Chapter 3.4 - The Pacific Equatorial Age Transect: Cenozoic Ocean and Climate History (Integrated Ocean Drilling Program Expeditions 320 & 321)

Abstract

Abstract Integrated Ocean Drilling Program Expeditions 320 & 321, “Pacific Equatorial Age Transect” (PEAT) (Sites U1331–U1338), recovered a continuous Cenozoic record of the equatorial Pacific by coring above the paleoposition of the Equator at successive crustal ages on the Pacific plate. These sediments record the evolution of the equatorial climate system throughout most of the Cenozoic. PEAT allowed the reconstruction of extreme changes of the calcium carbonate compensation depth across major geological boundaries during the last 53 million years. The expeditions obtained a biogenic sediment archive from the early Eocene greenhouse, the Eocene cooling, the Eocene–Oligocene transition, the “one cold pole” Oligocene, the Oligocene–Miocene transition, and the middle Miocene cooling and Pliocene, including two excellent Neogene sections. Together with previous ocean drilling and seismic stratigraphy in the equatorial Pacific, the results allow a synoptic view on the climatic evolution of the Pacific. In this chapter, we summarize the results published so far, and focus on the overall aim of obtaining a Cenozoic “megasplice,” which is a high-resolution record of Cenozoic climate and environmental conditions from a small set of closely related sites from the paleoequatorial Pacific.