In the Leg 87A holes, 45 ash layers were sampled in Recent to upper Pliocene strata. The main volcanogenic deposits came from single eruptions or subcontemporaneous eruptions of cognate volcanoes. Some of them are mixed ashes produced from multiple eruptions and accumulated in reworked sediments. The petrographic and geochemical patterns indicate rhyolitic and dacitic compositions; andesitic glasses are scarce. We infer a magmatic affinity with calc-alkaline sources and a possible origin from the volcanic arc of southwestern Japan. A few samples may originate from the alkaline volcanism of southwestern Japan or the area south of Korea and the Sea of Japan.

Supplement to: Pouclet, André; Fujioka, Kantaro; Charvet, Jacques; Cadet, Jean-Paul (1986): Petrography and geochemistry of volcanic ash layers from Leg 87A, Nankai Trough (South Japan). In: Kagami, H; Karig, DE; Coulbourn, WT; et al. (eds.), Initial Reports of the Deep Sea Drilling Project, Washington (U.S. Govt. Printing Office), 87, 695-701