『Abstract
The total terrestrial manganese ore deposits amount to about 6.4×10⁹ tonnes of which 5.3×10⁹ tonnes (82%) are Precambrian and 1.1×10⁹ tonnes (18%) Mesozoic and Cenozoic. Deep-sea manganese nodules formed since the lower Miocene unconformity (12 Ma B.P.) hold about 10¹¹ tonnes Mn (about 16 times the manganese in terrestrial deposits). The development of deep-sea manganese nodules is a reflection of global cooling and resulted from the transition of the sluggish Cretaceous ocean with warm saline bottom water to the post-Eocene ocean with cold, well-oxygenated bottom currents. Important climatic and oceanographic events occurred at the Eocene-Oligocene boundary and more particularly at the lower Miocene unconformity which marks the period of increased Antarctic Bottom Water circulation. By contrast, the giant shallow-water manganese deposits of the Lower Jurassic to Oligocene are associated with anoxia and high sea-level stands. The two types of deposit reflect different oceanographic conditions and tend not to be contemporaneous. Mass balance considerations suggest that the present-day input of manganese into the oceans is in balance with its deposition in manganese nodules and sediments with perhaps 90% of the input being from hydrothermal sources, although this is speculative. The scale of present-day deep-sea manganese nodule formation suggests that we live in the manganese era.』

Introduction
Terrestrial manganese reserves
Processes in manganese accumulation
Cenozoic marine manganese
Discussion
Acknowledgements
References