The vesiculated layer in the anomalous diogenite Northwest Africa 12973
- Author(s)
- Lidia Pittarello, Ludovic Ferrière, Stepan M. Chernonozhkin, Frank Vanhaecke, Steven Goderis
- Abstract
Diogenites, which are part of the howardite–eucrite–diogenite (HED) group, are considered to represent rocks from the lower crust and mantle of a differentiated planetary body, likely the asteroid 4 Vesta. The Northwest Africa 12973 (NWA 12973) meteorite was classified as an anomalous diogenite due to the occurrence of a vesiculated layer. This work reports on the petrographic and geochemical study of two fragments of this meteorite, aiming to better constrain the origin of the vesiculated layer. Whereas the interior of NWA 12973 (here called host) presents the typical characteristics of an olivine diogenite, that is, coarse-grained pyroxene, olivine ribbons, chromite, and accessory phases, the vesiculated layer presents a fine-grained pyroxene groundmass with local rounded relics of olivine and interstitial chromite and metal, and is characterized by abundant large vesicles. The contact between the vesiculated layer and the host is sharply defined. The composition of individual minerals does not show any significant differences between the host and the vesiculated layer, suggesting in situ melting. Geothermobarometry indicates a slightly higher crystallization temperature at lower pressure for the vesiculated layer, consistent with melting and crystallization under lower crustal conditions upon exhumation. The trigger for the local melting was likely a large impact event, which was responsible for adiabatic decompression in the central area or deep faulting and frictional melting.
- Organisation(s)
- Department of Lithospheric Research
- External organisation(s)
- Naturhistorisches Museum Wien (NHM), Ghent University , Vrije Universiteit Brussel
- Journal
- Meteoritics and Planetary Science
- Volume
- 58
- Pages
- 1677-1690
- No. of pages
- 14
- ISSN
- 1086-9379
- DOI
- https://doi.org/10.1111/maps.14091
- Publication date
- 11-2023
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 105120 Petrology, 105105 Geochemistry
- ASJC Scopus subject areas
- Geophysics, Space and Planetary Science
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/0605c11f-b274-4056-9964-09ed6917c545