The Piancaldoli meteorite: A forgotten primitive LL3.10 ordinary chondrite

1Yves Marrocchi,2Lydie Bonal,3Jérome Gattacceca,1Laurette Piani,2Pierre Beck,4Richard Greenwood,2Jolantha Eschrig,1Anne Basque,5Pasquale Mario Nuccio,6,7Franco Foresta Martin
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13552]
1CRPG, CNRS, Université de Lorraine, UMR 7358, Vandoeuvre‐lès‐Nancy, 54501 France
2Institut de Planétologie et d’Astrophysique de Grenoble, Grenoble, France
3Aix‐Marseille Univ, CNRS, IRD, Coll France, INRAE, CEREGE, Aix‐en‐Provence
4PSS, Open University, Walton Hall, Milton Keynes, MK7 6AA UK
5Università di Palermo, Palermo, Italy
6Instituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, 90146 Palermo, Italy
7Laboratorio Museo di Scienze della Terra, Ustica, Palermo, Italy
Published by Arrangement with John Wiley & Sons

The Piancaldoli ordinary chondrite fell in northern Italy on August 10, 1968. Preliminary studies led to its classification as an LL3.4 unequilibrated ordinary chondrite. However, recent developments in classification procedures have prompted us to re‐examine its mineralogical, petrographic, spectroscopic, chemical, and isotopic features in a multi‐technique study. Raman spectra and magnetic properties indicate that Piancaldoli experienced minimal thermal metamorphism, consistent with its high bulk hydrogen content and the Cr contents of ferroan olivines in its type II chondrules. In combination with findings of previous studies, our data thus confirm the variability of Cr contents in ferroan olivines in type II chondrules as a proxy of thermal metamorphism. Furthermore, our results reveal that Piancaldoli is less altered than previously reported and should be reclassified as an LL3.10 unequilibrated ordinary chondrite. Our results also imply that the bulk deuterium enrichment, as observed in Piancaldoli (LL3.10), Bishunpur (LL3.15), and Semarkona (LL3.00), is a specific signature of the most primitive unequilibrated ordinary chondrites. Based on our results, we propose that, to date, Piancaldoli is the second least‐altered unequilibrated ordinary chondrite fall after Semarkona. This work reiterates the importance of meteorite collections worldwide as fundamental resources for studying the formation conditions and evolution of our solar system.

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