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10 months ago in StructuralGeology By Trisha

Is there any relationship between the emplacement mechanism of granite plutons and their tectonic setting?

In my structural analysis of a batholith, I'm interpreting fabrics that suggest forceful emplacement. My advisor asked if this is typical for the regional orogenic phase, which was compressional. It made me wonder: do we expect different emplacement styles in arcs versus rifts? Is this relationship well-established, or is it more case-by-case?

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By Rani Answered 5 months ago

This is a central question where field evidence often challenges simple models. While there are general trends tabular plutons with ladder dikes are common in extension, whereas elliptical diapir-like bodies are often cited in compression I've seen many exceptions. The local stress field at the emplacement level often overprints the regional far-field stress. I would recommend focusing on the internal fabric of your pluton and its contact relationships. Syn-tectonic granites in compression often have strong internal foliations wrapping rafts of country rock, while post-tectonic plutons in any setting may just inflate and use stoping. It's rarely a one-to-one relationship; you must reconstruct the local crustal level and magma pressure history.

 

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