Evidence of El Niņo Events Recorded in Middle Pliocene Corals of the Tartaro Formation, Bulacan


Tsuyoshi Watanabe (Hokkaido Univ., JPN), Atsushi Suzuki (AIST, JPN), Tomoki Kase (National Science Museum, JPN), Shoshiro Minobe (Hokkaido Univ., JPN), Yolanda Maac Aguilar (Bureau of Mine and Geosciences, Philippines), Koji Kameo (Chiba Univ. JPN), Kayo Minoshima (AIST, JPN), Ryoji Wani (National Science Museum, JPN)
and Hodaka Kawahata (Univ. of Tokyo, JPN)




During the Pliocene warm period (PWP; 5-3 Ma), the global surface temperature was higher by about 3°C than the present. In this epoch, the oceanic condition can be studied in the context of global warmth relative to today. However, the role of El Niņo-Southern Oscillation (ENSO) in this greenhouse warming remains controversial because of the lack of the information about seasonal to inter-annual variability of sea surface water in the low latitude regions. Here, we present a 35-years coral oxygen isotopic record with monthly resolution deduced from well-preserved fossil corals in muddy sand layers of the Middle Pliocene (3.5-3.8 Ma) Tartaro Formation in northern Luzon, Philippines. Several significant attenuations of seasonal amplitude were found in 18O/16O ratios of PWP coral record, which were also detected in the recent corals during modern El Nino events. Our data suggests that east-western movements of Western Pacific Warm Pool (WPWP) are still active and caused ENSO events during this warm period.



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