0000000000977711
AUTHOR
Florian Peine
Concept of Biogenic Ferromanganese Crust Formation: Coccoliths as Bio-seeds in Crusts from Central Atlantic Ocean (Senghor Seamount/Cape Verde)
At depths of 2,000 to 3,000 m, seamounts from the Cape Verde archipelago (Central Atlantic Ocean) are largely covered with ferromanganese crusts. Here we studied 60 to 150 mm thick crusts from the Senghor Seamount (depth: 2257.4 m). The crusts have a non lamellated texture and are covered with spherical nodules. The chemical composition shows a dominance of MnO2 (26.1%) and Fe2O3 (38.8%) with considerable amounts of Co (0.74%) and TiO2 (2.1%). Analysis by scanning electron probe microanalyzer (EPMA) revealed a well defined compositional zonation of micro-layers; the distribution pattern of Mn does not match that of Fe. Analysis by high resolution scanning electron microscopy (SEM) revealed…
Thorium-234 derived information on particle residence times and sediment deposition in shallow waters of the south-western Baltic Sea
Abstract Activities of the naturally occurring, short-lived and highly particle-reactive radionuclide tracer 234 Th in the dissolved and particulate phase were measured at three shallow-water stations (maximum water depths: 15.6, 22.7 and 30.1 m) in Mecklenburg Bay (south-western Baltic Sea) to constrain the time scales of the dynamics and the depositional fate of particulate matter. Activities of particle-associated (> 0.4 μm) and total (particulate + dissolved) 234 Th were in the range of 0.08–0.11 dpm L − 1 and 0.11–0.20 dpm L − 1 , respectively. The activity ratio of total 234 Th and its long-lived and conservative parent nuclide 238 U was well below unity (range: 0.09–0.19) indicating …