Antarctic Meteorite Petrographic Description

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Sample Petrographic Description

Sample Number

LAP 03639

Newsletter

29,2

Location

LaPaz Ice Field

Field Number

16019

Dimensions (cm)

9.0 x 5.5 x 3.6

Weight (g)

139.94

Original Classification

R Chondrite

Updated Classification

R4 Chondrite

Pairing

LAP 03639; LAP 031144; LAP 031387; LAP 03731; LAP 03793; LAP 03902; LAP 04845

Mineral Composition (%Fa & %Fs)

Fayalite (mol%): 19-38;Ferrosilite (mol%): 13-29

Weathering

A/B

Fracturing

Macroscopic Description - Cecilia Satterwhite

The exteriors of these R chondrites have brown/black fusion crust with some evaporites. The interiors are gray with some large light and dark inclusions. Some oxidation and rust is present.

Thin Section Description (,2) - Valerie Reynolds, Tim McCoy

The sections are so similar that a single description suffices. The sections consist of ~50% of well-defined, small (up to 1 mm) chondrules set in a slightly recrystallized matrix of silicates and sulfides (both troilite and pentlandite). Olivines are nearly homogeneous (Fa_35-38, with a small tail of analyses down to Fa₆) and pyroxenes exhibit a larger range (Fs_1-30). The meteorites are R chondrites, probably of petrologic type 4.

Reclassification Notes (AMN 31,1)

Reclassified as R4 Chondrite in AMN 31,1.

Antarctic Meteorite Images for Sample LAP 03639

Field Photo(s) :

ANSMET LAP 03639 - Field Number: 16019, NASA Photo Number: jsc2019e007503

Field photo image(s) courtesy of the ANSMET (ANtarctic Search for METeorites) Program, Case Western Reserve University and the University of Utah

References for Sample LAP03639

Schrader, D.L., Davidson, J., McCoy, T.J., Zega, T.J., Russell, S.S., Domanik, K.J., and King, A.J., 2021, The Fe/S ratio of pyrrhotite group sulfides in chondrites: An indicator of oxidation and implications for return samples from asteroids Ryugu and Bennu. , Geochimica et Cosmochimica Acta, 303 , 66–91 , https://doi.org/10.1016/j.gca.2021.03.019 .

Cournède, C., Gattacceca, J., Rochette, P., & Shuster, D. L., 2020, Paleomagnetism of Rumuruti chondrites suggests a partially differentiated parent body. , Earth and Planetary Science Letters, 533 , 116042 , https://doi.org/10.1016/j.epsl.2019.116042 .

Schrader, D. L., Davidson, J., McCoy, T.J., 2016, Widespread evidence for high-temperature formation of pentlandite in chondrites. , Geochimica et Cosmochimica Acta, 189 , 2016 , 359–376 .

Khan, R., Shirai, N., Ebihara, M., 2015, Chemical characteristic of R chondrites in the light of P, REEs, Th and U abundances. , Earth and Planetary Science Letters, 422 , 18-27 , http://dx.doi.org/10.1016/j.epsl.2015.04.008 .

Isa, J., Rubin, A. E., Wasson, J. T., 2014, R-chondrite bulk-chemical compositions and diverse oxides: Implications for parent-body processes. , Geochimica et Cosmochimica Acta, 124 , 1-Jan-14 , 131-151 , ISSN 0016-7037 , http://dx.doi.org/10.1016/j.gca.2013.09.018 .

Gardner-Vandy, K. G., Lauretta, D. S., Mccoy, T. J., 2013, A petrologic, thermodynamic and experimental study of brachinites: Partial melt residues of an R chondrite-like precursor. , Geochimica et Cosmochimica Acta, 122 , 1-Dec-13 , 36-57 , ISSN 0016-7037 , http://dx.doi.org/10.1016/j.gca.2013.07.035 .

Bischoff, A., Vogel, N., Roszjar, J., 2011, The Rumuruti chondrite group. , Chemie der Erde - Geochemistry, 71 Issue 2 , May-11 , 101-133 , ISSN 0009-2819 , http://dx.doi.org/10.1016/j.chemer.2011.02.005 .

RELAB, , Reflectance Experiment Lab , catalogue of samples, .

Antarctic Meteorite Petrographic Description

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