Nebular history of amoeboid olivine aggregates |
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| Authors: | N SUGIURA M I PETAEV M KIMURA A MIYAZAKI H HIYAGON |
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| Institution: | 1. Department of Earth and Planetary Science, University of Tokyo, 7‐3‐1, Hongo, Bunkyo‐ku, Tokyo, Japan;2. Harvard‐Smithsonian Center for Astrophysics and Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138, USA;3. Faculty of Science, Ibaraki University, Mito 310‐8512, Japan |
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| Abstract: | Abstract— Minor element (Ca, Cr, and Mn) concentrations in amoeboid olivine aggregates (AOAs) from primitive chondrites were measured and compared with those predicted by equilibrium condensation in the solar nebula. CaO concentrations in forsterite are low, particularly in porous aggregates. A plausible explanation appears that an equilibrium Ca activity was not maintained during the olivine condensation. CaO and MnO in forsterite are negatively correlated, with CaO being higher in compact aggregates. This suggests that the compact aggregates formed either by a prolonged reheating of the porous aggregates or by condensation and aggregation of forsterite during a very slow cooling in the nebula. |
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