First-series transition element concentrations (Co, Cr, Cu, Fe, Mn, Ni, V, Zn) are examined in 27 solid bitumens from the United States, Canada, Mexico and Spain. Results are compared with organic geochemical parameters for whole bitumen and extractable organic matter, and the origin of metals in solid bitumens is discussed. In general, Co, Cr, and Cu are present in concentrations less than 100 ppm; Mn, Ni, and Zn from 10 to 1000 ppm; and Fe and V at levels greater than 1000 ppm.13C NMR aromaticity values (fa) in the sample set are controlled predominantly by maturity level (rather than source influence). Whereas the V/(V+Ni) ratio and the V concentration do not correlate with fa in the sample set, Ni concentration increases with increasing fa. These metal-fa relationships are probably due to the occurrence of V and Ni in host complexes of different stabilities.The chemical composition of sedimentary organic matter is controlled by original source influences and the effects of maturation, migration, and post-migration alteration. Data presented here provide support for source-control and maturity effects (particularly for Ni) on the composition of solid bitumens. The effect of metal gain and loss from migrating fluids (both water and oil) is not understood. Implications of future technological developments, including on-line liquid chromatography-inductively coupled plasma-mass spectrometry and liquid chromatography-mass spectrometry, are noted.
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- Occurrence and Significance of Metals in Solid Bitumens: An Organic Geochemical Approach
J. A. Curiale
- Springer Berlin Heidelberg