Testing fundamental constraints on the origin of planetary materials

• Applicants: Privatdozent Dr. Dominik Hezel; Professor Dr. Herbert Palme
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 314056533

The major component of most primitive, chondritic meteorites are chondrules, <0.1 to 2 mm sized, once molten droplets with igneous textures. Understanding the origin and formation of chondrules is one of the most important questions in meteoritics. The planned research will shed more light on the mechanism of chondrule formation. Carbonaceous chondrites contain about 50% chondrules and 50% fine-grained matrix. Both components have different chemical compositions. The combination of both is in many cases spot on the solar composition. We have shown this kind of relationship for Fe, Mg, Si, and Cr. We also found that refractory elements in chondrules and matrix are sometimes fractionated, such as high Ti/Al ratios in chondrules and low ratios in matrix of CR meteorites or occasional fractionations of Ca and Al, as is the case in CV chondrites. Recently, we even found a complementary relationship in the trace elements Hf and W, as well as in W-isotopes. This is of particular importance, because the Hf-W system can be used to date chondrule and matrix formation. This provides an even more detailed understanding of the chondrule matrix relationship. We demonstrated this in a recent publication. Understanding the chondrule matrix relationship will provide pivotal constraints to support and reject currently suggested hypotheses for chondrule formation. In addition, a scenario for chondrule formation may be concluded.¿In the present project we propose to study the origin of the chondrule-matrix fractionations. In addition, we want to extent our previous studies that focused on carbonaceous chondrites to other chondrite groups, R and ordinary chondrites. To understand complementarity and its implications for chondrule formation, we need extensive analyses of matrix and chondrules, which will be obtained by electron microprobe and solution based MC-ICP-MS analysis.

• DFG Programme: Research Grants