Dominion Range map and summary of seasonsSeason - # collected

1985 - 11

2003 - 140

2008 - 519

2010 - 896

2014 – 562

2018 - 865

Total - 2993

Ungrouped chondrite - 1CK5 - 1CM1 - 1CM2 – 11CO3 – 16CR2 – 4CV3 – 4

EH3 – 1EL6 – 1

H imp melt – 1H 3.X – 3L imp melt – 5L 3.X – 12LL imp melt – 3LL 3.X – 5

Chondrites

Ungrouped achondrite - 1Diogenite – 1Eucrite – 9Howardites – 10Irons – 4Lunar breccia – 5Mesosiderite – 1Ureilite - 5

Orange = featured in this PPT

Achondrites

AchondritesDOM 10100 (howardites) Dacitic clast

From Hahn et al. (2017)

Achondrites DOM 10100

DOM 08001 – 1.3 kg (eucrite)

Howardite contains dacite clasts, ultramafic mantle phases and is basically a treasure trove of Vestan differentiation products

From Hahn (2016)

AchondritesDOM 10662

Shock mosaicisedureilite (very rare) compared to standard ureilites like

DOM 18130

Achondrites Ungrouped achondrite DOM 14289 may be related to other ungrouped achondrites that resemble expected Vestan mantle lithologies

Achondrites

• DOM 18173

ungrouped iron

• DOM 10122

mesosiderite

DOM 14170

ungrouped iron

Ungrouped irons are a significant fraction of Antarctic irons and do not have a ready explanation

Achondrites – 5 paired lunar breccias

Ordinary chondrites: LL Shower ?

2014statistics

0

100

200

300

400

500

600

3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 5.2 5.4

nu

mb

er m

easu

rem

ents

Magnetic Susceptibility (log X)

DOM all seasons (n= ~ 2000)

L

H

LL

Revised classifications for DOM equil. ord. chon.

Subset of ~600 – have

both MS and Fa content

- good correlation

Clear

divisions

into H, L, LL

for all ~2000

EOC with

MS data

Spot checking of LLs by thin section and microprobe/SEM revealed that LL shower is actually an L Shower; confirmed with magnetic susceptibility

Revised classifications for DOM

Updated now for 2043 samples

Combination of SEM, oil,

magnetic susceptibility, EMPA

DOM18 by SEM will be consistent

with these

423, 21%

1482, 72%

138, 7%

H L LL

Early classifications were indicating ~60%

LL chondrites from DOM (2003, 2008,

2010), but closer inspection revealed Ls

being mis-classified as LLs.

LL shower is actually L Shower

DOM 03181 5.4 kg L3.5 chondriteDOM 03318 2.96 kg L5 chondrite

DOM 14003 L3.6

DOM 03253 – 1.2 kg H5 chondrite

Other Ordinary chondrites

Other chondrites

• DOM 14021 EH

• Impact melts – DOM 10848, DOM 10302, DOM 08002

• DOM 18071 – CM2

• DOM 14239 - CM1

• DOM 03183 – CM2

Carbonaceous chondrites

Used to correlate mineralogy and spectral characteristics of aqueous alteration

From Garenne et al. (2014)

Carbonaceous chondrites• DOM 10077 – CR2

0

10

20

30

40

50

60

70

80

90

1985 1990 1995 2000 2005 2010 2015 2020

# al

loca

tio

ns

Year

CR chondrites - 718 allocations

CR chondrites recovered over several decades, as well as newly discovered samples, have provided new constraints on the nature of:* nucleosynthetic processes via pre-solar grains

* organic compounds in the early solar system

* dust/gas ratios and oxidation states in the solar system

* the origin of chondrules and FeNi metal

* hydrated materials in matrix and rare clasts

DOM 03238 anomalous CO3 – magnetite-rich (7.6%)

Carbonaceous chondrites

DOM 08006 – CO3 (+ 08004 pairs)

Very primitive (3.05)

and supporting studies of

- amino acids

- pre-solar grains

- CAIs

DOM 08006 – 667 g

Simon and Grossman, 2015 Haenecour et al., 2017 Burton et al., 2012

Nittler et al., 2013

Carbonaceous chondrites

DOM 08006

DOM 08004

DOM 08351

Field photos

DOM 10900

DOM 10104

DOM 10847DOM 10121DOM 10101

DOM 08006

DOM 08004

DOM 08351

Additional masses from 2010-11 season

DOM 10900

DOM 14359

DOM 10104

DOM 10847

DOM 14127

DOM 10121DOM 10101

DOM 14305

DOM 08006

DOM 08004

DOM 14019

DOM 08351

A total of 14 CO3 from Dominion Range

Pairing called into question by Simon and Grossman (2015) who showed that refractory inclusion population in DOM 08004 and DOM 08006 are different.

Alexander et al. (2018) also show that DOM 08004 and DOM 08006 have distinct H, C, and N compositions and isotopic values.

DOM 08006 was originally identified as primitive using Cr in olivine approach of Grossman and Brearley (2005).

Given the scientifically valuable nature of the CO 3.05 and the large masses of many of the pairing group members, we have taken a close look at all 14 samples using MS and Cr in olivine approach.

(from Righter et al., 2019, Metsoc meeting)

Name Weight_g_DOM 08004 294.5DOM 08006 667.3DOM 08139 21.8DOM 08351 26.3DOM 10101 241.8DOM 10104 201DOM 10121 16.2DOM 10299 14.8DOM 10847 97.2DOM 10900 26.1DOM 14019 158.3DOM 14127 103.9DOM 14305 133.1DOM 14359 393

Most are paired with DOM 08004 - are they paired or not?

DOM 10847

ResultsThese samples all fall along the trend of Cr2O3 versus s-Cr2O3 defined by previous studies of CO chondrites (Grossman and Brearley, 2005). Many masses examined have primitive characteristics like DOM 08006: DOM 08139, DOM 08351, DOM 10104, DOM 10847, DOM 10900, and DOM 14359 all have high avg. Cr contents and relatively low s-Cr2O3, and represent a total mass of 1.4 kg. On the other hand, DOM 08004, DOM 10101, DOM 10121, DOM 10299, and DOM 14305 all have higher s-Cr2O3, and fall on the trend of more thermally altered, perhaps as 3.1. Finally, DOM14019 and DOM 14127 have slightly lower s-Cr2O3, and are thus likely 3.15.

3.00

3.053.10

3.15

Grossman and Brearley (2005) Righter et al. (2019) Metsoc

2 or more falls? Not all masses have been analyzed for all properties, but some correlations exist between NTL, MS, Cr in olivine, H-C-N bulk and isotopes

Could be 3 different groups – 3.05, 3.10, 3.15 // analyses of additional masses would help define the groupings

3.5

3.7

3.9

4.1

4.3

4.5

4.7

4.9

5.1

5.3

5.5

0.15 0.2 0.25 0.3 0.35 0.4

magnetic s

usceptibili

ty

Cr2O3 (wt.%) in olivine (avg.)

3.5

3.7

3.9

4.1

4.3

4.5

4.7

4.9

5.1

5.3

5.5

0 10 20 30

magnetic s

usceptibili

ty

Natural thermoluminescence

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 0.1 0.2 0.3 0.4 0.5

Cr 2

O3

(wt.

%)

in o

livin

e (

avg.)

C (wt%)

3.05

3.05

3.05

3.103.103.10

3.15

3.10

3.10

NTL data from Sears (2016) GCA 188, 106-124H, C, N data from Alexander et al. (2018) Space Science Reviews 214, 36-59.Figures from Righter et al. (2019) Metsoc