Free fatty acid analysis of the early proterozoic animikie group,Minnesota and Ontario |
| |
Authors: | J.S. Janks R.M. Matherly A.F. Koster van Groos |
| |
Affiliation: | 1. Texaco Inc, Bellaire Research Laboratories, P.O. Box 425, Bellaire, TX 77401, U.S.A.;2. Di-Chem, A Division of Dresser Industries, 10201 Westheimer, Building 1A, Rm 202, Houston, TX 77042, U.S.A.;3. Department of Geological Science, University of Illinois at Chicago Circle, Chicago, IL 60680, U.S.A. |
| |
Abstract: | The Early Proterozoic iron formation-slate sequences of the Animikie Group have been analyzed for fatty acids and the results discussed in light of the regional metamorphic history and kerogen H/C and N/C atomic ratios. No fatty acids, free or inorganically bound, were detected. The highest H/C ratios are found in the Gunflint (mean = 0.57) and lowest in the Virginia State (0.19). The lower H/C ratio in the Biwabik (mean = 0.45) is interpreted as a function of higher metamorphic grade in that iron formation. The absence of fatty acids is attributed to dehydrogenation and cyclization of the original material to the present H/C ratio of about 0.5. The Gunflint Iron-Formation, which represents those conditions most likely to preserve chemical fossils in the Animikie Group has already exceeded minimum conditions for fatty acid preservation. Hydrogen to carbon ratios in pelitic rocks are consistently lower than their underlying iron-formation. It is suggested that sulfur and/or clay alter the kinetics of the dehydrogenation reaction, creating lower H/C ratios in the pelites. |
| |
Keywords: | Animikie Group Proterozoic fatty acids Minnesota kerogen |
本文献已被 ScienceDirect 等数据库收录! |
|