| Abstract: | Banded iron formations occur in greenstone belts in which volcanic rocks are predominant. Greenstone belts are not restricted to the Archaean (>2500 Ma), as is commonly perceived, but they continued to form, albeit in lesser abundance, in the Proterozoic. Thus, banded iron formations which are closely associated with volcanic sequences occur in several well-documented early-mid Proterozoic greenstone belts. Examples are the Yavapai belts at Jerome in Arizona, the Trans-Amazonian belts in Guiana, and the Dalma belts of the Singhbhum region of NE India. Stratigraphic and sedimentological studies are needed to establish the similarities and differences of these iron formations with those in Archaean greenstone belts, and with the banded iron formations which were common in cratonic-shelf environments in the early-mid Proterozoic. |
