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Moderately volatile element fractionation in chondrites constrained by isotope dilution and Cd and Zn isotopes

Volatile elements in chondrites are usually depleted relative to CI chondrites. To disentangle the processes that affected volatile elements in the protoplanetary disk and on parent bodies, we present high-precision isotope dilution concentration data for S, Cu, Zn, Ga, Se, Ag, Cd, In, Sn, Te and Tl as well as Cd and Zn stable isotope compositions for carbonaceous, ordinary, enstatite and Rumuruti chondrites.

In carbonaceous chondrites, volatile elements with 50% condensation temperatures (TC) between 1040 and 800 K show a progressive depletion with decreasing TC, while volatile elements with 800 K > TC > 500 K are almost unfractionated, exhibiting a “hockey-stick” depletion pattern that represents the primary volatile element signature of carbonaceous chondrites.

Ordinary and Rumuruti chondrites show a similar pattern of volatile element depletion, but only for Cu, Ga, Ag, Zn, Te and Sn. The covariation of Zn, Te and Sn abundances with matrix abundances in ordinary and Rumuruti chondrites suggests that they contain a primitive CI-like matrix component just like the carbonaceous chondrites. Sulfur and Se are less depleted in ordinary and Rumuruti chondrites, indicating different physicochemical conditions in their formation regions. The unsystematic behavior of the most volatile elements Cd, In and Tl along with Cd and Zn (only ordinary chondrites) stable isotope fractionation suggest secondary redistribution processes on the respective parent bodies due to open system thermal metamorphism.

Enstatite chondrites show no such systematic volatile element abundance patterns with TC. Notably, their depletion pattern reveal similarities with those of evaporation experiments using carbonaceous chondrite powders under reduced conditions.

Details

Author
Ninja Braukmüller1, Claudia Funk2, Wafa Abouchami3, Harvey Pickard4, Mark Rehkämper4, Alessandro Bragagni5, Stephen Galer6, Carsten Münker2, Harry Becker7, Frank Wombacher2
Institutionen
1Institut für Geologische Wissenschaften, Freie Universität Berlin, Malteserstr. 74-100, 12249 Berlin, Germany;Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49b, 50674 Köln, Germany; 2Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49b, 50674 Köln, Germany; 3Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49b, 50674 Köln, Germany;Max-Planck-Institut für Chemie, Hahn-Meitner-Weg 1, 55128 Mainz, Germany; 4Department of Earth Science and Engineering, Imperial College London, Royal School of Mines, Prince Consort Rd, Kensington London, SW7 2AZ UK; 5Dipartimento di Scienze della Terra, Università degli Studi di Firenze, via La Pira 4, 50121 Firenze, Italy; 6Max-Planck-Institut für Chemie, Hahn-Meitner-Weg 1, 55128 Mainz, Germany; 7Institut für Geologische Wissenschaften, Freie Universität Berlin, Malteserstr. 74-100, 12249 Berlin, Germany
Veranstaltung
GeoMinKöln 2022
Datum
2022
DOI
10.48380/sms0-v489
Geolocation
Asteroid belt

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