R7: Petrology, Mineralogy and Economic geology (Joint Session with Society of Resource Geology)

[R7-07] Geology and Epithermal gold-silver mineralization of Bousawa deposit in Akita, Japan

*Kazuki Hirata¹, Yasushi Watanabe¹, Takuya Echigo¹, Shougo Aoki¹ (1. Akita Univ. )

Keywords:Vermiculite, DTA, Early Miocene, Epithermal Au-Ag deposit, XRD

The alteration zones are divided into three zones: kaolinite zone, sericite K-feldspar zone, and chlorite zone, especially the kaolinite zone overprints. Vermiculite was observed in the study area based on XRD and DTA. The lithology and vermiculite indicates that the formation occurred onshore on the continent, and altered minerals indicates that the deposit was formed by alkali-neutral fluids at ≧ 200℃. The quartz veins suggests that the Au-Ag mineralization was caused by boiling, which is consistent with the distribution of kaolinite of steam heated alteration origin.