PETROGRAPHY AND GENESIS OF ORGANIC-MATTER IN THE PALEOPROTEROZOIC URANIFEROUS CONGLOMERATES OF THE ELLIOT LAKE REGION, ONTARIO

Organic matter present in uraniferous paleoplacer deposits in the Elli ot Lake-Blind River region, Canada, falls into two distinct types base d on morphology, reflectance in oil, and bireflectance. Organic matter of the second type is primary and biogenic and probably represents th e metamorphosed remnants of cyanobacterial mats. It consists of finely laminated kerogens with high reflectance (%Ro(max) = 4.02-7.31) and h igh bireflectance. Under cross-polars it shows a textural pattern simi lar to that of thinly laminated organic matter. The level of thermal m aturation is in the range of prehnite-pumpellyite to lower greenschist metamorphic facies. The first type consists of homogeneous, globular, migrated bitumen. These bitumens are isotropic to weakly anisotropic with a reflectance ranging from 0.72 to 1.32% (Ro(max)). Globular bitu men is essentially unmetamorphosed and follows the ''normal'' bitumen maturation pathway. Both types of organic matter have contributed to t he uraniferous mineralization of the Elliot Lake region.