Magnetic properties of the lunar crystalline rock and fines

Magnetic measurements have shown that nondiamagnetic minerals in a lunar crystalline rock of type B are (free Fe(2)+ in paramagnetic pyroxenes) : (antiferromagnetic FeSiO(3)) : (antiferromagnetic FeTiO(3)) : (ferromagnetic iron) = 4.3 : 7 : 20 : 0.08 in weight percentage. The abundance of ferromagnetic Fe in the lunar fines is about 7.5 times its abundance in the crystalline rock. The natural remanent magnetization of the crystalline rock of 7.5 x 10(-6) emu/ g in intensity may not be attributable to its thermoremanent magnetization.     

Argon-40/ argon-39 dating of lunar rock samples

Seven crystalline rock samples returned by Apollo 11 have been analyzed in detail by means of the (40)Ar-(-39)Ar dating technique. The extent of radiogenic argon loss in these samples ranges from 7 percent to >/= 48 percent. Potassium-argon ages, corrected for the effects of this loss, cluster relatively closely around the value of 3.7 x 10(9) years. Most of the vulcanism associated with the formation of the Mare Tranquillitatis presumably occurred around 3.7 x 10(9) years ago. A major cause of the escape of gas from lunar rock is probably the impact event which ejected the rock from its place of origin to its place of discovery. Upper limits for the times at which these impact events occurred have been estimated.     

Search for magnetite in lunar rocks and fines

Magnetite crystals larger than 2 micrometers are absent from rocks and fines. Smaller opaque spheres in the fines can tentatively be identified as magnetite. Their concentration is not higher than 1 x 10(-6) particle per particle smaller than 1 millimeter. In the fines from the sampling site, the contribution of material similar to type 1 carbonaceous meteorites is insignificant, either because it never existed, or because it was evaporated or comminuted by impact or was diluted by indigenous material. Other magnetite habits typical of carbonaceous meteorites or possibly of cosmic dust or comets were also sought without success-such as rods, platelets, framboids, spherulites, and idiomorphic crystals.     

Bio-organic compounds and glassy microparticles in lunar fines and other materials

Acid hydrolyzates of aqueous extracts indicated: glycine, alanine, glutamic acid, serine, aspartic acid, threonine, and I-diaminopropionic acid. The sources of these amino acids may be terrestrial contaminants, fuel exhaust products, or indigenous lunar material. The lunar particles found in the sample include: (i) spherules, rotational ellipsoids, dumbbells, tear-drops, rings, and crescents which have (ii) diameters of 0.1 to 500 microns; (iii) budlike features on the particles; and (iv) chemical inhomogeneity (electron probe). Some of the processes and results inferred for the moon have been simulated by the electron beam and low pressure of the electron microscope. Basalt (Kilauea-lki) and chondrite (Orgueil) have been found to behave similarly.     

Infrared and thermal properties of lunar rock

The infrared absorption properties of lunar rock throughout the range 2 to 2000 micrometers were investigated and, in addition, direct measurements of specific heat and thermal conductivity of rock samples were made. The results suggest that pure radiation is an important, if not dominant, process in heat flow in the lunar surface layer. A new method for determining the mean conductivity of this layer gives somewhat lower values than earlier earth-based measurements. There is also evidence to suggest that, at depths of about 10 meters, the rock is still of a porous and fragmental nature.     

Isotopic analysis of rare gases from stepwise heating of lunar fines and rocks

Highlights of a first effort in sorting out rare gases in lunar material are solar wind rare gases in abundance; variable (20)Ne/(22)Ne but constant (21)Ne/ (22)Ne ratios in fractions of the trapped neon; cosmogenic rare gases similar to those found in meteorites, except for copious (131)Xe in one rock but not in another; at Tranquillity Base a rock 4.1 x 10(9) years old which reached the surface 35 to 65 million years ago, amid soil whose particles have typically been within a meter of the surface for 10(9) years or more.     

Magnetic properties of lunar dust and rock samples

Determinations on 20-to 80-milligram portions of the rock samples and the -150 mesh fraction of the lunar dust show pronounced Curie points between 680 degrees and 780 degrees C. Remanent intensities of five rock fragments vary from 8.4 x 10(-5) to 0.30 X J0(-5) emu/gram. Upon demagnetization, two of the samples had only viscous magnetization and two other samples had stable magnetizations with remanent coercivities in excess of 50 oersteds. Partial thermal demagnetization suggests that these apparently stable moments may have been acquired in a magnetic field in excess of 1500 gammas. xsxs.     

Water and carbon in rusty lunar rock 66095

Lunar rock 66095 contains a hydrated iron oxide and has an unusual amount of water for a lunar rock (140 to 750 parts per million), 90 percent of which is released below 690 degrees C. The deltaof water released at these low temperatures varies from -75 to -140 per mil relative to standard mean ocean water (SMOW). The small amount of water released between 690 degrees and 1300 degrees C has a delta of about -175 +/-25 per mil SMOW. These delta values are not unusual for terrestrial water. The delta(18)O of water extracted from 110 degrees to 400 degrees C has a value of +5+/- I per mil SMOW, similar to the value for lunar silicates from rock 66095 and different from the value of -4 to -22 per mil found for samples of terrestrial rust including samples of rusted meteoritic iron. The amount of carbon varies from 11 to 59 parts per million with a delta(13)C from -20 to -30 per mil relative to Pee Dee belemnite. Only very small amounts of reduced species (such as hydrogen, carbon monoxide, and methane) were found, in contrast to the analyses of other lunar rocks. Although it is possible that most of the water in the iron oxide (goethite) may be terrestrial in origin or may have exchanged with terrestrial water during sample return and handling, evidence presented herein suggests that this did not happen and that some lunar water may have a deltaD that is indistinguishable from that of terrestrial water.     

Evidence for compounds hydrolyzable to amino acids in aqueous extracts of apollo 11 and apollo 12 lunar fines

Hydrolyzates of aqueous extracts of Apollo 11 fines, an Apollo 12 trench sample, and an Apollo 12 surface sample have been analyzed on an ultrasensitive amino acid analyzer. The total content of amino acids recovered ranged from 20 to 70 parts per billion of lunar soil. Amino acids are not recovered by the direct hydrolysis of lunar fines, presumably because of decomposition in the presence of the large excess of lunar mineral. As judged by retention time, glycine is the dominant amino acid found; alanine is secondarily present in each case in the profile. Only a few amino acids have been recorded in each analysis. The pattern is relatively consistent in the samples from the three locations; the pattern from either hydrolyzed or unhydrolyzed extracts differs markedly from that of hydrolyzed or unhydrolyzed handprints. The evidence is not consistent with contamination of the kind expected by many investigators.     

Gas-retention and cosmic-ray exposure ages of lunar rock 15555

The last lava flow in the Hadley Rille area of Mare Imbrium, as inferred from an argon-40-argon-39 experiment on a plagioclase separate from the lunar basalt 15555, occurred 3.31+/-0.03x10(9) years ago. An argon-40-argon-39 experiment on a whole rock sample shows significant loss of radiogenic argon-40 and yields a well-defined, high-temperature plateau indicating a lower age of 3.22+/-0.03x10(9) years. A cosmic-ray exposure age of 90+/-10x10(6) years is determined from the ratio of spallogenic argon-38 to calcium.     

Pattern of bombardment-produced radionuclides in rock 10017 and in lunar soil

A large number of radionuclides have been measured as a function of depth in lunar rock 10017 and in bulk fines. Data are reported on (10)Be, (22)Na, (26)Al, (36)Cl, (49)V, (53)mn, (54)Mn (55)Fe, (56)Co, (57)Co, and (59)Ni and on upper limits for (46)Sc, (48)V, (51)Cr, and (60)Co. The results for several nuclides show striking evidence of excess surface production attributable to solar flare particles. Data for short-lived species, (56)Co, (57)CO, (54)Mn, (55)Fe, and (22)Na, appear consistent with fluxes from known recent events. Long-lived species demonstrate the existence of solar flare protons and alphas at least for the last 10(5) to 10(6) years, at fluxes comparable to those now observerved.     

Petrology of unshocked crystalline rocks and shock effects in lunar rocks and minerals

On the basis of rock modes, textures, and mineralogy, unshocked crystalline rocks are classified into a dominant ilmenite-rich suite (subdivided into intersertal, ophitic, and hornfels types) and a subordinate feldspar-rich suite (subdivided into poikilitic and granular types). Weakly to moderately shocked rocks show high strain-rate deformation and solid-state transformation of minerals to glasses; intensely shocked rocks are converted to rock glasses. Data on an unknown calcium-bearing iron metasilicate are presented.     

Chemical composition of sawdust from lunar rock 12013 and comparison of a java tektite with the rock

Abundances of 11 major and minor elements and 11 trace elements have been determined by instrumental neutron activation analysis of two Apollo 12013 rock fragments, a sample of rock 12013,17 sawdust, and a Java tektite (J2). Although the abundances of major elements in tektite J2 are similar to those of rock 12013, comparison of the minor and trace elements shows that no fragment or sawdust of rock 12013 that has been analyzed to date is chemically similar to tektite glass. Rock sawdust is representative of "whole rock" composition only if the amount of contamination from the sawing process is known. After appropriate correction for saw wire contamination, analyses of sawdust yield fairly accurate averaged elemental compositions of complex clastic lunar and other rocks.     

Lunar atmosphere as a source of argon-40 and other lunar surface elements

The lunar atmosphere is the likely source of excess argon-40 in lunar surface material; about 8.5 percent of the argon-40 released into the lunar atmosphere will be implanted in the surface material by photoionization and subsequent interaction with fields in the solar wind. The atmosphere is also likely to be the source of other unexpected surface elements or of solar wind elements that impact from non-solar wind directions.     

Experimental petrology of lunar material: the nature of mascons, seas, and the lunar interior

One-atmosphere melting data show that Apollo 11 samples are near cotectic. Melting relations at pressures up to 35 kilobars show that clinopyroxenite or amphibole peridotite are possible lunar interiors. Mascons cannot be eclogite; they may be ilmenite accumulate. Hot lunar surface material will boil off alkalis.     

Excess lead in "rusty rock" 66095 and implications for an early lunar differentiation

Apollo 16 breccia 66095 contains a remarkably high amount of lead (15 parts per million), 85 percent of which is not supported by uranium and thorium in the rock. An acid leach experiment coupled with separate analyses of the whole rock and mineral fractions for uranium, thorium, and lead indicate that the excess lead has a lunar source and was apparently introduced about 4.0 x 10(9) years ago. The data also suggest that a major lunar crustal differentiation occurred about 4.47 x 10(9) years ago.     

Pressure enhancement of ion mobilities in liquid silicates from computer simulation studies to 800 kilobars

Ion dynamics computer simulation methods show that for many liquid silicates, like silica itself, the component diffusion coefficients show anomalous pressure dependences. This implies that their viscosities have negative pressure dependences. Overall, there is an interesting degree of analogy between the fundamental binary solutions of geochemistry and the aqueous solutions of common experience; however, due to the stronger bonding in silicate systems, the anomalies are much more persistent. Diffusivity maxima occur at pressures of 200 to 300 kilobars and are correlated with a prevalence of fivefold coordination of silicon ions. The relevance of these findings to planetary dynamics and thermophysical modeling problems is briefly considered.     

Chemistry, geochronology, and petrogenesis of lunar sample 15555

Lunar sample 15555 is a mare type basalt generally similar in chemical composition to the Apollo 12 basalts. Sample 15555 is older than any Apollo 12 basalt but younger than the Apollo 14 basalts analyzed thus far.     

Rubidium-strontium, uranium, and thorium-lead dating of lunar material

Rubidiuom and stronztiulm concentrations and strontium isotopic compositions have been measutred on whole rock samples and density fractions of microgabbro. Density fractionis on two rocks define isochrons of 3400 and 4500 million years with large uincertainties owing to low enrichment of radiogenic strontium. Lead from fine surface material is highly radiogenic. An age of 4750 million years has been calculated from the ratio of (207)Pb/(206)Pb. The concentrations of uiranium, thorium, and lead isotopes are consistent with the evolution of lead in a 4700-million-year-old closed system characterized by the ratios of uranium to lead and of thoriunm to lead in this sutrface material.