Speaker
Prof.
Martin Bizzarro
(Centre for Star and Planet Formation)
Description
Chondrite meteorites are fragments of asteroids that did not undergo melting and differentiation and, thus, provide a record of the earliest stages of the solar protoplanetary disk. Ordinary and enstatite chondrites are derived from parent asteroids that originated in the accretion region of terrestrial planets whereas the parent asteroids of the water-rich carbonaceous chondrites most likely accreted in the giant planet region. The dominant constituent of chondrites are millimeter-sized chondrules formed by transient heating events in the protoplanetary disk. Although it has long been accepted that chondrules formed 1 to 2 Myr after condensation of the solar system first solids, calcium-aluminium-rich inclusions (CAIs), recent high-resolution uranium-corrected Pb-Pb dates indicate that chondrule formation started contemporaneously with CAIs and lasted ~3 Myr. Moreover, chondrules from individual chondrites show variability in 54Cr/52Cr ratios, which track genetic relationships between early-formed solids and their respective reservoirs. Collectively, these observations indicate that chondrules from individual chondrite groups originated in different regions of the protoplanetary disk and were subsequently transported to the accretion regions of their respective parent bodies.
In this talk, we report new uranium-corrected Pb-Pb ages as well as 54Cr/52Cr ratios for chondrules from enstatite, ordinary and various classes of carbonaceous chondrites. Our results indicate that chondrule populations from individual chondrite groups show a comparable age range of ~3 Myr. Chondrules from enstatite and ordinary chondrites show 54Cr/52Cr ratios restricted to inner solar system compositions. In contrast, carbonaceous chondrite chondrules record greater 54Cr/52Cr variability, with both inner and outer solar system signatures. These data require different outward mass transport regimes but limited inward transport of outer solar system material in the formation region of terrestrial planets during the main accretion phase of chondrite parent asteroids. We explore the role of protostellar jets and disk winds as potential mass transport mechanisms to account for the observed meteoritic data.
Primary author
Prof.
Martin Bizzarro
(Centre for Star and Planet Formation)
