of the Moon, 781 pp., Lunar and PlanetaryInstitute, Houston, 1986. silicon isotopesin ALHA-81005, Geophys.Res. Lett., 10, 799-800, the Moon, edited by W. K. Hartmann, R. J. Phillips, and G. J. Hawke, B. R., P. D. Spudis,and P. E. Clark, The origin of selected 1983. Taylor, pp. 673-698, Lunar and PlanetaryInstitute, Houston, 1986b. lunar geochemicalanomalies: Implications for early volcanismand McKay, D., and A. Basu,The productioncurve for agglutinatesin Rode, O. D., and A. V. Ivanov, Grain-size distribution of Luna-24 the formation of light plains, Earth, Moon, and Planets,32, 257- planetaryregoliths, Proc. Lunar Planet.Sci. Conf 14th,in J. Geophys. regolithsamples, Sol. Sys. Res., 18, 1-3, 1984. 273, 1985. Res., 88, BI93-BI99, 1983. Runcorn, S. K., The primeval axis of rotation of the Moon, Philos. Heusser,E., N. Mailer, and E. K. Jessberger,Return to Fra Mauro: McKay, D., D. D. Bogard, R. V. Morris, R. L. Korotev, P. Johnson, Trans. R. Soc. London, 313, 77-83, 1984. nøAr?Arages (abstract), Meteoritics, 20, 660-661, 1985. and S. J. Wentworth, Apollo 16 regolith breccias:characterization Ryder, G., and R. Ostertag,ALHA-81005: Moon, Mars, Petrography, Hobbs,B. A., and L. L. Hood, F. Herbert, and C. P. Sonett,An upper and evidencefor early formationin the mega-regolith,Proc. Lunar and Giordano Bruno, Geophys.Res. Lett., 10, 791-794, 1983. bound on the radius of a highly electricallyconducting lunar core, Planet. Sci. Conf. 16th, in J. Geophys.Res., 91, D277-D303, 1985. Ryder, G., and B. Spettel,The parental magmafor some rocks from Proc. Lunar Planet. ScœConf 14th, in J. Geophys.Res., 88, B97- McKay, G., J. Wagstaff, and S.-R. Yang, Zirconium, hafnium, and the norite I subzoneof the Stillwatercomplex: a lunar analogstudy, BI02, 1983. rareearth element partition coefficients for ilmeniteand other minerals Proc. Lunar Planet. Sct. Conf 15th, in J. Geophys.Res., 90, C591- Hobbs,B. A., L. L. Hood, F. Herbert,and C. P. Sonett,Low-frequency in high-Ti lunar mare basalts:an experimentalstudy, Proc. Lunar C600, 1983. electromagneticinduction in the moon: linearizedinverse theory and Planet.Sci. Conf 16th, in J. Geophys.Res., 91, D229-D237, 1986. Salpas,P. A., L. A. Haskin, and I. S. McCallurn, Stillwater anorthosites: lunar core calculations,Geophys. J. R. Astron. Soc., 79, 691-696, McKinley, J.P., G. J. Taylor, K. Keil, M.-S. Ma, and R. A. Schmitt, A lunar analog?Proc. Lunar Planet. Sci. Conf. 14th, in J. Geophys. 1984.o Apollo 16:Impact melt sheets, contrasting nature of the CayleyPlains Res., 88, B27-B39, 1983. Hood, L. L., and S. M. Cisowski, Paleomagnetismof the Moon and and DescartesMountains, and geologichistory, Proc. Lunar Planet. Score R., in Antarctic Meteorite Newsletter, 5, No. 4, 1982. meteorites,Rev. Geophys.Space Phys., 21, 676-684, 1983. Sci. Conf 14th, in J. Geophys.Res., 89, B513-B524, 1984. Schultz, P. H., and P. D. Spudis, Beginningand end of lunar mare Hood,L. L., andA. Vickery,Magnetic field amplification and generation Mendell,W. W. (Ed.), Lunar Basesand SpaceActivities of the 21st volcanism, Nature, 302, 233-236, 1983. in hypervelocity meteoroid impacts with application to lunar Century,868 pp., Lunar and PlanetaryInstitute, Houston, 1985. See,T. H., E Hrrz, and R. V. Morris, Apollo 16 impact-meltsplashes: paleomagnetism,Proc. Lunar Planet.Sct. Conf 15th, in J. Geophys. Melosh,H. J., Ejectionof rockfragments from planetarybodies, Geology Petrographyand major-elementcomposition, Proc. Lunar Planet. Res., 89, C211-C223, 1984. 13, 144-145, 1985. Sci. Conf 17th, in J. Geophys.Res., 91, in press,1986. Hood, L. L., and J. H. Jones, Lunar compositionand structure:II. Morris, R. V., T. H. See, and E Hrrz, Compositionof the Cayley Shervais,J. W., L. A. Taylor, andJ. C. Laul, Ancientcrustal components Theoreticalseismic velocity models (abstract), in Lunar and Planetary Formationat Apollo 16 as inferredfrom impactmelt splashes,Proc. in the Fra Mauro breccias,Proc. Lunar Planet. Sci. Conf 14th, ScienceXVII, pp. 352-353, Lunar and PlanetaryInstitute, Houston, Lunar Planet. Sct. Conf 17th, in J. Geophys.Res., 91, in press, in J. Geophys.Res., 88, BI77-BI92, 1983. 1986. 1986. Shervais,J. W., L. A. Taylor, J. C. Laul, and M. R. Smith, Pristine Hrrz, F., M. J. Cintala, T. H. See, F. Cardenas,and T. D. Thompson, Mueller, S. W., and R. J. Phillips,Implications for lunar composition highlands clasts in consortium breccia 14305: petrology and Grain size evolution and fractionation trends in an experimental froman investigationof the Nakamura seismic velocity model geochemistry,Proc. Lunar Planet. Sci. Conf 15th, in J. Geophys. regolith, Proc. Lunar Planet. Sct. Conf 15th, in J. Geophys.Res., (abstract),in Lfinarand PlanetaryScience XVII, pp. 575-576, Lunar Res.,89, C25-C.40,1984. 89, C183-C196, 1984. and Planetary Institute, Houston, 1986. Shervais,J. W., L. A. Taylor, and M. M. Lindstrom,Apollo 14 mare Hughes,S.S., and R. A. Schmitt,Zr-Hf-Ta fractionationduring lunar Muller, A., Palisa Catena: small volcano chains in the western part basalts:petrology and geochemistryof clastsfrom consortiumbreccia evolution, Proc. Lunar Planet. Sci. Conf 16th, in J. Geophys.Res., of the centralhighlands, Moon and Planets,28, 23-27, 1983. 14321, Proc. Lunar Planet. Sct. Conf 15th, in J. Geophys. Res., 90, D31-D45, 1985. Muller, A., A. B. Binder, Linear crater chains:Indication of a volcanic 90, C375-C395, 1985a. James, O. B., and M. K. Flohr, Subdivisionof the Mg-suite noritic origin, Moon and Planets,28, 87-107, 1983. Shervais,J. W., L. A. Taylor, J. C. Laul, C.-Y. Shih, and L. E. Nyquist, rocks into Mg-gabbronoritesand Mg-norites, Proc. Lunar Planet. Nagata, T., and M. Funaki, Magnetic propertiesof Yamato-791197 Very high potassium(VHK) basalt: complicationsin mare basalt Sci. Conf 13th, in J. Geophys.Res., 88, A603-A614, 1983 meteoritein comparisonwith those of Apollo 15418 lunar breccia petrogenesis,Proc. Lunar Planet. ScœConf 16th, in J. Geophys. James, O. B., M. K. Flohr, and M. M. Lindstrom, Petrologyand (abstract),in PapersPresented to the TenthSymposium on Antarctic Res., 90, D3-DI8, 1985b. chemistryof lunar dimict breccia 61015, Proc. Lunar Planet. Sci. Meteorites,pp. 117-119,National Instituteof Polar Research,Tokyo, Shih, C.-Y., L. E. Nyquist, D. D. Bogard,J. L. Wooden, B. M. Bansal, Conf 15th, in J. Geophys.Res., 89, C63-C86, 1984. 1985. and H. Wiesmann,Chronology and petrogenesisof a 1.8 g lunar Kaczaral, P. W., J. E. Dennison,and M. E. Lipschutz,Yamato-791197: Nakamura, Y., Seismicvelocity structure of the lunar mantle,J. Geophys. graniticclast: 14321,1062,Geochtm. Cosmochim. Acta, 49, 411-426, A trace element-richlunar highlandssample (abstract), in Papers Res., 88, 677-686, 1983. 1985. Presentedto the TenthSymposium on AntarcticMeteorites, pp. I01- Nakamura, N., D. M. Unruh, and M. Tatsumoto, REE, Rb-Sr and Shih, C.-Y., L. E. Nyquist, D. D. Bogard, B. M. Bansal,H. Wiesmann, 102,National Instituteof Polar Research,Tokyo, 1985. U-Pb systematicsof "lunar" meteoriteYamato-791197 (abstract), in P. Johnson,J. W. Shervais,and L. A. Taylor, Geochronologyand Kaneoka,1., andN. Takaoka,•øAr-39Ar analyses of Yamato-791197, PapersPresented to the Tenth Symposiumon Antarctic Meteorites, petrogenesisof Apollo 14 very high potassiummare basalts,Proc. in PapersPresented to the TenthSymposium on AntarcticMeteorites, pp. 103-105,National Instituteof Polar Research,Tokyo, 1985. Lunar Planet. Sci. Conf. 16th, in J. Geophys.Res., 91, D214-D228, p. 107,National Institute of Polar Research,Tokyo, 1985. Nakamura, Y., H. Fujimaki, N. Nakamura, M. Tatsumoto, G. A. 1986. Keihm, S. J., Interpretation of the lunar microwave brightness McKay, and J. Wagstaft, Hf, Zr, and REE partition coefficients temperaturespectrum: feasibility of orbitalheat-flow mapping, Icarus, betweenilmenite and liquid: implications for lunarpetrogenesis, Proc. Shirley, D. N., A partially molten magma oceanmodel, Proc. Lunar 60, 568-589, 1984. Lunar Planet. Sci. Conf 16th, in J. Geophys.Res., 91, D239-D250, Planet. Sci. Conf. 13th, in J. Geophys.Res., 88, A519-A527, 1983. Kipp, M. E., and H. J. Melosh, Origin of the moon: a preliminary 1986a. Shirley, J. H., Shallow moonquakesand large shallow earthquakes: numericalstudy of collidingplanets (abstract), in Lunar and Planetary Nakamura, N., D. M. Unruh, M. Tatsumoto,T. Fujiwara,and O. Okano, a temporal correlation,Earth Planet. Sci. Lett., 76, 241-253, 1986. ScienceXVII, pp. 420-421, Lunar and PlanetaryInstitute, Houston, REE abundanceand Pb-Pb isotopic characteristicsof the lunar Simon, S. B., and J. J. Papike, Petrologyof the Apollo 12 highland 1986. meteorite, Yamato-82192 (abstract), in Papers Presented to the component,Proc. Lunar Planet.Scœ Conf. 16th, in J. Geophys.Res., Kreutzberger,M. E., M. J. Drake, and J. H. Jones,Origin of earth's EleventhSympostum on AntarcucMeteorites, pp. 647-648, National 90, D47-D60, 1985. moon: constraints from alkali volatile trace elements, Geochim. Instituteof Polar Research,Tokyo, 1986b. Simon, S. B., J. J. Papike, C. K, Shearer,and J. C. Laul, Petrology Cosmochim.Acta, 50, 91-98, 1986. Newsom, H. E., The lunar core and the origin of the Moon, Trans. of the Apollo l I highlandcomponent, Proc. Lunar Planet.Sci. Conf. Korotev,R. L., R. V. Morris, and H. V. Lauer,Jr., Stratigraphyand Am. Geophys.Union, 65, 369-370, 1984. 14th, in J. Geophys.Res., 88, BI03-BI38, 1983. geochemistryof the Stone Mountain core, Proc. Lunar Planet. Sci. Nishiizumi,K., M. T. Murrell,and J. R. Arnold,S•Mn profiles in four Simon, S. B., J. J. Papike, and C. K. Shearer,Petrology of Apollo Conf 15th, in J. Geophys.Res., 89, C143-C160, 1984. Apollo surface cores, Proc. Lunar Planet. Sci. Conf 14th, in J. 11 regolith breccias,Proc. Lunar Planet. Sci. 15th, in J. Geophys. Lambeck,K., Bandediron formation,Nature, 320, 574, 1986. Geophys.Res., 88, B211-B219, 1983. Res., 89, C108-C132, 1984. Laul, J. C., Chemistryof the Apollo 12 highlandcomponent, Proc. Nlshiizumi,K., D. Elmore,X. Z. Ma, and J. R. Arnold, løBeand Simon, S. B., J. J. Papike, D.C. Gosselin,and J. C. Laul, Petrology Lunar Planet. Sct. Conf 16th, in J. Geophys.Res., 91, D251-D261, •6C1depth profiles in an Apollo15 drill core,Earth Planet. Sct. and chemistryof Apollo 12 regolith breccias,Proc. Lunar Planet. 1986. Lett., 70, 157-163, 1984a. Sci. Conf. 16th, in J. Geophys.Res., 90, D75-D86, 1985a. Laul, J. C., J. J. Papike, S. B. Simon, and C. K. Sheeres,Chemistry Nishiizumi,K., J. Klein,R. Middleton,and J. R. Arnold,26A1 depth Simon, S. B., J. J. Papike, F. Hrrz, and T. H. See, An experimental of the Apollo 11highland component, Proc. Lunar Planet.Sct. Conf profile in Apollo 15 drill core, Earth Planet. Sci. Lett., 70, 164- investigationof agglutinatemelting mechanisms:shocked mixtures 14th, in J. Geophys.Res., 88, BI39-BI49, 1983. 168, 1984b. of sodium and potassiumfeldspars, Proc. Lunar Planet. Sct. Conf. Laul, J. C., M. R. Smith, J. J. Papike, and S. B. Simon, Agglutinates Nishiizumi, K., J. Klein, R. Middleton, P. W. Kubik, and J. R. Arnold, 16th, in J. Geophys.Res., 90, D103-D115, 1985b. as recordersof regolithevolution: application to the Apollo 17 drill Exposure history of four lunar meteorites(abstract), in Papers Smrekar,S., and C. M. Pieters,Near-infrared spectroscopy of probable core, Proc. Lunar Planet Sci. Conf 15th, in J. Geophys.Res., 89, Presentedto the EleventhSymposium on AntarcticMeteorites, pp. impact melt from threelarge lunar highlandscraters, Icarus, 63, 442- C161-C170, 1984. 58-59, National Instituteof Polar Research,Tokyo, 1986. 452, 1986. LGO ScienceWorkshop Members, Contributions of a LunarGeoscience Norris,S. J., P. K. Swan, I. P. Wright,M. M. Grady,and C. T. Pillinger, Smith, M. R., J. C. Laul, S.C. Simon, and J. J. Papike, Chemistry Observer(LGO) Mission to fundamentalquestions in lunar science, A searchfor correlatable,isotopically light carbon and nitrogen and petrology of Apollo 12 drive tube 12027, Proc. Lunar Planet. Department of Geological Sciences and the Anthrographic componentsin lunar sorts and breccias,Proc. Lunar Planet. Sct. Sci. Conf. 15th, in J Geophys.Res., 90, C507-C516, 1985. Laboratoryof SouthernMethodist University, 86 pp., 1986. Conf 14th, in J. Geophys.Res., 88, B200-B210, 1983. Spangler,R. R., and J. W. Delano, History of the Apollo 15 yellow Lindstrom,M., Alkali gabbronorite,ultra-KREEPy melt rock, and the Ostertag, R., A. Bischoft, H. Palme, B. Spettel, D. StOffier, G. impact glassand sample15426 and 15427,Proc. Lunar Planet. Sci. diversesuite of clastsin North Ray Crater feldspathicfragmental Weckworth, and H. Wanke, Lunar meteorite Yamato-791197: A lunar Conf. 14th, in J. Geophys.Res., 89, B478-B486, 1984. breccia67975, Proc. Lunar Planet. Sci. Conf 15th,in J. Geophys. highland regolith breccia(abstract), Papers Presentedto the Tenth Spangler,R. R., R. Warasila,and J. W. Delano,39Ar-nøAr ages for Res., 89, C50-C62, 1984. Symposiumon Antarcttc Meteorites,pp. 95-97, National Institute the Apollo 15 greenand yellowvolcanic glasses, Proc. Lunar Planet. Lindstrom, M. M., and D. J. Lindstrom, Lunar granulitesand their of Polar Research,Tokyo, 1985. Sci. Conf. 14th, in J. Geophys.Res., 89, B487-B497, 1984. precursoranorthositic norites of the early lunar crust, Proc. Lunar O'Keefe, J. A., The coming revolution in planetology,Trans. Am. SpecialSession: Lunar Meteorites,in PapersPresented to the Tenth Planet. Sci. Conf 16th, in J. Geophys.Res., 91, D263-D276, 1986. Geophys.Unton, 66, 89-90, 1985. Symposiumon AntarcticMeteorites, pp. 87-126, NationalInstitute Lindstrom, M. M., S. A. Knapp, J. W. Shervais,and L. A. Taylor, Palme, H., B. Spettel, H. Wanke, A. Bischoff,and D. Strffier, Early of Polar Research,Tokyo, 1985. Magnesian anorthosites and associatedtroctolites and dunite in differentiation of the Moon: evidence from trace elements in SpecialSession: Lunar Meteorites,In PapersPresented to the Eleventh Apollo 14breccias, Proc. Lunar Planet.Sct. Conf 15th,In J. Geophys. plagioclase,Proc. Lunar Planet. Sct. Conf 15th, in J. Geophys.Res., Symposiumon Antarctic Meteorites, pp. 25-59, National Institute Res., 89, C41-C49, 1984. 89, C3-C15, 1984. of Polar Research,Tokyo, 1986. Lindstrom, M. M., D. J. Lindstrom, R. L. Korotev, and L. A. Haskin, Potter, A. E., W. Mendell, and T. Morgan, Lunar luminescenceand Spudis,P., Apollo 16 site geologyand impact melts:implications for 2814 RYDER:THE MOON

the geologichistory of the lunar highlands,Proc. Lunar Planet. Sci. volcanismin the lunar highlands,Earth Planet.Sct. Lett., 66, 33- Petrologyand chemistryof two "large"granite clasts from the Moon, 15th, in J. Geophys.Res., 89, C95-C107, 1984. 47, 1983. Earth Planet. ScœLett., 64, 175-185, 1983a. Spudre, P. D., and G. Ryder, Geology and petrology of the Apollo Taylor, S. R., PlanetaryScience: A Lunar Perspecttve,481 pp., Lunar Warren, P. H., G. J. Taylor, K. Keil, G. W. Kallemeyn,D. N. Shirley, !5 landing site: past, present,and future understanding,Trans. Am. an d Planetary Institute, Houston, 1982. and J. T. Wasson, Seventhforay: Whitlockite-richlithologies, a Geophys.Umon, 66, 721-726, 1985. Taylor, S. R., The Origin of the Moon: geochemicalconsiderations, diopside-bearingtroctolitic anorthosite, ferroan anorthosites,and Spudis, P. D., and G. Ryder (Eds.), Workshop on the geology and in Origin of the Moon, editedby W. K. Hartmann, R. J. Phillips, KREEP, Proc. Lunar Planet. Sci. Conf 14th, in J. Geophys.Res., petrologyof the Apollo 15 landingsite, LPI Tech.Rpt. 86-03, 126 and G. J. Taylor, pp. 125-143, Lunar and Planetary Institute, 88, BI51-BI64, 1983b. pp., Lunar and PlanetaryInstitute, Houston, 1986. Houston, 1986. Warren, P. H., G. J. Taylor and K. Kiel, Regolith brecciaAllan Hills Spudis,P. D., B. R. Hawke, and P. Lucey, Compositionof Orientale Thompson, A. C., and D. J. Stevenson,Two phase gravitational A81005: Evidenceof lunar origin, and petrographyof pristineand basindeposits and •mplicationsfor the lunar basin-formingprocess, instabilitiesin thin diskswith applicationto the originof the Moon nonpristineclasts, Geophys. Res. Lett., 10, 779-783,1983c. Proc. Lunar Planet. Sci. Conf 15th, in J. Geophys.Res., 89, C197- (abstract), in Lunar and Planetary ScienceXIV, pp. 787-788, Lunar Warren, P. H., D. N. Shirley,and G. W. Kallemeyn,A potpourri of C210, 1984. and PlanetaryInstitute, Houston, 1983. pristineMoon rocks,including a VHK mare basaltand a unique, Stevenson,D. J., Originof the Moon--thecollision hypothesis, Ann. Trego, K. D., Implied origin for the cratersOrcus Patera and Schiller augite-richApollo 17 anorthosite,Proc. Lunar Planet. Sci. Conf Rev. Earth Planet. SCi.,in press,1986. from the lunar Channel Bouvard, Earth, Moon, and Planets, 33, 16th, in J. Geophys.Res., 91, D319-D330, 1986a. St6ffler,D., A. Bischoff,R. Borchardt,A. Burghele,A. Deutsch,E. 99-102, 1985. Warren,P. H., E. A. Jerte,and G. W. Kallemeyn,Pristine Moon rocks: K. Jessberger,R. Ostertag,H. Palme, B. Spettel,W. U. Reimold, a "large" felsite and a metal-richferroan anorthosite,Proc. Lunar Treiman,A. H., and M. J. Drake, Origin of lunar meteoriteALHA81005: Planet. Sct. Conf 17th, in J. Geophys.Res., 91 in press,1986b. K. Wacker, and H. W/inke, Compositionand evolutionof the lunar Clues from the presenceof terrae clastsand a very low-titanium crust in the DescartesHighlands, Apollo 16, Proc. Lunar Planet. Weber, H. H., O. Brann,and F. Begemann,A new noblegas abundance mare basaltclast, Geophys.Res. Lett., 10, 783-787, 1983. pattern in a lunar meteorite:Yamato-82192, in PapersPresented to Sci. Conf 15th, in J. Geophys.Res., 90, C449-C506, 1985. Tuniz, C., D. K. Pal, R. K. Moniot, W. Savin, T. H. Kruse, G. E Sutton, S. R., Thermoluminescenceof Antarctic meteorite Yamato- theEleventh Symposium on AntarcticMeteorites, pp. 53-55, National Herzog, and J. C. Evans, Recentcosmic ray exposurehistory of Institute of Polar Research,Tokyo, 1986. 791197and comparisonwith ALHA-81005 and lunar fines(abstract)• ALHA81005, Geophys.Res. Lett., 10, 804-807, 1983. in PapersPresented to the TenthSymposium on AntarcticMeteorites, Wetherill,G. W., Accumulationof theterrestrial planets and implications Unruh, D. M., P. Stille, P. J. Patchett,and M. Tatsumoto,Lu-Hf and pp. 111-113, National Instituteof Polar Research,Tokyo, 1985. concerninglunar origin, in Origin of the Moon, edited by W. K. Sm-Nd evolution in lunar mare basalts, Proc. Lunar Planet. Sc•. Sutton, S. R., and G. Crozaz,Thermoluminescence and nuclearparticle Hartmann , R. J. Phillips and G. J. Taylor, pp. 519-550, Lunar Conf. 14th, in d. Geophys.Res., 89, B459-B477, 1984. tracks in ALHA-81005: Evidencefor a brief transit time, Geophys. and PlanetaryInstitute, Houston, 1986. Walker, D., Lunar and terrestrialcrust formation, Proc. Lunar Planet. Res. Lett., 10, 809-912, 1983. Wood, J. A., Moon over Mauna Loa: A review of hypothesesof Sci. Conf. 14th, in J. Geophys.Res., 88, BI7-B25, 1983. Swindle, T. D., M. W. Caffee, C. M. Hohenberg,G. B. Hudson, J. formationof Earth'sMoon, in Origin of the Moon, editedby W. C. Laul, S. B. Simon, and J. J. Papike, Noble gas component Walker,D., andW. S. Kiefer,Xenolith digestion in largemagma bodies, K. Hartmann,R. J. Phillips,and G. J. Taylor,pp. 17-55, Lunar Proc. Lunar Planet.Sci. Conf. 15th, in J. Geophys.Res., 90, C585- and PlanetaryInstitute, Houston, 1986. organizationin Apollo14 breccia14218: 129I and 244pu regolith C590, 1985. chronology,Proc. Lunar Planet.Sct. Conf 15th,in J. Geophys.Res., Wu, S.S. C., Topographicmapping of the Moon, Earth, Moon, and 90, C517-C539, 1985. Walker,J. C. G., andK. J. Z•hnle,•unar modaltide and distance Planets,31, 165-172, 1985. Takahash•,K., H. Shimizu,and A. Masuda,Cosmochronological studies to the Moon duringthe Precambrian,Nature, 320, 600-602, 1986. Yanai, K., and H. Kojima, Yamato-791197:A lunar meteoritein the and REE abundance of lunar meteorites (abstract), in Papers W/inke, H. and G. Dreibus, Geochemical evidencefor the formation Japanesecollection of Antarcticmeteorites, Mere. Nat. Inst. Polar Presentedto the Eleventh Symposium on Antarctic Meteorites, pp. of the Moon by impactqnducedfission of the proto-Earth,in Origin Res., Spec. IssueNo. 35, 18-34, 1984. 43-44, National Institute of Polar Research,Tokyo, 1986. of the Moon, edited by W. K. Hartmann, R. J. Phillips, and G. Yanai, K., and H. Kojiima, Yamato-82193meteorite: the third lunar Takaoka, N., Noble-gasstudy of lunar meteoriteY82192 (abstract) in J. Taylor,pp. 649-672, Lunar and PlanetaryInstitute, Houston, 1986. meteoritecollected at the Yamato Mountains, Antarctica (abstract), PapersPresented to EleventhSymposium on Antarctic Meteorites, Warren, P. H., The magma oceanconcept and lunar evolution, Ann. Meteoritics, 20, 790-791, 1985. pp.49-52, National Institute of PolarResearch, Tokyo, 1986. Rev. Earth Planet. Sci., 13, 201-240, 1985. Yanai, K., H. Kojima, and S. Ikadai, Four lunar meteoritesincluding Takaoka, N., Noble gasesin Yamato-791197:Evidence for lunar origin Warren, P. H., Anorthositeassimilation and the origifi of the Mg/ new specimenof Yamato-82193,preliminary examination, curation, (abstract),in PapersPresented to the TenthSymposium on Antarctic Fe-related bimodality of pristine Moon rocks: support for the and allocationfor consortiumstudies (abstract), in PapersPresented Meteorites,pp. 114-116,National Institute of PolarResearch, Tokyo, magmaspherehypothesis, Proc. Lunar Planet. Sct. Conf 16th, •n to the Eleventh Symposiumon Antarctic Meteorites, pp. 25-27, 1985. J. Geophys.Res., 91, D331-D343, 1986. National Institute of Polar Research,Tokyo, 1986. Takeda,H., H. Mori, and T. Taga•,Mineralogy of lunar meteorites, Warren, P. H., and G. W. Kallemeyn,Geochemistry of lunar meteorite Yanai, K., H. Kojimma, and T. Katsushima, Lunar meteoritesin Yamato-82192 and 82193 with reference to exploration of lunar Yamato-82192:Comparison with Yamato-791197,ALHA-81005, and Japanesecollection of the Yamato Meteorites(abstract), Meteoritics, highlands(abstract), in PapersPresented to the EleventhSymposium other lunar samples(abstract), in PapersPresented to the Eleventh 19, 342-343, 1984. on Antarctic Meteorites, pp. 37-39, National Institute of Polar Symposiumon AntarcticMeteorites, pp. 31-33, NationalInstitute G. Ryder, Lunar and Planetary Institute, 3303 NASA Road 1, Research,Tokyo, 1986. of Polar Research,Tokyo, 1986. Houston TX 77058 Tatsumoto,M., W. R. Premo, and D. M. Unruh, Origin of lead from Warren, P. H., and G. W. Kallemeyn,Pristine rocks (Eighth Foray): greenglass of 15426;a searchfor primitivelunar lead, Proc.Lunar "Plagiophile"element ratios, crustal genesis, and the bulk composition (Received September 11, 1986; Planet Sci. Conf 17th, in J. Geophys.Res., 91, in press,1986. of the Moon, Proc. Lunar Planet. Sci. Conf 15th, in J. Geophys. Taylor, L. T., J. W. Shervais,R. H. Hunter, C.-Y. Shih, B. M. Bansal, Res., 89, C 16-C24, 1984. revised January 13, 1987; J. Wooden, L. E. Nyquist,and J. C. Laul, Pre-4.2 AE mare-basalt Warren, P. H., G. J. Taylor, K. Keil, D. N. Shirley,and J. T. Wasson, accepted January 13 1987.)