赤道太平洋域の中央~西部に設置されたセディメントトラップ試料を用いて,浮遊性有孔虫の水温躍層種Pulleniatina obliquiloculataの石灰化水深を推定し,同種のマグネシウム/カルシウム古水温計が水温躍層付近の指標として有効であることを確認した.また,オントンジャワ海台で得られた海底堆積物コアについて,2種の有孔虫マグネシウム/カルシウム古水温計を用いて過去100万年間の表層水温・躍層水温を復元し,氷期-間氷期スケールにおける水温変動とさらに長期的な数十万年スケールの水温変動が存在することを明らかにした.
Calcification depth of planktonic foraminifera, Pulleniatina obliquiloculata, is estimated using sediment trap samples moored in the central and western equatorial Pacific. It is confirmed that Mg/Ca thermometry of this species is useful for reconstructing thermocline temperature in this regions. Past sea surface and thermocline temperatures were reconstructed by Mg/Ca thermometry of two planktonic foraminiferal species using a sediment core retrieved from the Ontong Java Plateau. Reconstructed temperatures showed glacial-interglacial change as well as variability in much longer timescale. The results suggest that the ocean-atmosphere interaction played significant role in long-term temperature regulation in the western tropical Pacific region.