The Ohno Volcanic Rocks in eastern Kyusyu occur at the western tip of the Setouchi Volcanic Rocks. Previously reported K-Ar ages of the Ohno Volcanic Rocks range from . to . Ma. Here we present the results of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) zircon U-Pb analyses of three felsic rocks from the Ohno Volcanic Rocks. We obtained mean U-Pb ages as follows: . . Ma ( σ) for the Shiraiwasan pyroclastic flow deposit at the lowermost horizon within the sequence, . .

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... Ma for the Koguraki Tuff, and . . Ma for the Miyakeyama pyroclastic flow deposit at the uppermost horizon within the sequence. Our results indicate that the Ohno Volcanic Rocks, except for the high-Mg andesite found only as dikes, were formed over a shorter period than previously considered (ca. m.y.).