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A R Cameron - One of the best experts on this subject based on the ideXlab platform.

  • The petrology and origin of coals from the lower Carboniferous Mattson formation, southwestern district of Mackenzie, Canada
    International Journal of Coal Geology, 1993
    Co-Authors: J. Potter, B C Richards, A R Cameron
    Abstract:

    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.

  • The petrology and origin of coals from the lower Carboniferous Mattson formation, southwestern district of Mackenzie, Canada
    International Journal of Coal Geology, 1993
    Co-Authors: J. Potter, B C Richards, A R Cameron
    Abstract:

    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.

G.j. Nowak - One of the best experts on this subject based on the ideXlab platform.

  • Petrological recognition of bituminous Inertinite enriched coals of the Lower Silesian Coal Basin (Central Sudetes, SW Poland)
    International Journal of Coal Geology, 2015
    Co-Authors: M. Uglik, G.j. Nowak
    Abstract:

    Abstract Upper Carboniferous bituminous coals of the Lower Silesian Coal Basin occur in three main coal-bearing regions: the Walbrzych region (in the N), the Nowa Ruda region (in the SE), and the Slupiec region (in the SSE). In contrast to the Walbrzych region, coals representing Żacler Formation from the Nowa Ruda and Slupiec regions display elevated (up to 39.0% mmf) Inertinite abundances. These coals were analyzed petrographically to determine what factors may have caused such Inertinite-enriched coal formation and how these factors may have influenced the surrounding palaeoenvironment. The results of microscopic analyses show high amounts of vitrinite, relatively high content of Inertinite, low quantities of liptinite, and low to high abundances of minerals. Values of random vitrinite reflectance are fairly constant (average 1.07% and 1.19% in the Slupiec and Nowa Ruda regions, respectively), and designate these coals as a medium volatile bituminous. The reflectance of Inertinite varies significantly from 1.58% to 4.90%. This parameter has been used as a basis for further wildfire studies. The values of Inertinite reflectance and studies of its distribution and morphology imply occurrence of diversified types of wildfires: ground, surface, and crown fires, though surface fires distinctly prevailed (estimated temperatures ranging from 405 °C to 615 °C). The evidences for ground and crown fires are scarce and suggest just occasional episodes of such wildfires or may indicate transport of charred material from another source area. Domination of microscopic charcoal may suggest transport by wind, but other transportation pathways (e.g. by water) cannot be excluded. Negative correlation of Inertinite macerals and inorganic matter in some parts of studied profiles may reflect impact of wildfire on local erosional–depositional system, where increased share of mineral matter may suggest post-fire clastic-dominated input due to enhanced soil erosion.

  • ABSTRACT: Comparative petrographic studies of the Carboniferous bituminous coals from the Lower Silesian Coal Basin (Central Sudetes, SW Poland) with special reference to Inertinite-rich coals.
    2013
    Co-Authors: G.j. Nowak, M. Uglik
    Abstract:

    Carboniferous bituminous coals from the Lower Silesian Coal Basin (LSCB) show high diversity in petrographic characteristics. Depending on particular coal seam and particular part of the basin, they show variable proportions between vitrinites, liptinites and Inertinites and differ in random vitrinite reflectance (Ro). Most of the Lower Silesian coals are vitrinite-rich and vary in thermal maturity from low rank coals to anthracites. The coal seams from both the E and SE part of the basin (the Nowa Ruda and Soupiec regions respectively) display enrichments in Inertinite in their maceral composition. These seams represent theacler Formation (Westphalian A-C in age in traditional Carboniferous division). They have been selected as a study object because of their relatively high Inertinite content. The results have been compared with previously published data on Lower Silesian coals, particularly from northwestern part of the LSCB (the Waobrzych region) (e.g. Kwieciska & Nowak, 1997; Nowak 1997a, b, c, 1998, 2000). The goal of the research was to determine the factors that could cause Inertinite enriched coal formation. In contrast to Waobrzych region (low to high vitrinite content, low to medium Inertinite content and constant amount of liptinite), coals from Nowa Ruda and Soupiec regions show elevated (medium to high) Inertinite content, moderate to high vitrinite content and negligible to low liptinite amounts. The most abundant Inertinite macerals in investigated seams are semifusinite (up to 16.0 vol.%) and fusinite (up to 11.4 vol.%)(mineral-included basis). However, the Nowa Ruda seams exhibit greater fluctuations of fusinite and semifusinite content than in the Soupiec seams. Furthermore, in the lowermost part of the Soupiec profile the amount of Inertinite macerals decreases at the expense of mineral matter. The vitrinite reflectance measurements clearly demonstrate the difference between the Waobrzych and Nowa Ruda-Soupiec regions. In the Waobrzych region the vitrinite Ro varies significantly from 0,63% to over 3% while in the Nowa Ruda and Soupiec regions remains fairly constant in the range of 1,07%-1,19%. The reflectance of Inertinite (fusinite, semifusinite, macrinite, secretinite and funginite) was measured only on Nowa Ruda - Soupiec region samples and display a great variability of values from 1,23% to 4,90% with 2,55% on average.

Jonathan P. Mathews - One of the best experts on this subject based on the ideXlab platform.

  • The characterisation of slow-heated Inertinite- and vitrinite-rich coals from the South African coalfields
    Fuel, 2015
    Co-Authors: Mokone J. Roberts, Raymond C. Everson, Hein W.j.p. Neomagus, Daniel Van Niekerk, Gregory N. Okolo, Jonathan P. Mathews
    Abstract:

    Abstract The development of coal char structures with pyrolysis has been extensively investigated but has traditionally been focused on the carboniferous coals in the northern Hemisphere. In this investigation, the properties of pyrolysis chars generated from Inertinite- and vitrinite-rich coals (81% and 91% mmb by volume, respectively) collected from selected South African coalfields were determined. Chars were generated at 450, 700 and 1000 °C. The properties of coals and chars were examined using the chemical, physical, petrographic, solid-state 13 C NMR and X-ray diffraction analytical techniques. The objective was to generate results for further studies including molecular modelling and atomistic reaction kinetics. A good correlation was found between the total maceral scan (rank) and aromaticity as the pyrolysis temperature increased, as well as between the aromaticity measurements with XRD and NMR techniques. The chemical structure of the intertinite-rich and vitrinite-rich chars at 700–1000 °C was remarkably similar in terms of the proximate, ultimate, total maceral scan and aromaticity values. Greater transition occurred in the vitrinite-rich coal, implying a thermally more activated coal. Differences in the physical structure of the chars at these temperatures were observed in terms of the surface area using the Dubinin–Radushkevich (D–R), the Brunauer–Emmet–Teller (BET) and Langmuir methods as well the microporosity from the CO 2 adsorption method. The macerals were not distinguishable at 700–1000 °C. However, the differences in maceral composition of the coals resulted in substantially different char forms during thermal conversion. The intertinite-rich coal formed more denser chars and higher proportions of thicker-walled networks (60–65% by volume). The vitrinite- rich coal showed higher proportions of isotropic “coke” (91–95% by volume), which contributes to a high distribution of surface area and micropores. Therefore, on a chemical level, the high temperature chars were similar. Differences existed in the physical structure at high temperatures. The physical structures, char forms and crystallite diameter ( L a ) significantly distinguished the chars at high temperatures, where L a for Inertinite-rich chars was 37.6 A compared with 30.7 A for the vitrinite-rich chars. The L a property, in particular, played a significant role in investigations for the molecular structural properties of the Inertinite- and vitrinite-rich chars, including their reactivity behaviour with carbon dioxide gas.

  • Molecular representations of Permian-aged vitrinite-rich and Inertinite-rich South African coals
    Fuel, 2010
    Co-Authors: Daniel Van Niekerk, Jonathan P. Mathews
    Abstract:

    Abstract Molecular representations for two Permian-aged South African coals, Inertinite-rich Highveld (dominated by semifusinite) and vitrinite-rich Waterberg were constructed based on analytical data. High-resolution transmission electron microscopy (HRTEM) was used to determine the size and distribution of aromatic fringes, thereby affording the base aromatic skeleton for each coal model. Sulfur, nitrogen, oxygen and aliphatic side chains and crosslinks were added to the aromatic skeletons according to 13 C NMR and literature data. The individual molecules were assembled into three-dimensional structures and were in agreement with experimental data (NMR, mass spectrometry and elemental analyses data). These models were structurally diverse with a molecular weight ranging from 78 to 1900 amu. The vitrinite-rich coal model consists of 18,572 atoms and 191 individual molecules and the Inertinite-rich coal model consists of 14,242 atoms and 158 individual molecules. These were the first molecular representations for South African vitrinite-rich and Inertinite-rich coals. The Inertinite-rich Highveld coal model was more aromatic with a larger portion of the aromatic carbons polycondensed. The vitrinite-rich Waterberg coal model was more aliphatic and contained more aliphatic side chains and longer aliphatic crosslinks. Although these coals have very similar average molecular structures according to the various analytical data, subtle differences in the experimental data lead to significant structural differences in the models.

  • Petrographic and reflectance analysis of solvent-swelled and solvent-extracted South African vitrinite-rich and Inertinite-rich coals
    International Journal of Coal Geology, 2010
    Co-Authors: Daniel Van Niekerk, Gareth D. Mitchell, Jonathan P. Mathews
    Abstract:

    Maceral transitions during solvent swelling and extraction of two South African coals similar in rank and age, but different in maceral composition, were evaluated. Inertinite-rich Highveld coal (dominated by semifusinite) and vitrinite-rich Waterberg coal were used. Maceral-group analysis of solvent-extracted and solvent-swelled residues showed no changes in the maceral composition for both coals. Solvent-extracted residues exhibited significant observable changes of some particles: particle fracturing, decrease in reflectance and rounding of particle edges. Inertinite-rich coal exhibited extensive fracturing during solvent treatment. Random reflectance analyses of both coals showed that solvent treatment reduces reflectance values of both vitrinite and Inertinite. Vitrinite reflectograms showed a shift from the dominant reflecting V-types to lower-reflecting V-types. The Inertinite reflectograms exhibited an increase in the number of reflecting Inertinite-types (I-types) with solvent treatment, resulting in a broadening of the reflectograms. The changes in reflectance between the original and solvent-treated coal may be attributed to a combination of structural, elemental or surface changes. Current data for these South African coals suggests a relationship between solvent extraction and mean random reflectance: the higher the extraction yields the lower the mean random reflectance.

  • Structural characterization of vitrinite-rich and Inertinite-rich Permian-aged South African bituminous coals
    International Journal of Coal Geology, 2008
    Co-Authors: Daniel Van Niekerk, Ronald J. Pugmire, Mark S. Solum, Paul C. Painter, Jonathan P. Mathews
    Abstract:

    Abstract Two South African coals of the same rank and age, but different in maceral composition were subjected to extensive structural analyses. Inertinite-rich Highveld coal (dominated by semifusinite) and vitrinite-rich Waterberg coal were studied to determine structural differences and similarities. The two coals had similar carbon content (∼ 84%, dmmf) and vitrinite reflectance (mean-maximum 0.71% for vitrinite-rich vs. 0.75% for Inertinite-rich), but differed in hydrogen content (6.23% for vitrinite-rich and 4.53% for Inertinite-rich). The Inertinite-rich coal was more aromatic (86% for Inertinite-rich and 76% for vitrinite-rich) and more polycondensed (indicated by a higher bridgehead carbon content). The Inertinite-rich coal was structurally more ordered, with a higher degree of crystalline stacking. Both coals had similar average aromatic cluster sizes (16 carbons for vitrinite-rich and 18 carbons for Inertinite-rich) and number of cluster attachments (6 attachments for vitrinite-rich and 5 attachments for Inertinite-rich). Mass spectrometry showed that both coals consist of similar molecular weight distributions; ranging to approximately 1700 m/z with a maximum abundance of ∼ 450 m/z for the vitrinite-rich coal and ∼ 550 m/z for the Inertinite-rich coal. Compared to the Argonne Premium coals the South African vitrinite-rich Waterberg coal was comparable to the coals in the high-volatile bituminous range and Inertinite-rich Highveld was closer to the medium- to low-volatile bituminous range. Both coals were surprisingly similar in bulk characterization, although Inertinite-rich Highveld coal was structurally more ordered, hydrogen deficient, and more aromatic.

Rafael Kandiyoti - One of the best experts on this subject based on the ideXlab platform.

  • Catalytic hydrocracking of primary maceral concentrate extracts prepared in a flowing solvent reactor
    Fuel, 2002
    Co-Authors: V. Begon, Isabel Suelves, María Jesús Lázaro, Alan A. Herod, Rafael Kandiyoti
    Abstract:

    Abstract Differences between the behaviour of coal macerals during liquefaction and catalytic hydrocracking were investigated. The liquefaction experiments were carried out in tetralin, using a flowing solvent reactor. The extracts were catalytically hydrocracked in a micro-bomb reactor, using a commercial catalyst. Extracts and hydrocracked products were characterised by size exclusion chromatography (SEC), UV-fluorescence spectroscopy (UV-F), probe-mass spectrometry and thermogravimetric analysis. Conversions of the vitrinite and the liptinite concentrates during liquefaction were high (∼89%), while Inertinite samples yielded a little over 20% extract. For Inertinites, the emerging picture was consistent with high cross-link density. Liptinite was extracted less completely at lower temperatures and more slowly at high temperatures compared to corresponding vitrinites and vitrinitic coals. Long chain aliphatics released from the liptinite concentrate between 340 and 390°C appeared likely to have originated in lower-molecular mass material occluded in the sample matrix and dissolving in tetralin prior to the onset of massive covalent bond scission. SEC chromatograms showed material of larger MMs in liptinite and vitrinite extracts than in the Inertinite extract. The molecular mass distributions broadened with increasing extraction temperature. Catalytic hydrocracking experiments were carried out in a micro-bomb reactor for 10 and 120 min at 440°C, under 190 bar of hydrogen. In hydrocracking, the liptinite was the slowest extract to react at short reaction times (∼10 min). However, at longer reaction times, its products showed the smallest MM-distribution. Smaller differences were observed between the chromatograms of the 10 and 120 min hydrocracked products of the Inertinite extract. Differences between spectra of the three extracts would strongly suggest the presence of larger (and apparently irreducible) polycyclic aromatic ring systems, in the hydrocracked products of the Inertinite extract.

  • High-pressure pyrolysis and CO2-gasification of coal maceral concentrates: conversions and char combustion reactivities
    Fuel, 1999
    Co-Authors: A. Megaritis, R. C. Messenböck, Denis R. Dugwell, I.n. Chatzakis, Rafael Kandiyoti
    Abstract:

    The gasification behaviour of maceral concentrates was examined in a fixed-bed and a wire-mesh reactor. 'Extents of gasification' were calculated by subtracting sample weight loss during pyrolysis (He) from weight loss in CO2-gasification. The effect of holding time (10 and 200 s) and pressure (1 and 20 bar) on conversions and on combustion reactivities of chars were studied. During short hold-time gasification experiments (10 s), liptinites gave the highest conversions, followed by the vitrinites and the Inertinites. Vitrinite conversions decreased sharply above 90% elemental-C content. Extents of gasification were found to be in the order: vitrinites > liptinites > Inertinites. However, at 200 s, a marked increase in Inertinite conversion translated into a clear change of relative ordering to: Inertinites > vitrinites > liptinites. The high gasification reactivities of Inertinites at longer times appear to be related to a more rigid and porous structure, but the late surge suggests that an induction period is needed. More detailed time series data are required. Relative combustion reactivities of chars were generally observed to decrease with (i) pressure, (ii) time at temperature and (iii) increasing elemental carbon content. The data indicated that orders of gasification reactivities may be predicted from the order of combustion reactivities of pyrolysis chars. Inertinite concentrate chars were more reactive. However, the difference in reactivity between Inertinite chars and other samples was reduced when the Inertinites were heated rapidly - possibly owing to melting at the higher heating rates.

  • pyrolysis of coal maceral concentrates under pf combustion conditions i changes in volatile release and char combustibility as a function of rank
    Fuel, 1998
    Co-Authors: H Y Cai, R. C. Messenböck, Denis R. Dugwell, A. Megaritis, M Dix, Rafael Kandiyoti
    Abstract:

    Abstract The pyrolytic behaviour of sets of maceral concentrates have been examined under conditions similar to those of pf-combustion. Relative combustion reactivities of chars prepared during the pyrolysis experiments have been compared by standard methods. As expected, for samples of similar elemental C-content, total volatile release decreased as: liptinite > vitrinite > Inertinite. The data indicates the absence of synergistic effects between vitrinite and Inertinite during pyrolysis. The sensitivity of pyrolysis yields to Inertinite content was found to diminish with increasing coal sample rank. In marked contrast to the order established for volatile release, combustion reactivities of maceral chars (of similar carbon content) may be ranked in the order: Inertinite > vitrinite > liptinite. A direct comparison with maceral concentrates from the same coal was undertaken. Vitrinite/Inertinite graded samples of a South African coal were pyrolysed at 1500°C: these chars exhibited increasing reactivity with increasing Inertinite concentration, but observed differences in reactivity between samples from the same coal were not large. Furthermore, for a higher rank coal, char reactivities were found to be essentially independent of original Inertinite concentration. It is clearly possible for chars from low volatile coals to be relatively reactive. However, there appears to be no reason to suggest that ‘reactive Inertinites’ might release volatile matter in quantities comparable to those of vitrinites from the same coal.

  • Comparison by g.c.-m.s. of liquefaction extracts from coal maceral concentrates
    Fuel, 1995
    Co-Authors: Dominique Brodzki, Afif Abou-akar, Gérald Djéga-mariadassou, Rafael Kandiyoti
    Abstract:

    Abstract Differences between the compositions of partly hydrocracked hexane-soluble extract fractions from the liquefaction of maceral concentrates were investigated by gas chromatography-mass spectrometry. The technique identifies components within only a relatively narrow range of molecular masses, but some systematic differences were nevertheless observed. Dibenzofuran derivatives were significantly more abundant in extracts derived from Inertinite concentrate than in liptinite or vitrinite extracts. Within the retention time interval where dibenzofuran and its derivatives were identified in Inertinite extracts, products prepared from liptinite and vitrinite concentrates were found primarily to contain biphenyls and acenaphthene derivatives. Extract fractions from Inertinite were also characterized by almost negligible contents of phenol derivatives, a class of compounds much in evidence in the liptinite and vitrinite extract fractions. These findings have suggested some differences between oxygen functionalities in, and types of chemical bonds connecting, basic structural units in different coal macerals. Basic structural units in Inertinites appear to be joined more frequently by alkyl or other bridges than by linear ether bonds, in comparison with other maceral groups. This provides one likely structural explanation for the relatively low yields obtained during the liquefaction of the Inertinite concentrate.

J. Potter - One of the best experts on this subject based on the ideXlab platform.

  • The petrology and origin of coals from the lower Carboniferous Mattson formation, southwestern district of Mackenzie, Canada
    International Journal of Coal Geology, 1993
    Co-Authors: J. Potter, B C Richards, A R Cameron
    Abstract:

    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.

  • The petrology and origin of coals from the lower Carboniferous Mattson formation, southwestern district of Mackenzie, Canada
    International Journal of Coal Geology, 1993
    Co-Authors: J. Potter, B C Richards, A R Cameron
    Abstract:

    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.