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

Wieser, Penny E. and Vukmanovic, Zoja and Kilian, Rüdiger and Ringe, Emilie and Holness, Marian B. and Maclennan, John and Edmonds, Marie (2019) To sink, swim, twin, or nucleate: A critical appraisal of crystal aggregation processes. Geology, 47 (10). pp. 948-952. ISSN 0091-7613 DOI https://doi.org/10.1130/G46660.1

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Official URL: https://doi.org/10.1130/G46660.1

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.

Item Type: Article
Uncontrolled Keywords: 2019AREP; IA76
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
07 - Gold Open Access
12 - PhD
Journal or Publication Title: Geology
Volume: 47
Page Range: pp. 948-952
Identification Number: https://doi.org/10.1130/G46660.1
Depositing User: Sarah Humbert
Date Deposited: 06 Mar 2020 11:19
Last Modified: 06 Mar 2020 11:19
URI: http://eprints.esc.cam.ac.uk/id/eprint/4644

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