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Size evolution of micropyrite from diagenesis to low-grade metamorphism

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Cárdenes, Víctor and Merinero Palomares, Raúl and López-Mungira, Aurora and Rubio Ordoñez, Álvaro and Pitcairn, Iain K. and Cnudde, Veerle (2019) Size evolution of micropyrite from diagenesis to low-grade metamorphism. In Metamorphic Geology: Microscale to Mountain Belts. Special Publications (478). Geological Society, London, pp. 137-144. ISBN 978-1-78620-400-4

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Official URL: https://sp.lyellcollection.org/content/early/2018/03/28/SP478.2



Abstract

Size distribution and evolution of framboidal and euhedral microscopic crystals of pyrite (micropyrites, MPy) have been used for the last thirty years to deduce palaeo-redox conditions. The analysis of the MPy distributions can give valuable information about these palaeo-redox conditions. However, other information can also be retrieved from this type of analysis. In this work, we propose that the formation of new populations of MPy is a proxy of the transition from the anchizone to the epizone. High-resolution X-ray tomography (micro-CT) was used to determine the size distributions of MPy hosted in pelitic rocks subjected to different grades of low temperature metamorphism. These data were filtered and statistically analysed, which allowed us to find a statistical representative size distribution of the MPy present in the samples. The metamorphic grade was determined using the Kübler Index in combination with petrological and scanning electron microscopy (SEM) examination. The results show a relationship between metamorphic grade and MPy size distributions, and that new populations of MPy formed due to the effects of metamorphism. This new methodology for MPy size distribution has different potential applications in some fields of Earth sciences, such as palaeoenvironment reconstruction, ore mining or metamorphic petrology.


Item Type:Book Section
Subjects:Sciences > Geology > Petrology
ID Code:55837
Deposited On:17 Jun 2019 18:13
Last Modified:18 Jun 2019 09:29

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