Figure 1
From: Arima hot spring waters as a deep-seated brine from subducting slab
Locality and tectonic setting of the Arima hot springs (small red circle), modified from Hirose et al. (2008). The pink area involving Arima shows the arbitrary boundary of the ‘Kinki Spot,’ where anomalously high 3He/4He ratios have been observed (Sano and Wakita 1985; Sano et al. 2009). Contour lines indicate the upper surface of the subducted Philippine Sea Plate, and the triangles denote Quaternary volcanoes.