『Abstract
Metallogenesis of manganese in apace and time is reviewed here
in the light of the progressive development of the atmosphere,
the hydrosphere and the lithosphere attendant with the varied
styles of tectonism. Economic deposits of manganese first appeared
c.3000 Ma ago, postdating by at least 800 million years the oldest
known geological sequence containing iron-formation and base-metal
sulfide ores. The development of manganese deposits in the Archean
as a whole, vis-a-vis that of iron-formation and stratiform massive
sulfides, was minor. This is possibly a reflection of the composition
of the then endogenic exhalations and/or the character of the
atmosphere and the hydrosphere. The geologic setting of the manganese
deposits of this age was always atypical of the Archean period.
Deposition of manganese was intensified with the advent of the
Proterozoic with the changing tectonic style leading to stabilization
of the cratons and oxygenation of the hydrosphere and the atmosphere.
Large to superlarge deposits were formed mainly through terrigenous
input during this period. The Mesozoic era ushered in the supremacy
of manganese deposition and the peak was reached in Cenozoic time.
This was largely due to the formation of giant shallow-water deposits
in areas of marine transgression as well as deposition of manganese-rich
nodules and crusts in deep-sea environments.
Three major aspects of manganese metallogenesis stand out as most
important but enigmatic. These are: (a) the extreme fractionation
of iron and manganese in nature and their reverse trend of metallogenic
development; (b) the universal record of shallow-water deposition
of manganese in land-based deposits in contrast with the deep-sea
milieu observed in modern basins; and (c) the common evidence
of biological activity in close association with manganese deposition
which could be either causal or casual. All these aspects merit
further in-depth study and metallogenic analysis in a broad spectrum.』
Introduction
Archean inception
Proterozoic growth
Phanerozoic supremacy
General remarks
Summary and conclusions
Acknowledgements
References