The Organic Petrology and Thermal Maturity of Lower Carboniferous and Upper Devonian Source Rocks in the Liard Basin, at Jackfish Gap-Yohin Ridge and North Beaver River, Northern Canada: Implications for Hydrocarbon Exploration

• Published in: Energy sources 1993-04, Vol.15 (2), p.289-314
• Main Authors: POTTER, JUDITH, RICHARDS, BARRY C., GOODARZI, FARIBORZ
• Format: Article
• Language: English
• Subjects: 01 COAL, LIGNITE, AND PEAT; 010600 - Coal, Lignite, & Peat- Properties & Composition; 02 PETROLEUM; 020200 - Petroleum- Reserves, Geology, & Exploration; 03 NATURAL GAS; 030200 - Natural Gas- Reserves, Geology, & Exploration; 04 OIL SHALES AND TAR SANDS; 040500 - Oil Shales & Tar Sands- Properties & Composition; BITUMENS; BITUMINOUS MATERIALS; CANADA; CARBONACEOUS MATERIALS; CARBONIFEROUS PERIOD; catagenic gas; CHEMICAL ANALYSIS; CHEMISTRY; CLASSIFICATION; COAL; CORRELATIONS; DATA; DEPTH; DEVELOPED COUNTRIES; DEVONIAN PERIOD; DIMENSIONS; ENERGY SOURCES; EXPERIMENTAL DATA; EXPLORATION; FOSSIL FUELS; FUELS; GEOCHEMISTRY; GEOLOGIC AGES; GEOLOGIC DEPOSITS; GEOLOGIC FORMATIONS; GEOLOGY; GEOMORPHOLOGY; INFORMATION; KEROGEN; MACERALS; MATERIALS; MATTER; MATURATION; MINERAL RESOURCES; NATURAL GAS DEPOSITS; NORTH AMERICA; NUMERICAL DATA; OIL SHALES; OPTICAL PROPERTIES; ORGANIC COMPOUNDS; ORGANIC MATTER; ORIGIN; OTHER ORGANIC COMPOUNDS; PALEOZOIC ERA; PETROLEUM DEPOSITS; PETROLOGY; PHYSICAL PROPERTIES; primary bitumens; reflectance; REFLECTIVITY; RESOURCES; ROCKS; SAPROPELIC COAL; sapropelic coals; SEDIMENTARY ROCKS; SHALES; SOURCE ROCKS; SURFACE PROPERTIES; TAR; VITRINITE
• ISSN: 0090-8312; 1521-0510
• DOI: 10.1080/00908319308909028

Organic petrology and geochemical studies (Rock-Eval/TOC) were carried out on shales from the Besa River (Upper Devonian-Lower Carboniferous), Yohin, Clausen, Prophet, Golata, and Mattson Formations (Lower Carboniferous) in exposed sequences at Jackfish Gap-Yohin Ridge and in a subsurface section in the North Beaver River area of the Liard Basin. Basinal shales of the Besa River Fm. have TOC values ranging from 1 to 4% and contain abundant type II, dominantly amorphous, kerogen of marine origin. Shales in the Yohin Fm. (slope to neritic shelf), Clausen Fm. (basin and slope deposits), Prophet Fm. (carbonate slope), and Golata Formations are of mixed marine and terrestrial origins and yield TOC values of 1 to 3%. Kerogen in the Golata (prodelta shales) and Yohin Formations are dominated by terrestrial components, while the Clausen and Flett kerogen comprises marine liptinites and bitumens. Kerogen from the deltaic Mattson shales at Jackfish Gap are types 11 and 111, having mixed marine and terrestrial origins consistent with shallow, nearshore, subtidal environments. The coals, which are rich in inertinite and liptinite (up to 30%), are sapropelic and probably lacustrine in origin. Algal laminites associated with coals in the Upper Mattson have ≥ 10% TOC values, while non-laminite shales contain between 2 and 5% TOC. Comparable measured and calculated vitrinite reflectance data indicate that kerogen in the Lower Carboniferous at Jackfish Gap is mature (0·5-1·1%). Kerogen in correlative formations in the subsurface at North Beaver River is more marine. Vilrinites are rare and oxidized, but four populations ofbitu- mens are distinguished on the basis of relative reflectivity and morphological or between depth and reflectance of bitumens A and B are very good (r 2 = 0·97%). Vitrinite reflectance data calculated from bitumen reflectance measurements for the Besa River (1·6-2·1%), Prophet (1·5%). and Golata (1·2%) indicate that they are potential sources of catagenic gas. The Mattson kerogen is mature (0·84-1·0% VR 0 ), oil and gas-prone.