『Abstract
　Many (bio)geochemical processes that bring about changes in sediment chemistry normally begin at the sediment-water interface, continue at depth within the sediment column and may persist throughout the lifetime of sediments. Because of the differential reactivity of sedimentary phosphate phases in response to diagenesis, dissolution/precipitation and biological cycling, the oxygen isotope ratios of phosphate (δ¹⁸Op) can carry a distinct signature of these processes, as well as inform on the origin of specific P phases. Here, we present results of sequential sediment extraction (SEDEX) analyses combined with δ¹⁸Op measurements, aimed at characterizing authigenic and detrital phosphate phases in continental margin sediments from three sites (Sites 1227, 1228 and 1229) along the Peru Margin collected during ODP Leg 201. Our results show that the amount of P in different reservoirs varies significantly in the upper 50 m of the sediment column, but with a consistent pattern, for example, detrital P is highest in siliciclastic-rich layers. The δ¹⁸Op values of authigenic phosphate vary between 20.2‰ and 24.8‰ and can be classified into at least two major groups: authigenic phosphate precipitated at /near the sediment-water interface in equilibrium with paleo-water oxygen isotope ratios (δ¹⁸Ow) and temperature, and phosphate derived from hydrolysis of organic matter (Porg) with subsequent incomplete to complete re-equilibration and precipitated deeper in the sediments column. The δ¹⁸Op values of detrital phosphate, which vary from 7.7-15.4‰, suggest two possible terrigenous sources and their mixtures in different proportions: phosphate from igneous/metamorphic rocks and phosphate precipitated in source regions in equilibrium with δ¹⁸Ow of meteoric water. More importantly, original isotopic compositions of at least one phase of authigenic phosphates and all detrital phosphates are not altered by diagenesis and other biogeochemical changes within the sediment column. These findings help to understand the origin and provenance of P phases and paleoenvironmental conditions at/near the sediment-water interface, and to infer post-depositional activities within the sediment column.』

1. Introduction
2. Study area and methods
　2.1. Leg 201: description of Sites 1227, 1228 and 1229
　2.2. Sequential extraction of sedimentary P phases
　2.3. Determination of phosphate concentration
　2.4. Isotopic analysis of extracted phosphate
3. Results
　3.1. P speciation at Sites 1227, 1228 and 1229
　　3.1.1. Dissolved phosphate in porewater
　　3.1.2. Sedimentary P phases
　3.2. δ¹⁸O values of sedimentary phosphates
4. Discussion
　4.1. Porewater DIP profile: an indicator of authigenic phosphate precipitation
　4.2. Relationship of sedimentary P phases to sediment geochemistry
　4.3. Isotopic composition of authigenic phosphates: primary and post-depositional signatures
　　4.3.1. δ¹⁸Op values of authigenic phosphates in zones of intense microbial activity
　　4.3.2. Authigenic phosphates in equilibrium with paleo-porewater δ¹⁸Ow and paleo-temperature
　　4.3.3. Authigenic phosphates in equilibrium (and lighter) with modern porewater δ¹⁸Ow and temperature
　4.4. Origin and provenance of detrital phosphates
　　4.4.1. Sources of detrital phosphates in the Peru Margin sediments
　　4.4.2. δ¹⁸Op values of detrital phosphates do not change due to diagenetic and biological activities
5. Conclusions
Acknowledgments
References

※リンの連続抽出は、Ruttenberg（1992）により開発され、Anderson and Delaney（2000）により修正された、SEDEX法が用いられた。