A major geothermal anomaly in the Gulf of California

We have mapped a 3-km wide, high heat flow anomaly with a maximum value of 30 μcalorie cm ⁻² s⁻¹ within a zone of seafloor extension in the central Gulf of California. From seismic reflection data and thermal modelling we suggest that the anomaly is caused by a 1-km wide basaltic intrusion which is roughly 100 m deep and less than 18,000 yr old.