Shergottites Dhofar 019, SaU 005, Shergotty, and Zagami: ⁴⁰Ar‐³⁹Ar chronology and trapped Martian atmospheric and interior argon

Abstract

Ar and other chronometers argue for primary rather than secondary events. The cosmic ray exposure ages calculated from cosmogenic argon are 15.7 ± 0.7 Ma (Dhofar 019), 1.0-1.6 Ma (SaU 005), 2.1-2.5 Ma (Shergotty) and 2.2-3.0 Ma (Zagami).

Thermal and irradiation history of lunar meteorite Dhofar 280

“…, these extractions form a trend almost parallel to the 39 Ar/ 40 Ar axis, as well as indicating an age close to 0 Ga. As impact ejection is too weak to reset the Ar‐Ar clock (see studies on numerous Martian meteorites where Ar‐Ar ages are always higher than CRE ages, for example, Korochantseva et al. , ; Meyer ), partial resetting of the clock requires a stronger thermal event preceding the mild ejection impact. Correcting the intermediate‐temperature fractions of 1180–1270 °C for trapped Ar with 40 Ar/ 36 Ar ratios of 17.5 ± 0.2 (Fig. ), a weighted mean age of 890 ± 230 Ma is obtained (Fig.…”

“…; and shocked plagioclase by Korochantseva et al. ). This high‐temperature degassing is characterized by rather constant K/Ca ratios (the last ~30% of the fractional 39 Ar release, corresponding to the temperatures ˃1240 °C; Fig.…”

Terrestrial and Martian weathering signatures of xenon components in shergottite mineral separates

“…Reported crystallization ages are relatively young (<1 Ga) compared with the nakhlites (about 1.3 Ga), with a number between 165 and 180 Ma (e.g., Shergotty; Nyquist et al. 2001a) whereas others have ages of 700–900 Ma (e.g., SaU 005; Korochantseva et al. 2009).…”

The history of the Tissint meteorite, from its crystallization on Mars to its exposure in space: New geochemical, isotopic, and cosmogenic nuclide data

“…Ages for Martian meteorites are from Korochantseva et al. () and from the compilation in Brandon et al. ().…”

“…Yang et al (2015). Ages for Martian meteorites are from Korochantseva et al (2009) and from the compilation in Brandon et al (2012). b) Zr/Nb versus Nb/Th diagram adopted after Condie (2018).…”