Oxygen isotope systematics of ordinary chondrite chondrules: insights into the inner solar system planetary reservoir

Date & time

4–5pm 17 July 2018

Speakers

Mr Leo Baeza (RSES)

Event series

Contacts

 Antony Burnham

Triple oxygen isotope measurements (16O, 17O, and 18O) revolutionized our understanding of meteoritics and cosmochemistry since the discovery of large and ubiquitous oxygen isotopic anomalies in refractory inclusions within carbonaceous chondrite meteorites in the early 70s. Since then, oxygen isotope variation in meteorites and their components became an important tracer of the processes and physicochemical conditions that occurred in the formative epochs of the solar system.

Primitive meteorites known as chondrites are samples of asteroidal bodies that avoided planetary scale processing and their high-temperature components, e.g. millimeter- to centimeter-sized spheres (chondrules) and calcium-aluminum-rich inclusions, were formed and/or thermally processed during the birth of the solar system. Therefore, some of their characteristics (e.g. oxygen isotope composition) should be intimately related to the nebular gas present in their protoplanetary disk formation region, which in turn offers clues about the material available to form planetesimals and planets. In this regard, it has been proposed that chondrite asteroids accreted specific chondrule groups or ‘chondrule populations’ in terms of oxygen isotopes but this hypothesis has never been statistically assessed.

Systematic in situ measurements of oxygen isotope composition of chondrule olivine from ordinary chondrites (H, L, and LL groups) by SHRIMP-SI and a robust statistical assessment allowed us to conclude for the first time that the different ordinary chondrite parent bodies sampled the same main population of chondrules in their accretion location.

I will discuss the implications of our results at different scales, from chondrule formation to galactic context, during the school seminar.

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