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Ganapathy, R.

Publications and source records attributed to Ganapathy, R..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

The abundances of zirconium and hafnium in the solar system

The concentrations of zirconium and hafnium have been determined in the Orgueil, Murchison, Allende, Bruderheim, and Alais meteorites by radiochemical neutron activation analysis. The mean Zr/Hf weight ratio in the first four of these meteorites is 31.3 (plus or minus 2.2), indicating no major fractionation of Zr from Hf. Alais contains anomalously high amounts of many refractory lithophile elements, including Zr and Hf. Orgueil contains 3.1 ppm Zr and 0.11 ppm Hf, corresponding to 9.0 and 0.16 atoms, respectively, relative to 1 million Si atoms.

Ganapathy, R.↗
NASA NTRS1975

Meteoritic trace elements in lunar rock 14321, 184

Measurements are given for sixteen trace elements determined by radiochemical neutron activation analysis in six samples of four components of lunar rock 14321, 184. The samples were of basalt (1B), matrix (9A), microbreccia-2 (15), and microbreccia-3 (14A, 16A, and 19A) components. The ancient meteoritic components in the samples were determined according to the ratios of siderophile elements (Ir/Au and Ge/Au) found in the samples.

Morgan, J. W.↗
NASA NTRS1975

Meteoritic material in four terrestrial meteorite craters

In the reported studies of meteoritic material on the moon an attempt was made to characterize the nature of the projectile from the abundance pattern of certain diagnostic trace elements, such as Ir, Re, Ni, Au, Ge, Sb, and Bi. Analyses were conducted of 47 samples from 4 terrestrial meteorite craters. The main object in the investigation was to show that the nature of the projectile could be reliably inferred from the trace-element pattern of the ejecta. In this connection material was analyzed from two terrestrial craters where the projectile itself was known. A second objective was to characterize the projectile at two craters where no discrete meteoritic fragments had been found.

Morgan, J. W.↗
NASA NTRS1975

Volatile elements in Allende inclusions

New data are presented on the relatively volatile elements (Mn, Na, and Cl) in coarse- and fine-grained Ca/Al-rich inclusions of different textures and mineralogy in the Allende meteorite. It is shown that the coarse-grained inclusions condensed from the solar nebula at high temperature and contained vanishingly small quantities of volatile elements at that time. Later, volatiles were added to these during the metamorphism of the Allende parent body. The fine-grained inclusions were also affected by the addition of volatiles during this metamorphism but, unlike the coarse-grained ones, they incorporated large amounts of volatiles when they condensed from the solar nebula, accounting for their higher volatile element contents.

Grossman, L.↗
NASA NTRS1974

Siderophile and volatile trace elements in 72255 and 72275

Of six samples from boulder 1 at Station 2, four contain a unique meteoritic component, which is attributed to the Crisium projectile. The other two samples are meteorite free, igneous rocks: an unusual, alkali- and Ge-rich pigeonitic basalt, and an alkali-poor norite of unexceptional trace element chemistry.

Morgan, J. W.↗
NASA NTRS1974

Meteoritic material on the moon

Micrometeorites, ancient planetesimal debris from the early intense bombardment, and debris of recent, crater-forming projectiles are discussed and their amounts and compositions have been determined from trace element studies. The micrometeorite component is uniformly distrubuted over the entire lunar surface, but is seen most clearly in mare soils whereas, the ancient component is seen in highland breccias and soils. A few properties of the basin-forming objects are inferred from the trace element data. An attempt is made to reconstruct the bombardment history of the moon from the observation that only basin-forming objects fell on the moon after crustal differentiation. The apparent half-life of basin-forming bodies is close to the calculated value for earth-crossing planetesimals. It is shown that a gap in radiometric ages is expected between the Imbrium and Nectaris impacts, because all 7 basins formed in this interval lie on the farside or east limb.

Morgan, J. W.↗
NASA NTRS1974

Bulk compositions of the moon and earth, estimated from meteorites

The present work calculates the bulk compositions of the earth and moon, based on the assumption that these planets formed by the same processes as chondrites. In terms of the model presented, the earth contains 9.2% early condensate and 1.5% carbonaceous, volatile-rich silicate. For the moon these percentages are 30.1 and 0.04, respectively. When lunar and terrestrial basalt data are normalized to these model compositions, element abundance patterns based on the percentages (assuming that each component carried its cosmic complement of trace elements) demonstrate the essential identity of igneous processes on both celestial bodies.

Ganapathy, R.↗
NASA NTRS1974

Meteoritic and volatile elements in Apollo 16 rocks and in separated phases from 14306

Recent evidence from two sources provides a basis for a reexamination of the relationship between the stratigraphy at the Apollo 16 site and the trace element distribution. Information concerning the surface exposure ages makes it possible to relate many samples to specific local impact events. At least five ancient meteoritic components have been tentatively assigned to individual basin-forming impacts on the basis of trace element analyses of Apollo 17 rocks. Attention is given to a petrographic examination of separates from two soils from Station 11 (North Ray Crater).

Ganapathy, R.↗
NASA NTRS1974

Lunar basins - Tentative characterization of projectiles, from meteoritic elements in Apollo 17 boulders

The ancient meteoritic components are considered, taking into account the significance of high siderophile abundances in highland rocks. Because this component occurs in breccias which have remained closed systems for at least 3.9 aeons, it can properly be called an ancient meteoritic component. It appears that the ancient meteoritic bodies represent a distinct population, different from present-day meteorites. Attention is given to the assignment of the lunar meteorite groups to individual basins and to the origin of basin-forming objects.

Morgan, J. W.↗
NASA NTRS1974

The simultaneous determination of 20 trace elements in terrestrial, lunar and meteoritic material by radiochemical neutron activation analysis

A radiochemical neutron activation method has been developed and applied to determine the content of 20 trace elements (Ag, Au, Bi, Br, Cd, Co, Cs, Cu, Ga, Ge, In, Ir, Ni, Rb, Re, Sb, Te, Tl, and Zn) in 45 terrestrial, 230 lunar, and 70 meteoritic samples. Results obtained for the U.S.G.S. standard basalt BCR-1 indicate that the inherent precision for most elements is 10% or better. The values obtained for the trace elements investigated are compared to those previously reported in the literature. Data for Type I carbonaceous chondrites show their compositions to be far more uniform than previously supposed. The values obtained for several elements represent significant revisions in the accepted cosmic abundances. These new values include: Zn, 1250; Cd, 1.51; and Ir, 0.72 atoms/million Si atoms. Further results have provided insight into the meteoritic material and accretion of the moon, and give evidence of lunar highland vulcanism.

Keays, R. R.↗
NASA NTRS1973

Meteoritic material on the moon.

Three types of meteoritic material are found on the moon: micrometeorites, ancient planetesimal debris from the 'early intense bombardment,' and debris of recent, crater-forming projectiles. Their amounts and compositions have been determined from trace element studies. The micrometeorite component is uniformly distributed over the entire lunar surface, but is seen most clearly in mare soils. It has a primitive, Cl-chondrite-like composition, and comprises 1-1.5% of mature soils. The ancient component is seen in highland breccias and soils more than 3.9 AE old. It has a fractionated composition, with volatiles depleted relative to siderophiles. The abundance pattern does not match that of any known meteorite class. The crater-forming component has remained elusive. Only a possible hint of this component has been seen, in ejecta from Dune Crater and Apollo 12 KREEP glasses of possibly Copernican origin.

Anders, E.↗
NASA NTRS1973

Volatile elements in Apollo 16 samples - Possible evidence for outgassing of the moon.

Several Apollo 16 breccias, including one containing goethite, are strikingly enriched in volatile elements such as bromine, cadmium, germanium, antimony, thallium, and zinc. Similar but smaller enrichments are found in all highland soils. It appears that volcanic processes took place in the lunar highlands, involving the release of volatiles including water. The lunar thallium/uranium ratio is .0002 of the cosmic ratio, which suggests that the moon's original water content could not have exceeded the equivalent of a layer 22 meters deep. The cataclastic anorthosites at the Apollo 16 site may represent deep ejecta from the Nectaris basin.

Krahenbuhl, U.↗
NASA NTRS1973

Abundance of 17 trace elements in carbonaceous chondrites.

Seventeen trace elements (Ag, Au, Bi, Br, Cd, Cs, Ge, In, Ir, Rb, Re, Sb, Se, Te, Tl, U, and Zn) were measured by neutron activation analysis in eight C1 samples (1 Alais, 3 Ivuna, 4 Orgueil and in three C2 samples (one each of Mighei, Murchison, Murray). The results show far less scatter than earlier literature data. The standard deviation of a single measurement from the mean of eight C1 samples lies between 2 and 14%, except for the following four elements: Au, Ag, Rb, and Br. The first two probably reflect contamination and sample heterogeneity, the last two, analytical error. Apparently C1 chondrites have a far more uniform composition than some authors have claimed.

Kraehenbuehl, U.↗
NASA NTRS1973

Luna 20 soil - Abundance of 17 trace elements.

Review of the results of radiochemical neutron activation analysis of two Luna 20 fine soil and breccia samples for the abundance of 17 mainly siderophile and volatile elements that are strongly depleted in lunar surface rocks and hence represent sensitive indicators of meteoritic materials. These results are compared with those previously obtained for Apollo 16 soils. Some of the source rocks of Luna 20 regolith are identified.

Morgan, J. W.↗
NASA NTRS1973

Noble gases in eleven H-chondrites.

Review of the results of measurements of noble gases in powdered aliquots of 11 H-chondrites whose trace element contents have been previously determined by Laul et al. (1973). The measurements were made on a 4.5-inch radius, Reynolds-type mass spectrometer, using conventional techniques.

Ganapathy, R.↗
NASA NTRS1973

Lunar crater Copernicus - Search for debris of impacting body at Apollo 12 site.

In an attempt to characterize meteoritic material at the Apollo 12 site, 4 KREEP concentrates from soil 12033 have been analyzed by neutron activation analysis. These contain a meteoritic component in which siderophile Ir, Re, and Sb are depleted by about a factor of 2, while volatile Se, Zn, Ag, and Bi are depleted by a factor of more than 5 relative to Au. This pattern does not closely resemble any major chondrite or iron meteorite group, but is very similar to that observed in high-alkali samples from Apollo 14. The meteoritic component in KREEP at both sites is therefore predominantly derived from Imbrian ejecta. However, a second, small component of primitive composition seems to be present in Apollo 12 KREEP, judging from the slight, uniform enrichments in Ir, Re, Sb, and Zn relative to Au. This component does not seem to be due to micrometeorites. If it is attributed to the Copernican projectile, the crater Copernicus may have been formed by a cometary nucleus, 4 km in diameter, with an impact velocity of 30 to 40 km/sec. These conclusions depend critically on the assumption that the meteoritic component in Apollo 12 KREEP is representative of the entire impact.

Morgan, J. W.↗