Timing of mineralization in the Ikuno polymetallic vein-type deposit, southwest Japan: Constraints from zircon U–Pb ages of Late Cretaceous igneous rocks

Abstract

In this study, geological relationships and zircon U–Pb dating are used to constrain the timing of Cretaceous mineralization in the Ikuno mining area, southwest Japan. The Ikuno deposit is characterized by crosscutting relationships between ore veins and various dikes. These field relationships suggest that zircon U–Pb dating of the pre- and post-ore rocks can provide robust constraints on the age of the ore veins. Zircon U–Pb dating of pre- and post-ore dikes in the Ikuno deposit yielded concordant U–Pb ages of 75.9 and 74.5 Ma, respectively. Based on the ages obtained in this study, mineralization occurred at ca. 75 Ma and lasted only a short period of time.