CO-DIAGENESIS OF IRON AND PHOSPHORUS IN HYDROTHERMAL SEDIMENTS FROM THE SOUTHERN EAST PACIFIC RISE: IMPLICATIONS FOR THE EVALUATION OF PALEOSEAWATER PHOSPHATE CONCENTRATIONS
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dc.contributor.author | Poulton S.W. | |
dc.contributor.author | Canfield D.E. | |
dc.date.accessioned | 2024-08-09T04:00:34Z | |
dc.date.available | 2024-08-09T04:00:34Z | |
dc.date.issued | 2006 | |
dc.identifier | https://elibrary.ru/item.asp?id=12091587 | |
dc.identifier.citation | Geochimica et Cosmochimica Acta, 2006, 70, 23 SPEC. ISS., 5883-5898 | |
dc.identifier.issn | 0016-7037 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/44637 | |
dc.description.abstract | We present a detailed study of the co-diagenesis of Fe and P in hydrothermal plume fallout sediments from ?19?S on the southern East Pacific Rise. Three distal sediment cores from 340-1130 km from the ridge crest, collected during DSDP Leg 92, were analysed for solid phase Fe and P associations using sequential chemical extraction techniques. The sediments at all sites are enriched in hydrothermal Fe (oxyhydr)oxides, but during diagenesis a large proportion of the primary ferrihydrite precipitates are transformed to the more stable mineral form of goethite and to a lesser extent to clay minerals, resulting in the release to solution of scavenged P. However, a significant proportion of this P is retained within the sediment, by incorporation into secondary goethite, by precipitation as authigenic apatite, and by readsorption to Fe (oxyhydr)oxides. Molar P/Fe ratios for these sediments are significantly lower than those measured in plume particles from more northern localities along the southern East Pacific Rise, and show a distinct downcore decrease to a depth of ?12 m. Molar P/Fe ratios are then relatively constant to a depth of ?35 m. The Fe and P speciation data indicate that diagenetic modification of the sediments is largely complete by a depth of 2.5 m, and thus depth trends in molar P/Fe ratios can not solely be explained by losses of P from the sediment by diffusion to the overlying water column during early diagenesis. Instead, these sediments are likely recording changes in dissolved P concentrations off the SEPR, possibly as a result of redistribution of nutrients in response to changes in oceanic circulation over the last 10 million years. Furthermore, the relatively low molar P/Fe ratios observed throughout these sediments are not necessarily solely due to losses of scavenged P by diffusion to the overlying water column during diagenesis, but may also reflect post-depositional oxidation of pyrite originating from the volatile-rich vents of the southern East Pacific Rise. This study suggests that the molar P/Fe ratio of oxic Fe-rich sediments may serve as a proxy of relative changes in paleoseawater phosphate concentrations, particularly if Fe sulfide minerals are not an important component during transport and deposition. ? 2006 Elsevier Inc. All rights reserved. | |
dc.subject | APATITE | |
dc.subject | AUTHIGENIC MINERAL | |
dc.subject | CORE ANALYSIS | |
dc.subject | DIAGENESIS | |
dc.subject | DIFFUSION | |
dc.subject | GOETHITE | |
dc.subject | HYDROTHERMAL PLUME | |
dc.subject | IRON | |
dc.subject | PHOSPHORUS | |
dc.subject | SEDIMENT CHEMISTRY | |
dc.subject | EAST PACIFIC RISE | |
dc.subject | PACIFIC OCEAN | |
dc.title | CO-DIAGENESIS OF IRON AND PHOSPHORUS IN HYDROTHERMAL SEDIMENTS FROM THE SOUTHERN EAST PACIFIC RISE: IMPLICATIONS FOR THE EVALUATION OF PALEOSEAWATER PHOSPHATE CONCENTRATIONS | |
dc.type | Статья | |
dc.identifier.doi | 10.1016/j.gca.2006.01.030 |
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