Catastrophic fragmentation of asteroids: evidence from meteorites |
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Authors: | K Keil H Haack ERD Scott |
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Institution: | aHawaii Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, HI 96822, U.S.A. |
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Abstract: | Meteorites are impact-derived fragments from ≈ 85 parent bodies. For seven of these bodies, the meteorites record evidence suggesting that they may have been catastrophically fragmented. We identify three types of catastrophic events: (a) impact and reassembly events > 4.4 Gy ago, involving molten or very hot parent bodies(> 1200°C); this affected the parent bodies of the ureilites, Shallowater, and the mesosiderites. In each case, the fragments cooled rapidly (≈ 1–1000°C day−1) and then reassembled, (b) Later impacts involving cold bodies which, in some cases, reassembled; this occurred on the H and L ordinary chondrite parent bodies. The L parent body probably suffered another catastrophic event about 500 My ago. (c) Recent impacts of cold, multi-kilometer-sized bodies that generated meter-sized meteoroids; this occurred on the parent bodies of the IIIAB irons (650 My ago), the IVA irons (400 My ago), and the H ordinary chondrite (7 My ago). |
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