Reclassification of Some Carbonaceous and Ordinary Chondrites, HEDs and a Lunar Meteorite
In a few previous newsletters (AMN 30, no. 2, 31 no. 1) we announced US Antarctic meteorite reclassifications of various chondrites and achondrites, in light of new data obtained since the original classifications. Continuing to update our database, here are listed re-classifications of various HED, carbonaceous, enstatite and ordinary chondrites. These are based on either new published information, or correction of terminology.
GENERIC |
NEW CLASS |
CURRENT CLASS |
REASON OR ISSUE |
|---|---|---|---|
EET 96010 |
CM2 |
CV3 |
see notes and [3,4] |
WIS 91600 |
CM2 |
C2 |
see notes and [27] |
EET 96286 |
CR2 |
CV3 |
see notes and [1,2] |
MET 01017 |
CV3 anom |
CR2 |
see notes and [1] |
EET 96026 |
CV3 reduced |
R |
see notes and [3,4,5,6,7] |
MET 01149 |
R3 |
CK3 |
see notes |
MIL 07006 |
Lunar feldspathic breccia |
Lunar basaltic breccia |
see notes and [18] and [26] |
| MET 00452 | L(LL)3.05 |
H3.5 |
[8] |
MET 00526 |
L(LL)3.05 |
H3.0 |
[8] |
GRO 95502 |
L3.2 |
L3.5 |
[8] |
GRO 95544 |
L3.2 |
L3.5 |
[8] |
MET 96503 |
L3.10 |
L3.6 |
[8] |
ALHA81001 |
Eu “ub” |
Eu “pm” |
not a polymict eucrite, [9,10,11] |
LEW 87010 |
Eu “ub” |
Eu “pm” |
see notes and [10], [13] |
RKPA80204 |
Eu “br” |
Eu “ub” |
ssee notes and [10], [13], [14] |
GRO95633 |
Howardite |
Eu “br” |
see notes and [10], [12] |
RKPA80207 |
H3.2-3.7 |
L3.2/3.7 |
it is a breccia, so hyphen, not slashes |
ALH 85062 |
H3.5-4 |
L3.5/4 |
it is a breccia, so hyphen, not slashes |
ALHA81024 |
H3.6 |
L3.6 |
H: [20] |
WIS 91627 |
H3.8 |
H3.7 |
3.8: [17] |
ALHA78149 |
H4 |
L3 |
H4: [16] |
LEW 88021 |
H4 |
L4 |
H4: Met Bull 83, 1999 |
EET 83221 |
H4-6 |
H4/6 |
it is a breccia, so hyphen, not slashes |
ALH 84006 |
H4/5 |
H4-5 |
it is transitional, so slashes, not hyphen |
ALHA78147 |
H5/6 |
H5-6 |
it is transitional, so slashes, not hyphen |
EET 96188 |
L/LL3.2 |
L(LL)3.2 |
Parentheses is the wrong notation here |
ALHA77252 |
L3-6 |
L3.8 |
L3-6 from orig. desc.; not paired with 77216 |
LEW 86549 |
L3.0-3.7 |
L3.0/3.7 |
it is a breccia, so hyphen, not slashes |
RKP 86700 |
L3.0-3.9 |
L3.0/3.9 |
it is a breccia, so hyphen, not slashes |
GRO 95539 |
L3.1 |
L3 |
3.1: [17] |
LEW 86022 |
L3.2-3.5 |
L3.2/3.5 |
it is a breccia, so hyphen, not slashes |
EET 83395 |
L3.2-3.6 |
L3.2/3.6 |
it is a breccia, so hyphen, not slashes |
MAC 88199 |
L3.3 |
L3.4 |
3,3: [17] |
LEW 86307 |
L3.3-3.5 |
L3.3/3.5 |
it is a breccia, so hyphen, not slashes |
EET 83399 |
L3.3-3.6 |
L3.3/3.6 |
it is a breccia, so hyphen, not slashes |
EET 83260 |
L3.3-3.7 |
L3.3/3.7 |
it is a breccia, so hyphen, not slashes |
ALH 83008 |
L3.4-3.7 |
L3.4/3.7 |
it is a breccia, so hyphen, not slashes |
EET 82601 |
L3.5-3.7 |
L3.5/3.7 |
it is a breccia, so hyphen, not slashes |
RKPA79008 |
L3.5-3.8 |
L3.5/3.8 |
it is a breccia, so hyphen, not slashes |
LEW 86021 |
L3.5-3.9 |
L3.5/3.9 |
it is a breccia, so hyphen, not slashes |
RKPA80256 |
L3.6-4 |
L3.6/4 |
it is a breccia, so hyphen, not slashes |
ALHA77216 |
L3.7-3.9 |
L3.7/3.9 |
it is a breccia, so hyphen, not slashes |
ALHA79022 |
L3.7-4 |
L3.7/4 |
it is a breccia, so hyphen, not slashes |
EET 90628 |
L3.4 |
L3.5 |
3.4: [17] |
GRO 95505 |
L3.4 |
L3.3 |
3.4: [24] [17] |
LEW 88175 |
L3.4 |
LL3.8 |
3.4: [17] |
QUE 93705 |
L3.4 |
L3.7 |
3.7: [17] |
LEW 87284 |
L3.5 |
L3.6 |
3.5: [17] |
ALH 84086 |
L3.8 |
LL3.8 |
L: [19] |
TIL 82408 |
LL3.1-3.5 |
LL3.1/3.5 |
it is a breccia, so hyphen, not slashes |
ALH 83010 |
LL3.3 |
L3.3 |
LL: [19] |
ALHA81251 |
LL3.3 |
LL3.2/3.4 |
3.3: [22] |
LEW 88561 |
LL3.3 |
LL3.6 |
3.3: [17] |
ALHA79003 |
LL3.4 |
LL3 |
3.4: [21] |
ALHA78119 |
LL3.5 |
L3.5 |
LL: [19] |
ALHA77304 |
LL3.7 |
L4 |
3.7: [15] |
QUE 99861 |
LL5/6 |
LL5-6 |
it is transitional, so slashes, not hyphen |
GRO 95645 |
CM1 |
C2 |
|
EET 90986 |
CM2 |
C2 |
see notes below |
EET 92103 |
CM2 |
C2 |
“ |
EET 96018 |
CM2 |
C2 |
“ |
EET 96029 |
CM2 |
C2 |
“ |
GRA 98005 |
CM2 |
C2 |
“ |
LON 94101 |
CM2 |
C2 |
“ |
LON 94102 |
CM2 |
C2 |
“ |
MCY 92500 |
CM2 |
C2 |
“ |
MCY 92502 |
CM2 |
C2 |
“ |
PCA 91084 |
CM2 |
C2 |
“ |
PCA 91147 |
CM2 |
C2 |
“ |
PCA 91203 |
CM2 |
C2 |
“ |
PCA 91327 |
CM2 |
C2 |
“ |
QUE 93004 |
CM2 |
C2 |
“ |
QUE 93006 |
CM2 |
C2 |
“ |
QUE 93017 |
CM2 |
C2 |
“ |
QUE 94220 |
CM2 |
C2 |
“ |
QUE 94222 |
CM2 |
C2 |
“ |
QUE 94582 |
CM2 |
C2 |
“ |
QUE 94734 |
CM2 |
C2 |
“ |
QUE 97003 |
CM2 |
C2 |
“ |
QUE 97005 |
CM2 |
C2 |
“ |
RKP 92400 |
CM2 |
C2 |
“ |
RKP 92401 |
CM2 |
C2 |
“ |
RKP 92402 |
CM2 |
C2 |
“ |
TIL 91722 |
CM2 |
C2 |
“ |
EET 96031 |
H4-anom |
H4 |
anomalous due to reduced nature (AMN 21(1)) |
EET 96037 |
H4-anom |
H4 |
anomalous due to reduced nature (AMN 21(1)) |
EET 96040 |
H4-anom |
H4 |
anomalous due to reduced nature (AMN 21(1)) |
EET 96047 |
H4-anom |
H4 |
anomalous due to reduced nature (AMN 21(1)) |
EET 96123 |
H4-anom |
H4 |
anomalous due to reduced nature (AMN 21(1)) |
QUE 94570 |
L4-anom |
C4 |
a reduced L chondrite: [25] |
Specific Sample Notes:
Chondrites
MET 01017 original classification in AMN 26, no. 2, as a CR2 chondrite, but several studies have brought information to light that is inconsistent with that classification. Raman data, as well as isotopic data for C, H, and O indicate this meteorite is not a CR2, but a CV3 (possibly reduced) chondrite ([1] Busemann et al., 2007). Because the type of CV3 is not clear, and it has anomalous properties, we will reclassify it as CV3 an.
EET 96286 original classification in AMN 21, no. 2 as a CV3 chondrite, but several studies have brought information to light that is inconsistent with that classification. Raman data, as well as isotopic data for C, H, and O indicate this meteorite is not a CV3, but a CR2 chondrite ([1] Busemann et al., 2007; [2] Makide et al., 2009).
EET 96026 original classification in AMN 21 no. 1, as an R chondrite, but several studies have brought information to light that is inconsistent with that classification. Oxygen isotope data ([3] Clayton and Mayeda, 2003), as well as magnetic susceptibility data ([4] Rochette et al., 2008) indicate this meteorite is not an R chondrite, but a CV3 chondrite.
EET 96010 original classification in AMN 21, no. 1 as an CV3 chondrite, but several studies have brought information to light that is inconsistent with that classification. Oxygen isotope data ([3] Clayton and Mayeda, 2003), as well as magnetic susceptibility data ([4] Rochette et al., 2008) and bulk compositional data ([5] Moriarty et al., 2009; [6,7] Tonui et al., 2001, 2002) indicate this meteorite is not an CV3 chondrite, but a CM2 chondrite, and one with extensive hydration like Belgica 7904.
WIS 91600 originally classified as a C2 chondrite. Oxygen isotope data ([3] Clayton and Mayeda, 2003), and bulk compositional data ([5] Moriarty et al., 2009) indicate this meteorite has a bulk composition like CM, but has seen extensive hydration like Belgica 7904.
MET 01149 original classification in AMN 26, no. 2 (and Met Bull. 88) as a CK3 chondrite, but several unpublished studies have yielded information inconsistent with this classification. Because of the small nature of the sample, and the relatively rare class of CK3, the curator has decided to change this classification even with unpublished data to avoid confusion from requestors. MET 01149 is re-classified as an R3 because it contains many grains of Fa39 olivine, R-chondrite-size chondrules, and several cryptocrystalline chondrules (which are very rare in CK chondrites). INAA data generated at UCLA indicates that the rock has low abundances of refractory lithophile elements and relatively high Fe, consistent with an R-chondrite classification. (A. E. Rubin, 2009, pers. comm.).
Lunar meteorite
MIL 07006 original classification in AMN 31, no. 2 as a lunar basaltic breccia, but additional studies of more thin sections have revealed a predominance of feldspathic material over basaltic [18,26]. This is also reflected in the bulk composition which has high Al2O3 like other feldspathic regolith breccia [18]. MIL 07006 is reclassified as an lunar anorthositic regolith breccia.
HED meteorites
ALHA81001 original classification in AMN 6, no. 1, as an anomalous eucrite. Later reclassified in AMN 17, no. 1, as a polymict eucrite. Numerous thin sections reveal no brecciation and subsequent chemical and textural studies ([9] Warren et al, 1996; [10] Mittlefehldt and Lindstrom, 2003 and [11] Mayne et al. 2009) all suggest reclassification as unbrecciated eucrite.
GRO 95633 original classification in AMN 20, no. 2, as a brecciated eucrite. Subsequent studies and numerous thin sections reveal various eucritic lithologies and also orthopyroxene. Bulk compositions of [10] Mittlefehldt and Lindstrom, 2003 and [12] Okamoto et al. (2004) indicate clear >10% mixture of diogenitic material with the eucritic material. Therefore this sample is reclassified as a howardite.
LEW 87010 original classification in AMN 11, no. 2 as a eucrite. Later reclassified in AMN 17, no. 1, as a polymict eucrite, but listed in MetBase 7.1 as monomict (brecciated eucrite). Subsequent studies and several thin sections reveal no brecciation, and compositional studies of [13] Warren et al, 2009 and [10] Mittlefehldt and Lindstrom, 2003 all show very low siderophile element concentrations. Therefore this sample is reclassified as an unbrecciated eucrite.
RKPA80204 original classification in AMN 4, no. 2, as a eucrite. Later reclassified in AMN 17, no. 1, as a eucrite unbrecciated. Subsequent studies and numerous thin sections reveal brecciation ([14] Yamaguchi et al., 1997) and low siderophile elements consistent with a monomict breccia ([13] Warren et al, 2009; [10] Mittlefehldt and Lindstrom, 2003). Therefore this sample is reclassified as a brecciated eucrite.
HEDs considered for reclassification but not changed: ALH 85015 this is a small sample so limited sections are available. Only one shows eucritic material, so it’s classification as a diogenite stands.
EET 92023 this sample was suggested to be polymict based on high siderophile element concentrations, but there is no evidence for breccciation in any sections. Instead it appears that the higher metal contents are contributing to the high siderophile element concentrations. Therefore, this sample remains classified as an unbrecciated eucrite. It is possible that it is a clast from a mesosiderite, but this would require additional studies to verify.
EET 90020 there are some literature reports of hand sample regions that look fine grained and possibly brecciated, but all thin sections of this sample exhibit no brecciation, but instead have a fine grained and course grained portions. Both of these have triple junctions boundaries indicating heating to metamorphic conditions. Additionally, vugs are reported in some areas. Nonetheless the classification as an unbrecciated eucrites stands. Other notes and references: Many carbonaceous chondrites were initially classified as C2 in early newsletters. These are mostly CM2, based on matrix properties, chondrules abundance and sizes, and therefore all these samples have been reclassified more specifically here as CM2. [1] Busemann, H. et al., (2007) Characterization of insoluble organic matter in primitive meteorites by microRaman spectroscopy. Meteoritics & Planetary Science 42, 1387–1416.
[2] Makide, K. et al., (2009) Oxygen- and magnesium-isotope compositions of calcium–aluminum-rich inclusions from CR2 carbonaceous chondrites. Geochimica et Cosmochimica Acta 73, 5018–5050.
[3] Clayton R. N. and Mayeda T. K. 2003. Oxygen isotopes in carbonaceous chondrites (abstract). International Symposium on the Evolution of Solar System Materials: A New perspective from Antarctic Meteorites. National Institute of Polar Research, Tokyo, Japan, 13-14.
[4] Rochette et al., 2008 Magnetic classification of stony meteorites: 2. Non-ordinary chondrites. Meteoritics & Planetary Science 43, 959–980.
[5] Moriarty, G. et al. (2009) Compositions of four unusual CM or CM-related Antarctic chondrites. Chemie der Erde – Geochemistry 69, 161-168.
[6] Tonui, E. et al. (2001) Petrographic and Chemical Evidence of Thermal Metamorphism in New Carbonaceous Chondrites. Meteoritics & Planetary Science, vol. 36, Supplement, p.A207.
[7] Tonui, E. et al. (2002) Petrographic, chemical and spectroscopic data on thermally metamorphosed carbonaceous chondrites (abstract #1288). 33rd Lunar and Planetary Science Conference. CD-ROM.
[8] Grossman, J.N. and Brearley, A. (2005) MaPS 40, 87-122
[9] P.H.Warren et al., Papers 21st Symp. Ant. Met., NIPR Tokyo, 1996, p.195
[10] Mittlefehldt, D.W., and Lindstrom, M.M. (2003) Geochemistry of eucrites: Genesis of basaltic eucrites, and Hf and Ta as petrogenetic indicators for altered Antarctic eucrites. Geochimica et Cosmochimica Acta, 67, no. 10, 1911-1935.
[12] C.Okamato et al., Papers 28th Symp. Ant. Met., NIPR Tokyo, (2004) p.68 (abs.).
[11] Mayne, R.G., McSween, Jr., H.Y., McCoy, T.J., and Gale, A., (2009) Petrology of the unbrecciated eucrites. Geochimica et Cosmochimica Acta, 73, 794-819.
[13] Warren P. H., Kallemeyn, G.W., Huber, H., Ulff-Møller, and Choe, W., (2009) Siderophile and other geochemical constraints on mixing relationships among HED-meteoritic breccias. Geochimica et Cosmochimica Acta, 73, iss. 19, p. 5918-5943.
[14] Yamaguchi, A. et al. (1997) Shock and thermal history of equilibrated eucrites from Antarctica. Antarctic Meteorite Research. Twentyfirst Symposium on Antarctic Meteorites, NIPR Symposium No. 10, National Institute of Polar Research, p.415.
[15] Scott, E.R.D. (1984) Smith. Contrib. Earth Sci. 26, 75.
[16] Kojima, H. and K. Yanai (1996), Meteorite News vol. 6, no. 1, errata leaf
[17] Benoit, P. et al. (2002) Meteoritics & Planetary Science 37, 793.
[18] Korotev, R.L. et al. (2009) LPSC XL, #1137.
[19] Ozaki et al. (1999) 24th Symp. Ant Met. NIPR, 154.
[20] Sears, D.W.G. and Weeks, K. (1986) GCA 50, 2815.
[21] Scott, E.R.D. et al. (1982) Meteoritics 17, 65.
[22] Sears, D.W.G. and Hasan (1987) Surv. Geophys. 9.
[23] Kallemeyn, G. (1998) Meteoritics & Planetary Science 33, A81.
[24] P.Benoit and D.W.G.Sears, AMN, 1997, 20(2), p.13
[25] Kallemeyn, G. (1998) Meteoritics & Planetary Science 33, A80.
[26] Liu, Y. et al. (2009) LPSC XL, #2105.