title: Trachyandesitic volcanism in the early Solar System.
abstract: Volcanism is a substantial process during crustal growth on planetary bodies and well documented to have occurred in the early Solar System from the recognition of numerous basaltic meteorites. Considering the ureilite parent body (UPB), the compositions of magmas that formed a potential UPB crust and were complementary to the ultramafic ureilite mantle rocks are poorly constrained. Among the Almahata Sitta meteorites, a unique trachyandesite lava (with an oxygen isotope composition identical to that of common ureilites) documents the presence of volatile- and SiO2-rich magmas on the UPB. The magma was extracted at low degrees of disequilibrium partial melting of the UPB mantle. This trachyandesite extends the range of known ancient volcanic, crust-forming rocks and documents that volcanic rocks, similar in composition to trachyandesites on Earth, also formed on small planetary bodies ∼ 4.56 billion years ago. It also extends the volcanic activity on the UPB by ∼ 1 million years (Ma) and thus constrains the time of disruption of the body to later than 6.5 Ma after the formation of Ca-Al-rich inclusions.
authors.affiliation: Institut für Planetologie and bischoa@uni-muenster.de.
authors.forename: Addi
authors.initials: A
authors.lastname: Bischoff
authors.affiliation: Institut für Planetologie and.
authors.forename: Marian
authors.initials: M
authors.lastname: Horstmann
authors.affiliation: Institut Universitaire Européen de la Mer, Université de Bretagne Occidentale, 29280 Plouzané, France;
authors.forename: Jean-Alix
authors.initials: JA
authors.lastname: Barrat
authors.affiliation: Institut de Physique du Globe, 75235 Paris, France;
authors.forename: Marc
authors.initials: M
authors.lastname: Chaussidon
authors.affiliation: Geowissenschaftliches Zentrum, Universität Göttingen, 37077 Göttingen, Germany;
authors.forename: Andreas
authors.initials: A
authors.lastname: Pack
authors.affiliation: Geowissenschaftliches Zentrum, Universität Göttingen, 37077 Göttingen, Germany; Institut für Geologie und Mineralogie, Universität zu Köln, 50674 Köln, Germany; and.
authors.forename: Daniel
authors.initials: D
authors.lastname: Herwartz
authors.affiliation: Institut für Planetologie and.
authors.forename: Dustin
authors.initials: D
authors.lastname: Ward
authors.affiliation: Institut für Mineralogie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany;
authors.forename: Christian
authors.initials: C
authors.lastname: Vollmer
authors.affiliation: Meteorite Museum, 55430 Oberwesel, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Decker
keywords: achondrites; differentiated meteorites; differentiation; meteorite parent body