177 Chronology of Orogenesis: Unlocking the Timelines of Mountain Building

The focus of this session is the use of geochronological methods (including but not limited to U-Pb, Ar/Ar, FT, (U/Th)-He) to establish the timing of key events in mountain building, including different orogenic phases, exhumation, and uplift rates.

Tuesday, 21 October 2025
8:00 AM - 12:00 PM
HBGCC, 304C

Reassessing Long-Term Exhumation Rates in Magmatic Terranes

Paper number: 177-8
Program: Technical Sessions
Time: 9:34 AM – 9:49 AM

Authors

Abstract

Crustal exhumation is central to mountain building, weathering, and sediment production processes, which significantly influence the composition and behavior of Earth’s oceans and atmosphere. It also controls the formation, enrichment, and preservation of porphyry copper deposits, which are vital for the global green energy transition. Exhumation rates are typically determined from rock cooling histories combined with a geothermal model. However, in magmatically-active regions, models can overpredict exhumation rates because the elevated heat signature is mistakenly attributed to advection driven by rapid exhumation. We present a method to accurately constrain exhumation histories in magmatic terranes that combines thermokinematic modeling of thermochronometric cooling histories with independent geobarometric constraints on the total exhumed crustal thickness. Focusing on the Central Andes, we find that accounting for magmatic heat results in exhumed crustal thicknesses within error of the independent constraints, whereas ignoring it results in exhumed thicknesses up to three times greater than geologically plausible.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-414145

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