Coal-Bearing Depositional Systems

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

“…This is indicated by global transgressions during 58.5-52.8 Ma. The signatures are seen in the Late Paleocene-Early Eocene sedimentary Diessel (1992) discusses that a wet forest may also produce a peat having similar petrographic composition as that of marsh peats provided a favourable condition prevails in the basin for microbial destruction. Variation of GI, TPI, GWI and VI values with depth in the lignite seams of Cambay Basin is shown in Fig.…”

“…To characterize the paleomires of the Australian Permian coals, Diessel (1986) introduced two indices, gelification index (GI) and tissue preservation index (TPI). Less humified structured and strongly humified unstructured tissue derived macerals indicate the degree of humification and the vegetation type (Diessel 1992). Accordingly, a high TPI value suggests a high subsidence rate of basin and dominance of wood derived tissues, and a low TPI suggests a low subsidence rate with high humification.…”

On the fundamental difference between coal rank and coal type

“…At the most basic level, coal properties are a function of three fundamental parameters of coal composition, each of which is determined by some aspect of the coal's origin and evolution (after Diessel, 1992;Suárez-Ruiz et al, 2012;Taylor et al, 1998;Ward, 1984; among others):…”

“…Generally, preclusion or great reduction of sediment from the peatland has been attributed to mechanisms such as displacement of sediment deposition inland of coastal mires by rising sea level (e.g., Diessel, 1992;Flint et al, 1995); doming of the peat body, thus raising the surface above the sedimentary system (e.g., Ferm and Cavaroc, 1968;Greb et al, 1999); or baffling of sediment by vegetation growing at the margin of the peatland (e.g., Eble and Hower, 1995;Kravits and Crelling, 1981;Moore, 1991). These models implicitly or explicitly assume that peat formation takes place syndepositionally with local siliciclastic deposition.…”

“…14. Relationships between petrography-based facies indicators and biomarker composition indicate that the preservation of plant tissue (as shown using the tissue preservation index, or TPI; Diessel, 1992) is strongly influenced by the contribution of conifers to peat formation, whereas gelification index (GI) reflects bacterial activity, that is in turn governed by the water-table within the mire Fig. 13.…”