5-4 Alpine Permafrost Distribution and Dynamics in the High Dry Andes of Chile & Argentina: Insights from Filo del Sol

Session: Advances in Mountain Hydrology: Connecting Cryosphere, Surface, and Subsurface Processes

Presenting Author:

Authors:

Abstract:

In the High Dry Andes of Chile and Argentina, permafrost and ground ice has been increasingly recognized as a key component of the cryosphere, contributing to seasonal water availability, sediment transport, and landscape stability. However, its extent remains poorly mapped due to the arid climate, rugged terrain, and limited seasonal access window. Therefore, the Filo del Sol Project, a proposed mining excavation on the Argentina-Chile border, offers the unique opportunity for sustained long-term monitoring of high mountain permafrost. Our effort—spanning three austral summer field seasons (March 2022 to March 2025)—aims to generate a spatially explicit model of permafrost distribution and active layer behavior to support long-term assessments of hydrological resilience and climate vulnerability.

Traditional predictors such as elevation and latitude are insufficient in this setting, where permafrost is instead controlled by a complex interplay of precipitation/snow, solar radiation, debris cover, and microtopography. We integrate continuous surface temperature sensor data (20 cm depth), historical borehole thermistor records, and a new set of nested thermistor arrays installed in four-meter-deep pits. The rare availability of deep borehole thermistor data and a wide ground temperature sensor array offers substantial multidimensional analysis of the active layer's dynamics, areal extent, depth, and thickness. These data were complemented with satellite-derived Normalized Difference Snow Index (NDSI) maps, surface light-based snow detection records, and high-resolution solar radiation data from an on-site weather station. Collectively, these inputs were used to model mean annual ground surface temperature (MAGST), calibrate with empirical observations, and generate a probabilistic permafrost distribution map. Our lab is in the unique position to verify ice presence through direct excavation to further validate model results. This transition from exploratory mapping to calibrated modeling marks a major step toward understanding the sensitivity of permafrost to climate forcing and its potential role in sustaining mountain water budgets in the face of future climate change.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7699

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