1 0 0 0 OA 房総半島南部嶺岡帯における蛇紋岩と玄武岩の産状
In the Mineoka district serpentinite is intruded into the Paleogene Mineoka Group and probable Miocene sediments in three narrow zones extending in the E-W direction. Pillowed basalt is exposed in association with the serpentinite. In the Mineoka hills pillowed basalt occupies the ridges of the hills and is underlain by serpentinite. A part of the pillowed basalt appears to grade downwards to dolerite dike complex. A small amount of picrite basalt showing a remarkable pillow structure is also exposed in the area. It is likely that the serpentinite was intruded into the Paleogene and Neogene sediments along some weak zones and exposed on the sea-floor in a time of Neogene age. Then basaltic magma ascended along the weak zones and extruded on the sea-floor to form pillowed basalt.