Fossil manganese deposits buried within DSDP/ODP cores, Legs 1-126

Probable in-situ manganese deposits larger than 1 cm in diameter buried in ODP/DSDP cores were selected for study after examining previous descriptions of the manganese deposits in site reports and the ODP data base. Most of the selected samples from 11 cores occur at or just above sedimentary hiatuses or in slowly deposited sediments and are overlain by rapidly deposited sediments of biogenic, terrigenous or volcanogenic origin. The changes in sedimentation recorded in the lithostratigraphic sections around these deposits are closely related to changes in tectonic evolution, deep water circulation or biological productivity at the sites. The similarity in composition and structure of the buried deposits to those of the modern manganese nodules and crusts with no evidence of post-depositional change suggest that buried manganese deposits may be used as indicators of past sedimentary conditions during which they formed. Their major components are hydrogenetic and earlydiagenetic manganese minerals as well as detrital minerals. The characteristics of these manganese deposits suggests that similar processes of deposition have taken place since the Paleogene or older.

The distribution of zinc, cadmium, copper and iron in seawater of the Iceland-Faroe Ridge area

During the International ICES Expedition "Overflow '73" a total of 174 samples from 18 stations were collected by R. V. "Meteor" in the waters of the Iceland-Faroe Ridge area. They were filtered on board ship (through 0.4 mym "Nuclepore" filters), then stored in 500 cm**3 quartz bottles (at -20 °C) and analyzed in air-filtered laboratories on land for zinc and cadmium by means of the differential pulse anodic stripping voltammetry technique and copper and iron by flameless atomic absorption spectrometry. The overall averages of 1.9 myg Zn l**-1, 0.07 myg Cd l**-1, 0.5 myg Cu l**-1 and 0.9 myg Fe l**-1 are in good agreement with recent "baseline" studies of open-ocean waters. The mixture of low salinity water masses from the North Iceland Shelf/Arctic Intermediate Waters seem to maintain distinctly lower concentration of Cd, Cu and Fe than the waters from the North Atlantic and the Norwegian Sea where quite similar mean values are found. There is only little evidence for the assumption that overflow events on the ridge are influencing the concentrations of dissolved metals in the near-bottom layers.