Pliocene–Pleistocene planktonic foraminifera from the East Pacific Ocean off Costa Rica and their paleoceanographic implications

Planktonic foraminifera from the Ocean Drilling Program Holes 1039B, 1040C and 1043A off Costa Rica in the East Pacific Ocean indicate that the surface seawater temperature abruptly declined four times during the late Pliocene-early Pleistocene. These events occurred in the lower part of Zone N19 (5–4.2 Ma), the basal part of Zone N22 (ca. 2 Ma), the middle part of Zone N22 (ca. 1.5 Ma) and the basal part of Zone N23 (ca. 0.65 Ma). The maximum divergence of surface- and intermediate-water dwellers begins at the basal part of Zone N22 (ca. 2 Ma), which signals cooling episodes and faunal changes, suggesting responses to the closing of the Central American Seaway.