The clearly manifested asymmetry of the ocean-floor manganese accumulation is believed to have been associated with the world-largest Early Proterozoic Mn- and Fe-ore formations on the world-largest Early Proterozoic spread-apart continental blocks of the Indian-Atlantic segment of the Earth. In the Indian-Pacific sector the ores are concentrated in the ocean-floor, the surrounding continents being devoid of any comparable ore deposits. The authors analyze the origin of this phenomenon. Discussing the geochemical aspects of oceanic ore formation, they emphasize that Mn is more associated with the hydrosphere than Fe. The history of the sea water origin is much older than the age of the modern ocean-floor. The persistent renewal of the ocean-floor, propagating away from the spreading centers, leads to the fact that the accumulation of manganese, closely associated with water, continues without any interruptions, is not controlled by the age of the ocean-floor, but depends substantially on the time and mechanism of any ocean basin formation. A model is offered for the formation of the Early Proterozoic manganese ore deposits, the historical unity and origin of which allows one to reconstruct the positions of South America, Africa, and India in this ancient supercontinent. The modern positions of these ore deposits agrees with the known views on the Mesozoic breakup of the supercontinent and on the spreading of its blocks. These events took place in the Indo-Atlantic sector of the Earth and resulted in the formation of some young ocean-floor with the respective Mn accumulation. The ancient Indian-Pacific sector of the World Ocean was formed of the ancient Pacific Ocean and its western wedge, cut-off by Australia as it moved to the north. The Mn accumulation there was an order of magnitude older, as proved by the huge Mn ore deposits. The asymmetry of the ore genesis agrees with the known geotectonic views on the structural asymmetry of the Earth.
manganese accumulation, sea water origin, formation of the Early Proterozoic manganese ore deposits.
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