Topographic signature of magmatic emplacement at depth: The case of the Larderello-Travale Geothermal area (Northern Apennines, Italy)

Abstract

Magmatism is an important driver of topographic change. However, our understanding of its long-term impact on topographic evolution remains incomplete. We investigate the potential surface response to magmatic intrusions in the active Larderello-Travale geothermal field, in the northern Italian Apennines. Here, multiple igneous bodies have intruded since the Pliocene causing at least 500 m of large-wavelength surface uplift. We combine available stratigraphic information with a new set of morphological analyses and river inversion models to quantify, the magnitude, rate, and spatial distribution of uplift throughout the last 3.5 Ma. In describing the style of the uplift, we report a temporal and spatial correlation between rock uplift pulses and middle crust magma injections.

For the first time in this area, we document the positive feedback between different magma injections and local surface responses (e.g., river incision). We use a surface evolution model to suggest a potential scenario of magma emplacement over time. In this sense, we suggest that at the very beginning, uplift rates were higher to the north of the current thermal anomaly, and only after the uplift migrated further south. This could indicate that the deep source of the Larderello-Travale geothermal field might not be precisely located underneath the current thermal anomaly. This would allow undocumented plutons (deep enough such that they are not evidenced by shallow thermal anomalies) to be tracked, leading to more conscious and effective strategies for geothermal exploration.