The Origin of Manganese Nodules: A Combined Theory with Special Reference to Palagonitization

Abstract

Manganese responsible for nodular development is derived from both the oceans and the continents. The bulk of manganese is probably derived through continental weathering. Ferruginous compounds are incorporated into ocean-bottom sediment layers through submarine volcanism. Terrigenous manganese accretes by the catalytic action (or possibly a redox reaction) of iron and ferromanganiferous complexes present at the sediment-water interface. This results in the formation of manganese nodules which are at once the products of both normal continental and normal oceanic weathering . The rate of manganese accretion is partially dependent upon the rate of diagenetic palagonitization. New measurements indicate linear manganese accretion rates range from 1.7 to 8.7 mm/10^6 years. Rates for volumetric manganese accretion range from 110 to 1;300 mm^3/ 10^6 years. Initial development proceeds at the more rapid rate and subsequent accretion at the slower rate. Manganese nodules with centers other than volcanic debris (shark's tooth centers) may be formed as a result of related catalytic mechanisms.