Jan L. Hellmann, currently a postdoc at the Institut für Planetologie, University of Münster, Germany, is awarded the 2021 Pellas-Ryder Award for his paper titled “Origin of volatile element depletion among carbonaceous chondrites” published in Earth & Planetary Science Letters in 2020. Jan Hellmann was a PhD student at the Institut für Planetologie, University of Münster, working with Thorsten Kleine, when the paper was submitted. He analyzed the isotopic composition of tellurium, a moderately volatile element, in carbonaceous chondrites to find that mass-dependent Te isotope fractionation correlated with matrix mass fraction and nucleosynthetic chromium isotope compositions. Jan’s work showed that each carbonaceous chondrite class has its own Te isotope composition, and that the lighter Te isotopes are enriched in the most volatile depleted carbonaceous chondrites, particularly in the chondrule-dominated portion, a result implying that condensation rather than the expected evaporation processes controlled volatile distribution. He observed that CR chondrites do not follow the trend defined by Te isotopes vs. Cr-54 anomalies implying a distinct provenance for CRs in contrast to other carbonaceous chondrites. Jan also showed that the CI-relative abundance of the terrestrial composition is not uniquely linked to accretion of CI-like material but could be supplied by accretion of any type of carbonaceous chondrite. The Pellas-Ryder committee considered his contribution to have “long-term impact on the meteorite and planetary community”.
The Pellas-Ryder award is jointly sponsored by The Meteoritical Society and the Planetary Geology Division of the Geological Society of America. Jan Hellmann will receive a certificate at the Geological Society of America’s Annual Meeting in Portland, USA.