| Summary: | 1999-12 Six samples of ferromanganese nodules taken from a knoll and a seamount off Wilkes Land, Antarctica, have been analyzed by ICP-AES and their geochemical characteristics have been compared with those of Pacific nodules. The Antarctic nodules have slightly concentric structures with rough surface texture similar to those of early diagenetic Pacific ferromanganese nodules. However, mineralogy, transition metal contents (Mn, Fe, Ni and Cu) and the rare earth element (REE) patterns, suggest that the Antarctic nodules are more similar to hydrogenous Pacific ferromanganese nodules. The Antarctic nodules have higher values of positive Ce anomalies and Co/(Ni+Cu) ratios, but have lower Mn, P, Ni, Cu and V contents than hydrogenous type Pacific nodules. In addition, the Mn content correlates with the Co content in the Antarctic nodules. These features suggest that the Antarctic nodules contain hardly any diagenetic component. This is possibly related to the fact that all Antarctic samples were collected above the CCD. In the Antarctic Ocean, biogenic productivity is generally high, but most of the organic material is decomposed before it reaches the sediment because of the high oxygen content of the water column in the Antarctic Ocean. The Antarctic samples represent more hydrogenous materials even when compared with the hydrogenous nodules from the Pacific Ocean. 国立情報学研究所で電子化したコンテンツを使用している。 departmental bulletin paper
|
|---|