By Benjamin James Andrews

Smithsonian Institution, National Museum of Natural History


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SNGPlag. Supersaturation Nucleation and Growth of Plagioclase: a forward model of plagioclase nucleation and growth in decompressing magma. This tool models how plagioclase crystallization in a decompressing magma (of user specified composition) during a specified decompression path. User specifies magma composition via an excel input file. SNGPlag uses MELTS webservices to determine the plagioclase fraction as a function of pressure and temperature. The user then specifies initial and final pressures, temperature, decompression path (continuous, single-step, multi-step, accelerating, or decelerating), decompression rate, initial phenocryst or antecryst content, initial crystal size distributions, and crystal geometry. Up to 10 sets of conditions can be run at a time to facilitate comparison. SNGPlag returns the time dependent sample crystallinity, crystal size distribution, number density, and characteristic crystal sizes. For single runs, SNGPlag also renders a 3D volume illustrating the crystallized population of microlites, antecrysts, and phenocrysts; this volume can be viewed as a perspective volume or as a thin section. SNGPlag outputs are saved to a .XLS workbook and a series of .TIF and .FIG (Matlab) figures.

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Researchers should cite this work as follows:

  • Benjamin James Andrews (2019), "SNGPlag,"

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