Refractory Material from Early Times (REMELT)

Basic data for this project

Description

The isotopic composition among meteorites from planetary bodies reveals a fundamental dichotomy between inner solar noncarbonaceous(NC) and outer solar carbonaceous (CC) objects. The origin of and process responsible for this dichotomy are unknown and the understanding of the evolution of the early planetary disc towards the large scale isotopic anomaly remains a crucial task in cosmochemistry. In previous works, the applicant was able to showthat Al-rich chondrules play a key-role in solving this task. Al-rich chondrules are components of chondritic meteorites, the most primitive samples from the time of formation of our early solar system.Their precursors contains refractory material like Ca,Al-rich inclusions(CAIs) and amoeboid olivine aggregates (AOAs), which are seen asthe first solids in our solar system. The described large scale dichotomy is also visible in the differing 50 Ti isotopic systematics ofAl-rich chondrules from ordinary chondrites (NC region) and CO chondrites (CC region). Al-rich chondrules from CO chondrites have an excess in 50Ti, which is typical for CAIs and AOAs, whereas Al-rich chondrules from ordinary chondrites do not. This leads to the conclusion that a so far unknown refractory material was present in the inner solar system which is different in its isotopic composition from CAIs and AOAs. The main aim of the work is to learn more about this new refractory material and to reveal the origin, the evolution, and the genetic relationship between the different refractory components in meteorite groups of the inner solar system (NC chondrites). To fulfil this task, this project will produce a complete dataset (mineralogy, rare earth elements, as well as Ti, O, and Mg isotopics) from each refractory object (10 to 15 Al-rich chondrules and 5 to10 CAIs/AOAs) in order to connect the Ti-isotopic data with the O- and Mg-isotopic systematics for the first time. This will expose if the so far unknown refractory material is present in all NC chondrites. This would create a new and distinct refractory material group which is different torefractory material from CC chondrites. Such knowledge is crucial for understanding and modelling the distribution of the first particles in the early solar system. If the prevalent Al-rich chondrules included CAI like material, the current models would underestimate the CAI abundances in meteorites within the inner solar system. Conversely, if different refractory materials are present in the NC chondrites, then the basic assumption of a single formation region or a very short formation time for refractory inclusions is wrong. Regardless of what the proposed study reveals, it will change our view of the origin and distribution of the first particles, and thus expand existing models.