COMPOSITION OF LOW-TEMPERATURE FE-MN MINE RALS IN METALLIFEROUS SEDIMENTS OF THE TAG AREA (MID-ATLANTIC RIDGE)

Coarse-grained material from 348 cm long core collected near the base of the relict hydrothermal mound was studied. Thr material is composed of debris products. Bacteria-like particles of low-temperature iron-b earing minerals (goethite and nontronite) are abundant in the lower pa rt of the core (59-348 cm). Ferrihydrite and hematie occur at some hor izons of the lower part. Goethite, nontronite and ferrihydrite result from transformation of protoferrihydrite. Ferrihydrite is the only pro tohematite phase. Nontronite practically disappears, but low-temperatu re hydrothermal and hydrogenous Mn-oxihydroxides appear in the upper l ow-metalliferous part of the core. This is an evidence of decrease of decrease of hydrothermal activity and later - of its extinction within the hydrothermal mound.