Inversely graded pisolites of manganese oxide in the mid-Cretaceous manganese giant at Groote Eylandt, Australia, were deposited during a regional fall in sea level, as indicated by their relationships to wave-cut benches. Dissolved manganese was concentrated in relatively anoxic waters of the intracratonic basin during a marine transgression and precipitated as oxides and carbonates during a regression. Ore bodies ultimately formed by concentration of abundant particulate manganese by a tidal-lag mechanism.

First Page Preview

First page PDF preview
You do not currently have access to this article.