177-6 Reassessing Long-Term Exhumation Rates in Magmatic Terranes

Session: Chronology of Orogenesis: Unlocking the Timelines of Mountain Building

Presenting Author:

Frances Cooper

Authors:

Cooper, Frances J¹, Adams, Byron A², Dahlström, Simon IR³, Ehlers, Todd A⁴, van Soest, Matthijs C⁵, Hodges, Kip V⁶, Jicha, Brian R⁷, Singer, Brad S⁸, Cortes Yañez, Jaime⁹, Perkins, Rebecca J¹⁰

(1) Department of Earth Sciences, University College London, London, United Kingdom, (2) Department of Earth Sciences, University College London, London, United Kingdom, (3) School of Earth Sciences, University of Bristol, Bristol, United Kingdom, (4) School of Geographical and Earth Sciences, University of Glasgow, Glasgow, United Kingdom, (5) School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA, (6) School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA, (7) Department of Geoscience, University of Wisconsin-Madison, Madison, Wisconsin, USA, (8) Department of Geoscience, University of Wisconsin-Madison, Madison, Wisconsin, USA, (9) BHP, Tucson, Arizona, USA, (10) BHP, London, United Kingdom,

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 Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10030

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