Antarctic Meteorite NewsletterNewsletter Number 33,1

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 itís 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.