- Email: [email protected]
Highly aluminous glasses in lunar soils and the nature of the lunar highlands
Efighly aluminousglasses in lunar soils and the nature lu.narhighlanas
of the
ARCR: M. REID, W. I. RIDLEY, RUSSELLS. HARMON, JEFF WAXUER, ROBIN BRETT NASA MannedSpacecraftCenter,Houston,Texas 77058 PETR JAKEE~* Lunar Science Institute, Houston, Texas 77058
and R. W. BROWN Lockheed Electronics (Reaeived 29 November 1971;
Company, Houston, Texas 77058 accepted dn revised
form 27 Mar& 1972)
Al&&--Approximately 25 per cent of the glasses in two Apollo 14 soil samples and in the soils at two levels in the Luua 16 core have compositions equivalent to anorthositic gabbro. Reassessment of the non-mare glass components iu the Apollo 11 and 12 soils shows that glasses with the composition of auorthositic gabbro are common to both; gabbroic auorthosite glasses are lees common, and anorthositic glasses, rare. Auorthositic gabbro glasses have the same major element composition at all four sites, and resemble the Surveyor 7 aualysis from a ‘highlaud’ site. Thus, strong presumptive evidence exists that material with this specifk ctomposition is abuudaut in the lunar highlands. INTRODUCTION
of rock samples returned by the Apollo 11 and 12 and the Luna 16 missions have characterized basaltic rocks in three mare areas. Non-mare samples, from the Apollo 14 landing site in the Fra Mauro area, are currently being studied. The breccias and soils from these sites contain not only locally derived rock fragments but also impact-derived material from a wide area around the landing site. Thus, soil and breccia samples, in contrast to the igneous rocks, provide information on a range of rock types from areas not directly sampled. Chemical compositions so far observed among lunar rocks can be divided into four major groups. (1) Mare basalt is the principal component of the mare soils at the Apollo 11 and 12 and Luna 16 sites. All basaltic rocks from the three mare sites have common characteristics (e.g. high Fe, Ti, Ca/Al) but have distinctly different compositions. In soils from the Apollo 14 site, mare-type glasses comprise 10 to 12 per cent of the glass grains (APOLLOSOIL SURVEY,1971, 1972; REID et al., 1972a). (2) Fra Mauro basalt has been recognized as a significant non-mare component in some Apollo 12 soils and has been called KREEP, norite, gray mottled fragments, and non-mare basalt (FUCHS, 1970; MEYER and HUBBARD, 1970; MARVIN et al., 1971; ANDERSON and SMZTH, 1971; HUBBARD and GAST, 1971; KEIL et at., ]L971). These high-alumina, high-rare-earth basalts have been recognized as a minor component in the Apollo 11 soils and are the dominant material at the Apollo 14 site.
STUDIES
* Present address: Geological Survey, Hradebni 9, Praha 1, Czechoslovakia, 903
904
ARCH M. REID et al.
Because of their abundance at the Apollo 14 site (APOLLO SOIL SURVEY, 1971, 1972 REID et al., 1972a,b), they are here called Fra Mauro basalts. (3) A high-silica component (granite, rhyolite, granophyre) was reported as a minor component in the Apollo 12 (MARVIN et al., 1971; MACONet al., 1971) and Apollo 14 soils (APOLLOSOIL SURVEY, 1971, 1972). (4) “Anorthosite,” the so-called anorthositic component, was first recognized at the Apollo 11 site as a non-mare constituent in the soil. Several authors have proposed that feldspar-rich material may be representative of the lunar highlands (WOOD et al., 1970; SMITE et al., 1970; SHORT, 1970; KEIL et al., 1970). Similar material was found in lesser amounts in the Apollo 12 soils, and similar or related material occurs at the Apollo 14 and Luna 16 sites (APOLLO SOIL SURVEY, 1971, 1972; REID et al., 1972a; VINOQRADOV,1971; JAKEE~ et al., 1972). Thenature of this component is the prime concern of this paper. Our measurements and those of others (WARNER, 1972) on the nature of this component in the lunar soils indicate that it is not predominantly anorthositic. Rather the dominant composition is equivalent to anorthositic gabbro. Materials of this composition form a major component of the soils at all three mare sites and also at the Fra Mauro site. METHODS We have adopted a somewhat different method from that of other investigators in studying the provenance of particles in the lunar soils. The nature of the lunar soils has previously been studied in part from a ‘mixing model’ approach in which the known soil chemistry is approximated by mixing proportions of known and/or hypothetical end-member compositions. Alternatively, the make-up of the soil has been estimated by classifying the grain types petrographically and analyzing selected members from each class. Our approach has been to analyze (using microprobe techniques) all amenable glasses within a random area in each of several grain mounts and to measure the contribution of grains with specific compositions. With sufficient analytical data, preferred glass compositions can be established and we have used these to infer the composition of the parent rocks (e.g. APOLLO SOIL SURVEY, 1971). Disadvantages of this approach are that the coarser soil fractions are excluded and that large numbers of analyses are required to attain statistically significant data on the proportions of the components. PRINZ et al. (1971) have shown that some but not all of the glass types in the Apollo 11 soil have counterparts in lithic fragments from the soils and breccias. STEELE and SMITH (1972) suggest that some Apollo 14 lithic fragments of igneous character have compositions not found in the glasses analyzed by the APOLLOSOIL SURVEY (1971). Lithic fragments may provide a better guide to the composition of the parent rocks but sufficient data have probably not yet been accumulated to allow the recognition of preferred compositions. This lack of data also precludes a detailed comparison between the compositions of glasses and lithic fragments. DEFINITIONS Earlier work (Ciao et al., 1970; GLASS, 1971; APOLLOSOIL SURVEY, 1971) has shown that glass compositions, particularly where preferred compositions can be demonstrated from a large number of analyses, can provide a useful measure of the
Highly aluminous glasses in lunar soils and the nature of the lunar highlands
905
nature of the rock types contributing to the soil. It is convenient to express these glass compositions in terms of equivalent rock names. Because only glass compositions are known, several rock names that correspond to different textures may be equivalent to a single glass composition. For the high-C& high-Al glasses, we have adopted the classification used to describe the Adirondack anorthosite suite (BUDDINGTON, 1939). Thus, anorthosite has 0 to 10 per cent mafic minerals; gabbroic anorthosite, 10 to 22-5 per cent; anorthositic gabbro, 22.5 to 35 per cent; and gabbro, 35 to 65 per cent. With only glass compositions, we base the classification on the proportions of phases in the norm. The minor differences introduced by using normative minerals do not affect the conclusions reached here. This classification provides a convenient framework for discusssion of these glass compositions and facilitates comparison with other data (e.g. WOOD, 1970). The various names are used to describe chemical composi-
tions with no implications as to the origin of these glasses or their parent materials. APOLLO 14 SOIL More than 500 glasses from two Apollo 14 soils, 14259 and 14156, have been analyzed, and the two soils proved to be similar (APOLLOSOILSURVEY,1971, 1972; REID et al., 1972a). Data from both samples are combined in a plot of CaO compared with A&O, (Fig. 1). Preferred groupings can be seen within the wide range of CaO and A&O, values. Glasses with CaO/Al,O, < 0.8 fall into two major groups that have almost identical Ca/Al ratios. The Fra Mauro basaltic glasses form a discrete group with A&O, less than 21 weight per cent. Glasses with greater than 21 weight per cent Al,O, (the highly aluminous glasses) are our major concern in this paper.
L 6
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
Weight
%A1203
Fig. 1. Plot of CaO as a function of Al,O, (weight per cent) for glasses from two Apollo 14 soil samples, 14259 and 14156. Meteorite line represents the constant CaO/A1,03 ratio of chondritic and achondritic meteorites. Hexagon marks the position of Apollo 14 rock 14310. 6
ARCH
906
M. REKD et al.
The highly aluminous glasses form a relatively uniform group so that any classification that subdivides this group could be artificial. In our studies of the Apollo 14 soil (APOLLO SOIL SURVIEY,1971) we recognized two subgroups: glasses with Al,O, 21 to 30 weight per cent (type E Fra Mauro basalta) and glasses with AlaO, > 30 per cent (gabbroic anorthosite or type F basalt). This classification was based on natural breaks in the frequency of analyses and can be extended to the other sites. Most highly aluminous glasses in the Fra Mauro soils have A&O, between 21 and 30 weight per cent. A much smaller portion of the glasses falls in the category with Al,O, > 30. Of the 169 glasses in the Fra Mauro soil with A&O, > 21 weight per cent, using the cl~sification based on percentage of normative minerals, 12 per aent are oompositiona~y equivalent to gabbros ; 79 per cent to ~orthositic gabbros; 6 per cent to gabbroic anorthosite; and 3 per cent to anorthosite, The highly aluminous glasses form a well-d&ned group equivaIent in composition to anorthositic gabbro; glasses equivalent to gabbroic anorthosite are not common, and anorthosite glasses are rare. X.tUNA
16 SOIL
We have recently completed 264 analyses of glasses from the soil sampled by the Luna 16 probe in Mare Fecunditatis. Most of the glasses are basaltic in composition and resemble basalts from other mare sites in their high Fe and Ti contents and in their high CalAl ratios. However, a significant number of glasses are rich in Ca and Al (A&O, > 21 weight per cent, CaO + AlaO, > 36 weight per cent) and thus are highly fel~pathi~. Many of these glasses are similar in major element composition to Apollo I4 anorthositio gabbro glasses; they show a similar range in Ca and Al with little variation in CalAl ratio. Again, a natural grouping can be found with most glasses corresponding in composition to anorthositio gabbro and only minor amounts corresponding to gabbroic anorthosite and anorthosite. Thus, a major component in the Luna 16 mare soil is almost identical in composition to a major component from the Apollo 14 site (Table 1). This comparison Table 1. Average
compositionof glasses in the lunar soil with AlaO, grectter than 21 weight per cent Average mmposition (weight per cent) Apollo 14
Oxides SiO, TiO, A& %O* Fe0 MS0 cao NG %O Number of glasses Pem3ntage of tow glasses
Apollo 11’
ApolIo 12*
14269
45.17 (5*31)t 0.74 (l-17) 2mi5 (3a3)
46.21 (4.76) O-36(0.19) 25.90 (2.85)
45.49 (2.26) 0.44 (O-41) 25.77 (2.70)
6.35 6.77 14-82 0.42 0.04
4.63 8.19 13.98 0.26 o-05
6.53 7-26 14.63 0.35 o-13
120 27.8
(3.64) (3.63) (3.07) (0.46) (0.06)
(1.69) (4.14) (3.61) (O-36) (O-04)
(1.92) (2.27) (1.99) (O-39) (0.22)
14156 46.74 0.40 26.21 0.09 6.76 7.46 14.59 0.22 o-04
(1.10) (0.34) (2.67) (0.03) (lm3) (l-78) (1.57) (0*16) (O-07)
Lulls If3 44.77 0.46 27.29 0.10 b-41 6-84 16.20 0.26 0.07
24
130
41
80
17.3
33.3
29-3
22-Q
* Data for Apollo 11 end 12 are from the literature rsnd are not from random surveys. t Numbers in parentbessa are one standmd deviation.
(2.12) (0.49) (4.62) (0.07) (3.29) (3.32) (2.37) (0.25) (O-12)
Highly aluminous glasses in lunar soils and the nature of the lunar highlands
907
can be extended to the Apollo 11 and 12 sites, and the amounts and nature of the highly aluminous material in these soils is reassessed below. APOLLO 11 AND 1.2 sorns Much has been written on the anorthositic component in the Apollo 11 soils, and many analyses of glasses and lithio fragments that are high in feldspathic constituents exist in the literature. WOOD (1970) estimates that the light-colored crystalline fragments in the Apollo 11 soil comprise 36 per cent anorthosite, 45 per cent gabbroic anorthosite, and 20 per cent anorthositic gabbro. A series of histograms of the total normative feldspar for glasses with A&O, > 21 weight per cent from four sites is shown in Fig. 2. The data for the Apollo 14 and Luna 16 soils are from random surveys of glass compositions. The Apollo 14 samples show a tight grouping around a preferred composition with 70 per cent normative feldspar and around a possible minor mode with more than 90 per cent normative feldspar. Despite the complex nature of impact processes and the different scales on which these may occur, the range of values is small. These glasses apparently derive from a single rock type that is equivalent in composition to anorthositic gabbro. Of the Apollo 14 glasses with more than 65 per cent normative feldspar, 90 per cent are anorthositic gabbro in composition, 7 per cent are gabbroic anorthosite, and only 3 per cent are anorthosite. Comparable figures for Luna 16 glasses
10 5 15 0E
i
5F 10 OL
&
*
Apollo14 14156 L -
40 35 30 ; !
25 20
:
15
Apollo 14 14259
2 10 ii 5 0
--
; II
1 50
_
-
_Apoflo
12
I
I
I
I
60
70
80
90
Total nwmative
I 100
feldspar
Fig. 2. Histogram of total normative feldspar for glassesfrom the Apollo 11 and 12 sites (WAGER, 1972), from two soils at the Apollo I4 site (APOLLOSOIL SURTEY, 1971, 1972; REID et d., 1972a) and from the Luna 16 soils (VINO~~O~, 1971; JAEE~ et al., 1971).
908
ABCJH XI.
REID et al.
are 72 per cent anorthositic gabbro, 12 per cent gabbroie anorthosite and 16 per cent anorthosite. To compare the Apollo II and 12 soils, data have been drawn from several sources in the literature (WARNER,1972). Published glass analyses are generally not random surveys. The compilation in Fig. 2 shows that the nature of the non-mare component at the Apollo 11 and 12 sites is essentially identical to the anorthositic gabbro composition described previously. Both plots show a preferred grouping around 70 per cent normative feldspar and small amounts of gabbroic anorthosite or anorthosite. Only the Apollo 11 glasses show a clustering of values with more than 90 per cent normative feldspar. Despite this grouping, anorthositic gabbro compositions are apparently more abundant than ano~hosi~. Even this minor anorthosite component may be an overestimate, because glasses with more than 94 per cent normative feldspar may represent not only rock melts but also feldspar melts or maskelynite grams. DISCUSSION The soils at all four lunar landing sites contain a substantial amount (17 to 33 per cent) of glasses with Al,O, greater than 21 weight per cent and Fe, Ti and Ca/Al ratios indicative of a non-mare origin. This non-mare component has essentially the same composition (equivalent to anorthositic gabbro) at each site. Glass compositions from four widely separated lunar sites are compared in Table 1. The similarity of the compositions is striking. A better comparison is afforded in Table 2, in which Table 2. Median compositions of glasses in the hmar soil with Al,O, greater than 21 weight per cent Median composition (weight per cent) Oxido Apollo 11
Apollo 12
Apollo 14 14259 14156
44.62 0.04 25.78
44.81 0.30 26.76
45.10 0.29 25-28
5.01 8.40 14.85 0.20 0.05
6.75 8.20 14.68
%O
5.47 7.55 14.92 O-28 O-01
Total
99.03
99.37
99.54
SiO, TiO,
Fe0 Ma0 C&O X%&.0
Number of glasses Nomative minerals Orthoclase Albite Anorthite Diopside Hypmthene Olivine Chromite Ilmenite Fe/Fe t_ Mg in silioste AnlAb + An in plagioolase
120
24
0.3 2.4 68.9 4.1 13.1 9.5 0.8 0.275 0.935
o-19 0.05
130 0.3 1.6 68.0 3.9 16.2 9.0
0.6 0.241 0*97&i
0.6 0.273 O-976
Luna 16
surveyor*
44.97 O-32 26*00 0.10 5.53 7.85 14.84 0.26 O*Ol
45
100*18
GEZ
SF
41
80
45.60 0.29 25.46 0.09 5.79 8.15 14.62 0.17 0.01
0.1 1.4 68.7 3.1 19.2 7.0 0.1 0.6 O-275 0.978
.-
22 5 7 18 0.7
0.1 I.1 67.9 2.3 20.5 7.0 0.2 0.7 0.269 0.983
* Oxide composition consistent with Surveyor 7 analyticttl results from TURKEVXXI (1971); for disoussion of assumptions and error estimates.
see this
paper
Highly chminous
glames in lunar soils
and the natureof the lunarhighlands
909
the median compositions are shown for the four landing sites for glasses with more than 21 weight per cent A&O,. Well-mixed lunar soils are composed of material from a wide area of the lunar surface. Thus, the lunar soils should commonly contain a minor component derived from the highland regions. If highland material is fairly homogeneous, soil from a mare site should contain a distinctive non-mare component. Material equivalent in composition to anorthositic gabbro makes a substantial contribution to the soils in Mare Tranquillitatis, Mare ~ecun~tatis, Oceanus Procellarum, and the Fra 3lauro area. Fra Mauro basalt or KREEP is rare at both the Mare Tranquillitatis and Mare Fecunditatis sites and is too rich in potassium to be a major highland rock type (METZGERet al., 1972). The only direct analysis of highland material, made by Surveyor 7 (TLJRKE:VTCH, 1971) corresponds to anorthositic gabbro rather than anorthosite. The comparison between the Surveyor analysis and the anorthositic gabbro compositions from the four lunar sites is made in Table 2. We suggest that material with this composition is a major rock type in the lunar highlands. This conclusion is essentially in accord with preliminary Apollo 15 X-ray fluorescence data obtained during lunar orbit (ADLERet al., 1972). The low K content (K,O N 0.05 weight per cent) is in apparent agreement with the preliminary y-ray data from Apollo 15 (M~TZ~ERet aI., 1972). The rocks from which these gIasses are derived apparently have an anorthositic gabbro composition with more aIumina than terrestrial high-alumina basalts. We propose the name Highland basalt for this particular composition, Further studies may show that the use of the term basalt is inappropriate, but the textures of the parent rocks, and whether the parent rock is volcanic or plutonic, are unknown. These glasses have similar major element compositions at four widely separated sites, suggesting they may be derived from a homogeneous source. This constancy is difficult to reconcile with derivation from coarse-grain heterogeneous cumulates, The parent rocks for Highland basalt glasses may be fine grained igneous rocks derived from highly aluminous liquids. In a H,O-free environment these compositions have very high liquidus temperatures, compared to te~est~al lavas. Such liquids, if partial melts, would derive from even more aluminous parent material. The existence of liquids of Highland basalt composition early in lunar history implies very high temperatures ( >1400°C), extensive melting and probably extensive fractionation. It further implies that portions of the outer layers of the moon were very highly aluminous (A&O,, 25 weight per cent or higher). The al~~ative model is to consider Highland basalt as a cumulate. Feldspar rich compositions may be produced by accumulation of early formed feldspar from a parental basaltic liquid. This model for the genesis of Highland basalt material is consistent with its low K content and with its high Mg/Fe ratio. The Highland basalt glasses found in the Apollo 14 soils show a range in abundances of normative mafic phases, but fairly constant Mg/Fe ratios. Such a relationship is consistent with an original accumulate origin (WAGES and BROWN, 1968). In addition, some coarse soil samples and rare breccia clasts in the ApolIo 14 samples have a mineral assemblage like that expected for Highland basalt, and though fine grained, do show intercumulate textures. If the Highland basalt compositions represent cumulates from a basaltic parent
910
ARCH M. REID et al.
then the parent must have feldspar as a major phase and thus be a high-alumina basalt. The basaltic parent materials of the Fra Mauro basaltic glasses (or KREEP basalt) and specific rocks such as 14310 and 14073 (e.g. WALKER etaE., 1972; BROJV-N and PECKETT, 1971)have feldspar as a liquidus phase and could produce feldspar cumulates. The glass data (REID etal.,1972b) and the X-ray and y-ray data from Apollo 15 (ADLER et aZ., 1972; METZQER et al., 1972) suggest that Fra Mauro basalts are not as widespread on the lunar surface as anorthositic gabbro. In view of this evidence it appears unlikely that Fra Mauro basalt (KREEP) is the parent of the Highland basalt. The chemical composition of Highland basalt suggests a parent material that is a high-alumina basalt without the highly fractionated trace element chemistry of Fra Mauro material. CoNCLusIoNs We conclude that the major non-mare glass component at all sampled mare sites has the composition of anorthositic gabbro. The other major non-mare component in mare soils, Fra Mauro basalt (KREEP, norite), is actually more abundant than Highland basalt in many Apollo 12 soils but is rare in Apollo 11 and Luna 16 soils. Highland basalt is also an important glass type in the Fra Mauro soil. The average major element composition of the anorthositic gabbros from each site is remarkably uniform, and the total glass population shows small variance. This component appears to reflect a major feldspathic rock type in the lunar highlands. These rocks may represent basaltic liquids or anorthositic gabbro accumulates. Most schemes for evolution of the moon involve the formation of an anorthosite crust (e.g. WOOD et aZ., 1970; SMITH et al., 1970) by some accumulative process. The hypothesis that the dominant Highland rock has the composition of anorthositic gabbro still requires that Al- and Ca-rich material be abundant in the outer parts of the moon early in lunar history (e.g. GAST and MCCONNELL, 1972). Acknowledgemed~We thank P. RICHARDSONfor help in data handling. P&r Jakeg was supported by contract number NSR 09-051-001 between the National Aeronautics and Space Administration and the Universities Space Research Association. W. I. Ridley was supported by a National Research Council Resident Research Associate&p. This paper constitutes the Lunar Science Institute contribution number 81. REFERENCES ADLER I., Tnordmr~ J., GERARDJ., Lowm P., SCHMEDEBECK R., BLOD~ETH., ELLER E., YIN L., LAMOTHER., GORENSTEIN P. and BJORKF~OL~~ P. (1972) Apollo 16 geochemicalX-ray fluorescenceexperiment: Preliminary report. Scie7ace175, 436-440. ANDERSONA. T., Jr. and SM.ITEJ. V. (1971) Nature, occurrence, and exotic origin of “gray mottled” (Luny Rock) basalts in Apollo 12 soils and breccias. Proc. Second Lunar Sci. Conf., Geochim. Cosmochim. Acta, Suppl. 2, Vol. 1, pp. 431-438, M.I.T. APOLLOSOIL SURVEY (1971) Apollo 14: Nature and origin of rock types in soil from the Fra Mauro formation. Earth Planet. Ski. Lett. 12, 49-64. APOLLOSOIL SURVEY(1972) Phase chemistry of Apollo 14 soil sample 14259. In preparation. BROWN G. M. and PECKETTA. (1971) Selective volatilization on the lunar surface: Evidence from Apollo 14 feldspar-phyric basalts. Nature 234, 262-266. BUDDIN~TONA. F. (1939) Adirondack igneous rocks and their metamorphism. cfeol.Sot. Amer. Mem. 7, l-354.
Highly aluminous glasses in lunar soils and the nature of the lunar highlands
911
CHAO E. C. T., BOREMAN J. A., MINKIN J. A., JAX~S 0. B. and DESBOROUUH G. A. (1970)
Lunar glasses of impact origin: Physical and chemical characteristics and geological implications. J. ffeophys. Res. 75, 7445-7479. FTJOHS L. H. (1970) Orthopyroxene-plagioclasefragments in the lunar soil from Apollo 12. Scieme 169, 866-868. GAST P. W. and MCCONNICLL R. K. Jr. (1972) Evidence for initial chemical layering of the moon. Lunar Science--III, Abstracts Third .Lww Sci. Conf., Lunar Science Institute Contrib. 88. GLASSB. P. (1971) Investigations of glass recovered from Apollo 12 sample 12057. J. ffeophya. Res. 78, 6649-5657. HUBBARD N. J. and GAST P. W. (1971) Chemical composition and origin of nonmare lunar basalts. Proc. Second _i%mr Sci. Conf., Geochim. Cosmochim. Acta, Suppl. 2, Vol. 2, pp. 999-1020, M.I.T. JANE&P., WARNERJ., RIDLEY W. I., REID A. M., HARMONR. S., BRETTR. and BROWSR. W. (1972) Petrology of a portion of the Mare Fecunditatis regolith. Earth Planet. Sci. Lett. 13, 257-271. KEIL K., BUNCH T. E. and PRINZ M. (1970) Mineralogy and composition of Apollo 11 lunar samples. Proc. Fir& Lmmr Sci. Conf., Geochim. Cosmochim. Acta Suppl. 1, Vol. 1, pp. 561-598, Pergamon. KEIL K., PRINZ M. and BUNCH T. E. (1971) Mineralogy, petrology and chemistry of some Apollo 12 samples. Proc. Secorad&war Sci. Conf., Geochim. Cosmochim. Acta, Suppl. 2, Vol. 1, pp. 679-699, M.I.T. MARVINU. B., WOOD J. A., TAYLORG. J., REID J. B., Jr., POWELLB. N., DICKEYJ. S., Jr. and BOWI~RJ. F. (1971) Relative proportions and probable sources of rock fragments in the Apollo 12 soil samples. Proc. Second Lunar Sci. Conf., Geochim. Cosmochim. Acta, Suppl. 2, Vol. 1, pp. 679-699, M.I.T. MASONB., MELSONW. G., HJXNDERSON E. P., JAROSEWICH E. and NELENJ. (1971) Mineralogy and petrography of some Apollo 12 samples. Second Lunar Sci. Conf. (unpublishedproceed-
ings) . METZQERA. E., TROMBKAJ. I., PETERSON L. E., REEDY R. C. and ARNOLDJ. R. (1972) A first look at the lunar orbital gamma ray data. Lunar Science-III, Abstracts, Third Lunar Sci. Conf. Lunar Science Institute Contrib. 88. MEYERC. Jr. and HUBBARDN. J. (1970) High potassium, high phosphorusglass as an important rock type in the Apollo 12 soil samples. (Abatr.) Metewitim 5, 210-211. PRINZ M., BUNCHT. E. and KEIL K. (1971) Composition and origin of lithic fragments and glasses in Apollo 11 samples. Contr. Mineral. Petrol. 82, 211-230. REID A. M., RILEY W. I., JA~YE& P. and HARMONR. S. (1972a) Compositions of glasses in lunar soil 14156. In preparation. REID A. M., RIDLEY W. I., WARNERJ., HARYON R. S. and BRETTR. (1972b) Chemistry of highland and mare baealts as inferred from glasses in the lunar soils. Lunar Science-III, Abstracts Third LwbcwSci. Conf. Lunar Science Institute Contrib. 88. RIDLEY W. I., WILLJXXSR. J., TAKEDAH., BROWYN R. W. and BRETTR. (1971) Petrology of Fra Mauro basalt 14310. In preparation. SHORTN. M. (1970) Evidence and implications of shock metamorphism in lunar samples. Proc. B’irst Lunar Sci. Conf., Geochim. Cosmochim. Acta, Suppl. 1, Vol. 1, pp. 865-871. Pergamon. SMITHJ. V., ANDERSONA. T., NEWTONR. C., OLSENE. J. and WYLLIE P. J. (1970) Petrologic history of the moon inferred from petrography, mineralogy and petrogenesis of Apollo 11 rocks. Proc. B’irst Lunar Sci. Conf., Geochim. Cosmochim. Acta, Suppl. 1, Vol. 1, pp. 897-925. Pergamon. STEELEI. M. and SMITHJ. V. (1972) Mineralogy, petrology, bulk electron-microprobeanalyses from Apollo 14, 15 and Luna 16. Lunar Science--III, Abstracts Third Lunar Sci. Conf., Lunar Science Institute Contrib. 88. TURKEVICHA. L. (1971) Comparison of the analytical results from the Surveyor, Apollo, and Luna missions. Proc. Second Lunar Sci. Conf., Geochim. Cosmochim. Acta Suppl. 2, Vol. 2, pp. 1209-1215, M.I.T. VINOURADOV A. P. (1971) Preliminary data on lunar ground brought to Earth by automatic
912
ARCH M. REID et al.
probe “Lnna-16.” PTOC.Second L-mm Ski. Gonf., Geochim. Cosmochim. A&a, Suppl. 2, Vol. 1, pp. 1-16, M.I.T. WAGER L. R. and BROWNG. A/I. (1968) Laywed Igneowr Rocks, 2nd edition. Oliver and Boyd. WALE= D., LONGHI J. and I&YS J. F. (1972) Experimental petrology and origin of Fra Mauro rocks and soil. Lunar Science-III, Abstmcts Third Lmwr Sci. Conf., Lunar Science Institute Contrib. 88. WARNERJ. (1972) Unpublished compilation of Apollo chemical, age and modal information on file in the NASA MSC Curator’s Office, Rouston, Texas. WOOD J. A. (1970) Petrology of the lunar soil and geophytied implications. J. ffeo~~~~. Ree, 75,6497-+X13. WOOD J. A., DICKEYJ. S. Jr., MAl%mNU. B. and POWELLB. N. (1970f Lunar anorthositesand a geophysical model of the moon. Proc. .B%wtLunar Sci. Conf., Geochim. Cosmochim. Acta, Suppl. 1, Vol. 1, pp. 965-988, Pergamon.
of the
ARCR: M. REID, W. I. RIDLEY, RUSSELLS. HARMON, JEFF WAXUER, ROBIN BRETT NASA MannedSpacecraftCenter,Houston,Texas 77058 PETR JAKEE~* Lunar Science Institute, Houston, Texas 77058
and R. W. BROWN Lockheed Electronics (Reaeived 29 November 1971;
Company, Houston, Texas 77058 accepted dn revised
form 27 Mar& 1972)
Al&&--Approximately 25 per cent of the glasses in two Apollo 14 soil samples and in the soils at two levels in the Luua 16 core have compositions equivalent to anorthositic gabbro. Reassessment of the non-mare glass components iu the Apollo 11 and 12 soils shows that glasses with the composition of auorthositic gabbro are common to both; gabbroic auorthosite glasses are lees common, and anorthositic glasses, rare. Auorthositic gabbro glasses have the same major element composition at all four sites, and resemble the Surveyor 7 aualysis from a ‘highlaud’ site. Thus, strong presumptive evidence exists that material with this specifk ctomposition is abuudaut in the lunar highlands. INTRODUCTION
of rock samples returned by the Apollo 11 and 12 and the Luna 16 missions have characterized basaltic rocks in three mare areas. Non-mare samples, from the Apollo 14 landing site in the Fra Mauro area, are currently being studied. The breccias and soils from these sites contain not only locally derived rock fragments but also impact-derived material from a wide area around the landing site. Thus, soil and breccia samples, in contrast to the igneous rocks, provide information on a range of rock types from areas not directly sampled. Chemical compositions so far observed among lunar rocks can be divided into four major groups. (1) Mare basalt is the principal component of the mare soils at the Apollo 11 and 12 and Luna 16 sites. All basaltic rocks from the three mare sites have common characteristics (e.g. high Fe, Ti, Ca/Al) but have distinctly different compositions. In soils from the Apollo 14 site, mare-type glasses comprise 10 to 12 per cent of the glass grains (APOLLOSOIL SURVEY,1971, 1972; REID et al., 1972a). (2) Fra Mauro basalt has been recognized as a significant non-mare component in some Apollo 12 soils and has been called KREEP, norite, gray mottled fragments, and non-mare basalt (FUCHS, 1970; MEYER and HUBBARD, 1970; MARVIN et al., 1971; ANDERSON and SMZTH, 1971; HUBBARD and GAST, 1971; KEIL et at., ]L971). These high-alumina, high-rare-earth basalts have been recognized as a minor component in the Apollo 11 soils and are the dominant material at the Apollo 14 site.
STUDIES
* Present address: Geological Survey, Hradebni 9, Praha 1, Czechoslovakia, 903
904
ARCH M. REID et al.
Because of their abundance at the Apollo 14 site (APOLLO SOIL SURVEY, 1971, 1972 REID et al., 1972a,b), they are here called Fra Mauro basalts. (3) A high-silica component (granite, rhyolite, granophyre) was reported as a minor component in the Apollo 12 (MARVIN et al., 1971; MACONet al., 1971) and Apollo 14 soils (APOLLOSOIL SURVEY, 1971, 1972). (4) “Anorthosite,” the so-called anorthositic component, was first recognized at the Apollo 11 site as a non-mare constituent in the soil. Several authors have proposed that feldspar-rich material may be representative of the lunar highlands (WOOD et al., 1970; SMITE et al., 1970; SHORT, 1970; KEIL et al., 1970). Similar material was found in lesser amounts in the Apollo 12 soils, and similar or related material occurs at the Apollo 14 and Luna 16 sites (APOLLO SOIL SURVEY, 1971, 1972; REID et al., 1972a; VINOQRADOV,1971; JAKEE~ et al., 1972). Thenature of this component is the prime concern of this paper. Our measurements and those of others (WARNER, 1972) on the nature of this component in the lunar soils indicate that it is not predominantly anorthositic. Rather the dominant composition is equivalent to anorthositic gabbro. Materials of this composition form a major component of the soils at all three mare sites and also at the Fra Mauro site. METHODS We have adopted a somewhat different method from that of other investigators in studying the provenance of particles in the lunar soils. The nature of the lunar soils has previously been studied in part from a ‘mixing model’ approach in which the known soil chemistry is approximated by mixing proportions of known and/or hypothetical end-member compositions. Alternatively, the make-up of the soil has been estimated by classifying the grain types petrographically and analyzing selected members from each class. Our approach has been to analyze (using microprobe techniques) all amenable glasses within a random area in each of several grain mounts and to measure the contribution of grains with specific compositions. With sufficient analytical data, preferred glass compositions can be established and we have used these to infer the composition of the parent rocks (e.g. APOLLO SOIL SURVEY, 1971). Disadvantages of this approach are that the coarser soil fractions are excluded and that large numbers of analyses are required to attain statistically significant data on the proportions of the components. PRINZ et al. (1971) have shown that some but not all of the glass types in the Apollo 11 soil have counterparts in lithic fragments from the soils and breccias. STEELE and SMITH (1972) suggest that some Apollo 14 lithic fragments of igneous character have compositions not found in the glasses analyzed by the APOLLOSOIL SURVEY (1971). Lithic fragments may provide a better guide to the composition of the parent rocks but sufficient data have probably not yet been accumulated to allow the recognition of preferred compositions. This lack of data also precludes a detailed comparison between the compositions of glasses and lithic fragments. DEFINITIONS Earlier work (Ciao et al., 1970; GLASS, 1971; APOLLOSOIL SURVEY, 1971) has shown that glass compositions, particularly where preferred compositions can be demonstrated from a large number of analyses, can provide a useful measure of the
Highly aluminous glasses in lunar soils and the nature of the lunar highlands
905
nature of the rock types contributing to the soil. It is convenient to express these glass compositions in terms of equivalent rock names. Because only glass compositions are known, several rock names that correspond to different textures may be equivalent to a single glass composition. For the high-C& high-Al glasses, we have adopted the classification used to describe the Adirondack anorthosite suite (BUDDINGTON, 1939). Thus, anorthosite has 0 to 10 per cent mafic minerals; gabbroic anorthosite, 10 to 22-5 per cent; anorthositic gabbro, 22.5 to 35 per cent; and gabbro, 35 to 65 per cent. With only glass compositions, we base the classification on the proportions of phases in the norm. The minor differences introduced by using normative minerals do not affect the conclusions reached here. This classification provides a convenient framework for discusssion of these glass compositions and facilitates comparison with other data (e.g. WOOD, 1970). The various names are used to describe chemical composi-
tions with no implications as to the origin of these glasses or their parent materials. APOLLO 14 SOIL More than 500 glasses from two Apollo 14 soils, 14259 and 14156, have been analyzed, and the two soils proved to be similar (APOLLOSOILSURVEY,1971, 1972; REID et al., 1972a). Data from both samples are combined in a plot of CaO compared with A&O, (Fig. 1). Preferred groupings can be seen within the wide range of CaO and A&O, values. Glasses with CaO/Al,O, < 0.8 fall into two major groups that have almost identical Ca/Al ratios. The Fra Mauro basaltic glasses form a discrete group with A&O, less than 21 weight per cent. Glasses with greater than 21 weight per cent Al,O, (the highly aluminous glasses) are our major concern in this paper.
L 6
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
Weight
%A1203
Fig. 1. Plot of CaO as a function of Al,O, (weight per cent) for glasses from two Apollo 14 soil samples, 14259 and 14156. Meteorite line represents the constant CaO/A1,03 ratio of chondritic and achondritic meteorites. Hexagon marks the position of Apollo 14 rock 14310. 6
ARCH
906
M. REKD et al.
The highly aluminous glasses form a relatively uniform group so that any classification that subdivides this group could be artificial. In our studies of the Apollo 14 soil (APOLLO SOIL SURVIEY,1971) we recognized two subgroups: glasses with Al,O, 21 to 30 weight per cent (type E Fra Mauro basalta) and glasses with AlaO, > 30 per cent (gabbroic anorthosite or type F basalt). This classification was based on natural breaks in the frequency of analyses and can be extended to the other sites. Most highly aluminous glasses in the Fra Mauro soils have A&O, between 21 and 30 weight per cent. A much smaller portion of the glasses falls in the category with Al,O, > 30. Of the 169 glasses in the Fra Mauro soil with A&O, > 21 weight per cent, using the cl~sification based on percentage of normative minerals, 12 per aent are oompositiona~y equivalent to gabbros ; 79 per cent to ~orthositic gabbros; 6 per cent to gabbroic anorthosite; and 3 per cent to anorthosite, The highly aluminous glasses form a well-d&ned group equivaIent in composition to anorthositic gabbro; glasses equivalent to gabbroic anorthosite are not common, and anorthosite glasses are rare. X.tUNA
16 SOIL
We have recently completed 264 analyses of glasses from the soil sampled by the Luna 16 probe in Mare Fecunditatis. Most of the glasses are basaltic in composition and resemble basalts from other mare sites in their high Fe and Ti contents and in their high CalAl ratios. However, a significant number of glasses are rich in Ca and Al (A&O, > 21 weight per cent, CaO + AlaO, > 36 weight per cent) and thus are highly fel~pathi~. Many of these glasses are similar in major element composition to Apollo I4 anorthositio gabbro glasses; they show a similar range in Ca and Al with little variation in CalAl ratio. Again, a natural grouping can be found with most glasses corresponding in composition to anorthositio gabbro and only minor amounts corresponding to gabbroic anorthosite and anorthosite. Thus, a major component in the Luna 16 mare soil is almost identical in composition to a major component from the Apollo 14 site (Table 1). This comparison Table 1. Average
compositionof glasses in the lunar soil with AlaO, grectter than 21 weight per cent Average mmposition (weight per cent) Apollo 14
Oxides SiO, TiO, A& %O* Fe0 MS0 cao NG %O Number of glasses Pem3ntage of tow glasses
Apollo 11’
ApolIo 12*
14269
45.17 (5*31)t 0.74 (l-17) 2mi5 (3a3)
46.21 (4.76) O-36(0.19) 25.90 (2.85)
45.49 (2.26) 0.44 (O-41) 25.77 (2.70)
6.35 6.77 14-82 0.42 0.04
4.63 8.19 13.98 0.26 o-05
6.53 7-26 14.63 0.35 o-13
120 27.8
(3.64) (3.63) (3.07) (0.46) (0.06)
(1.69) (4.14) (3.61) (O-36) (O-04)
(1.92) (2.27) (1.99) (O-39) (0.22)
14156 46.74 0.40 26.21 0.09 6.76 7.46 14.59 0.22 o-04
(1.10) (0.34) (2.67) (0.03) (lm3) (l-78) (1.57) (0*16) (O-07)
Lulls If3 44.77 0.46 27.29 0.10 b-41 6-84 16.20 0.26 0.07
24
130
41
80
17.3
33.3
29-3
22-Q
* Data for Apollo 11 end 12 are from the literature rsnd are not from random surveys. t Numbers in parentbessa are one standmd deviation.
(2.12) (0.49) (4.62) (0.07) (3.29) (3.32) (2.37) (0.25) (O-12)
Highly aluminous glasses in lunar soils and the nature of the lunar highlands
907
can be extended to the Apollo 11 and 12 sites, and the amounts and nature of the highly aluminous material in these soils is reassessed below. APOLLO 11 AND 1.2 sorns Much has been written on the anorthositic component in the Apollo 11 soils, and many analyses of glasses and lithio fragments that are high in feldspathic constituents exist in the literature. WOOD (1970) estimates that the light-colored crystalline fragments in the Apollo 11 soil comprise 36 per cent anorthosite, 45 per cent gabbroic anorthosite, and 20 per cent anorthositic gabbro. A series of histograms of the total normative feldspar for glasses with A&O, > 21 weight per cent from four sites is shown in Fig. 2. The data for the Apollo 14 and Luna 16 soils are from random surveys of glass compositions. The Apollo 14 samples show a tight grouping around a preferred composition with 70 per cent normative feldspar and around a possible minor mode with more than 90 per cent normative feldspar. Despite the complex nature of impact processes and the different scales on which these may occur, the range of values is small. These glasses apparently derive from a single rock type that is equivalent in composition to anorthositic gabbro. Of the Apollo 14 glasses with more than 65 per cent normative feldspar, 90 per cent are anorthositic gabbro in composition, 7 per cent are gabbroic anorthosite, and only 3 per cent are anorthosite. Comparable figures for Luna 16 glasses
10 5 15 0E
i
5F 10 OL
&
*
Apollo14 14156 L -
40 35 30 ; !
25 20
:
15
Apollo 14 14259
2 10 ii 5 0
--
; II
1 50
_
-
_Apoflo
12
I
I
I
I
60
70
80
90
Total nwmative
I 100
feldspar
Fig. 2. Histogram of total normative feldspar for glassesfrom the Apollo 11 and 12 sites (WAGER, 1972), from two soils at the Apollo I4 site (APOLLOSOIL SURTEY, 1971, 1972; REID et d., 1972a) and from the Luna 16 soils (VINO~~O~, 1971; JAEE~ et al., 1971).
908
ABCJH XI.
REID et al.
are 72 per cent anorthositic gabbro, 12 per cent gabbroie anorthosite and 16 per cent anorthosite. To compare the Apollo II and 12 soils, data have been drawn from several sources in the literature (WARNER,1972). Published glass analyses are generally not random surveys. The compilation in Fig. 2 shows that the nature of the non-mare component at the Apollo 11 and 12 sites is essentially identical to the anorthositic gabbro composition described previously. Both plots show a preferred grouping around 70 per cent normative feldspar and small amounts of gabbroic anorthosite or anorthosite. Only the Apollo 11 glasses show a clustering of values with more than 90 per cent normative feldspar. Despite this grouping, anorthositic gabbro compositions are apparently more abundant than ano~hosi~. Even this minor anorthosite component may be an overestimate, because glasses with more than 94 per cent normative feldspar may represent not only rock melts but also feldspar melts or maskelynite grams. DISCUSSION The soils at all four lunar landing sites contain a substantial amount (17 to 33 per cent) of glasses with Al,O, greater than 21 weight per cent and Fe, Ti and Ca/Al ratios indicative of a non-mare origin. This non-mare component has essentially the same composition (equivalent to anorthositic gabbro) at each site. Glass compositions from four widely separated lunar sites are compared in Table 1. The similarity of the compositions is striking. A better comparison is afforded in Table 2, in which Table 2. Median compositions of glasses in the hmar soil with Al,O, greater than 21 weight per cent Median composition (weight per cent) Oxido Apollo 11
Apollo 12
Apollo 14 14259 14156
44.62 0.04 25.78
44.81 0.30 26.76
45.10 0.29 25-28
5.01 8.40 14.85 0.20 0.05
6.75 8.20 14.68
%O
5.47 7.55 14.92 O-28 O-01
Total
99.03
99.37
99.54
SiO, TiO,
Fe0 Ma0 C&O X%&.0
Number of glasses Nomative minerals Orthoclase Albite Anorthite Diopside Hypmthene Olivine Chromite Ilmenite Fe/Fe t_ Mg in silioste AnlAb + An in plagioolase
120
24
0.3 2.4 68.9 4.1 13.1 9.5 0.8 0.275 0.935
o-19 0.05
130 0.3 1.6 68.0 3.9 16.2 9.0
0.6 0.241 0*97&i
0.6 0.273 O-976
Luna 16
surveyor*
44.97 O-32 26*00 0.10 5.53 7.85 14.84 0.26 O*Ol
45
100*18
GEZ
SF
41
80
45.60 0.29 25.46 0.09 5.79 8.15 14.62 0.17 0.01
0.1 1.4 68.7 3.1 19.2 7.0 0.1 0.6 O-275 0.978
.-
22 5 7 18 0.7
0.1 I.1 67.9 2.3 20.5 7.0 0.2 0.7 0.269 0.983
* Oxide composition consistent with Surveyor 7 analyticttl results from TURKEVXXI (1971); for disoussion of assumptions and error estimates.
see this
paper
Highly chminous
glames in lunar soils
and the natureof the lunarhighlands
909
the median compositions are shown for the four landing sites for glasses with more than 21 weight per cent A&O,. Well-mixed lunar soils are composed of material from a wide area of the lunar surface. Thus, the lunar soils should commonly contain a minor component derived from the highland regions. If highland material is fairly homogeneous, soil from a mare site should contain a distinctive non-mare component. Material equivalent in composition to anorthositic gabbro makes a substantial contribution to the soils in Mare Tranquillitatis, Mare ~ecun~tatis, Oceanus Procellarum, and the Fra 3lauro area. Fra Mauro basalt or KREEP is rare at both the Mare Tranquillitatis and Mare Fecunditatis sites and is too rich in potassium to be a major highland rock type (METZGERet al., 1972). The only direct analysis of highland material, made by Surveyor 7 (TLJRKE:VTCH, 1971) corresponds to anorthositic gabbro rather than anorthosite. The comparison between the Surveyor analysis and the anorthositic gabbro compositions from the four lunar sites is made in Table 2. We suggest that material with this composition is a major rock type in the lunar highlands. This conclusion is essentially in accord with preliminary Apollo 15 X-ray fluorescence data obtained during lunar orbit (ADLERet al., 1972). The low K content (K,O N 0.05 weight per cent) is in apparent agreement with the preliminary y-ray data from Apollo 15 (M~TZ~ERet aI., 1972). The rocks from which these gIasses are derived apparently have an anorthositic gabbro composition with more aIumina than terrestrial high-alumina basalts. We propose the name Highland basalt for this particular composition, Further studies may show that the use of the term basalt is inappropriate, but the textures of the parent rocks, and whether the parent rock is volcanic or plutonic, are unknown. These glasses have similar major element compositions at four widely separated sites, suggesting they may be derived from a homogeneous source. This constancy is difficult to reconcile with derivation from coarse-grain heterogeneous cumulates, The parent rocks for Highland basalt glasses may be fine grained igneous rocks derived from highly aluminous liquids. In a H,O-free environment these compositions have very high liquidus temperatures, compared to te~est~al lavas. Such liquids, if partial melts, would derive from even more aluminous parent material. The existence of liquids of Highland basalt composition early in lunar history implies very high temperatures ( >1400°C), extensive melting and probably extensive fractionation. It further implies that portions of the outer layers of the moon were very highly aluminous (A&O,, 25 weight per cent or higher). The al~~ative model is to consider Highland basalt as a cumulate. Feldspar rich compositions may be produced by accumulation of early formed feldspar from a parental basaltic liquid. This model for the genesis of Highland basalt material is consistent with its low K content and with its high Mg/Fe ratio. The Highland basalt glasses found in the Apollo 14 soils show a range in abundances of normative mafic phases, but fairly constant Mg/Fe ratios. Such a relationship is consistent with an original accumulate origin (WAGES and BROWN, 1968). In addition, some coarse soil samples and rare breccia clasts in the ApolIo 14 samples have a mineral assemblage like that expected for Highland basalt, and though fine grained, do show intercumulate textures. If the Highland basalt compositions represent cumulates from a basaltic parent
910
ARCH M. REID et al.
then the parent must have feldspar as a major phase and thus be a high-alumina basalt. The basaltic parent materials of the Fra Mauro basaltic glasses (or KREEP basalt) and specific rocks such as 14310 and 14073 (e.g. WALKER etaE., 1972; BROJV-N and PECKETT, 1971)have feldspar as a liquidus phase and could produce feldspar cumulates. The glass data (REID etal.,1972b) and the X-ray and y-ray data from Apollo 15 (ADLER et aZ., 1972; METZQER et al., 1972) suggest that Fra Mauro basalts are not as widespread on the lunar surface as anorthositic gabbro. In view of this evidence it appears unlikely that Fra Mauro basalt (KREEP) is the parent of the Highland basalt. The chemical composition of Highland basalt suggests a parent material that is a high-alumina basalt without the highly fractionated trace element chemistry of Fra Mauro material. CoNCLusIoNs We conclude that the major non-mare glass component at all sampled mare sites has the composition of anorthositic gabbro. The other major non-mare component in mare soils, Fra Mauro basalt (KREEP, norite), is actually more abundant than Highland basalt in many Apollo 12 soils but is rare in Apollo 11 and Luna 16 soils. Highland basalt is also an important glass type in the Fra Mauro soil. The average major element composition of the anorthositic gabbros from each site is remarkably uniform, and the total glass population shows small variance. This component appears to reflect a major feldspathic rock type in the lunar highlands. These rocks may represent basaltic liquids or anorthositic gabbro accumulates. Most schemes for evolution of the moon involve the formation of an anorthosite crust (e.g. WOOD et aZ., 1970; SMITH et al., 1970) by some accumulative process. The hypothesis that the dominant Highland rock has the composition of anorthositic gabbro still requires that Al- and Ca-rich material be abundant in the outer parts of the moon early in lunar history (e.g. GAST and MCCONNELL, 1972). Acknowledgemed~We thank P. RICHARDSONfor help in data handling. P&r Jakeg was supported by contract number NSR 09-051-001 between the National Aeronautics and Space Administration and the Universities Space Research Association. W. I. Ridley was supported by a National Research Council Resident Research Associate&p. This paper constitutes the Lunar Science Institute contribution number 81. REFERENCES ADLER I., Tnordmr~ J., GERARDJ., Lowm P., SCHMEDEBECK R., BLOD~ETH., ELLER E., YIN L., LAMOTHER., GORENSTEIN P. and BJORKF~OL~~ P. (1972) Apollo 16 geochemicalX-ray fluorescenceexperiment: Preliminary report. Scie7ace175, 436-440. ANDERSONA. T., Jr. and SM.ITEJ. V. (1971) Nature, occurrence, and exotic origin of “gray mottled” (Luny Rock) basalts in Apollo 12 soils and breccias. Proc. Second Lunar Sci. Conf., Geochim. Cosmochim. Acta, Suppl. 2, Vol. 1, pp. 431-438, M.I.T. APOLLOSOIL SURVEY (1971) Apollo 14: Nature and origin of rock types in soil from the Fra Mauro formation. Earth Planet. Ski. Lett. 12, 49-64. APOLLOSOIL SURVEY(1972) Phase chemistry of Apollo 14 soil sample 14259. In preparation. BROWN G. M. and PECKETTA. (1971) Selective volatilization on the lunar surface: Evidence from Apollo 14 feldspar-phyric basalts. Nature 234, 262-266. BUDDIN~TONA. F. (1939) Adirondack igneous rocks and their metamorphism. cfeol.Sot. Amer. Mem. 7, l-354.
Highly aluminous glasses in lunar soils and the nature of the lunar highlands
911
CHAO E. C. T., BOREMAN J. A., MINKIN J. A., JAX~S 0. B. and DESBOROUUH G. A. (1970)
Lunar glasses of impact origin: Physical and chemical characteristics and geological implications. J. ffeophys. Res. 75, 7445-7479. FTJOHS L. H. (1970) Orthopyroxene-plagioclasefragments in the lunar soil from Apollo 12. Scieme 169, 866-868. GAST P. W. and MCCONNICLL R. K. Jr. (1972) Evidence for initial chemical layering of the moon. Lunar Science--III, Abstracts Third .Lww Sci. Conf., Lunar Science Institute Contrib. 88. GLASSB. P. (1971) Investigations of glass recovered from Apollo 12 sample 12057. J. ffeophya. Res. 78, 6649-5657. HUBBARD N. J. and GAST P. W. (1971) Chemical composition and origin of nonmare lunar basalts. Proc. Second _i%mr Sci. Conf., Geochim. Cosmochim. Acta, Suppl. 2, Vol. 2, pp. 999-1020, M.I.T. JANE&P., WARNERJ., RIDLEY W. I., REID A. M., HARMONR. S., BRETTR. and BROWSR. W. (1972) Petrology of a portion of the Mare Fecunditatis regolith. Earth Planet. Sci. Lett. 13, 257-271. KEIL K., BUNCH T. E. and PRINZ M. (1970) Mineralogy and composition of Apollo 11 lunar samples. Proc. Fir& Lmmr Sci. Conf., Geochim. Cosmochim. Acta Suppl. 1, Vol. 1, pp. 561-598, Pergamon. KEIL K., PRINZ M. and BUNCH T. E. (1971) Mineralogy, petrology and chemistry of some Apollo 12 samples. Proc. Secorad&war Sci. Conf., Geochim. Cosmochim. Acta, Suppl. 2, Vol. 1, pp. 679-699, M.I.T. MARVINU. B., WOOD J. A., TAYLORG. J., REID J. B., Jr., POWELLB. N., DICKEYJ. S., Jr. and BOWI~RJ. F. (1971) Relative proportions and probable sources of rock fragments in the Apollo 12 soil samples. Proc. Second Lunar Sci. Conf., Geochim. Cosmochim. Acta, Suppl. 2, Vol. 1, pp. 679-699, M.I.T. MASONB., MELSONW. G., HJXNDERSON E. P., JAROSEWICH E. and NELENJ. (1971) Mineralogy and petrography of some Apollo 12 samples. Second Lunar Sci. Conf. (unpublishedproceed-
ings) . METZQERA. E., TROMBKAJ. I., PETERSON L. E., REEDY R. C. and ARNOLDJ. R. (1972) A first look at the lunar orbital gamma ray data. Lunar Science-III, Abstracts, Third Lunar Sci. Conf. Lunar Science Institute Contrib. 88. MEYERC. Jr. and HUBBARDN. J. (1970) High potassium, high phosphorusglass as an important rock type in the Apollo 12 soil samples. (Abatr.) Metewitim 5, 210-211. PRINZ M., BUNCHT. E. and KEIL K. (1971) Composition and origin of lithic fragments and glasses in Apollo 11 samples. Contr. Mineral. Petrol. 82, 211-230. REID A. M., RILEY W. I., JA~YE& P. and HARMONR. S. (1972a) Compositions of glasses in lunar soil 14156. In preparation. REID A. M., RIDLEY W. I., WARNERJ., HARYON R. S. and BRETTR. (1972b) Chemistry of highland and mare baealts as inferred from glasses in the lunar soils. Lunar Science-III, Abstracts Third LwbcwSci. Conf. Lunar Science Institute Contrib. 88. RIDLEY W. I., WILLJXXSR. J., TAKEDAH., BROWYN R. W. and BRETTR. (1971) Petrology of Fra Mauro basalt 14310. In preparation. SHORTN. M. (1970) Evidence and implications of shock metamorphism in lunar samples. Proc. B’irst Lunar Sci. Conf., Geochim. Cosmochim. Acta, Suppl. 1, Vol. 1, pp. 865-871. Pergamon. SMITHJ. V., ANDERSONA. T., NEWTONR. C., OLSENE. J. and WYLLIE P. J. (1970) Petrologic history of the moon inferred from petrography, mineralogy and petrogenesis of Apollo 11 rocks. Proc. B’irst Lunar Sci. Conf., Geochim. Cosmochim. Acta, Suppl. 1, Vol. 1, pp. 897-925. Pergamon. STEELEI. M. and SMITHJ. V. (1972) Mineralogy, petrology, bulk electron-microprobeanalyses from Apollo 14, 15 and Luna 16. Lunar Science--III, Abstracts Third Lunar Sci. Conf., Lunar Science Institute Contrib. 88. TURKEVICHA. L. (1971) Comparison of the analytical results from the Surveyor, Apollo, and Luna missions. Proc. Second Lunar Sci. Conf., Geochim. Cosmochim. Acta Suppl. 2, Vol. 2, pp. 1209-1215, M.I.T. VINOURADOV A. P. (1971) Preliminary data on lunar ground brought to Earth by automatic
912
ARCH M. REID et al.
probe “Lnna-16.” PTOC.Second L-mm Ski. Gonf., Geochim. Cosmochim. A&a, Suppl. 2, Vol. 1, pp. 1-16, M.I.T. WAGER L. R. and BROWNG. A/I. (1968) Laywed Igneowr Rocks, 2nd edition. Oliver and Boyd. WALE= D., LONGHI J. and I&YS J. F. (1972) Experimental petrology and origin of Fra Mauro rocks and soil. Lunar Science-III, Abstmcts Third Lmwr Sci. Conf., Lunar Science Institute Contrib. 88. WARNERJ. (1972) Unpublished compilation of Apollo chemical, age and modal information on file in the NASA MSC Curator’s Office, Rouston, Texas. WOOD J. A. (1970) Petrology of the lunar soil and geophytied implications. J. ffeo~~~~. Ree, 75,6497-+X13. WOOD J. A., DICKEYJ. S. Jr., MAl%mNU. B. and POWELLB. N. (1970f Lunar anorthositesand a geophysical model of the moon. Proc. .B%wtLunar Sci. Conf., Geochim. Cosmochim. Acta, Suppl. 1, Vol. 1, pp. 965-988, Pergamon.