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AF31 Base Visit Book Ellsworth AFB
AF31 Base Visit Book Ellsworth AFB
Date:
October 24, 2005
Creator:
United States. Defense Base Closure and Realignment Commission.
System:
The UNT Digital Library
DA5 Base Visit Book Defense Agencies Leased Space - VA (DISA)
DA5 Base Visit Book Defense Agencies Leased Space - VA (DISA)
Date:
October 24, 2005
Creator:
United States. Defense Base Closure and Realignment Commission.
System:
The UNT Digital Library
Constraints on the Origin of Chondrules and CAIs from Short-Lived and Long-Lived Radionuclides
The high time resolution Pb-Pb ages and short-lived nuclide based relative ages for CAIs and chondrules are reviewed. The solar system started at 4567.2 {+-} 0.6Ma inferred from the high precision Pb-Pb ages of CAIs. Time scales of CAIs ({le}0.1Myr), chondrules (1-3Myr), and early asteroidal differentiation ({ge}3Myr) inferred from {sup 26}Al relative ages are comparable to the time scale estimated from astronomical observations of young star; proto star, classical T Tauri star and week-lined T Tauri star, respectively. Pb-Pb ages of chondrules also indicate chondrule formation occur within 1-3 Myr after CAIs. Mn-Cr isochron ages of chondrules are similar to or within 2 Myr after CAI formation. Chondrules from different classes of chondrites show the same range of {sup 26}Al ages in spite of their different oxygen isotopes, indicating that chondrule formed in the localized environment. The {sup 26}Al ages of chondrules in each chondrite class show a hint of correlation with their chemical compositions, which implies the process of elemental fractionation during chondrule formation events.
Date:
October 24, 2005
Creator:
Kita, N. T.; Huss, G. R.; Tachibana, S.; Amelin, Y.; Nyquist, L. E. & Hutcheon, I. D.
System:
The UNT Digital Library