Differences in the degree of weathering between Antarctic and non-Antarctic meteorites inferred from infrared diffuse reflectance spectra

Journal Article · Tue Jan 01 04:00:00 EST 1991 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(91)90402-Q· OSTI ID:5920984

Miyamoto, M ^[1]

---

1. Univ. of Tokyo (Japan)

Infrared diffuse reflectance spectra were measured for Antarctic and non-Antarctic meteorites to compare the degree of terrestrial weathering by using the integrated intensity of absorption bands near 3 {mu}m caused by hydrous minerals and the intensity of absorption bands near 7.4 {mu}m (1,350 cm{sup {minus}1}) probably caused by hydrous carbonates. Non-Antarctic ordinary chondrite finds usually show large values of the integrated intensity of the 3 {mu}m band, whereas non-Antarctic ordinary chondrite falls show small intensities. Some Antarctic ordinary chondrites are as fresh as non-Antarctic ordinary chondrite falls in the sense of the integrated intensity of the 3 {mu}m band. Some Antarctic eucrites show large values of the integrated intensity of the 3 {mu}m band, although the degree of weathering on the A-B-C scale is reported to be A. Weathering-produced hydrous carbonates seem to be ubiquitous in Antarctic ordinary chondrites, because the spectra of all the Antarctic ordinary chondrites measured show the presence of the 7.4 {mu}m band. Non-Antarctic ordinary chondrite falls show very weak 7.4 {mu}m bands, suggesting only little weathering-produced hydrous carbonates. Diffuse reflectance spectra were also measured for the mixtures of akaganeite, goethite, artinite, or calcite with the Nuevo Mercurio (H5) ordinary chondrite to examine spectral changes and to compare them with those of meteorites. Absorption bands near 7 {mu}m of diffuse reflectance spectra are sensitive to the presence of carbonates.

• OSTI ID: 5920984
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 55:1; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ABSORPTION SPECTRA
ABSORPTION SPECTROSCOPY
AGE ESTIMATION
ANTARCTIC REGIONS
ANTARCTICA
CHEMICAL COMPOSITION
CHEMISTRY
CHONDRITES
COMPARATIVE EVALUATIONS
DISSOLUTION
GEOCHEMISTRY
INFRARED SPECTRA
METEORITES
MINERALOGY
POLAR REGIONS
SPECTRA
SPECTROSCOPY
STONE METEORITES
STRUCTURAL CHEMICAL ANALYSIS
WEATHERING