Radium Isotopes Contribution to Geothermal Exploration in Central Italy

Abstract

Naturally occurring uranium and thorium decay series have recently shown to be potential tools for the study of water dominated geothermal systems. Ra-224, Ra-226, and Rn-222 measurements together with environmental isotopes and chemical elements determinations have been performed thermal springs and geothermal fluids from deep wells of Italy. This region is characterized by a positive heat flow density anomaly, geothermal reservoir is generally made up by mesozoic limestones covered by low permeability rocks. The main lithotypes of the region have been characterized for the radioactivity. The obtained results, evaluated on the basis of a conceptual model provided new insights in the of interaction between geothermal fluids and host rock. The principal results provide information on mixing processes. on the source rocks and on the contact time between water and host rocks.