Alexander R. Cameron

Mineral matter and elemental concentrations in selected western canadian coals

Abstract Major and trace element analyses were performed on coals from various locations in western Canada, and on low-temperature (150 °C) and high-temperature (1000 °C) coal ash produced from these coals. Elemental analyses were carried out by X-ray fluorescence spectroscopy and intense neutron activation analyses. Based on their trace elements, the coals in this study fall into two groups: 1. low-rank coals (lignite-subbituminous) of late Cretaceous and Tertiary age; and 2. high-rank coal (bituminous-semianthracite) of Jurassic-Cretaceous age. The elemental analyses of the coals and coal ash indicate that the local conditions had considerable influence on the concentrations of certain trace elements. Antimony and selenium in coals are the only elements which are enriched relative to concentrations in the earths crust; arsenic is concentrated in lignite to subbituminous coal, but is depleted in bituminous-anthracite coals; as expected the ash of these coals showed many more instances of enrichment.

Organic Petrology and Elemental Distribution in Thermally Altered Coals from Telkwa, British Columbia

Abstract Thermal alteration of both organic and inorganic components of a coal seam from Telkwa, British Columbia, is examined, using reflected light microscopy, x-ray diffraction (XRD), and neutron activation analysis (INAA). The alteration resulted from intrusion of an alkali basaltic dike. The organic components of coal (macerals) at the contact with the intrusion are coked and developed strong anisotropy. The temperature of formation of this coke is estimated at >750°C and possibly >900°C with a fast rate of heating. However, coal at a distance of 120 cm from the dike is unaltered. Some liptinite macerals retained their original morphology in the altered residue but developed stronger anisotropy than the altered coal groundmass. Pseudovitrinite became reactive and developed fluidity in the altered coals. Original botanical morphology of pseudovitrinite superimposed by mosaic textures is still present in altered coal. Assimilation of less reactive components of coal by reactive components is observed i...

Palynofacies, coal petrographic facies and depositional environments: Amphitheatre formation (Eocene to Oligocene) and Ravenscrag Formation (Maastrichtian to Paleocene), Canada☆

Abstract Low rank coals from two disparate geological settings have been subjected to petrographic and palynological analysis. The stratigraphic units studied and their locations are the Amphitheatre Formation, St Elias Mountains, Yukon Territory, of Eocene to Oligocene age; and the base of the Ravenscrag Formation, south-central Saskatchewan, of latest Cretaceous to earliest Paleocene age. The depositional setting of the Amphitheatre Formation ranges from distal sand-dominated braided stream and lacustrine environments to proximal gravel-dominated fluvial environments. The coals are low in inertinite ( 85%). In localities with a dominance of angiosperm pollen the relative abundance of eu-ulminite B and densinite is greatest whereas in the ones with a dominantly coniferous pollen assemblage eu-ulminite A is the most prominent maceral. These observations suggest as an immediate cause/effect relationship, an at least partial dependance of present maceral content on floral precursors. This in turn probably reflects a certain combination of depositional environment conditions (pH, Eh, temperature, etc.), that likely controlled the plant community and the preservation of vegetal matter. The depositional environment of coals from the basal part of the Ravenscrag Formation contrasts sharply with that of the Amphitheatre. The Ravenscrag coals formed within a low energy, stable, floodplain environment. Palynological and coal maceral profiles for the basal Ravenscrag Formation coal, which spans the Cretaceous-Tertiary boundary, indicates that the environment of deposition progressed from an open canopied swamp forest with areas of open water, through a phase of low-lying to open water swamps with herbaceous, pterophytic vegetation to, at least locally, raised bogs. The change in coal petrography across the Cretaceous-Tertiary boundary is shown to be relatively minor in comparison to subsequent changes in coal petrography in the earliest Paleocene and to changes that occur in the palynological assemblages across the boundary interval.

Petrography of low rank coals with reference to liquefaction potential

Abstract Ten sub-bituminous coals were analyzed petrographically and chemically as part of a program by the Alberta Research Council to investigate the compositional properties of Alberta coals and relationship to liquefaction potential. In addition, four lignites, two from Saskatchewan and one each from Texas and North Dakota, were studied for comparative purposes. Liquefaction experiments were carried out on three of the Alberta coals and on density fractions of the two U.S. lignites. Petrographically the ten sub-bituminous coals could be divided into two populations; one with high huminite and liptinite contents (>90%) and one with substantially lower contents (70–75%). The two U.S. lignites showed huminite plus liptinite contents of less than 70% while the Saskatchewan coals were somewhat higher. Reflectance measurements on the sub-bituminous coals showed a range of 0.33 to 0.51 with a rough correlation to the ASTM rank designations of these coals. Reflectivities determined on the lignites were generally lower. Float-sink fractionation of the two U.S. lignites and two sub-bituminous coals showed enrichment of huminite and liptinite in the lighter fractions and inertinite and mineral matter in the heavier splits. Examination of the relationship between liquefaction yields and petrographic composition showed a rough positive correlation with huminite-liptinite content. Examination of liquefaction residues suggested total conversion of the liptinite, extensive conversion of huminite and possible partial conversion and reactivity of the semifusinite maceral of the inertinite group.

Coal resources of Northern Canada with emphasis on Whitehorse trough, Bonnet Plume Basin and Brackett Basin

Abstract In the Yukon Territory and District of Mackenzie, coal-bearing strata, ranging in age from Mississippian to Oligocene, have been found in some 27 areas. In the Yukon, such rocks underlie 37,000 km 2 , while in the District of Mackenzie, 3000 km 2 are believed to contain coal in the Brackett Basin alone, with additional potential in the Liard River, Godlin Lake and Great Bear Lake areas. The three most important basins are the Whitehorse Trough and Bonnet Plume Basin in the Yukon Territory and the Brackett Basin in the District of Mackenzie. In the Whitehorse Trough, coal exploration has been carried out at Mount Granger near Whitehorse and at Division Mountain, west of Braeburn. Coal mining has been actively carried on at Carmacks and Tantalus Butte. The Whitehorse Trough coals are in the Laberge Group and Tantalus Formation (Jurassic to Cretaceous in age). In the Bonnet Plume Basin, the age of the coal is Cretaceous to Tertiary, and it occurs in the Bonnet Plume Formation. In the Brackett Basin, again the age is Cretaceous to Tertiary, and the main coal-bearing unit is the Summit Creek Formation. At Mount Granger, igneous intrusives have influenced maturation, and ranks range from low volatile bituminous to meta-anthracite. At Division Mountain and Tantalus/Carmacks, the coal is of high volatile bituminous rank. At Bonnet Plume, most of the coals are also high volatile bituminous, whereas in the Brackett Basin, the rank is lignite. Total inferred resources for the three basins mentioned above are about 5000 Mtons, with by far the larger resources occurring in the Bonnet Plume and Brackett Basins.

Organic petrology of an early Paleocene coal zone, Wabamun, Alberta: palynology, petrography and geochemistry

Abstract An interdisciplinary investigation of a section through the early Paleocene Ardley coal zone at Wabamun, Alberta reveals that there are distinct vertical variations in the palynological, petrographical and geochemical properties reflecting changes in the original depositional environment. Palynological assemblages are dominated by Taxodiaceaepollenites hiatus revealing that the original coal-accumulating mires were inhabited by taxodiaceous vegetation. Subordinate palynomorphs include varied gymnosperm pollen other than T. hiatus, Laevigatosporites spp (fern spores of polypodiaceous affinity), Stereisporites spp (mosses including Sphagnum ) and Osmundacidites sp. (Family Osmundaceae). Coal petrography reveals that these coals are inertinite-rich. Abundant fusinite (pyrofusinite), along with semi-fusinite and inertodetrinite comprise up to 65% of the maceral assemblages. Huminite macerals are predominantly eu-ulminite B with lesser eu-ulminite A, densinite and geli-huminite (gelified huminite lacking any remnant cell structure). Liptinite macerals include resinite, sporinite and cutinite. Thinner, stratigraphically lower seams at Wabamun (seams Nos 6-3) consist predominantly of bright coal with high huminite contents. Palynofloral assemblages are comprised of T. hiatus with few abundances of other palynomorphs, suggesting that the original depositional environment was low-lying, dominated by taxodiaceous vegetation, and frequently flooded as evidenced by numerous shale partings, high ash contents and relatively high sulphur percentages. The thick No. 2 seam displays a distinct dulling-up petrographic profile resulting from increasing inertinite contents. Coupled with increased abundances of Stereisporites spp, this may be evidence of localized ombrogeny within the original Wabamun mires, and may support a genetic relationship between Stereisporites sp. and inertodetrinite. The No. 1 seam consists of abundant fibrous (fusain-rich) coal. Modes of origin of this fibrous coal include extreme oxidation due to prolonged drought and possibly forest fires. Elevated ash contents within the Nos 1 and 2 seams may be a result of this oxidation of organic matter and concentration of the inorganics, as well as airborne volcanic ash as evidenced by numerous bentonite bands within these coals. Sulphur contents are extremely low, as low as 0.05% reflecting a terrestrial depositional environment.

Coal and oil shale of Early Carboniferous age in northern Canada: significance for paleoenvironmental and paleoclimatic interpretations

Abstract Lower Carboniferous (Mississippian) coal beds and oil shale occur at several locations in northern Canada. In the northern Yukon Territory coal of semi-anthracite/anthracite rank ( R 0 max % = 2.72–4.03) occurs in the Kayak Formation in the British Mountains and at Hoidahl Dome near the headwaters of Blow River. Farther south in the Liard Basin, Northwest Territories, coals of high volatile bituminous rank ( R 0 max % = 0.67–0.80) are known to occur in the Mattson Formation. In the Arctic Islands thicker beds of the Emma Fiord Formation, the oldest unit in the Sverdrup Basin, contain thin coal seams and oil shale on Devon Island, near the southern edge of the basin and on Axel Heiberg and Ellesmere islands on the north side of the basin. Organic matter in the Devon Island section is at a low maturity level ( R 0 m % = 0.26–0.50), whereas that from Ellesmere and Axel Heiberg has reached the level of meta-anthracite ( R 0 max % = > 5.0). Depositional environments for these carbonaceous sediments were different. The coal-bearing Kayak strata accumulated in a coastal plain setting overlain transgressively by younger marine beds. The Mattson coal beds appear to have formed in a prograding delta, but coal and oil shale in the Emma Fiord were deposited in lacustrine environments in a rift basin. These Canadian occurrences resemble penecontemporaneous deposits in Svalbard and elsewhere, adjacent to the present-day Arctic Ocean. They formed at low latitudes where conditions were favourable for the preservation of carbonaceous matter. Prior to the opening of the Arctic Ocean basin in Mesozoic times, sites of the mainland were undoubtedly closer to sites in the Arctic Islands than they are today.

The petrology and origin of coals from the lower Carboniferous Mattson formation, southwestern district of Mackenzie, Canada

Abstract Petrographic analyses were carried out on thin coals and coaly sediments from the Lower Carboniferous Mattson Formation at Clausen Creek and Jackfish Gap-Yohin Ridge in the northern part of the Liard Basin, northern Canada. The composition and optical characteristics indicate that the coals are high-volatile bituminous B, predominantly sapropelic (canneloid) and accumulated subaquatically. The coals are dominantly composed of inertinite-rich and exinite-rich durities with subsidiary inertites and clarodurites; vitrite is minor and liptite is rare. The inertinite-rich microlithotypes are dominated by semifusinite, but micrinite, semimacrinite and ?resino-inertinites are abundant. Sporinite, comprising megaspores, crassispores, tenuispores and miospores, is the dominant liptinite maceral with subsidiary cutinite and minor alginite. Except for pyrite, mineral matter is minimal. Three populations of telocollinite are observed: a low-reflectance variety (I), commonly associated with micrinite (as vitrinertite), displays weak brown fluorescence and a reflectance some 0.4-0.5% lower than type II; type II is non-fluorescing telocollinite, with intermediate reflectance (0.67-0.74% R o m), it occurs as vitrite and is also associated with micrinite; and a higher-reflectance telocollinite (III), having no fluorescence or association with micrinite, has variable reflectance (0.74-0.8% R o m) implying higher oxidation or gelification levels. The abundance of semimacrinite, macrinite and ?resino-inertinites in inertites and durites (I) suggests that much of the peat accumulated subaquatically. Furthermore, fluorescing vitrinite and an abundance of micrinite (derived by oxidation or coalification of bituminite), suggest that the coal accumulated under anaerobic conditions. The predominance of semifusinite in humic laminae and micrinite in sapropelic layers suggests extensive surface or near-surface oxidation of the peat. Oxidised sporinites suggest that they were wind-borne. Depositional environment is interpreted as marginal marine, perhaps in shallow lakes in the middle to upper delta plain. Peat accumulations probably began subaquatically at the oxygen-hydrogen sulphide interface, but periodic subaerial exposure and natural oxidation gave rise to the high inertinite coals. Upper Mattson coals are interbedded with algal laminites and probably accumulated in a lagoonal setting.

MANAGEMENT OF COAL MACERALS IN THE LIQUEFACTION OF LOW RANK COALS

ABSTRACT Three Alberta subbituminous coals were selected to investigate the contribution of different macerals to liquefaction. These coals represent the full range of geographic, rank and geological variations present In the Alberta Plains Coal Region. In addition, for comparison, two U.S. lignites (Texas and North Dakota) were included in these investigations. To enhance maceral concentration, density fractionation was carried out on these samples. Though liquefaction yields appear to increase with increase in vitrinite (huminite) content, a clear-cut correlation between conversion and maceral content is not established because of (a) uncertain behaviour of semi-inert macerals and (b) differences in behaviour within the vitrinite (huminite) macera1 group.