Three-dimensional patterns of garnet nucleation and growth

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doi: 10.1130/0091-7613(1998)026<0503:TDPOGN>2.3.CO;2
Authors:Daniel, Christopher G.; Spear, Frank S.
Author Affiliations:Primary:
Rensselaer Polytechnic Institute, Department of Earth and Environmental Sciences, Troy, NY, United States
Volume Title:Geology (Boulder)
Source:Geology (Boulder), 26(6), p.503-506. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613
Publication Date:1998
Note:In English. 16 refs.; illus.
Summary:Three-dimensional compositional zoning patterns in garnet-zone garnets from Harpswell Neck, Maine, United States, suggest complex patterns of nucleation and growth. Compositional zoning is often asymmetric, and core compositions do not always coincide with the geometric center of the garnet. In detail, garnet zoning patterns show multiple, isolated, high-MnO areas that we interpret as sites of garnet nucleation. If it is assumed that garnet growth is close to equilibrium and the Mn zoning is not significantly modified by diffusion, then the MnO contours or isosurfaces can serve as a proxy for patterns of garnet nucleation and growth. Computer-generated, three-dimensional animations of these patchwork MnO zoning patterns reveal that many garnets contain multiple nuclei that grew and coalesced to form a single crystal. New nuclei often appeared next to preexisting porphyroblasts and became incorporated into the growing crystal. Contrary to the widely held idea that garnets grow radially outward from a single nucleus, we propose that many of the garnets examined in this study grew by the coalescence of multiple nuclei.
Sections:Mineral data
Subsections:Silicates
Subjects:Computer animation; Crystal growth; Crystal zoning; Garnet group; Nesosilicates; Nucleation; Orthosilicates; P-T conditions; Patterns; Silicates; Three-dimensional models; Cumberland County Maine; Maine; United States; Harpswell Neck Maine
Coordinates:N433400 N440900 W0695200 W0705300
Abstract Numbers:99M/717
Record ID:1998037027
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
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