Petrography and Genesis of Organic Matter in the Paleoproterozoic Uraniferous Conglomerates of the Elliot Lake Region, Ontario

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Abstract
Organic matter present in uraniferous paleoplacer deposits in the Elliot Lake-Blind River region, Canada, falls into two distinct types based on morphology, reflectance in oil, and bireflectance. Organic matter of the second type is primary and biogenic and probably represents the metamorphosed remnants of cyanobacterial mats. It consists of finely laminated kerogens with high reflectance (%Romax — 4.02-7.31) and high bireflectance. Under cross-polars it shows a textural pattern similar to that of thinly laminated organic matter. The level of thermal maturation 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% (Romax)Globular bitumen is essentially unmetamorphosed and follows the (normal) bitumen maturation pathway. Both types of organic matter have contributed to the uraniferous mineralization of the Elliot Lake region.