The effects of terrestrial weathering on samarium‑neodymium isotopic composition of ordinary chondrites

Abstract

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Artificial weathering of an ordinary chondrite: Recommendations for the curation of Antarctic meteorites

“…From their recovery from the field to their storage in museum or research institute collections, meteorites are carefully maintained under controlled environments to greatly reduce the effects of terrestrial weathering (e.g., Righter et al, 2014). This is particularly the case for Antarctic meteorites, which are usually recovered in the field at subzero temperatures and show low alteration states compared to meteorites recovered in hot deserts.…”

“…Even though terrestrial weathering is unavoidable, it is nonetheless necessary to preserve collected meteorite samples in an environment that will slow or, ideally, stop its progression. To mitigate these effects, museums and research institutes worldwide have curation facilities entirely dedicated to meteorites (e.g., Righter et al, 2014). Such facilities vary significantly from one institute to the other, mainly depending on the nature of the meteoritic samples (e.g., unique volatile-rich falls such as the Tagish Lake meteorite require specifically designed curation facilities; McCubbin et al, 2019).…”

“…The most visible weathering products on meteorites are evaporites and rust (mainly Fe oxyhydroxides), which result from the precipitation of salts due to water evaporation and corrosion of metal within the rock, respectively (Benoit & Sears, 1999;Bland et al, 2006;Gooding, 1982Gooding, , 1986Jull et al, 1988;Lee & Bland, 2004;Losiak & Velbel, 2011;Velbel, 1988Velbel, , 2014Velbel & Gooding, 1990). Therefore, effects of terrestrial weathering are visible in most Antarctic meteorites, albeit to a much lower extent than in meteorites recovered under a more humid and/or hot climate (Bland et al, 2006;Maeda et al, 2021;Pourkhorsandi et al, 2021). Even though terrestrial weathering is unavoidable, it is nonetheless necessary to preserve collected meteorite samples in an environment that will slow or, ideally, stop its progression.…”

The effects of Antarctic alteration and sample heterogeneity on Sm-Nd and Lu-Hf systematics in H chondrites

“…Finds are generally characterized by a much longer terrestrial residence time than falls (roughly of the order of tens of kyr: e.g., Al-Kathri et al, 2015). Many finds become weathered during this long residence time, and this process can take place relatively rapidly, particularly in temperate and tropical zones, as well as in hot deserts (Bland et al, 2006;Pourkhorsandi et al, 2021). On average, Antarctic meteorites exhibit old terrestrial ages, on the order of hundreds of kyr (e.g., Nishiizumi et al, 1989), and these are better protected from terrestrial weathering while buried in the ice compared to finds collected from hot deserts (Whillans and Cassidy, 1983;Cassidy and Whillans, 1990).…”

Isotopic evolution of planetary crusts by hypervelocity impacts evidenced by Fe in microtektites

“…The Fe isotope ratio data together with a compilation of major and trace element concentrations measured in this work and in earlier studies 14 – 17 , 45 , 82 , 83 are provided in tabular form in the electronic supplementary material. Source data are provided with this paper.…”