Paleomagnetic Constraints on Mineralization Age of the Nansatsu-type Gold Deposits in Southern Kyushu, Japan |
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| Authors: | Tetsuichi TAKEDA Nobutaka SHIMADA Hirotomo UENO |
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| Institution: | Department of Earth and Planetary Sciences, Faculty of Science, Kyushu University, Fukuoka 812–8581, Japan;Department of Earth and Environmental Sciences, Faculty of Science, Kagoshima University, Kagoshima 890–0065, Japan |
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| Abstract: | Abstract: 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 age of each stage in each deposit was determined with paleomagnetic methods on 432 specimens from 312 oriented samples. As results, mineralization ages of stage I of each deposit 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-type gold deposits were formed contemporaneously. |
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| Keywords: | paleomagnetism magnetic polarity Nansatsu–type K–Ar age mineralization age |
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