Global Persistence of Intraplate Heat‑Flow AnomaliesReveals Limits of Tectonic Distance Control

Abstract

Surface heat flow is usually interpreted in plate‑tectonic terms: high values are expected near active boundaries, whereas lower values are expected in more stable intraplate regions. What is still uncertain, however, is how much of the global variability observed within the intraplate domain can really be explained by tectonic proximity alone. To address that question, we carried out a global point‑by‑point analysis of the 2024 release of the IHFC Global Heat Flow Database, combined with two independent tectonic datasets: the GEM Global Active Faults Database and the PB2002 plate‑boundary model. Within a fully reproducible workflow, we defined a canonical intraplate domain as all observations located at least 110 km from the nearest mapped tectonic structure (dist_min_km ≥ 110 km; N = 53,420). Within this canonical dataset, heat flow decreases on average with tectonic distance, but the effect is weak. In log‑log space, the main regression yields a negative slope (𝛽 about –0.11) and low explanatory power (R² about 0.06‑0.10). At the same time, high heat‑flow values remain present across the full range of tectonic distances, including regions located more than 2,000 km from mapped tectonic structures. We then applied three independent geophysical screening tests based on shallow seismicity, lithospheric strain rate, and Bouguer gravity anomalies. After this screening, 603 intraplate thermal anomalies remain. Taken together, these results show that tectonic distance captures part of the broad background structure of the global thermal field, but it does not explain the full variability of intraplate heat flow. The persistence of a geographically dispersed residual component therefore provides a quantitative observational constraint that is not represented by first‑order tectonic models and should be considered in future geodynamic interpretations of Earth’s thermal field.