GROWTH-RATES OF THE FERROMANGANESE NODULES FROM THE PACIFIC SUBEQUATORIAL BELT BY THE ALPHA-RADIOGRAPHIC TECHNIQUE

Ten pelagic ferromanganese nodules from the north-eastern equatorial P acific Ocean have been analyzed by the alpha-radiographic technique in order to expose the accretion rates of the nodules. The distributions of the total alpha - radioactivity obtained by the solid state track detectors (SSTD) of two types (LR-115 and CZ) characterize the growth processes of the nodules during the last 300 thousands years. The surf ace rinds of the nodules from the both regions (Clarion-Clipperton pro vince and Guatemala Basin) accumulated at 1-20 mm/Ma, only in some cas es till 100 mm/Ma. The measurement of different sides of the nodules - top, bottom and lateral - showed the evident asymmetry of the nodules accretion.