Theoretical growth of framboidal and sunflower pyrite using the R-package frambgrowth
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Framboids and sunflowers are the most ubiquitous shapes of sedimentary pyrite. Framboids are spherical aggregates of nanocrystals, while sunflowers are formed by overgrowth of framboids and represent intermediate stages in the transformation of framboids into euhedrae. The characterization of the size populations of these shapes provides critical information about the paleoredox conditions at time of formation and the subsequent changes in these conditions. This paper describes in detail an algorithm designed to model the growth and generate significant populations of both framboids and sunflowers, using functions of the statistical software R. The source code is provided as supplementary material to this paper. The algorithm uses several growth mechanisms based on dependence on or independence of the number of nanocrystals for framboids and the external diameter for sunflowers. Variability in the generated size populations depends on several parameters of the algorithm, such as the diameter of the nanocrystals, the initial diameter of the framboids and the maximum value of the random numbers. The resulting populations of framboids and sunflowers can be compared with data obtained from analysis of real samples in order to understand and model the genetic paleo-processes.
KeywordsPyrite framboids Pyrite sunflower R-package Redox conditions Computer simulation
This study is part of the work of the Research Group number 910197 of the Community of Madrid and the Complutense University of Madrid “Procesos Metalogenéticos en Sistemas Magmáticos e Hidrotermales.” Victor Cárdenes is grateful to his Marie Curie IEF grant 623082 TOMOSLATE, from the European Union’s Seventh Framework Programme for Research and Technological Development.
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