We examined 16 white opaque inclusions exposed on two polished slices of a Muong Nong-type Australasian tektite from Muong Phin, Laos. The inclusions usually consist of a core, surrounded by a froth layer, and a quartz neoblast layer. The cores are composed primarily of a mixture of silica glass, coesite, and quartz in varying proportions. A thin (up to ~4 μm) layer of SiO2-poor glass enriched in FeO, MgO, CaO, Al2O3, and TiO2 is observed as a bright halo in backscattered electron images around the quartz neoblasts and in places contains μm-sized crystals, which may be Fe,Mg-rich spinel. The distribution and textural relationships between the coesite-bearing inclusions and the tektite matrix point to an in situ formation of the coesite due to an impact, rather than to infall, from a nearby impact, into tektite melt produced by the aerial burst of a bolide. The quartz neoblasts probably formed by crystallization of silica melt squeezed out of the inclusion core during the development of the froth layer. The bright halo may be the result of silica diffusing from the adjacent tektite melt into the growing quartz neoblasts. We propose that the survival of coesite was possible due to the froth layer that acted as a heat sink during bubble expansion and then as a thermal insulator.

Glass, B., Folco, L., Masotta, M., Campanale, F. (2020). Coesite in a Muong Nong-type tektite from Muong Phin, Laos: Description, formation, and survival. METEORITICS & PLANETARY SCIENCE, 55(2), 253-273 [10.1111/maps.13433].

Coesite in a Muong Nong-type tektite from Muong Phin, Laos: Description, formation, and survival

Campanale F.
2020

Abstract

We examined 16 white opaque inclusions exposed on two polished slices of a Muong Nong-type Australasian tektite from Muong Phin, Laos. The inclusions usually consist of a core, surrounded by a froth layer, and a quartz neoblast layer. The cores are composed primarily of a mixture of silica glass, coesite, and quartz in varying proportions. A thin (up to ~4 μm) layer of SiO2-poor glass enriched in FeO, MgO, CaO, Al2O3, and TiO2 is observed as a bright halo in backscattered electron images around the quartz neoblasts and in places contains μm-sized crystals, which may be Fe,Mg-rich spinel. The distribution and textural relationships between the coesite-bearing inclusions and the tektite matrix point to an in situ formation of the coesite due to an impact, rather than to infall, from a nearby impact, into tektite melt produced by the aerial burst of a bolide. The quartz neoblasts probably formed by crystallization of silica melt squeezed out of the inclusion core during the development of the froth layer. The bright halo may be the result of silica diffusing from the adjacent tektite melt into the growing quartz neoblasts. We propose that the survival of coesite was possible due to the froth layer that acted as a heat sink during bubble expansion and then as a thermal insulator.
Articolo in rivista - Articolo scientifico
Muong Nong-type Australasian tektite, coesite-bearing inclusions, coesite formation
English
2020
55
2
253
273
reserved
Glass, B., Folco, L., Masotta, M., Campanale, F. (2020). Coesite in a Muong Nong-type tektite from Muong Phin, Laos: Description, formation, and survival. METEORITICS & PLANETARY SCIENCE, 55(2), 253-273 [10.1111/maps.13433].
File in questo prodotto:
File Dimensione Formato  
Glass-2020-Meteorit Planet Sci-VoR.pdf

Solo gestori archivio

Descrizione: Original Article
Tipologia di allegato: Publisher’s Version (Version of Record, VoR)
Licenza: Tutti i diritti riservati
Dimensione 2.94 MB
Formato Adobe PDF
2.94 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/415865
Citazioni
  • Scopus 8
  • ???jsp.display-item.citation.isi??? 8
Social impact