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Oxygen isotope composition of primitive achondrites (SNCs shown for comparison). Data for brachinites, winonaites, acapulcoite-lodranite clan from Greenwood et al. (2012). Data for ureilites from Clayton and Mayeda (1999). Data for Martian meteorites (SNCs) from Franchi et al. (1999) and compiled from laser fluorination analyses in the Meteoritical Bulletin. Δ17O calculated as: Δ17O = δ17O – 0.52δ18O. Individual winonaite and acapulcoite-lodranite clan samples are very highly susceptible to terrestrial weathering resulting in large shifts in δ18O and to a lesser extent Δ17O. Most analysis points for these two groups plotted on this diagram have been cleaned in EATG (ethanolamine thioglycollate) in order to reduce the influence of terrestrial weathering (see Greenwood et al., 2012 for further details). TFL: terrestrial fractionation line, Y&R: slope 1 line (Young and Russell, 1998), CCAM: carbonaceous chondrite anhydrous mineral line (Clayton et al., 1977; Clayton and Mayeda 1999). |
δ18O | δ17O | Δ17O: given | Δ17O: linear | Comment |
---|---|---|---|---|
2.724 | 0.184 | Not given | -1.232 | |
2.948 | 0.340 | Not given | -1.193 |
Name | Class | δ18O | δ17O | Δ17O: calc | Δ δ18O | Δ δ17O | Δ Δ17O |
---|---|---|---|---|---|---|---|
Hassi el Biod 002 | Pallasite, ungrouped | 2.8200 | 0.3380 | -1.128 | -0.02 | 0.08 | 0.08 |
Tafassasset | Achondrite-prim | 2.9400 | 0.1800 | -1.349 | 0.1 | -0.08 | -0.14 |
Northwest Africa 8287 | Acapulcoite | 2.9440 | 0.3560 | -1.175 | 0.11 | 0.09 | 0.04 |
Northwest Africa 468 | Iron, IAB-ung | 3.0100 | 0.1800 | -1.385 | 0.17 | -0.08 | -0.17 |
Northwest Africa 8287 | Acapulcoite | 2.5850 | 0.2360 | -1.108 | -0.25 | -0.03 | 0.1 |
Northwest Africa 8545 | Achondrite-ung | 2.9660 | 0.0040 | -1.538 | 0.13 | -0.26 | -0.33 |
Northwest Africa 6557 | Acapulcoite | 2.7900 | 0.5500 | -0.901 | -0.05 | 0.29 | 0.31 |
Northwest Africa 8158 | Eucrite | 3.0220 | 0.0000 | -1.571 | 0.19 | -0.26 | -0.36 |
Choteau | Pallasite, ungrouped | 2.5020 | 0.1520 | -1.149 | -0.33 | -0.11 | 0.06 |
Northwest Africa 8545 | Achondrite-ung | 3.1590 | 0.1200 | -1.523 | 0.32 | -0.14 | -0.31 |
Northwest Africa 4529 | Lodranite | 2.8940 | 0.6130 | -0.892 | 0.06 | 0.35 | 0.32 |
Northwest Africa 13754 | Lodranite | 2.5190 | 0.0840 | -1.226 | -0.32 | -0.18 | -0.01 |
Northwest Africa 6685 | Lodranite | 2.5000 | 0.1000 | -1.2 | -0.34 | -0.16 | 0.01 |
Northwest Africa 4478 | Lodranite | 2.4300 | 0.3000 | -0.964 | -0.41 | 0.04 | 0.25 |
Northwest Africa 8251 | Lodranite | 2.4280 | 0.3450 | -0.918 | -0.41 | 0.08 | 0.3 |
Northwest Africa 6557 | Acapulcoite | 3.0500 | 0.6400 | -0.946 | 0.21 | 0.38 | 0.27 |
Northwest Africa 8287 | Acapulcoite | 3.2000 | 0.5000 | -1.164 | 0.36 | 0.24 | 0.05 |
Northwest Africa 5782 | Acapulcoite/lodranite | 3.0300 | 0.6600 | -0.916 | 0.19 | 0.4 | 0.3 |
Northwest Africa 2400 | Achondrite-ung | 3.2700 | 0.1500 | -1.55 | 0.43 | -0.11 | -0.34 |
Northwest Africa 4478 | Lodranite | 2.4000 | 0.1100 | -1.138 | -0.44 | -0.15 | 0.07 |
Northwest Africa 13754 | Lodranite | 2.3920 | 0.1270 | -1.117 | -0.44 | -0.14 | 0.1 |
Northwest Africa 6921 | CR6 | 3.1810 | -0.0650 | -1.719 | 0.35 | -0.33 | -0.51 |
Northwest Africa 12869 | Achondrite-prim | 3.1810 | -0.0720 | -1.726 | 0.35 | -0.33 | -0.51 |
Northwest Africa 5782 | Acapulcoite/lodranite | 3.2400 | 0.5300 | -1.155 | 0.4 | 0.27 | 0.06 |