| Title | Geochemistry of dolomite fluorescence in response to thermal maturity: an example from Upper Ordovician Utica Shale of southern Quebec, Canada |
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| Author | Ardakani, O H ;
Sanei, H; Jackson, S E; Al-Aasm, I S |
| Source | International Journal of Coal Geology vol. 231, 103593, 2020 p. 1-12, https://doi.org/10.1016/j.coal.2020.103593 |
| Image |  |
| Year | 2020 |
| Alt Series | Natural Resources Canada, Contribution Series 20200433 |
| Publisher | Elsevier |
| Document | serial |
| Lang. | English |
| Media | on-line; digital |
| File format | pdf; html |
| Province | Quebec |
| NTS | 21L/03; 21L/04; 21L/05; 21L/06; 21L/11; 21L/12; 21L/13; 21L/14 |
| Lat/Long WENS | -72.0000 -71.0000 47.0000 46.0000 |
| Subjects | fossil fuels; geochemistry; Science and Technology; Nature and Environment; Upper Ordovician; petroleum resources; hydrocarbon potential; thermal maturation; bedrock geology; lithology; sedimentary
rocks; shales; dolomites; fluorescence analyses; colour; mass spectrometer analysis; electron probe analyses; zoning; geochemical analyses; minor element geochemistry; major element geochemistry; trace element geochemistry; Utica Shale; Phanerozoic;
Paleozoic; Ordovician |
| Illustrations | photomicrographs; plots; tables; spectra |
| Program | Geoscience for New Energy Supply (GNES) Shale Reservoir Characterization |
| Released | 2020 09 19 |
| Abstract | This study presents results of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) elemental analysis of scattered dolomite crystals in the Upper Ordovician Utica Shale of southern
Québec to investigate the geochemical cause(s) of color variation in dolomite fluorescence and its possible relationship to thermal maturity. Utica Shale dolomite crystals show fluorescence zonation under ultraviolet (UV) light, with a shift from
higher red/green quotient (R/G) in the crystal core to lower R/G in the crystal rims within dolomite crystal, while the crystal cores and rims R/G consistently increase with increasing thermal maturity.
The LA-ICP-MS results show a consistent
increase of Fe, Mn, Sr, Pb, and rare earth elements (REE) from crystal cores to rims, while Mg content shows the opposite trend. The decline in Mg content from the core to rim suggests depletion of Mg in the dolomitizing fluids during dolomite
growth. Iron and Fe/Mn ratio are the only parameters that varied systematically with Mg content. The negative correlation between the red/green (R/G) quotient and Fe/Mn ratio suggests that temperature likely had an overarching effect on the chemistry
of dolomite that ultimately controls the crystal zonation and its optical properties.
Our data suggest that dolomite fluorescence can potentially be used as an alternative thermal maturity indicator in mudrocks with low organic content. However,
compilation of a larger dataset is required to completely understand the relationship between dolomite R/G quotient and other established thermal maturity indicators. |
| Summary | (Plain Language Summary, not published)
This study presents results of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis of scattered dolomite crystals in the
Upper Ordovician Utica Shale of southern Québec to investigate the geochemical cause(s) of color variation in dolomite fluorescence and its possible relationship to thermal maturity variations. The initial results of the study (Haeri-Ardakani &
Sanei, 2015 IJCG) showed that there is a strong relationship between thermal maturity proxies (i.e., Ro) and dolomite fluorescence. Therefore, we used the same samples to further investigate the major geochemical dolomite fluorescence controlling
factor(s) and it's the possible relationship with burial temperature and thermal maturity. |
| GEOSCAN ID | 327280 |
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