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| Paper: |
Constraints on the Origin of Chondrules and CAIs from Short-lived and Long-Lived Radionuclides |
| Volume: |
341, Chondrites and the Protoplanetary Disk |
| Page: |
558 |
| Authors: |
Kita, N.T.; Huss, G.R.; Tachibana, S.; Amelin, Y.; Nyquist, L.E.; Hutcheon, I.D. |
| Abstract: |
The chronology of the first few million years (My) of solar system history is reviewed based on high-precision absolute (Pb-Pb) and relative (short-lived radionuclide) age data. Pb-Pb ages indicate that calcium-aluminum-rich inclusions (CAIs), the oldest known solar system objects, formed 4567.2±0.6 Ma ago. This is often referred to as the age of the solar system. Times of formation relative to the oldest CAIs for CAIs (≤0.3 My) and chondrules (1-3 My), and for early asteroidal differentiation (≥3 My) are comparable to time scales estimated from astronomical observations of low-mass young stars - protostars (class I), classical T Tauri stars (class II) and weak- lined T Tauri stars (class III), respectively. The Pb-Pb ages of chondrules also indicate chondrule formation occurred within 1-3 My after CAIs. The 53Mn-53Cr isochrons of bulk chondrules indicate chondrule formation contemporaneously with or within 2 My of CAI formation. Chondrules from different classes of chondrites show the same range of 26Al ages in spite of having differences in oxygen isotopic compositions, indicating that chondrules formed in localized environments. A broad correlation between compositions and 26Al-26Mg ages of chondrules in LL3 chondrites suggests elemental fractionation during chondrule formation. |
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