Worldwide Compilation of Young Igneous Rocks Ages Associated with High-Enthalpy Operating Geothermal Fields

Abstract

A database of the youngest dated igneous rocks found within the immediate area of 48 high-temperature geothermal fields has been compiled. Correlations are identified between the age of these igneous rocks, the volcanic environment and the power density (MW/km2) that has been achieved with power development on the fields. All the developed fields in this data set have associated igneous rocks that are younger than 2.9 Ma, and 77% of them are Pleistocene (0.0117 Ma -2.58 Ma). Moreover, 83% are younger than 0.5 Ma and their average age is 0.36 Ma. This strong correlation of young igneous activity at the surface being associated with high temperature fields is interpreted as highlighting the importance of magmatic activity as a heat source for these systems. Only fields associated with igneous activity younger than 0.5 Ma have a power density ≥ 20 MW/km2. The volcanic environment also seems to have an influence on the power density of the geothermal field, with the back-arc setting having the highest power density and youngest heat sources. These correlations may be useful to consider when evaluating the prospectivity of undrilled prospects where the age of volcanism has been assessed.