Research ArticlePLANETARY SCIENCE

Fumarolic-like activity on carbonaceous chondrite parent body

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Science Advances  03 Jul 2020:
Vol. 6, no. 27, eabb1166
DOI: 10.1126/sciadv.abb1166
  • Fig. 1 Backscattered scanning electron microscopy (BS-SEM) observation of high-temperature fumarolic incrustations from Kudryavy volcano, and secondary minerals in CV chondrites.

    (A) Large view of primary basaltic andesite porphyritic texture of fumarolic incrustations from Kudryavy volcano with corroded clinopyroxene and plagioclase (anorthite) bathed in a fine-grained microlithic groundmass and showing the scattered Ca-Fe–rich secondary phases. (B) Large view of Bali CV chondritic texture from secondary minerals in CV chondrites with chondrules (ch), CAI, and dark inclusion (DI) cemented by a fine-grained matrix (mx) and hosting Ca-Fe–rich secondary phases. (C) Vein filled with hedenbergite-diopside assemblage within the plagioclase and pyroxene groundmass of fumarolic incrustations from Kudryavy volcano. (D) Detail of a vein network filled with hedenbergite within the fine-grained olivine (fa50) groundmass of a dark inclusion of Allende from secondary minerals in CV chondrites. (E) SEM backscattered electron images coupled with energy-dispersive x-ray chemical maps of hedenbergite and andradite (reddish) patches in the groundmass of Kudryavy fumarolic rock sample 11C (red, calcium; blue, silicium; green, iron; light blue, aluminum; pink, sulfur; yellow, sodium; orange, magnesium; light green, chlorine; violet, titanium; purple, potassium). (F) Backscattered electron (BSE)–SEM images from secondary minerals in CV chondrites, coupled with energy-dispersive x-ray chemical maps of hedenbergite and andradite (reddish) patches in the matrix of Allende (red, calcium; blue, aluminum; green, iron). adr, andradite; an, anorthite; cpx, “primary” magmatic clinopyroxene; hd, hedenbergite.

  • Fig. 2 BSE-SEM observation of high-temperature fumarolic incrustations from Kudryavy and secondary minerals in CV chondrites.

    (A) Crusted cavity in the Kudryavy andesite groundmass with concentric filling of hedenbergite and andradite. Euhedral andradite or hedenbergite protrude from cavity walls forming negative crystals. (B) Crusted cavity with concentric filling of hedenbergite and andradite in Allende CV chondrite. Notice the similarities with the fumarolic incrustations. (C) Patch of hedenbergite and diopside within the Kudryavy andesite groundmass. (D) Patch of hedenbergite and diopside within the matrix of Allende CV chondrite. (E) Euhedral andradite with hedenbergite and diopside inclusion at cavity walls forming negative crystals. (F) Euhedral andradite with hedenbergite and diopside inclusion within the matrix of Allende forming negative crystals. Similarities between (E) and (F) are striking. di, diopside; fa50, fayalite 50.

  • Fig. 3 BSE-SEM observation of high-temperature fumarolic incrustations from Kudryavy and secondary minerals in CV chondrites.

    (A) Assemblage of Ca-Fe–rich minerals (andradite and hedenbergite) with Na-Al–rich silicates (nepheline and davyne) in the andesite groundmass. (B) Assemblage of Ca-Fe–rich minerals (andradite and hedenbergite) with Na-Al–rich silicates (nepheline) in the matrix of Allende CV chondrite. (C) Andradite chemical zoning pattern (pure andradite in light gray and grossular-rich composition in darker gray) in Kudryavy andesite incrustations. (D) Similar andradite zoning pattern here in contact with hedenbergite, within the porous matrix of Allende CV chondrite (pure andradite in light gray and grossular-rich composition in darker gray). (E) Patches of sodalite associated with davyne in Kudryavy andesite. (F) Patches of sodalite in the matrix of Allende CV chondrite. da, davyne; Kfs, K-feldspar; ne, nepheline; sdl, sodalite.

  • Fig. 4 Mineral composition.

    Pyroxene and pyroxenoid (A and B), garnet (C and D), and Na-Al–rich silicates (E and F) from CV-CO chondrites (A, C, and E) and from fumarolic incrustations of the Kudryavy volcano, Kurile Islands (B, D, and F). Similar phases with comparable range of composition are present in both environments. Wollastonite (wo), diopside, hedenbergite, andradite, grossular (gr), nepheline (ne), and sodalite (sd). Fe-rich wollastonite (B) and davyne (F) are only documented in Kudryavy and not in CV-CO chondrites.

  • Fig. 5 Silica activity versus temperature diagrams of secondary mineral stability fields from both CV chondrite and Kudryavy fumarolic incrustation settings.

    (A) Mineral stability in the systems Ca-Fe-Si-O without water (black) and Ca-Fe-Si-O-H with excess water (green). Stability field are calculated at IM buffered redox conditions and an indicative pressure of 2000 bar. The silica activity buffer curve nepheline/albite is also plotted. Characteristic Ca-Fe–rich assemblages in CV3 chondrites depict log(aSiO2)-T pathway for each CV3 lithologies and fixed redox conditions [see also (8)]. Green lines and green area mark the stability fields of hydrous phases. (B) Similar plot with Kudryavy setting assuming FMQ buffered redox conditions. In both plots, a single trend matches the diversity of Ca-Fe secondary phases (gray area and dashed arrow), suggesting these secondary phases in both terrestrial and extraterrestrial environments obey to the same set of intensive parameters [log fH2/fH2O, log fO2, log(aSiO2), T]; see text for explanations.

Supplementary Materials

  • Supplementary Materials

    Fumarolic-like activity on carbonaceous chondrite parent body

    Clément Ganino and Guy Libourel

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