JanHellmann

Jan Hellmann

Westfälische Wilhelms-Universität Münster - Planetology

Doctoral Student

Institut für Planetologie

Wilhelm-Klemm-Str. 10, D-48149 Münster

 

Awards

2018 - Wiley Award of the Meteoritical Society

2018 - American Geophysical Union Outstanding Student Presentation Award

 

Recent project work

Tellurium stable isotope fractionation in meteorites and terrestrial samples – Implications on the nature and origin of late accretion

The budget of the siderophile volatile element Te in the Earth’s mantle is thought to predominantly derive from late accretion of broadly chondritic material. To better constrain the nature and origin of the late-accreted material, we obtained mass-dependent Te isotopic data for terrestrial samples and a comprehensive set of chondrites. Tellurium stable isotope variations may arise as a result of nebular processes, leading to distinct isotopic compositions among chondrites, which allow to distinguish between different chondrite groups as potential sources of the late veneer. To this end, we developed a 123Te-125Te double spike method for the precise measurements of Te isotope variations by multi-collector ICP-MS. The Te stable isotopic composition of the bulk silicate Earth was precisely defined by analyses of several peridotites. Samples from the major chondrite classes display a range in Te isotopic compositions, and combined with their Se/Te ratios only some carbonaceous chondrite group overlap with the composition determined for the Earth's mantle.

 
Publications

2019

Hellmann, J. L., Kruijer, T. S., Van Orman, J. A., Metzler, K., Kleine, T., 2019: Hf-W chronology of ordinary chondrites. Geochimica et Cosmochimica Acta, Vol. 258, pp. 290-309. 10.1016/j.gca.2019.05.040

Archer, G. J., Walker, R. J., Tino, J., Blackburn, T., Kruijer, T. S., Hellmann, J. L., 2019: Siderophile Element Constraints on the Thermal History of the H Chondrite Parent body. Geochimica et Cosmochimica Acta, Vol. 245, pp. 556-576. 10.1016/j.gca.2018.11.012

2018

Kleine, T., Budde, G., Hellmann, J. L., Kruijer, T. S., Burkhardt, C., 2018: Tungsten Isotopes and the Origin of Chondrules and Chondrites. In Chondrules: Records of Protoplanetary Disk Processes, edited by Russell S S, Connolly Jr. H C, Krot A N, 276-299. Cambridge University Press. doi: 10.1017/9781108284073.010

 
Conferences

Hellmann, J. L., Hopp, T., Burkhardt, C. and T. Kleine (2019): Te stable isotopic constraints on the nature of late accretion. Goldschmidt Geochemistry Conference, Barcelona, Spain.

Hellmann, J. L., Hopp, T., Burkhardt, C. and T. Kleine (2018): Tellurium stable isotope variations among chondrites and terrestrial samples. American Geophysical Union Conference, Washington D.C., USA.

Hellmann, J. L., Fischer-Gödde, M. and T. Kleine (2018): Tellurium stable isotope measurements by double spike MC-ICPMS. Panerth Kolloquium, Nördlingen, Germany.