Formation Conditions of Refractory Inclusions and Chondrules in Chondritic Meteorites

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Chondrite meteorites contain the earliest solid material that formed within our Solar System, 4.6 billion years ago. These meteorites are predominantly made up of millimetre-sized particles known as chondrules, and very fine-grained (sub-micrometre) matrix. Refractory inclusions, millimetres to centimetres in size, are a third important component: objects named refractory inclusions include Calcium-Aluminium-rich Inclusions, or CAIs. Although we know that chondrules and some CAIs underwent melting and cooling on timescales of a few hours, within the first 2 million years of formation of the Solar System, we do not know what process was responsible for that heating. Models range from impact events to bow shock waves in the dusty protoplanetary disk. We can put constraints on the heating mechanism, as well as the dynamic evolution of different reservoirs of material within the disk, by studying the chemical and isotopic properties of these melted objects. This project will investigate the heating mechanism responsible for formation of refractory inclusions and chondrules, by combining petrologic studies of chondrite samples with laboratory experiments on refractory inclusion and chondrule analogues. Analytical techniques include scanning electron microscopy (SEM) for investigating mineralogy and textures of natural and experimental samples, electron microprobe (EPMA) for measuring the chemical compositions of minerals, and secondary ion mass spectrometry (SIMS) for measuring isotope compositions in individual grains. Experiments will be conducted in a one-atmosphere gas-mixing furnace.