volatile elements; isotope fractionation; Moon formation; meteorites; stable isotopes
Bouvier Laura C., Costa Maria M., Connelly James N., Jensen Ninna K., Wielandt Daniel, Storey Michael, Nemchin Alexander A., Whitehouse Martin J., Snape Joshua F., Bellucci Jeremy J., Moynier Frédéric, Agranier Arnaud, Gueguen Bleuenn, Schönbächler Maria, Bizzarro Martin (2018), Evidence for extremely rapid magma ocean crystallization and crust formation on Mars, in Nature
, 558(7711), 586-589.
Szymanowski Dawid, Fehr Manuela A., Guillong Marcel, Coble Matthew A., Wotzlaw Jörn-Frederik, Nasdala Lutz, Ellis Ben S., Bachmann Olivier, Schönbächler Maria (2018), Isotope-dilution anchoring of zircon reference materials for accurate Ti-in-zircon thermometry, in Chemical Geology
, 481, 146-154.
Palk Carl, Andreasen Rasmus, Rehkämper Mark, Stunt Alison, Kreissig Katharina, Coles Barry, Schönbächler Maria, Smith Caroline (2018), Variable Tl, Pb, and Cd concentrations and isotope compositions of enstatite and ordinary chondrites-Evidence for volatile element mobilization and decay of extinct 205 Pb, in Meteoritics & Planetary Science
, 53(2), 167-186.
Bischoff Addi, Barrat Jean-Alix, Bauer Kerstin, Burkhardt Christoph, Busemann Henner, Ebert Samuel, Gonsior Michael, Hakenmüller Janina, Haloda Jakub, Harries Dennis, Heinlein Dieter, Hiesinger Harald, Hochleitner Rupert, Hoffmann Viktor, Kaliwoda Melanie, Laubenstein Matthias, Maden Colin, Meier Matthias M. M., Morlok Andreas, Pack Andreas, Ruf Alexander, Schmitt-Kopplin Philippe, Schönbächler Maria, Steele Robert C. J., et al. (2017), The Stubenberg meteorite-An LL6 chondrite fragmental breccia recovered soon after precise prediction of the strewn field, in Meteoritics & Planetary Science
, 52(8), 1683-1703.
Akram W., Schönbächler M. (2016), Zirconium isotope constraints on the composition of Theia and current Moon-forming theories, in Earth and Planetary Science Letters
, 449, 302-310.
Iizuka Tsuyoshi, Lai Yi-Jen, Akram Waheed, Amelin Yuri, Schönbächler Maria (2016), The initial abundance and distribution of 92 Nb in the Solar System, in Earth and Planetary Science Letters
, 439, 172-181.
Akram W., Schönbächler M., Bisterzo S., Gallino R. (2015), Zirconium isotope evidence for the heterogeneous distribution of s-process materials in the solar system, in Geochimica et Cosmochimica Acta
, 165, 484-500.
Bridgestock L.J., Williams H., Rehkämper M., Larner F., Giscard M.D., Hammond S., Coles B., Andreasen R., Wood B.J., Theis K.J., Smith C.L., Benedix G.K., Schönbächler M. (2014), Unlocking the zinc isotope systematics of iron meteorites, in Earth and Planetary Science Letters
, 400, 153-164.
Recently the Moon-forming giant impact theory has attracted considerable attention. This theory proposes that the Earth’s Moon formed by a collision of the Earth with another body called Theia. The collision generated a hot debris disk around the Earth from which our Moon accreted. The new studies were motivated by the fact that the Earth and Moon share identical O and Ti isotope compositions (at ppm precision), while solar system bodies in general exhibit distinct isotopic O and Ti compositions. The standard giant impact model (Canup and Asphaug, 2001) predicts that the Moon predominately consists of impactor material with likely non-terrestrial isotope signatures. This is at odds with the striking isotopic similarity of the Earth - Moon system. The latest simulations (Canup, 2012; Cuk and Stewart, 2012; Reufer et al., 2012) show, however, that it is also possible to mainly build the Moon from terrestrial material, which facilitates the explanation of the Earth-Moon isotope similarities.Recently, novel evidence was presented indicating that the Moon displays a distinctly heavier Zn stable isotope composition relative to the Earth (Paniello et al., 2012). This was interpreted to be the result of isotope fractionation that occurred in the aftermath of the giant impact. Zinc as a moderately volatile element was volatilized during the giant impact and this was followed by partial re-condensation during which the light Zn isotopes were preferentially lost from the lunar accretion disk to space. The remaining material - enriched in heavy Zn isotopes - accreted to form the Moon. Noteworthy, it has also been recently proposed that the giant impact resulted in stable isotope fractionation of the refractory rare earth element (REE) Ytterbium (Yb) (Albalat et al., 2012). For Yb, however, the Moon displays a lighter isotopic composition relative to the Earth. This was attributed to stable isotope fractionation that occurred in the Earth’s atmosphere shortly after the giant impact. The authors suggest that once the high temperatures of the silicate vapor atmosphere (>3000 K) after the giant impact began to subside, the refractory element Yb started to condense early in the condensation sequence. The liquid phase then rained out and fell back to the Earth, while isotopically light vapor was dragged outwards, condensed outside the Roche limit where the Moon formed and in such a way was incorporated into the Moon.Assuming that these interpretations of Zn (moderately volatile) and Yb (refractory element) isotope data are correct, these observations provide strong constraints on the physical conditions during and in the aftermath of the giant impact. Stable isotope fractionation of refractory and moderately volatile elements requires distinct physical conditions (e.g., temperature, pressure and oxygen fugacity). Moreover, if Zn and Yb isotopes were fractionated through the Moon-forming giant impact, collateral mass-dependent effects are expected in the isotopic composition of other refractory and moderately volatile elements. However, very little is known about the stable isotope composition of refractory and most moderately volatile elements in lunar materials. For this reason I propose a comprehensive isotope study, in which the stable isotope compositions of refractory and moderately volatile elements are determined to identify mass-dependent isotope effects generated by the Moon-forming giant impact. Such collateral effects can be used to constrain the physical conditions in the aftermath of the giant impact or their absence will reveal that the Zn and Yb isotope differences observed between the Earth and the Moon are not generated by the Moon-forming giant impact. The new data will also be used to assess whether the Earth was built from chondrite-like materials, as assumed in many terrestrial accretion models.