Refractory Material from Early Times (REMELT)

Basic data for this project

Description

The isotopic composition among meteorites from planetary bodiesreveals a fundamental dichotomy between inner solar noncarbonaceous(NC) and outer solar carbonaceous (CC) objects. Theorigin of and process responsible for this dichotomy are unknown andthe understanding of the evolution of the early planetary disc towardsthe large scale isotopic anomaly remains a crucial task incosmochemistry. In previous works, the applicant was able to showthat Al-rich chondrules play a key-role in solving this task. Al-richchondrules are components of chondritic meteorites, the mostprimitive 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 scaledichotomy is also visible in the differing 50Ti isotopic systematics ofAl-rich chondrules from ordinary chondrites (NC region) and COchondrites (CC region). Al-rich chondrules from CO chondrites havean excess in 50Ti, which is typical for CAIs and AOAs, whereas Al-richchondrules from ordinary chondrites do not. This leads to theconclusion that a so far unknown refractory material was present inthe inner solar system which is different in its isotopic compositionfrom CAIs and AOAs. The main aim of the work is to learn more aboutthis new refractory material and to reveal the origin, the evolution, andthe genetic relationship between the different refractory componentsin meteorite groups of the inner solar system (NC chondrites). To fulfilthis task, this project will produce a complete dataset (mineralogy,rare earth elements, as well as Ti, O, and Mg isotopics) from eachrefractory 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-isotopicsystematics for the first time. This will expose if the so far unknownrefractory material is present in all NC chondrites. This would create anew and distinct refractory material group which is different torefractory material from CC chondrites. Such knowledge is crucial forunderstanding and modelling the distribution of the first particles in theearly solar system. If the prevalent Al-rich chondrules included CAIlikematerial, the current models would underestimate the CAIabundances in meteorites within the inner solar system. Conversely, ifdifferent refractory materials are present in the NC chondrites, thenthe basic assumption of a single formation region or a very shortformation time for refractory inclusions is wrong. Regardless of whatthe proposed study reveals, it will change our view of the origin anddistribution of the first particles, and thus expand existing models.