EASTERN EQUATORIAL PACIFIC PRODUCTIVITY VIA TWO GEOCHEMICAL PROXIES

Abstract

Drivers that influence oceanic productivity are not clearly constrained. However, sea level changes during glacial cycles have been proposed as a potential driver for productivity variations observed over warm and cold climate periods. In order to determine this, additional oceanic paleoproductivity data collection is necessary to estimate the ocean’s feedback in response to a dynamic climate. The eastern equatorial Pacific (EEP) is an ideal site for productivity studies due to its high levels of nutrients and deep upwelling. This research examines the phosphorous and barite geochemisty of four EEP sites while also comparing the sites’ glacial and interglacial productivity variations to the geochemistry and productivity results of an independent central equatorial pacific site. Phosphorus and other elemental data were collected from sites 845, 848, 849, and 853 (ODP Leg 138). Using a Ba/Ti and P/Ti proxy (“excess” proxies), distinct productivity variations during glacial and interglacial periods were observed. While the age model for these sites has been estimated, the observed variations more than likely agree with high productivity during glacial periods and lower productivity during interglacial periods. Central equatorial Pacific cores RR0603-03TC and RR0603-03JC (IODP site survey cruise for Proposal 626) have been used as a reference for geochemical concentration parameters, as well as a comparison tool for productivity variations among the central and eastern sites. The central equatorial geochemistry results provided support for sea level changes driving paleoproductivity variations. The similar variation patterns displayed by the EEP’s geochemical data in this research could provide additional support for this hypothesis.