Fumarolic-like activity on carbonaceous chondrite parent body

Abstract

<jats:p>Comparative planetology studies are key for understanding the main processes driving planetary formation and evolution. None have been yet applied to pristine asteroids formed in the solar protoplanetary disk, mainly because of their comminution during their 4.5-billion-year collisional lifetime. From remarkable textural, mineralogical, chemical, and thermodynamic similarities, we show that the high-temperature Kudryavy volcano fumarolic environment from Kurile Islands is a likely proxy of the Fe-alkali-halogen metasomatism on the CV and CO carbonaceous chondrite parent bodies. Ca-Fe–rich and Na-Al-Cl–rich secondary silicates in CV and CO chondrites are, thus, inferred to be fumarolic-like incrustations that precipitate from hot and reduced hydrothermal vapors after interactions with the wallrocks during buoyancy-driven Darcy flow percolation. These vapors may originate from the progressive heating and devolatilization of a chondritic protolith on their parent body or are remnant of the cooling of residual local nebular gases at the time of their primary planetesimal accretion.</jats:p>

The Fine‐Scale Magnetic History of the Allende Meteorite: Implications for the Structure of the Solar Nebula

“…Depending on the timescale of CRM acquisition compared to that of magnetic field reversals in the disk, this value may be the total magnetic field or its net vertical component. Rapid alteration in a fumarole‐like environment would predict CRM acquisition in as little as ~10 years, shorter than the expected field reversal timescale of 10 2 –10 3 yr (Bai, 2015; Ganino & Libourel, 2020), implying that the 122 µT best‐guess and >40 µT minimum values are a constraint on the total magnetic field.…”

“…The timing of these reactions may have been near the beginning (Krot et al., 1998, 2004) or the end (Ganino & Libourel, 2017) of the aqueous alteration sequence. In either case, the formation of Fe‐sulfide and awaruite is expected to have been contemporaneous or associated with a short delay of <10 2 years (Ganino & Libourel, 2020).…”

“…An important requirement for a CRM origin for the MT component is that no metamorphism above the 284°C apparent Curie temperature is permitted after pyrrhotite formation. Therefore, our interpretation of the MT component as a pyrrhotite CRM requires the sequence of events described in Ganino and Libourel (2017, 2020) where pyrrhotite formation post‐dates peak metamorphism.…”

“…Consequently, the time delay between the formation of datable secondary Fe‐bearing silicates (e.g., fayalite) and pyrrhotite in the fumarolic alteration framework is expected to be short, possibly on the order of 10 years by analogy with terrestrial fumaroles (Ganino & Libourel, 2020). Other chondrite studies have provided evidence for parent body alteration in such rapid, fumarole‐like systems.…”

“…The timing of these reactions may have been near the beginning (Krot et al, 1998(Krot et al, , 2004 or the end (Ganino & Libourel, 2017) of the aqueous alteration sequence. In either case, the formation of Fe-sulfide and awaruite is expected to have been contemporaneous or associated with a short delay of <10 2 years (Ganino & Libourel, 2020). conjectured that the higher permeability of the porous matrix compared to chondrules led to faster and therefore earlier aqueous alteration, leading to a time difference between the formation of the final ferromagnetic assemblages in the matrix and chondrules.…”