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Late middle Miocene through recent linear sedimentation rates were calculated for IODP Site U1338 in the eastern equatorial Pacific using available geomagnetic chron boundary data together with calcareous nannofossil and diatom biochronologic data. Rather than attempting to use every age-depth indicator for estimates of sedimentation rates, we selected 11 key control points to describe a low-resolution sedimentation history, thus permitting for scatter around the proposed interpolated rate lines.

The sedimentation rate history at Site U1338 mirrors the movement of the site from ~2°45′S of the Pacific Equator to its present location at 2°30′Ν of the Equator, crossing a high-productivity zone during the late middle Miocene through earliest Pliocene times and resulting in sedimentation rates on the order of 30–34 m/My. Sedimentation rates started at a modest rate (11 m/My) when the Site U1338 basalt crust was formed, ramped up in three steps to a tripling at ~13.2 Ma to 34 m/My, and decreased by 50% during the so-called carbonate crash between 10.0 and 9.1 Ma. The crash was followed by an increase to 30 m/My that lasted for ~4 My into the earliest Pliocene (5.0 Ma). Thereafter, sedimentation rates decreased successively in five steps to its present rate of 11 m/My.