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To sink, swim, twin, or nucleate: A critical appraisal of crystal aggregation processes

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Wieser, PE 
Kilian, R 
Holness, MB 

Abstract

jats:titleAbstract</jats:title> jats:pCrystal aggregates in igneous rocks have been variously ascribed to growth processes (e.g., twinning, heterogeneous nucleation, epitaxial growth, dendritic growth), or dynamical processes (e.g., synneusis, accumulation during settling). We tested these hypotheses by quantifying the relative orientation of adjacent crystals using electron backscatter diffraction. Both olivine aggregates from Kīlauea volcano (Hawaiʻi, USA) and chromite aggregates from the Bushveld Complex (South Africa) show diverse attachment geometries inconsistent with growth processes. Near-random attachments in chromite aggregates are consistent with accumulation by settling of individual crystals. Attachment geometries and prominent geochemical differences across grain boundaries in olivine aggregates are indicative of synneusis.</jats:p>

Description

Keywords

37 Earth Sciences, 3705 Geology

Journal Title

Geology

Conference Name

Journal ISSN

0091-7613
1943-2682

Volume Title

47

Publisher

Geological Society of America

Rights

All rights reserved