Modern iron ooids from a shallow-marine volcanic setting: Mahengetang, Indonesia

An unconsolidated submarine deposit of iron ooids and pisoids, located offshore the volcanic island Mahengetang, Indonesia, is described herein. The deposit occurs in a shallow-marine setting, in an area characterized by venting of hydrothermal fluids and expulsion of gas across the sediment-water interface. The ooid deposit is essentially pure to a minimum depth of 0.5 m and covers an area of at least 1000 m2. Ooids are composed of concentric …