Accretionary prism stratigraphy deduced from zircon U-Pb ages of tuffaceous horizons - a case study from the Shimanto supergroup exposed in Yakushima -

Abstract

Zircon U-Pb ages were determined for tuffaceous layers in the Shimanto Supergroup in Yakushima. The tuffaceous layer in east yielded U-Pb age of around 30 Ma, and the one in west yielded around 55 Ma. Our new U-Pb dating results imply that the sedimentary formation packages generally young toward east, in contrast to the previously suggested northwestward younging direction of the whole strata.