Characterization of insoluble organic matter from the Lower proterozoic huronian supergroup, Elliot Lake, Ontario
1993; Elsevier BV; Volume: 61; Issue: 3-4 Linguagem: Inglês
10.1016/0301-9268(93)90117-k
ISSN1872-7433
AutoresDavid J. Mossman, Fariborz Goodarzi, Thomas Gentzis,
Tópico(s)Atmospheric and Environmental Gas Dynamics
ResumoElliot Lake organic matter falls into two main groups: (1) stratiform kerogens with reflectance from 2.63 to 7.31% Ro(max), exhibit a high level of aromaticity and low atomic H/C ratios (0.41 − 0.60): (2) less aromatic disseminated globules, most resembling solid bitumen are of lower maturity, with Ro(max) from 0.72 to 1.32. and atomic H/C ratios 0.71 − 0.81. Stratiform kerogens, originated from cyanobacteria, have δ13C values from −15 to −25%. One exception with δ13C = − 31.8%, may have originated from methanogenic source biota: thus two genetically distinct populations of kerogen are tentatively recognized in Elliot Lake metasediments. Globular bitumens, remobilized by hydrous pyrolysis from kerogen, exhibit δ13C values ranging from −25% tp −33%0. The overall isotopic bimodality among Elliot Lake organic material is explained by analogy to petroleum generation from particulate kerogen that matured under conditions of catagenesis to metagenesis and was subjected to radiation over a long time. Barium, U, Th, Au, Pt, Pd and REE contents of Elliot Lake stratiform kerogen greatly exceed of average black shales. Except for As, Pt, Pd and Au, all metals (Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Se, Rb, Sr, Ag, Sb, Cs, Ba, Hf, Ta, W, Hg, Th and U) are more concentrated in stratiform kerogens than in the derivative bitumen. This signals a significant role for a low-temperature transfer of noble metals to migrating bitumen.
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