Reworking of BIF into GIF in the Sandur Schist Belt, India: Possible Evidence of Sea Level Changes in an Archaean Proto-Ocean

Granular iron formations (GIF) which are abundant in some Proterozoic, BIF bearing sedimentary basins are reported for the first time from the Archaean Sandur schist belt. These beds show lateral and vertical transition and repetition with oxide facies BIFs. Graded bedding and angular fragments are found in them. They consist mainly of iron and silicon oxides. Their trace clement and REE patterns itre similar to the BlFs from which they have been derived as a consequence of submarine erosion on the shelf through transgfession-regression cycles. Changes in sea level indicated by these structures were probably caused by volcanic activity and associated seismic tremors.