We just published former Brazilian M.S. student, Lucas R. Schiavetti's thesis research in the Journal of Metamorphic Geology. For his project, Lucas combined field mapping, thermodynamic modeling, and garnet geochronology in Brazil's Araçuaí "hot orogen" to determine how and why it stayed hot for so long. He found that rocks reached peak conditions of ~800°C at 20-35 km depth around 535-530 million years ago, then gradually moved to shallower depths while staying hot. The results suggest the Araçuaí orogen formed by continuous, long-term radioactive heating within the thickened crust rather than by episodic deep heating events.

Schiavetti, L.R., Meira, V.T., Mulcahy, S., Vervoort, J.D., Baker, P.L., Luvizotto, G.L., and Trindade, R.I.F., 2025, Confronting episodic vs. continuous heat sources in long-lived hot orogens: Insights from petrochronological studies in the Nova Venecia complex, Araçuaí orogen (SE Brazil): Journal of Metamorphic Geology, doi:10.1111/jmg.70007.