Sr, Nd, and Pb isotopic compositions and Ar-Ar ages of Western Pacific Seamount Province

Abstract

Recently, some Paleogene Ar-Ar ages were recently reported at Minamitorishima Island, the Chuo Seamount on Ogasawara Plateau and Uyeda Ridge located in the Western Pacific Seamounts Province (WPSP) which is an area recognized as group of short-lived Cretaceous hotspot tracks. Although the Ogasawara Plateau and Minamitorishima Island were already formed in Early Cretaceous, it is impossible to recognize as a continuous eruption since Early Cretaceous because of their too long hiatus. In this study, we analyzed acid-leached Sr, Nd, Pb isotopic composition and calculated the eruptive region based on Ar-Ar ages of the Paleogene lava sample to discuss the origin of the magma. The samples from four seamounts of the Cretaceous hotspot seamount trails (N-Wake) were simultaneously analyzed as well. The Paleogene samples from Minamitorishima Island and Chuo Seamount are clearly discriminated from the Cretaceous hotspot seamounts in both isotopic composition and eruptive site .