Sample Petrographic Description
Sample Number | LAP 04773 |
Newsletter | 30,1 |
Location | LaPaz Ice Field |
Field Number | 17035 |
Dimensions (cm) | 2.25 x 1.25 x 1.5 |
Weight (g) | 8.30 |
Original Classification | H4 Chondrite (Anomalous) |
Pairing | LAP 04757; LAP 04773; |
Mineral Composition (%Fa & %Fs) | |
Fayalite (mol%): 13;Ferrosilite (mol%): 13-16 | |
Weathering | |
C | |
Fracturing | |
A/B | |
Macroscopic Description - Kathleen McBride | |
Exteriors of these meteorites have dull brown/black fusion crust with oxidation haloes. The interiors reveal a rusty brown/black matrix with high metal content. | |
Thin Section Description (,2) - Tim McCoy, Valerie Reynolds | |
These meteorites are so similar that a single description suffices. The sections consist of abundant chondrules set in a metal- and sulfide-bearing, weathered matrix. Shock effects are present, including metal-sulfide melting at grain boundaries. Olivine is homogeneous at Fa13 and pyroxene exhibits a small range at Fs13-16. Links to the acapulcoites or low-FeO chondrites (Russell et al., 1998, MAPS 33, 853-856) should be considered, although LAP 04773/04757 are less metamorphosed than the former and more magnesian than is typical for the latter. | |
Oxygen Isotopic Composition - Doug Rumble, Geophysical Laboratory, Carnegie Institution of Washington | |
Analysis for two subsamples of LAP 04757 give: A) δ18O = +3.67, δ17O = +2.68, and Δ17O = 0.746; B) δ18O =+3.75, δ17O = +2.94, and Δ17O =0.97. These values plot above the terrestrial fractionation line, suggesting an unusual low FeO ordinary chondrite such as Burnwell. |
Antarctic Meteorite Images for Sample LAP 04773 | ||||
Thin Section Photo(s) : | ||||
References for Sample LAP04773 | |
Torrano, Z.A., Schrader, D.L., Davidson, J., Greenwood, R.C., Dunlap, D.R., and Wadhwa, M., 2021, The relationship between CM and CO chondrites: Insights from combined analyses of titanium, chromium, and oxygen isotopes in CM, CO, and ungrouped chondrites. Geochimica et Cosmochimica Acta, 301C, 70–90, https://doi.org/10.1016/j.gca.2021.03.004. | |
McCoy, T.J., 2015, Meteorite Misfits: Fuzzy Clues to Solar System Processes. In Righter, K., Corrigan, C.M., McCoy, T.J., and Harvey, R.P. Meteorites: A Pictorial Guide to the Collection, First Edition, AGU Wiley, pp. 145-152. |