• DOI:10.1126/science.1226919
• Corpus ID: 21965292

The Absolute Chronology and Thermal Processing of Solids in the Solar Protoplanetary Disk

@article{Connelly2012TheAC,
  title={The Absolute Chronology and Thermal Processing of Solids in the Solar Protoplanetary Disk},
  author={James N. Connelly and Martin Bizzarro and Alexander N. Krot and {\AA}ke Nordlund and Daniel Wielandt and Marina A. Ivanova},
  journal={Science},
  year={2012},
  volume={338},
  pages={651 - 655}
}

• J. Connelly, M. Bizzarro, +3 authors M. Ivanova
• Published 2 November 2012
• Geology, Physics
• Science

Dating the First Solids The solar system's first solids: calcium-aluminum–rich inclusions and chondrules are found in meteorites and provide a direct record of the dynamics of the solar protoplanetary disk that led to the formation of the solar system. Previous results indicate that chondrules formed 1 to 2 million years after the inclusions—an age difference that has been used in constructing models of chondrule formation. Based on uranium- and lead-isotope measurements of a collection of these primitive materials, Connelly et al. (p. 651) show that chondrules in fact started to form at the same time as the inclusions, 4.567 billion years ago, and that their formation took about 3 million years. Isotopic dating implies that, contrary to previous results, two types of primitive solar system solids formed coevally. Transient heating events that formed calcium-aluminum–rich inclusions (CAIs) and chondrules are fundamental processes in the evolution of the solar protoplanetary disk, but their chronology is not understood. Using U-corrected Pb-Pb dating, we determined absolute ages of individual CAIs and chondrules from primitive meteorites. CAIs define a brief formation interval corresponding to an age of 4567.30 ± 0.16 million years (My), whereas chondrule ages range from 4567.32 ± 0.42 to 4564.71 ± 0.30 My. These data refute the long-held view of an age gap between CAIs and chondrules and, instead, indicate that chondrule formation started contemporaneously with CAIs and lasted ~3 My. This time scale is similar to disk lifetimes inferred from astronomical observations, suggesting that the formation of CAIs and chondrules reflects a process intrinsically linked to the secular evolution of accretionary disks.