Reclassification of Villalbeto de la Peña—Occurrence of a winonaite‐related fragment in a hydrothermally metamorphosed polymict L‐chondritic breccia

Abstract

Abstract-The Villalbeto de la Peña meteorite that fell in 2004 in Spain was originally classified as a moderately shocked L6 ordinary chondrite. The recognition of fragments within the Villalbeto de la Peña meteorite clearly bears consequences for the previous classification of the rock. The oxygen isotope data clearly show that an exotic eye-catching, black, and plagioclase-(maskelynite)-rich clast is not of L chondrite heritage. Villalbeto de la Peña is, consequently, reclassified as a polymict chondritic breccia. The oxygen isotope data of the clast are more closely related to data for the winonaite Tierra Blanca and the anomalous silicate-bearing iron meteorite LEW 86211 than to the ordinary chondrite groups. The REE-pattern of the bulk inclusion indicates genetic similarities to those of differentiated rocks and their minerals (e.g., lunar anorthosites, eucritic, and winonaitic plagioclases) and points to an igneous origin. The An-content of the plagioclase within the inclusion is increasing from the fragment/host meteorite boundary (approximately An 10 ) toward the interior of the clast (approximately An 52 ). This is accompanied by a successive compositionally controlled transformation of plagioclase into maskelynite by shock. As found for plagioclase, compositions of individual spinels enclosed in plagioclase (maskelynite) also vary from the border toward the interior of the inclusion. In addition, huge variations in oxygen isotope composition were found correlating with distance into the object. The chemical and isotopical profiles observed in the fragment indicate postaccretionary metamorphism under the presence of a volatile phase.

The Stubenberg meteorite—An LL6 chondrite fragmental breccia recovered soon after precise prediction of the strewn field

“…Since no fragments of other petrologic type have been observed so far a classification as a LL6 breccia is appropriate. However, Stubenberg does not belong to the complicated breccias like Almahata Sitta (e.g., Bischoff et al 2010;Horstmann et al 2010;Goodrich et al 2014;Horstmann and Bischoff 2014) or to the complex regolith breccias among the L-and LL-group ordinary chondrites (Bischoff et al 1993(Bischoff et al , 2006(Bischoff et al , 2013aMetzler et al 2010Metzler et al , 2011 and is also different to the LL5-6 breccia Chelyabinsk (Bischoff et al 2013b;Righter et al 2015;Morlok et al 2017). This is consistent with the lack of solar wind implanted noble gases (Fig.…”

“…; Horstmann and Bischoff ) or to the complex regolith breccias among the L‐ and LL‐group ordinary chondrites (Bischoff et al. , , ; Metzler et al. , ) and is also different to the LL5‐6 breccia Chelyabinsk (Bischoff et al.…”

The Creston, California, meteorite fall and the origin of L chondrites

“…(), also plotting the Winonaite clast of Villalbeto de la Peña (Bischoff et al. ). (Color figure can be viewed at wileyonlinelibrary.com.…”

“…This meteorite is otherwise exceptional also because it has a Winonaite‐related fragment in a hydrothermally metamorphosed polymict L‐chondritic breccia (Bischoff and Schultz ; Bischoff et al. ), suggesting Villalbeto de la Peña came from a different source altogether (Fig. ).…”

“…Creston's CRE age and oxygen isotope compositions are similar to those of Villalbeto de la Peña (Llorca et al 2005), but Villalbeto de la Peña has a significantly different olivine Fa and pyroxene Fs mineral composition. This meteorite is otherwise exceptional also because it has a Winonaiterelated fragment in a hydrothermally metamorphosed polymict L-chondritic breccia (Bischoff and Schultz 2004;Bischoff et al 2013), suggesting Villalbeto de la Peña came from a different source altogether (Fig. 11).…”