Paleomagnetic constraints on mineralization age of the Nansatsu-type gold deposits in southern Kyushu, Japan

Two mineralization stages, stage I and stage II, have been identified from textural, mineralogical and crosscutting relationships in gold ore from the Nansatsu-type gold deposits of Kasuga, Iwato and Akeshi. Mineralization ag e of each stage in each deposit was determined with paleomagnetic methods o n 432 specimens from 312 oriented samples. As results, mineralization ages of stage I in these deposits fall in the same period, the reversed polarity subchron of 4.18-3.58 Ma, and those of stage II are limited in the normal and reversed polarity subchrons of 3.58-3.22 Ma. Contrasting with previous results based only on K-Ar ages, our conclusion shows that these Nansatsu-t ype gold deposits were formed contemporaneously.