Rapid characterisation of Mars' mantle reservoirs by in situ laser ablation 87Sr/86Sr analysis of shocked feldspar (maskelynite)

Petrogenesis of the Dar al Gani (DaG) 1.1 Ma ejection‐paired olivine‐phyric shergottites and implications for ~470 Ma Martian volcanism

“…The measured 87 Sr/ 86 Sr of maskelynite are variably radiogenic, with the least radiogenic 87 Sr/ 86 Sr of 0.70061 AE 0.00015 measured in DaG 476, which is comparable to previously reported data for DaG 476 ( 87 Sr/ 86 Sr = 0.70125; , and other depleted shergottites ( 87 Sr/ 86 Sr = ~0.701; e.g., Symes et al, 2008). This value is comparable to the 87 Sr/ 86 Sr measured in maskelynite from depleted olivine-phyric shergottites Tissint (0.70130) and NWA 10567 (0.70139; Burgin et al, 2023), as well as the leached bulk-rock fractions of Tissint (0.7007-0.7008; Brennecka et al, 2014;. Since radiogenic isotope compositions of meteorites recovered from hot desert environments can also be affected by terrestrial alteration (e.g., Burgin et al, 2023;Crozaz et al, 2003;Peel et al, 2023), the sequential increases in 87 Sr/ 86 Sr isotope ratios observed between DaG 476, DaG 670, DaG 735, and DaG 1037 may indicate that the in situ 87 Sr/ 86 Sr analyses are variably affected by terrestrial contamination.…”

“…This value is comparable to the 87 Sr/ 86 Sr measured in maskelynite from depleted olivine-phyric shergottites Tissint (0.70130) and NWA 10567 (0.70139; Burgin et al, 2023), as well as the leached bulk-rock fractions of Tissint (0.7007-0.7008; Brennecka et al, 2014;. Since radiogenic isotope compositions of meteorites recovered from hot desert environments can also be affected by terrestrial alteration (e.g., Burgin et al, 2023;Crozaz et al, 2003;Peel et al, 2023), the sequential increases in 87 Sr/ 86 Sr isotope ratios observed between DaG 476, DaG 670, DaG 735, and DaG 1037 may indicate that the in situ 87 Sr/ 86 Sr analyses are variably affected by terrestrial contamination. In this case, the analyses likely included terrestrially formed veinlets in the ablation stream.…”

“…The bulk‐rock REE and high field strength elements (Nb, Ta, Hf, Zr, or Y) of the DaG shergottites do not, however, show significant effects of this terrestrial alteration and the bulk‐rock REE profiles of DaG 476, DaG 670, and DaG 735 are consistent with other depleted shergottites (Figure S2), especially in their well‐defined groupings of Nb/Y, Zr/Y, and La/Yb (Figure 11). In other cases where terrestrial alteration is clear, bulk‐rock Ba, Sr, and U and mineral LREE concentrations are significantly affected (e.g., Barrat et al., 2001; Burgin et al., 2023; Crozaz & Wadhwa, 2001; Crozaz et al., 2003; Peel et al., 2023).…”

“…The 13 depleted shergottites with ejection ages of ~1.1 Ma are: Sayh al Uhaymir (SaU) 005, Northwest Africa (NWA) 1195, NWA 6162, Tissint, Yamato (Y)-980459, Larkman Nunatak (LAR) 12095/12440, NWA 4925, NWA 2046, NWA 2626, NWA 5789, NWA 8159, NWA 7635, andDar al Gani (DaG) 476 (e.g., Ali et al, 2017;Brennecka et al, 2014;Dunham et al, 2019;Lapen et al, 2017;Nishiizumi et al, 2011;Wadhwa et al, 2001). Other depleted shergottites such as NWA 10416, NWA 10567, NWA 10693, NWA 12450, NWA 13467, and NWA 4222 may also be connected to this suite, however, their ejection ages have not yet been determined (Burgin et al, 2023;Suarez et al, 2022a).…”

Multi‐zone fusion crust formation and classification of the 2004 Auckland meteorite (L6, S5, and W0)

“…Shock metamorphism‐induced textures recorded on the meteorite vary based on mineralogy; for example, olivine and pyroxene in the interior of Auckland appear to have undergone extensive fracturing and remain fractured, kamacite and taenite have recrystallized into smaller sub‐grains, and plagioclase is converted entirely to maskelynite. Maskelynite is mostly free of fractures compared to adjacent olivine and orthopyroxene crystals (Figure 4d), likely because it represents post‐peak shock quenching of a plagioclase composition liquid (e.g., Burgin et al., 2023; Chen & El Goresy, 2000). Stöffler et al.…”