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

Penny Wieser, Zoja Vukmanovic, Ruediger Kilian, Emilie Ringe, Marian B. Holness, John Maclennan, Marie Edmonds

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

Crystal 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.
Original languageEnglish
Pages (from-to)948–952
JournalGeology
Volume47
Issue number10
DOIs
Publication statusPublished - 20 Aug 2019

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