Brown coal maceral distributions in a modern domed tropical Indonesian peat and a comparison with maceral distributions in Middle Pennsylvanian–age Appalachian bituminous coal beds

Abstract

Analyses of modern Indonesian peat samples reveal that the optical characteristics of peat constituents are consistent with the characteristics of macérais observed in brown coal and, as found by previous workers, brown-coal maceral terminology can be used in the analysis of modern peat. A core from the margin and one from near the center of a domed peat deposit in Riau Province, Sumatra, reveal that the volume of huminite macérais representing well-preserved cell structures (red, red-gray, and gray textinite; ulminite; and corpo/textinite) decreases upward. Huminite macérais representing severely degraded (<20 microns) cellular debris (degraded textinite, attrinite, and densinite) increase uniformly from the base to the surface. Greater degradation of the huminite macérais in the upper peat layers in the interior of the deposit is interpreted to be the result of fungal activity that increased in response to increasingly aerobic conditions associated with the doming of the peat deposit. Aerobic conditions concurrent with the activities of fungi may result in incipient oxidation of the severely degraded huminite macérais. This oxidation could lead to the formation of degradosemifusinite, micrinite, and macrinite maceral precursors in the peat, which may become evident only upon coalification. The core at the margin was petrographically more homogeneous than the core from the center and was dominated by well-preserved huminite macérais except in the upper 1 m, which showed signs of aerobic degradation and was similar to the upper 1 m of the peat in the interior of the deposit. The Stockton and other Middle Pennsylvanian Appalachian coal beds show analogous vertical trends in vitrinite maceral composition.The succession from telocolliniterich, bright coal lithotypes in the lower benches upward to thin-banded/matrix collinite and desmocollinite in higher splint coal benches is believed to reflect a progression similar to that from the well-preserved textinite macérais in the lower portions of the peat cores to severely fragmented and degraded cellular materials (degraded textinite, attrinite, and densinite) in the upper portions of the cores. This pétrographie sequence from bright to splint coal in the Stockton and other Middle Pennsylvanian coal beds supports previous interpretations of an upward transition from planar to domed swamp accumulations.

Petrographic and Geochemical Characterization of Coals from Tiru Valley, Nagaland, NE India

“…Thus, plants sensitively react to the changes in local conditions and therefore, petrographic study provides a precise tool for the facies study Duan et al, 2011;Deng and Sun, 2011). Moreover, many researchers (Cohen and Spackman, 1972;Cohen et al, 1987;Grady et al, 1993;Hawke et al, 1996;Hawke et al, 1999;Shearer and Clarkson, 1998;Styan and Bustin, 1983;Sun et al, 2002;Sun, 2003) have related the petrographic components of coal with the paleoecological setting. For this purpose different maceral ratios are used.…”

Petrographic characteristics and paleoenvironmental history of Eocene lignites of Cambay basin, Western India

“…Petrography based facies models have been used to discuss the evolutionary history of the paleomires of the Cambay basin. Using petrological tools a number of researchers have successfully performed paleoecological reconstructions and contributions have been made by Cohen and Spackman (1972), Styan and Bustin (1983), Cohen et al (1987), Calder et al (1991), Grady et al (1993), Hawke et al (1996), Singh and Singh (1996), Shearer and Clarkson (1998), Sun et al (1998), Dai et al (2007), Jasper et al (2010), Singh et al (2010a, b), Deng and Sun (2011), and Singh et al (2012a, b, c, d). Detro-huminite is throughout high in the lignites of Cambay basin wherein densinite is more consistent.…”

Petrological Investigations of Oligocene Coals from Foreland Basin of Northeast India

“…Coal petrography based models can help in reconstruction of the depositional environments of the paleomire. It is believed that plants react to the changes in the environmental conditions very sensitively and the petrographic study can enable us to understand facies (Teichmüller and Teichmüller, 1975;Cohen and Spackman, 1972;Cohen et al, 1987;Grady et al, 1993;Hawke et al, 1996;Hawke et al, 1999;Shearer and Clarkson, 1998;Styan and Bustin, 1983;Singh and Singh, 1996). In recent years successful attempts have been made by several researchers to relate the petrographic components with the paleodepositional environment (Duan et al, 2011;Deng and Sun, 2011;Singh et al, 2010a,b;2012a,b).…”