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Title: Comparative molecular, elemental, and U-Pb isotopic composition of stratiform and dispersed-globular matter in the paleoproterozoic uraniferous metasediments, Elliot Lake, Canada

Journal Article · · Energy Sources; (United States)
 [1];  [2];  [3]
  1. Mount Allison Univ., Sackville, New Brunswick (Canada)
  2. Univ. of Arizona, Tucson (United States)
  3. Royal Ontario Museum, Toronto (Canada)

Uraninite and other uranium minerals at the Elliot Lake-Blind River uranium ore deposits are held mainly within syngenetic kerogen. Bitumen was generated from kerogen by hydrothermal solutions, through a process similar to hydrous pyrolysis. Liquid bitumen migrated away from its parent kerogen, but transported virtually no U and Th. However, bitumen has a large excess of [sup 206]Pb, which indicates that the liquid bitumen must have acted as a sink for mobile intermediate decay products of [sup 238]U, probably the noble gas, [sup 222]Rn. Bitumen was then converted by heat into a solid, consisting of highly condensed aromatic hydrocarbons, preventing Pb mobility. The upper intersection of U-Pb isotopic data is within error of the Nipissing diabase event, which suggests that this was responsible for almost totally resetting the U-Pb systems in the uraninite. The tectonic and thermal anomaly associated with emplacement of the Nipissing diabase may have also been responsible for formation and migration of bitumen into pores and fissures and for outgassing of [sup 222]Rn into the same openings, leading to the [sup 206]Pb anomaly. Uraniferous kerogen occurs mainly in stratiform layers. The kerogen has Ro[sub max] = 2.63 to 7.31%; it is highly aromatic in molecular composition, contains large clusters of aromatic hydrocarbon moieties, and its H/C atomic ratios range from 0.41 to 0.60. Bitumen, derived from the syngenetic kerogen, occurs as solid pore and fracture fillings, has Ro[sub max] = 0.72 to 1.32%, H/C atomic ratios of 0.71-0.81, and contains more alkyl substitutions on aromatic molecular components than the kerogen. A functional relationship between these two groups of organic matter is supported by their molecular compositions and [delta][sup 13]C signatures.

OSTI ID:
6424529
Journal Information:
Energy Sources; (United States), Vol. 15:2; ISSN 0090-8312
Country of Publication:
United States
Language:
English

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