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doi:10.2204/iodp.proc.320321.206.2013

Introduction

Biogenic silica (opal) produced by diatoms, silicoflagellates, radiolarians, and sponges is a major constituent of marine sediments and an important parameter for geochemical and paleoceanographic studies. Because of the observed links between diatom production and export productivity (Romero and Armand, 2010), biogenic silica is an indicator of the efficiency of the biological pump and export production (Dugdale et al., 1995).

High-resolution records of sedimentary proxies provide insights into fine-scale geochemical and biological responses to climate forcing. In conjunction with shipboard (geophysical/geochemical) measurements, shore-based biogenic silica records allow the high-resolution evaluation of paleoproductivity variations in surface waters and dissolution effects on long timescales. This provides researchers additional data sets that help to evaluate the effect of global climatic, tectonic, and geochemical events that were typical of the Neogene (Cortese et al., 2004) on the regional biological paleoproductivity.

One of the important accomplishments of Integrated Ocean Drilling Program (IODP) Expedition 321 was to recover continuous Neogene sedimentary sections. These represent the only complete Neogene sections in the equatorial Pacific that have high enough sedimentation rates to resolve orbitally forced paleoproductivity cycles (Pälike et al., 2010). To assess changes in (siliceous) paleoproductivity through time, the content of biogenic silica was determined in sediment from Site U1337. Our primary target for this and future work at this site is understanding the long-term relationship between the sedimentary signature of biogenic silica and climate and between tectonic and biogeochemical signatures during the Neogene in the eastern equatorial Pacific.

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