『Abstract
　Biological productivity in the modern equatorial Pacific Ocean, a region with high nutrients and low chlorophyll, is currently limited by the micronutrient Fe. In order to test whether Fe was limiting in the past and to identify potential pathways of Fe delivery that could drive Fe fertilization (i.e., dust delivery from eolian inputs vs. Fe supplied by the Equatorial Undercurrent), we chemically isolated the terrigenous material from sediment along a cross-equatorial transect in the central equatorial Pacific at 140゜W and at Ocean Drilling Program Site 850 in the eastern equatorial Pacific. We quantified the contribution from each potential Fe-bearing terrigenous source using a suite of chemical- and isotopic discrimination strategies as well as multivariate statistical techniques. We find that the distribution of the terrigenous sources (i.e., Asian loess, south American ash, Papua New Guinea, and ocean island basalt) varies through time, latitude, and climate. Regardless of which method is used to determine accumulation rate, there also is no relationship between flux of any particular Fe source and climate. Moreover, there is no connection between a particular Fe source or pathway (eolian vs. Undercurrent) to total productivity during the Last Glacial Maximum, Pleistocene glacial episodes, and the Miocene “Biogenic Bloom”. This would suggest an alternative process, such as an interoceanic reorganization of nutrient inventories, may be responsible for past changes in total export in the open ocean, rather than simply Fe supply from dust and/or Equatorial Undercurrent processes. Additionally, perhaps a change in Fe source or flux is related to a change in a particular component of the total productivity (e.g., the production of organic matter, calcium carbonate, or biogenic opal).

Keywords: iron; equatorial Pacific; dust; productivity; Equatorial Undercurrent』

1. Introduction
2. Tracing dissolved Fe sources via the terrigenous component
3. Sampling, sequential extractions, and chemical/isotopic analyses
　3.1. Sampling
　3.2. Sequential extractions
　3.3. Chemical and isotopic analyses
4. Characterizing source regions: strategies and approaches
　4.1. Assessment of potential sources
　4.2. Quantifying source region contributions: multivariate statistics
5. Chemical characterization and quantification of terrigenous (Fe) sources
　5.1. Relative contributions of Fe sources as a function of latitude
　5.2. Rb/Ti vs. Nd/Sm
6. Changes in relative contributions of Fe sources during glacial periods
　6.1. Multiple linear regression modeling
　6.2. Mass balance of potential input from Papua new Guinea
7. Flux of specific terrigenous Fe sources
8. Relationship between source of terrigenous Fe and biological productivity
　8.1. Fe source and export production
　8.2. Silica “leakage”?
　8.3. Tectonism in Papua New Guinea and the “Biogenic Bloom”
9. Summary and conclusions
Acknowledgements
Appendix A. Supplementary data
References