Constraints on the formation environment of two chondrule‐like igneous particles from comet 81P/Wild 2 |
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| Authors: | Zack Gainsforth Anna L Butterworth Julien Stodolna Andrew J Westphal Gary R Huss Kazu Nagashima Ryan Ogliore Donald E Brownlee David Joswiak Tolek Tyliszczak Alexandre S Simionovici |
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| Institution: | 1. Space Sciences Laboratory, University of California at Berkeley, Berkeley, California, USA;2. Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, Honolulu, Hawai‘i, USA;3. Department of Astronomy, University of Washington, Seattle, Washington, USA;4. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, USA;5. Institut des Sciences de la Terre, Observatoire des Sciences de l'Univers de Grenoble, Grenoble, France |
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| Abstract: | Using chemical and petrologic evidence and modeling, we deduce that two chondrule‐like particles named Iris and Callie, from Stardust cometary track C2052,12,74, formed in an environment very similar to that seen for type II chondrules in meteorites. Iris was heated near liquidus, equilibrated, and cooled at ≤100 °C h‐1 and within ≈2 log units of the IW buffer with a high partial pressure of Na such as would be present with dust enrichments of ≈103. There was no detectable metamorphic, nebular, or aqueous alteration. In previous work, Ogliore et al. (2012) reported that Iris formed late, >3 Myr after CAIs, assuming 26Al was homogenously distributed, and was rich in heavy oxygen. Iris may be similar to assemblages found only in interplanetary dust particles and Stardust cometary samples called Kool particles. Callie is chemically and isotopically very similar, but not identical to Iris. |
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