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How can I describe geological features of a plutonic rock (pegmatite) using XRF and microprobe data in diagrams?

My pegmatite zone contains lithian muscovite, various phosphates, topaz, and cassiterite. I have bulk-rock XRF and detailed mineral chemistry from the microprobe. I want to create figures that show zoning, paragenetic sequences, and possible melt-fluid evolution. Beyond simple binary plots, what are the most informative diagram types for such a mineralogically diverse system?

 

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By Shahruddin Jafri Answered 1 year ago

For pegmatites, I move beyond Harker diagrams. First, I would recommend a series of back-scattered electron (BSE) mosaic images from your microprobe sessions, annotated with key mineral phases this tells the spatial story. For chemistry, plot your mineral data on compositional ternary diagrams specific to each mineral group (e.g., Li-Fe-Mn for phosphates; Al-Fe-Mg for micas). To show evolution, plot trace elements (like Cs, Rb, Ta) in your micas or feldspars against their distance from the pegmatite margin. This often reveals clear zoning and fluid evolution trends that major elements alone can miss.

 

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