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Nord, G. L., Jr.

Publications and source records attributed to Nord, G. L., Jr..

9 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Remanent magnetization of a 'paramagnetic' composition in the ilmenite-hematite solid solution stress

In the ilmenite-hematite solid solution series, compositions more ilmenite-rich than Ilm(73)Hem(27) are classically thought to be paramagnetic at room temperature. Ilm(80)Hem(20) samples have nevertheless been synthesized that acquire hard saturation remanent and thermoremanent moments. From analysis of AC demagnetization data, the source of the measured remanence is believed to be a single-domain (SD) like material within the IlM(80)Hem(20) grains themselves. On the basis of transmission electron microscope observations, it is suggested that transformation-induced domain boundaries, which in part are enriched in hematite component relative to the bulk composition of the grains, could act as the magnetic carrier of the SD-like remanence.

Lawson, C. A.↗
NASA NTRS1977

Shock-produced olivine glass - First observation

Transmission electron microscope (TEM) observations of an experimentally shock-deformed single crystal of natural peridot, /Mg(0.88)Fe(0.12)/2SiO4, recovered from peak pressures of about 56 billion pascals revealed the presence of amorphous zones located within crystalline regions with a high density of tangled dislocations. This is the first reported observation of olivine glass. The shocked sample exhibits a wide variation in the degree of shock deformation on a small scale, and the glass appears to be intimately associated with the highest density of dislocations. This study suggests that olivine glass may be formed as a result of shock at pressures above about 50 to 55 billion pascals and that further TEM observations of naturally shocked olivines may demonstrate the presence of glass.

Jeanloz, R.↗
NASA NTRS1976

76535 - Thermal history deduced from pyroxene precipitation in anorthite

Plagioclase in the slowly cooled lunar troctolite 76535 contains abundant rows of inclusions shown by transmission electron microscopy, electron diffraction, and X-ray energy analysis to consist mainly of augite, pigeonite, orthopyroxene, pores, and an unidentified phase which is preferentially thinned out during sample preparation. A minor inclusion is Ni-Fe metal. The pyroxenes are interpreted to have exsolved from plagioclase in the solid state.

Nord, G. L., Jr.↗
NASA NTRS1973

Electron petrography of Apollo 14 and 15 breccias and shock-produced analogs

Six lunar breccias were studied in detail by optical and transmission electron microscopy and separated into two classes on the basis of presence or absence of recovery and recrystallization textures: Class A breccias with no recrystallization include samples 14063, 14301, and 15498; Class B breccias with recrystallization include samples 14321, 15455, and 15418. Samples of Apollo 16 soil (65010) experimentally shocked to 50, 100, and 250 kilobars pressure were sectioned and studied for comparison with the breccias. It is concluded that the Class A breccias were formed from unconsolidated lunar regolith by deformation due to shock waves of a few tens of kilobars. The Class B breccias could also have been produced from unconsolidated material at higher shock stresses, the annealing being achieved by the heating resulting from the shock deformation.

Christie, J. M.↗
NASA NTRS1972

Electron petrography of Apollo 14 and 15 rocks.

Comparative optical and high-voltage electron petrographic analyses of igneous rocks and several types of breccias the Fra Mauro and Apennine sites of Apollo 14 and 15 are reported and interpreted. The crystalline rocks are found to differ substantially from the Apollo 11 and 12 basalts. Substructures in the Apollo 14 breccias are complex. At least two bonding mechanisms can be discerned from the electron petrographic examination: (a) 'shock sintering' due to high pressures and temperatures associated with the shock waves of meteoritic impacts; and (b) lithification by glass bonding.

Lally, J. S.↗