Long term records of erosional change from marine ferromanganese crusts

Ferromanganese crusts from the Atlantic, Indian and Pacific Oceans record the Nd and Pb isotope compositions of the water masses from which they form as hydrogenous precipitates. The10Be/9Be-calibrated time series for crusts are compared to estimates based on Co-contents, from which the equatorial Pacific crusts studied are inferred to have recorded ca. 60 Ma of Pacific deep water history. Time series of ɛNd show that the oceans have maintained a strong provinciality in Nd isotopic composition, determined by terrigenous inputs, over periods of up to 60 Ma. Superimposed on the distinct basin-specific signatures are variations in Nd and Pb isotope time series which have been particularly marked over the last 5 Ma. It is shown that changes in erosional inputs, particularly associated with Himalayan uplift and the northern hemisphere glaciation have influenced Indian and Atlantic Ocean deep water isotopic compositions respectively. There is no evidence so far for an imprint of the final closure of the Panama Isthmus on the Pb and Nd isotopic composition in either Atlantic or Pacific deep water masses

Observation of manganese deposits in the Mariana-Phillipine basin regions during SONNE cruise SO57

The MARIANA I- expedition had three main aims: 1) Performance of an ODP-site pre-survey of a serpentinite diapir in the Mariana fore-arc region; 2) Investigation of volcanism and hydrothermalism in the Mariana back-arc basin; 3. Investigation of the distribution of manganese nodules and crusts in the Philippine basin. During the transect across the Philippine basin, 7 different regions comprising a total of 37 stations were sampled. Investigations were carried out in areas over the Kyushu-Palau and Central ridges, as well as in one shallow-water and 4 deep (~ 5000 m) water regions scattered across the basin. The shallow-water station yielded manganese-nodule-covered, semilithified foraminiferal sand. Larger nodules (up to 10 cm in diameter) were found on the Kyushu- Palau ridge. They were associated with foraminiferal sand and carbonate ooze. In addition, hydrogenetic manganese crusts were also dredged at both the Kyushu-Palau and Central ridges