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Chodos, A. A.

Publications and source records attributed to Chodos, A. A..

16 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Petrology, chemistry, age and irradiation history of Luna 24 samples

The results of petrological, chemical, isotopic age determination and irradiation studies of sample 24170 from the 170 cm depth of the regolith core returned from Mare Crisium by Luna 24 are presented. The sample is found to be comprised of fragments from a single igneous rock, with mineralogical evidence indicating it to be a mare basalt. The crystallization age is determined by Sm-Nd and Ar(40)-Ar(39) ages to be 3.30 AE, establishing the presence of relatively young flows. All soil samples show low trace element compositions with minimum contamination by KREEPUTh-rich materials. Rb-Sr and Sm-Nd relations reflect the absence of significant fractionation at ages younger than 4.5 AE. One soil sample shows extremely large neutron capture effects, imposing a new lower limit to the neutron production rate in the regolith and requiring the addition of irradiated materials from depth.

Wasserburg, G. J.↗
NASA NTRS1976

Petrography of isotopically-dated clasts in the Kapoeta howardite and petrologic constraints on the evolution of its parent body

Results are presented for petrographic and electron microprobe studies of the isotopically dated A, B, C, and rho basaltic rock fragments separated from the howardite Kapoeta. Other lithic clasts and numerous mineral fragments in thin sections of Kapoeta are investigated in order to outline the range in lithology and chemistry of the source materials from which the Kapoeta meteorite is derived. The data obtained are compared to those from other meteorite and lunar samples, with particular reference to the observational consequences for the evolution of the Kapoeta parent body. A major conclusion is that there is no clearcut evidence for young magmatism on the Kapoeta parent body. The observations preclude the interpretation that the Kapoeta is a simple mixture of eucrites and diogenites. In contrast to the moon, a source of anorthositic rocks does not appear to have been present on the Kapoeta parent body which involved chiefly pyroxene. The FeO-MnO relationships suggest that the source of the materials in the Kapoeta parent planet are fundamentally related.

Dymek, R. F.↗
NASA NTRS1976

Petrology and origin of Boulders no. 2 and no. 3, Apollo 17 Station 2

The paper presents petrographic and mineralogical data for five samples from Boulder 2 (72315, 72335, 72355, 72375, and 72395) and sample 72435 from Boulder 3 at Apollo 17 Station 2. All the samples were found to consist of a few percent megaclasts set in a fine-grained matrix, which is comprised of microclasts and a poikilitic to subophitic-textured groundmass that crystallized from a melt. The samples have similar modal mineralogies, mineral compositions, and bulk-chemical compositions.

Dymek, R. F.↗
NASA NTRS1974

Mineralogy, petrology, and chemistry of basalt fragments returned by Luna 16

Mineralogical, petrological, and chemical analyses, along with Rb-Sr age and Ar-40/Ar-39 measurements, were carried out with the B-1 sample returned from the Luna 16 mission. The sample, weighing 62 mg, is a fine-grain basalt of ophitic structure. It differs from the Apollo samples in that the pyroxene and plagioclass contents are almost identical, and the ilmenite content (7%) lies between those of the Apollo-11 and Apollo-12 samples. Chemically, it is characterized by a high Sr content and a high K/U ratio.

Albee, A. L.↗
NASA NTRS1972

Comparative petrology of Apollo 16 sample 68415 and Apollo 14 samples 14276 and 14310.

Petrographic and electron microprobe studies of Apollo 16 igneous rock 68415 and Apollo 14 rocks 14276 and 14310 show that all three samples differ from the mare basalts and are characterized by plagioclase as the first liquidus phase and by the abundance of plagioclase which is in part cumulate in origin. Major and minor element abundances and isotopic data prohibit the derivation of rocks like any of these samples from one another by magmatic fractionation during their crystallization. They could have originated by partial melting of an old, more Al-rich source material without isotopic equilibration with the residuum, by complete melting of three independent sources, or by contamination with old radiogenic material. The existence of such feldspathic basalts indicates that the generation of Al-rich magmas may have been an important and widespread lunar process.

Gancarz, A. J.↗
NASA NTRS1972

Mineralogy, petrology, and chemistry of a Luna 16 basaltic fragment, sample B-1.

Petrological, mineralogical, and chemical investigations of the B-1 Luna 16 sample have revealed that the sample is a fine-grained ophitic basalt which is distinguished from the Apollo samples by containing a single pyroxene, an ilmenite content intermediate to that of the Apollo samples, and subequal amounts of pyroxene and plagioclase. It is also distinguished by a high Sr content and a high K/U value.

Albee, A. L.↗
NASA NTRS1971

Uranium-bearing minerals of lunar rock 12013.

The U distribution in rock 12013 was studied by fission track and elemental mapping techniques. Major U-bearing phases are whitlockite, apatite, zircon, and phase beta, which is a Zr-Ti mineral rich in Fe, Nb, Y, REE, and containing up to 3.6% UO2, 4.7% ThO2 and 4.2% PbO. Calculated microprobe ages for phase beta average 4.0 b.y. and are in reasonable agreement with Rb-Sr and K-Ar ages. Phase beta plays a significant role in the U-Th-Pb systematics of rock 12012 and may play a similar role in the model ages of lunar soil.

Haines, E. L.↗
NASA NTRS1971

Petrologic and mineralogic investigation of some crystalline rocks returned by the Apollo 14 mission.

Apollo 14 crystalline rocks (14053 and 14310) and crystalline rock fragments (14001,7,1; 14001,7,3; 14073; 14167,8,1 and 14321,191,X-1) on which Rb/Sr, Ar-40/Ar-39, or cosmic ray exposure ages have been determined by our colleagues were studied with the electron microprobe and the petrographic microscope. Rock samples 14053 and 14310 are mineralogically and petrologically distinct from each other. On the basis of mineralogic and petrologic characteristics all of the fragments, except 14001,7,1, are correlative with rock 14310. Sample 14073 is an orthopyroxene basalt with chemical and mineralogic affinities to ?KREEP,' the ?magic' and ?cryptic' components. Fragment 14001,7,1 is very similar to Luny Rock I.

Gancarz, A. J.↗