Heat Flow Variability in a Tectonically Active Basin: Insights from the Guaymas Basins, Gulf of California

Heat flow was measured at eight sites in the Guaymas Basin, Gulf of California, during the International Ocean Discovery Program Expedition 385, aimed at understanding the basin's thermal regime and heat transfer mechanisms. The basin, characterized by distinct sedimentation rates, active tectonics, and magmatism, exhibited sedimentation-corrected heat flow values ranging from 119 to 221 mW/m², with significantly higher values (257–1003 mW/m²) observed at Ringvent, a site of a young sill intrusion. Thermal analysis indicates that heat in the Guaymas Basin is primarily dissipated by conduction for plate ages greater than 0.2 Ma, while younger plate ages experience transient cooling through both conduction and advection. At Ringvent, an active sill is cooling slowly through fluid circulation, with discharge velocities of 10–200 mm/yr and potential recharge sites located approximately 1 km from the sill's border. The cooling of the basin is governed by multiple timescales, from the short intervals between intrusions (~10³ years) to the long-term cooling of the entire crust over geological timescales (~10⁶ years). These findings provide new insights into the thermal dynamics and crustal evolution of the Guaymas Basin.